Volume 4 Issue 5

Reviews:

Equinox andMVT FamosSharp MZ-80KVersawriterWordeaseNetwork choicesBackgammon gameStock controlConvert 6502 toZ-80 code

MicroCentre introduce System Zero

Basic System Zero £587System Zero/D with DDF £2355

The System Zero is a small computerespecially designed for dedicatedapplications. It is particularly useful in processcontrol situations.In the basic model you get Cromemco'sfamous Z -80A single card computer, 1 k ofRAM, 4k of ROM, Control Basic, and anattractive cabinet. The motherboard provides3 extra card slots on the S-100 bus, fortailoring the system to particular applications.The basic model is designed for ROM -basedprograms, but it can be expanded by theaddition of memory and I/O cards. It is fullycompatible with all Cromemco peripherals,including floppy disks and hard disk systems.Suitably configured the System Zero can runany Cromemco operating system or softwarepackage.

....r3 crongeffic°

At the recent UK launch of the System Zero Computer, Cromemco's Technical DirectorRoger Melen presented a System Zero/D with 128k memory running Cromix. Here he isseen discussing the system with MicroCentre Director Andrew Smith (right).

systemzer

New SystemZero Computer with

quad -capacity DDF disk drive. The systemincludes built-in diagnostics for a quick system test of memory,

controller and disk drivesSystem Zero/DThis special version of the System Zerohas 64k of fast RAM, and a model DDF dualdisk drive. It includes two double -sideddouble -density 5 inch disk drives giving atotal of 780k bytes storage; and RDOS-2, anew resident disk operating system withterminal and printer drivers, and self -testdiagnostics.The System Zero/D is an exceedinglyinexpensive development computer ideal

for setting up dedicatedapplications to run in the basicmodel. It will support Cobol,Fortran IV, Ratfor, StructuredBasic, Lisp, RPG II, VVordProcessing, DBMS, and the fullrange of Cromemco's businessapplications software.

Operating systemThe System Zero/D will run anyCromemco operating systemprovided sufficient memory isavailable. The mimimunconfiguration of 4k ROM runscontrol Basic, with 64k RAM thesystem will run RDOS-2 orCDOS (compatible with CP/M);and with 128k the Zero/D willrun the Cromix system (based onUnix).

For Q Cromemco... call the experts

MicroCentreTel: 031-556 7354

Complete Micro Systems Ltd.,30 Dundas StreetEdinburgh EH3 6JN

Circle No. 101

Rev.

EqusnosNWT ToSharp NUVercaerntosWoydeaseNetwork <exec.SockgammemStock cooddlConvert OM toLBO code

Thinking Systems - page 74.

EditorPeter LaurieAssistant EditorDuncan ScotStaff WriterBill BennettProduction EditorToby WolpePrestel EditorMartin HaymanEditorial SecretaryTracy EbbettsConsultantsTechnical Nick HampshireSoftware Mike McDonaldEditorial: 0I -661 3500Advertisement ManagerDavid LakeAdvertisement ExecutivesPhilip KirbyKen WalfordAdvertising: 01-66 1 3021

Midlands office:David Harvett 021-356 4838Northern office:Ron Southall 061-872 8861Publishing DirectorChris HipwellPublished by IPC Electrical tlectronicPress Ltd. Quadrant House, TheQuadrant, Sutton. Surrey, SM2SAS.Tel: 01-661 3500. Telex/grams892084 BIPRESG.Typesetting and artwork by Bow-Towning Ltd. London EC IPrinted by Eden Fisher Ltd, Southend-on-SeaDistributed by IPC Sales and Distri-bution Ltd, 40 Bowling Green Lane,London EC I R ONESubscriptions: U.K., fEt per annum;Overseas C14 per annum: airmailrates available on application toSubscription Manager. IPC BusinessPress (S & D) Ltd, Oakfield House,Perrymourt Road, Haywards Heath,Sussex RH I 6 3DH, tel 0444 59188© IPC Business Press Ltd 1981ISSN 0141-5433Would-be authors are welcometo send articles to the Editor butPC cannot undertake to returnthem. Payment is at f30 per pub-lished page. Programs intendedfor publication should ideally bejustified to 22 or 44 or 66 char-acters per line.Submissions should be typed orcomputer -printed. Hand-writtenmaterial is liable to delay anderror.

Every effort is made to checkarticles and listings but PC cannotguarantee that programs willrun and can accept no respons-ibility for any errors.

CONTENTS41 Editorial / Financing the future

42 Feedback / MuPet; educational software; recursion

46 Printout / Sinclair ZX-81; BBC and Acorn; Alf music boards

55 Wordease / The machine -coded word processor for Nascom and other Z-80based systems

58 Equinox / David Watt reviews the Equinox and its partnership with MVT-Famos, the multi-user operating system

66 Sharp MZ-80K / An inspection, conducted by John Dawson, of theMZ-80K and its parade of peripherals

Versawriter II / The low-cost graphics tablet for Apple II

Thinking Systems / Economics and sociology are just two of thedisciplines Boris Allan uses to illustrate his exploration of system concepts

7174

8183 Applications / Computerisation in London's King's Road

85 Stock control / A Basic program

91 Micros at Marconi / Marconi proves that large-scale heavy industrydoes not only use mainframes

93 Network choices / Ethernet or Cambridge Ring?

96 Backgammon / This month's game

102 Duncan / Nascom 1's high-level interpreter

107 Pascal / This language can seriously damage your mental health - RaymondAnderson's warning

109 Z-80 Zodiac

110 ZX-80 Line-up

112 6502 Special

119 Tandy Forum120 Pet Corner121 Apple Pie122 Micromouse

123 User Groups

125 Book Reviews

126 6502 to Z-80 code / The first of two articles by David Peckett on a 6502 -to -

Z -80 translator

132 Pet Disc / P Krueger's assessment

135 Software Buyers' Guide147 The Hexadecimal Kid / Page 8 of Richard Forsyth's parable

Education / Robert Ferguson presents a trigonometry program

Prestel page number 45631

PRACTICAL COMPUTING May 1981 3

SUPERPAY£350

Easy to read departmentalanalysis with up to 20 rates ofpay and adjustments, for up to26 departments.

Automatic printing of year endP60's, P11's and P35 's.

III Automatic printing of credittransfers.

Automatic increase of all taxcodes for budget changes.

III Net Pay Rounding to anyamount less than £10.

PLUS all of BASICPAY'sstandard features.

BASICPAY £75 Automatic calculation of Tax

and NI for weekly, monthly,four weekly, or irregularpayment periods.

III Automatic advancement of taxweek for holiday periods.

III Automatic coin analysis forcash payments.

II Can produce individual payslips.II Option to process all employee

payslips automatically. Easy to install. Even

newcomers to computers canuse BASICPAY within a few hours.

Each program takes no more than 35 seconds per employee for build upto gross, net pay calculation, and printing a payslip in duplicate.That works out at only 2 hours each week for a typical payroll of 200, or just 15 minutes fora staff of 20.

SUPERPAY is designed for medium size companies which need a comprehensive, flexible, andeasy to use payroll; BASICPAY is for small companies who want a flexible, low cost systemwhich carries Commodore's seal of approval.

For the name of your local Computastore Agent, contact:

Is the payoutcosting you morethan it should?

SUPERPAY and BASICPAY - two payroll systemsfrom Computastore to cut the cost of payroll, whateverthe size of your company.Over the past two years Computastore Payroll systemshave proved their effectiveness for over 300 companies- ranging in size from six employees to over a thousand.

Suitable for all types of PET and CBMDisk, Computastore's SUPERPAYand BASICPAY are the only PayrollPrograms approved byCommodore.

COMpUtaStOrEgcxmca7:4' Computing for BusinessComputastore Ltd., 16 John Dalton St., Manchester M2 6HG. Tel: 061-832 4761

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4 PRACTICAL COMPUTING May 1981

Comart ApprovedDealers

Belfast0 & M Systems95 Dublin RoadTel: 0232 49440

BirminghamByteshop Computerland Ltd94/96 Hurst St, B5 4TDTel: 021 622 7149

CambridgeCambridge Computer Stores1 Emmanuel St, CB1 1NETel: 0223 68155

CornwallBenchmark ComputerSystems LtdTremena ManorTremena RoadSt Austell, PL25 5GGTel: 0726 610000

DublinLendac Data Systems Ltd8 Dawson StTel: 0001 372052

GlasgowByteshop Computerland LtdMagnet House61 Waterloo St, G2 7BPTel: 041 221 7409

LeedsHoldene LtdManchester Unity House11/12 Rampart RoadWoodhouse StTel: 0532 459459

LondonByteshop Computerland Ltd324 Euston RoadLondon W1Tel: 01-387 0505Digitus9 Macklin StreetCovent Garden WC2Tel: 01 405 6761

Jarrogate67 Tulsemere Road,West Norwood,London SE17Tel: 01-670 3674

ManchesterByteshop Computerland Ltd11 Gateway HousePiccadilly Station ApproachTel: 061 236 4737

NSC Computers29 Hanging DitchTel: 061 832 2269

NewburyNewbear Computing Store40 Bartholomew StTel: 0635 30505

NottinghamByteshop Computerland Ltd92A Upper Parliament St,NG I 6LFTel: 0602 40576

SheffieldHallam Computer Systems451 Eccleshall Road, S11 9PNTel: 0742 663125

SouthamptonXitan Systems23 Cumberland Place,SO1 2BBTel: 0703 38740

SudburyEurotec ConsultantsHolbrook HallLittle WaldingfordTel: 0206 262319

Warwick'Business & LeisureMicrocomputers16 The SquareKenilworthTel: 0926 512127

WatfordLux Computer Services108 The ParadeHigh StreetWatford WD11 2AWTel: 0923 29513

Comart Microcomputer dealersare located strategicallythroughout the country to givesupport, guidance andassistance. In the event ofdifficulty contact Comart direct.

Horizon Hard Disc adds a newdimension to cost effective

data processingWith its parentage already established as the

proven performer in its price range, North Star'sHard Disc Horizon is set to break new barriers incutting the cost of data storage and retrieval.

It offers 18 Megabytes of on line storage, and atcurrent prices that works out at less than 0.03p perbyte. And, with up to 10 times the speed ofoperation of the more conventional floppy discs,and the convenience of storing all your data on-line, it's a basic price incentive that's amplified

even more in reduced operating costs andefficiency.

Add to that the new North Star ApplicationSoftware, Word Processing, InformationManagement and Reporting System and you'llunderstand why we say that North Star is set fornew horizons of application.

Find out the facts about expanding your NorthStar Horizon today!

The U.K. Leaders in Microcomputer comartDevelopment, Application and Support.

St Neots HUNTINGDON Cambs PE19 2AFTel (0480) 215005 Telex: 32514 Comart G.

Circle No. 103

NEW SUPERBOARDSERIES II

41111413%.L.WIG CC

111411511111151111

Readybuilt&Tested \Vast? Its:New from OSI - Series II.Everything series I had butwith more on a single board.Ideal for the beginneror experienced engineer alike.It needs only a 5V 3A power supplyto be up and running.Fully expandable to aFloppy Disc and small business system.

STILL ONLY £149 625 lines jitter free Display. Memory Mapped Video Display with

upper/lower case graphics and gamingcharacters.

Software selectable Display24 x 2448 x 12

Uses the ultra powerful 6502 Micro. 8K Microsoft Basic in Rom. Full feature Basic runs faster than

currently available computers and all8080 based business computers.

4K static Ram on board expandableto 8K.

Full 53 Keyboard with upper/lower caseand user programmability.

Power on reset -standard. 2 second action break key. Kansas City standard Audio cassette

interface for high reliability.

+ P&P £3 50 + VAT

6 latch outputs available for controlpurposes.

8 bit Digital to Analogue converter. Full machine code monitor and I/O

utilities in Rom.

Superboard II Series II f 149.00 + VATBlack ABS case f 24.50+ VATExtra 4K Ram £ 14.00 + VATPSU 5A Ready Built f 23.00 + VATNumeric Key Pad Kit f 11.95+ VAT610 Expansion Board with 8K fitted(expandable to 24K) £150.00+ VATCD3P Floppy Disc £269.00 VATWEMON £ 19.95 + VAT

Series 2 User's ManualThe best single source ofinformation E6.95, no VAT

Video swap tape & UHF modulator FREE!

SOFTYThe completemicroprocessordevelopment systemfor the engineerand beginneralike.

Displays memory contents on standardUHF TV.

Can replace monitor Rom to test anddevelop programs.

Ideal training aid. Two 8 -bit I/O ports. Fast cassette interface. On -board Eprom programmer. Copies software. Simple modification for single rail.

Price: Kit £ 99.00 + VATReady built £120.00 + VATPSU f 20.00 + VATP&P f 1.50 + VAT

FREE 2716 with each Softy

STAKPAKUnique filingsystem composingstackable drawers,each containing2 digital quality C12cassettes. Completewith Index cards& blank labels

5 Stakpaks 110 cassettes;

£5.25 P&P 75p VAT

SEIKOSHAGPBOAThis Unihammer dot MatrixPrinter gives Normal andDouble Width Charactersas well as Dotresolution Graphics.

Printing Speed 30 cps Character Set 5 x 7

Matrix Print Density 12 CPI

at 80 CPL Paper Feed 8" Tractor Parallel Interface

Standard

Other InterfacesRS 232E49 + VATIEE 488 orApple £35 + VATPet £35 + VAT

£225P & P f4.50 - VAT

500 Sheets of.paper FREE!

EPSONTXBOA complete 80 column dotmatrix printer, available intractor or friction feedversions.

Speed: 125cps. Undirectional print PET compatible graph

11°

cs. £295Various Interfaces available from £35.00

P & P £4.50 + VAT

500 Sheets of paper FREE!

SUPERPRINT 800SPECIALOFFER

£299P & P £4.50 * VAT

This rugged and reliableprinter offers more featuresand flexibility thancompetitive units but at anew Special Offer price

64, 72, 80, 96, 120, or 132 characters/line. RS -232, 20ma, 1EEE-488 and Centronics Self -test switch. I/O fitted as standard. 16 baud rates to 19,200. Tractor and Friction Feed 60 lines per minute. Multiple character sets facility.

500 Sheets of paper FREE!

VIDEO GENIE 16K User Ram 12 K Microsoft

Basicin Rom.

64 x 16 lineDisplay

128 x 48 dot graphicsresolution.

Softwarecompatible withTRS80 level II.

Built in Cassette Recorder. Output and Control for Second Cassette. Full expansion via Expansion box to Disc -Printer

A completeComputer System

1'I I I I 'I I I

£289A Z80 based computer system with Full Keyboard and built inCassette recorder plus outputs for Monitor and/or TVParallel Printer Interface £35 + VAT

P & P f5+ VAT

ACCESSORIESTEX Eprom Eraser6Mhz Modulators8Mhz ModulatorsCassette Recorders8" Fan -Fold Paper500 sheets9'/z" Fan -Fold Paper500 sheetsTELEPRINTER ROLL9" B & W MonitorHEX PADASCII Keyboard 756CEGMON any versionSpace Invaders 8KBASF Floppy Discs - each

£33

£2.80£4.50

£13.95

£5.95

£5.95£3.00£65.00£3.50£40£29.50£4.60E2.85

ALL PRICES EXCLUSIVEOF VAT & CARRIAGE

%lit Jill] rm WATFORD ELECTRONICS

6 PRACTICAL COMPUTING May 1981

TTL 74(TEXAS) Series7400 117401 117402 11

7403 147404 147405 187406 367407 367408 177409 207410 17

74123 es74125 5074126 4574128 4574132 5674136 5574141 7574142 18574143 25074144 25074145 9074147 15074148 125

LS02 15L503 15LSO4 16LSO5 23LSO8 22LSO9 23LS10 20'LS11 32LS12 32LS13 40LS14 60LS15 40LS20 21

LS175 110LS181 295LS183 298LS189 126LS190 MLS191 95LS192 95LS193 99LS194 125LS195 130LS196 120LS197 85LS200 345

74504 73745132 138745138 240745158 240745188 210745189 158745194 360745241 54074S262 850745287 325745470 325745472 115074S475 825

7411 25 74150 130 LS21 32 LS202 346 75 Series7412 20 74151 70 LS22 35 LS221 120 75150 1407413 32 74153 70 LS26 44 LS240 165 75154 1507414 38 74154 120 LS27 35 LS241 165 75450 957416 30 74155 75 LS28 35 LS242 165 75451 707417 30 74156 75 LS30 20 LS243 185 75452 707420 19 74157 70 LS32 25 LS244 195 75454 2257421 38 74159 165 LS33 35 LS245 350 75491/2 897422 257423 28

74160 9974161 99

LS37 30LS38 35

LS247 135LS248 135 COMPUTER IC's

7425 28 74162 99 LS40 28 LS249 135 2114L -300n 1757426 43 74163 LS42 66 LS251 130 2114L -200n 2257427 32 74164 120 LS47 85 L5253 95 2532-32K E107428 35 74165 120 LS48 105 LS257 95 2708 3507430 19 74166 130 LS49 105 LS258 120 2732-450n £107432 27 74167 205 LS51 25 LS259 160 2716-5V 4507433 36 74170 205 LS54 30 LS261 450 4116 1997437 35 74172 375 LS55 30 LS266 75 6502 6757438 32 74173 110 LS63 150 LS273 180 6520 3257440 207441 687442 58

74174 10074175 8274176 80

LS73 45LS74 35LS75 45

LS275 320LS279 88LS280 250

6522 5706532 7956545 1450

7443 120 74177 85 LS76 45 LS283 90 6551 7857444 116 74178 110 LS78 50 LS290 130 6592 25727445 105 74179 150 LS83 105 LS293 130 6800 4907446 132 74180 90 LS85 80 LS295 215 6802 5957447 72 74181 280 LS86 38 LS298 215 6810 2807448 75 74182 85 LS90 50 LS299 420 6821 3157450 20 74184 130 LS91 125 LS300 175 6840 7507451 20 74185 130 L592 75 LS302 175 6850 3157453 20 74188 310 LS93 60 LS323 270 6852 3907454 20 74190 130 LS95 115 LS324 200 8080A 4507460 20 74191 120 LS96 120 LS325 320 8085A 11007470 40 74192 120 LS107 45 LS326 330 81L095 1257472 30 74193 120 LS109 75 LS327 315 81LS96 1257473 35 74194 102 LS112 40 LS346 185 81LS97 1257474 34 74195 75 LS113 75 LS347 150 8212 2107475 567476 40

74196 9974197 ss

LS114 40LS122 70

LS348 190LS352 185

8214 4258216 200

7480 52 74198 160 LS123 75 LS353 185 8251 4757481 120 74199 180 LS124 180 LS365 65 8253 9997482 75 74221 150 LS125 45 LS366 65 8609 15507483 90 74246 150 LS126 45 LS367 65 8T26A 1907484 99 74247 151 LS132 60 LS368 90 8-1284 1957485 105 74248 189 LS133 35 LS373 150 8T95N 1607486 33 74249 189 LS136 55 LS374 150 8T97N 1507489 205 74251 110 LS138 70 LS375 150 AY -3-1015 4207490 42 74265 66 LS139 70 LS377 199 AY -5-1013 3657491 84 74273 267 LS145 120 LS378 140 AY -5)2376 7507492 50 74278 249 LS147 210 LS379 215 MC1488 907493 57 74279 99 LS148 170 LS384 250 MC1489 907494 85 74283 149 LS151 90 LS385 420 MC14411 9507495 70 74284 350 LS153 85 LS386 85 MC14412 12507496 80 74285 350 LS155 75 LS390 140 MK4027-2 4507497 176 74290 107 LS156 85 LS393 140 RO-3-2513U 60074100 130 74293 135 LS157 70 LS395 210 R0-3-2513 60074104 62 74297 236 L0158 70 LS396 199 SFF96364E 95074105 62 74298 185 LS160 90 LS398 275 SFC71301 82074107 34 74365 95 LS161 98 LS399 230 TMS2716-3V 105074109 6074110 54

7436674367 ss

LS162 110LS163 95 LS447 195

TMS4027 325TMS6011 365

74111 68 74368 95 L5164 115 LS490 245 280CPU 2-5 65074112 170 74390 185 LS165 145 LS668 105 280ACPU 4M 82574116 170 74393 185 LS166 175 LS669 105 280 PIO 44074118 85 74490 185 LS168 210 LS670 270 ZBOA PIO 57574119 120 LS169 210 LS673 750 280 CTC 440

74LS Series74120 75 LS170 288 LS674 850 280A CTC 57574121 3574122 50

LSOO 13L501 13

LS173 105LS174 110

Z80 DART 02280A DART £15745 Series

CRYSTALS100KHz455KHzI MHz1.008M1.8432M2.0MHz2.4576M3.2768M3.57954M4.0MHz4.032M4.194304M4.433619M5.0MHz5.185M5.24288M6.0MHz6.144M6.5536M7.168M7.68MHz8.0MHz8.86723710.0MHz10.7MHz12.0MHz14.31818M16.0MHz18.0HMz18.432M26.69M27.648M38.6666748.0MHz100 OMHz

300370295295300305305150150290290270150290300390290295290290300290270290270290320290290290290330290270375

'D' CONNECTORS(Cannon type) Covers

Plugs Sockets plastic9 way 90p 118p

15 way 120p 167p 150p25 way 180p 280p 170p37 way 268p 390p 185p

DIL PLUGS(Headers)14 pin 44p16 pin 49p24 pin 88p40 pin 295p

DIL switchesSPST4 way 10 way85p 175p

6 way98p SPDT

8 way 4 way115p 190p

DIL SOCKETS(TEXAS) Low Wire

profile wrap8 pin 10p 25p

14 pin 10p 35p16 pin 10p 46p18 pin 16p 52p20 pin 22p 65p22 pin 205p 70p

p28 pin 35p24 in 3p

85p7

36 pin 105p40 pin 40p 109p

JUMPER LEADS(Ribbon Cable Assemblies)

S Ingle end DIP Jumpers length 24"

14 pin 145p 16 pin 165p24 pin 240p 40 pin 385p

Double end DIP J umpersLength No of pins

14 16 24 406" 185p 205p 300p 465p

12" 195p 215p 315p 490p36" 230p 250p 375p 595p

EDGE CONNECTORS (TEXAS)double type 1 156

2 x 10 way - 82p2x15 way 98p2 x 18 way 140p 120p2 x 22 way 150p 125p2 x25 way 165p 160p2 x30 way 188p2 x 36 way 197p2 x 40 way 205p2 x 43 way 250p

SPECIAL OFFER2114L -300n2114L -200n2532-32k2732-450n27082716-5v4116-16k

175p225p

£10f10

350p450p199p

The above is just a selection of our vast stocks ofbrand new, full spec, electronic components.To Order: Please add 15% VAT to all orders unlessstated. On orders of less than £10 add 40 p P&P.Terms of Business: Cash/Cheque/P.O.'s orBankers Draft with order.Access Orders: Minimum f10 please.Government, Education Authorities Er Trade Welcome.

JUST PHONE IN YOUR ORDER WE DO THE REST.

Buy it with Access

33/35 CARDIFF ROAD,WATFORD ,HERTS . Telephone 40588

e-MORIThe Definitive MonitorA 4k monitor specially designed toproduce the best from yourSuperboard, Superboard Series 2,UK101 or Enhanced System.Look at these superb facilities:

Full screen editing. Home cursor/screen clear facility. True insert/delete. Fully programmable cursor control with meaningful symbols

on screen. Single key Basic True ASCII keyboard routine. Auto remote control of tape recorder (requires only a relay). Open line facility. Named tape files. Two key video swap (Series 2 only). Bell (Series 2 only). Cursor indication of quotes mode. User definable flashing cursor character. User controllable command vectoring for your own machine

code routines. Full or partial scroll -up or scroll -down (callable by program). Auto list on error (displays faulty line upon carriage return). Single command save (automatically returns "list"). Centronics compatible printer driver.

Monitor functions include: Scrolling list in data mode. Warm restart vector. Fill memory. Search memory. Two save and three load routines. Floppy disc vector. Break handling routine. Tabular display of memory.

10 PRINT "FULL";20 PRINT "SCREEN";30 PRINT "BITING"40 REM

SAVEName file?NAMED TAPE FILES [SINGLE COMMAND SAVE]

SN ERROR IN 10OK10 PRT "AUTO LISTON ERROR"

10 PRINT" > PROG";20 PRINT " CURSOR"30 PRINT ">> CONTROL"40 PRINT ">> * MEANING"50 PRINT "SYMBOLS60 PRINT ", "

All this for onlyC19.95+ 50p P&P + VAT.

To order: Send £23.52 or phone yourACCESS number for same day despatch.

State version required.

PRACTICAL COMPUTING May 1981 Circle No. 104

7

The Commodore PEToffers you a safe passage

through the primeval swampof computerisation.

The miracle of microchip technology has made themain-frame computer seem like a dinosaur. But how manymicrocomputers will go the same way?

Without good software and support a micro-computer is less capable than your office calculator.So as competition grows amongst manufacturers in thisindustry, only those with the finest software and the bestsupporting facilities will survive.

SHARE A SECURE FUTURE WITH ACOMMODORE PET

We at Commodore have been producing high technology

products for over 20 years. And unlike most othermanufacturers of micro -computers, we make everythingourselves (including the silicon chips) to keep our costs to aminimum.

These cost savings are passed on to you in excellent valuefor money. So you can now buy a self-containedCommodore PET microcomputer for £450, or a completebusiness system (including Floppy Disk Unit and HighSpeed Printer) starting from as little as £2000.*

However, computer hardware can only be as good as thesoftware available. That's why, to maintain our position as

8 PRACTICAL COMPUTING May 1981

Britain's most popular microcomputer, we have made surethat the quality and versatility of our software is second tonone.

LARGEST, FINEST CHOICE OF SOFTWARE...To complement our microcomputers, we have the finest

and most comprehensive range of programs available in theU.K. today. This covers everything from such importantbusiness applications as Payroll, Stock Control, Accounting,Filing, Mailing; to our series in the field of Education. Eachprogram is thoroughly tried, tested and tailored toBRITISH needs. You won't catch us palming you off withan irrelevant American version!

...AT SURPRISINGLY LOW PRICESWith over 30,000 Commodore PETs employed in

Britain, the demand for programs is tremendous. Andthrough mass -production we are able to keep our costs toyou surprisingly low. So you can buy a Petpack program (oncassette) for between £5 and £50, while business programs(on disk) range from between £50 and £500.

OUR OWN UNIQUE TRAINING COURSESCommodore programs are designed with operational

simplicity in mind. Commands are in plain English andguidance is built into each package. So that even a strangerto computers can quickly feel at home with a PET.

Nevertheless, to maximise the potential of yourCommodore system, you will find a certain amount oftraining of immense value. Of the well-known names inmicrocomputers, Commodore is the only one to offer a

LONDON AREAAdda Computers Ltd,

W13, 01-579 5845Advanced Management Systems,

EC2, 01-638 9319C.S.S. (Business Equipment)

Ltd, E8, 01-2549293Centralex - London Ltd.

SE13, 01-3184213Computer Sales & Software

Centre Ltd,ILFORD, 01-554 3344

Cream Computer Shop,HARROW, 01-863 0833

Da Vinci Computer Shop,EDGWARE, 01-952 0526

Henderson Bennett,SE25, 01-654 5609

Home and Business Computers,[12, 01-472 5107

L &J Computers,NW9, 01-204 7525

Logic Box Ltd.SW1, 01-222 1122

Merchant Systems Ltd.EC4, 01-353 1464

Micro Computer Centre,SW14, 01-878 7044

Micro -Facilities Ltd,HAMPTON HILL. 01-979 4546

Sum lock Bondain Ltd,EC1, 01-250 0505

Sumlock Bondain Ltd.EC4, 01-626 0487

HOME COUNTIESMillhouse Designs Ltd,ALTON. 84517

H.S.V. Ltd,BASINGSTOKE, 62444

MMS Ltd,BEDFORD, 40601

C.D. M. Direct Data MarketingLtd, BRENTWOOD, 214168

Amplicon Micro Systems Ltd,BRIGHTON, 562163

T & V Johnson (MicrocomputersEtc) Ltd. CAMBERLEY, 20446

Cambridge Computer Store,CAMBRIDGE, 65334

Wego Computers Ltd.CATERHAM, 49235

Dataview Ltd,COLCHESTER, 78811

Amplicon Micro Systems Ltd,CRAWLEY, 26493

S.M.G. Microcomputers,GRAVESEND. 55813

South East Computers,HASTINGS, 426844

Bromwall Data Services Ltd.HATFIELD, 60980

Alpha Business Systems.HERTFORD, 57425

Commonsense Business SystemsLtd, HIGH VVYCOMBE, 40116

Kingsley Computers Ltd.HIGH WYCOMBE, 27342

Brent Computer Systems,KINGS LANGLEY, 65056

Computopia Ltd.LEIGHTON BUZZARD, 376600

South East Computers Ltd,MAIDSTONE, 681263

J.R. Ward Computers Ltd.MILTON KEYNES, 562850

Sumlock Bondain (East Anglia)Ltd, NORWICH, 26259

T & V Johnson (MicrocomputersEtc) Ltd, OXFORD, 721461

C.S.E. (Computers),READING, 61492

Slough Microshop.SLOUGH, 72470

Business Electronics,SOUTHAMPTON, 738248

H.S.V.Ltd,SOUTHAMPTON, 22131

Super -Vision,SOUTHAMPTON, 774023

Symtec Systems Ltd,SOUTHAMPTON, 38868

Stuart R Dean Ltd,SOUTHEND-ON-SEA, 62707

The Computer Room,TUNBRIDGE WELLS, 41644

Orchard Computer Services.WALLINGFORD, 35529

Photo Acoustics Ltd,WATFORD, 40698

Microchips,WINCHESTER 68085

PPM. Ltd,WOKING. 80111

Petalect Electronic ServicesLtd, WOKING, 69032

Oxford Computer Systems.WOODSTOCK, 812838

MIDLANDS &S. HUMBERSIDEC.B.S. Consultants,BIRMINGHAM, 772 8181

Computer Services MidlandsLtd, BIRMINGHAM. 382 4171

Marchant Business Systems Ltd,BIRMINGHAM, 706 8232

Micro Associates,BIRMINGHAM, 328 4574

Peach Data Services Ltd,BURTON -ON -TRENT, 44968

Jondane Associates Ltd,COVENTRY, 664400

Davidson -Richards Ltd,DERBY, 366803

Allen Computers,GRIMSBY, 40568

Caddis Computer Systems Ltd,HINCKLEY, 613544

Machsize Ltd,LEAMINGTON SPA, 312542

Arden Data Processing,LEICESTER, 22255

range of training courses and seminars. And these havealready proved of great benefit to thousands of PET users.

KEEP IN TOUCH WITH THE PET USERS'NEWSLETTER

Another unique way in which Commodore helps you getthe most out of your microcomputer is by publishing theregular PET Users' Newsletter. For an annual subscriptionof only £10 you can keep up-to-date with developments andshare new ideas and applications with over 3,000 PET users.

WORDPROCESSOR AS WELL AS COMPUTERIn addition to Commodore's own high quality range of

hardware and software, there are compatible products ofother manufacturers which have gained our official stamp ofapproval.

(CZtLook out for this sign.You'll find it on such famous programs as WORDPRO andWORDCRAFT, which turn your PET into a first-classwordprocessor; as well as on hardware like the MUPETsystem, which allows a number of PETs to be run with asingle, letter -quality printer.

PROFESSIONAL DEALER SUPPORTCOUNTRYWIDE

When you consult a Commodore dealer, you won't findyourself talking to a typewriter salesman. Our dealers arequalified to examine your needs, and to demonstrate whichhardware and software will suit you best. Trained engineersare at hand and a 24 -hour field maintenance service isavailable countrywide.

Roger Clark Business SystemsLtd, LEICESTER, 20455

Lowe Electronics,MATLOCK, 2817

A.J.R. Office Equipment ServicesLtd, NOTTINGHAM, 206647

Betos (Systems) Ltd,NOTTINGHAM, 48108

PEG Associates (ComputerSystems Ltd), RUGBY, 65756

Walters Computer Systems Ltd,STOURBRIDGE, 70811

System Micros Ltd,TELFORD, 460214

YORK &N. HUMBERSIDEAckroyd Typewriter & AddingMachine Co. Ltd,BRADFORD, 31835

Microprocessor Services,HULL, 23146

Holdene Ltd,LEEDS, 459459

South Midlands CommunicationsLtd, LEEDS, 782326

Yorkshire Electronics ServicesLtd, MORLEY, 522181

Computer Centre (Sheffield) Ltd,SHEFFIELD, 53519

Hallam Computer Systems,SHEFFIELD, 663125

Holbrook Business Systems Ltd,SHEFFIELD, 484466

NORTH EASTCurrie & Maughan,GATESHEAD, 774540

Elfton Ltd,HARTLEPOOL, 61770

Dyson Instruments,HETTON, 260452

Fiddes Marketing Ltd,NEWCASTLE, 815157

Format M icro Centre,NEWCASTLE 21093

Intex Datalog Ltd,STOCKTON-ON-TEES, 781193

S. WALES &WEST COUNTRYRadan Computational Ltd,BATH, 318483

C.S.S. (Bristol) Ltd,BRISTOL, 779452

T & V Johnson (MicrocomputersEtc) Ltd,BRISTOL, 422061

Sumlock Tabdown Ltd,BRISTOL, 276685

Sigma Systems Ltd,CARDIFF, 34869

Reeves Computers Ltd,CARMARTHEN, 32441

A.C. Systems,EXETER, 71718

Milequip Ltd,GLOUCESTER, 411010

Jeffrey Martin Computer ServicesLtd, NEWQUAY, 2863

Devon Computers,PAIGNTON, 526303

A.C. Systems,PLYMOUTH, 260861

J.A.D. Integrated Services,PLYMOUTH, 62616

Business Electronics,SOUTHAMPTON, 738248

Computer Supplies (Swansea),SWANSEA, 290047

NORTH WEST &N. WALESB & B (Computers) Ltd,BOLTON, 26644

Tharstern Ltd,BURNLEY, 38481

Megapalm Ltd,CARNFORTH, 3801

Catlands Information SystemsLtd, CHESTER, 46327

Catlands Information SystemsLtd, WILMSLOW, 527166

LIVERPOOLAughton Microsystems Ltd,LIVERPOOL, 548 7788

Stack Computer Services Ltd,LIVERPOOL, 933 5511

MANCHESTERAREAByte Shop Computerland,MANCHESTER, 236 4737

Computastore Limited,MANCHESTER, 832 4761

Cytek (UK) Ltd,MANCHESTER, 872 4682

Executive Reprographic Ltd.MANCHESTER, 228 1637

Professional Computer ServicesLtd, OLDHAM, 061-624 4065

SCOTLANDGate Microsystems Ltd,DUNDEE, 28194

Holdene Microsystems Ltd,EDINBURGH, 668 2727

Gate Microsystems Ltd.GLASGOW, 221 9372

Robox Ltd,GLASGOW, 8413

Thistle Computers (Macmicro),INVERNESS, 712774

Ayrshire Office Computers,KILMARNOCK, 42972

Thistle Computers,KIRKVVALL, 3140

N. IRELANDN. Ireland Computer Centre,

HOLLYWOOD, 6548

This list covers dealers participating in our advertising. "Prices quoted ex. VAT.

For your free literature pack send off the coupon to the address below.

Name Position

Address

Intended applicatior 08PR1

Or commodoreCommodore Information Services, 818 Leigh Road, Slough, Berks. SL1 4BD

Circle No. 105

Mail Order Softwarefrom the world's leading microsoftware supplier

Software for most popular 8080/Z80 computerdisk systems includingNORTH STAR HORIZON, VECTOR MZ,OHIO SCIENTIFIC, SUPERBRAIN, Z80 APPLE,CROMEMCO, RAIR BLACK BOX, DYNABYTE,SD SYSTEMS, RESEARCH MACHINES,EXIDY SORCERER, IMSAI, HEATH,and 8" IBM formats

Softwarewith Manual/

Manual Alone

DIGITAL RESEARCH

CPIM FDOS - Diskette Operating System complete with) Text Editor. Assembler. Debugger. File Manager and system

utilities. Available for wide variety of disk system includingNorth Star, Helios II. Micropolis, ICOM (all systems) and Altair.Supports computers such as Sorcerer, Horizon, Cromemco,Ohio Scientific, RAIR Black Box, Research Machines,Dynabybe, etc. from 175)115

CPIM version 2 (not all formats available immediately)E95/115

O CPIM for Apple 11* Softcard"

Z80 Microsoft BASIC - 80with high resolution graphicstW f..2501115

MPIM 11951125

O MAC - 8080 Macro Assembler. Full Intel macro definitions.Pseudo Ops include RPC, IRP, REPT, TITLE, PAGE, andMACLIB. Z-80 library included. Produces Intel absolute hexoutput plus symbols file for use by SID Isee below) ....155)110

O SID - 8090 symbolic debugger. Full trace, pass count andbreak-point program testing system with back -trace andhistogram utilities. When used with MAC, provides full symbolicdisplay of memory labels and equated values C45/E10

ZSID Includes Z80 mnemonics, requires Z80 CPU E50/110

CI TEX - Text formatter to create paginated, page -numbered andjustified copy from source text files, directable to disk or printer

145)110

DESPOOL - Program to permit simultaneous printing of datafrom disk while user executes another program from the console

130)11

MICROSOFT

O BASIC -80 - Disk Extended BASIC Interpreter Version 5, ANSIL compatible with long variable names, WHILE /WEND, chaining,

variable length file records £1551115

O BASIC Compiler - Language compatible with Version 5® Microsoft interpreter and 3-10 times faster execution. Produces

standard Microsoft relocatable binary output. IncludesI Macro -80. Also linkable to FORTRAN -80 or COBOL -80 code

modules £195/115

O FORTRAN -80 -ANSI '66 (except for COMPLEX) plus many0 extensions. Includes relocatable object compiler, linking loader,

library with manager. Also includes MACRO -80 (see below)1205(115

[7 COBOL -80 - ANSI '74 Relocatable object output. Format0 same as FORTRAN -80 and MACRO -80 modules. Complete

ISAM. Interactive ACCEPT DISPLAY, COPY, EXTENDl 325/115

u MACRO -80 - 80130/Z80 Macro Assembler. Intel and Zilog® mnemonics supported. Relocatable linkable output Loader,

Library Manager and Cross Reference List utilities included£751110

Softwarewith /Manua(

Manual Alone

XMACRO-86 - 8086 cross assembler. All Macro and utility© features of MACRO -80 package. Mnemonics slightly modified

from Intel ASM86. Compatability data sheet available .1155)115

17 EDIT -80 -. Very fast random access text editor for text with orwithout line numbers. Global and intra-line commandssupported. File compare utility included 145/110

EIDOS SYSTEMS KBASIC - Microsoft Disk Extended BASIC version 4.51© integrated with KISS Multi -Keyed Index Sequential and Direct

Access file management as 9 additional BASIC commands.KISS included as relocatable modules linkable to FORTRAN -93COBOL -80, and BASIC COMPILER. Specify CP/M version 1.4or 2.x when ordering. Requires 48K CP /M 1295)25To licensed users of Microsoft BASIC -80 IMBASICI 1215(125

MICROPRO SUPER -SORT 1 - Sort, merge, extract utility as absolute© executable program or linkable module in Microsoft format.

Sorts fixed or variable records with data in binary, BCD, PackedDecimal, EBCDIC, ASCII, floating, fixed point, exponential,field justified, etc. etc. Even variable number of fields per record!

£1251115

CI SUPER -SORT II - Above available as absolute pr6gram only0 1105(115

17 SUPER -SORT III - As II without SELECT/EXCLUDE© 175)115

0 WORD -MASTER Text Editor - In one mode has super -set ofC) CP /M's ED commands including global searching and

replacing, forward and backwards in file. In video -mode,provides full screen editor for users with serial addressable -cursor terminal 05/115

WORD -STAR - Menu driven visual word processing system© for use with standard terminals. Text formatting performed on

screen. Facilities for text paginate, page number, justify, center,underscore and PRINT. Edit facilities include global search andreplace, read/write to other text files, block move, etc RequiresCRT terminal with addressable cursor positioning E2551115

D WORD-STAR/MAIL-MERGE - As above with option forgproduction mailing of personalised documents with mail list fromDatastar or NAD £3151115

DATASTAR - Professional forms control entry and displaygsystem for key -to -disk data capture. Menu driven with built-inlearning aids. Input field verification by length, mask, attribute!i.e. uppercase, lowercase, numeric, auto dup., etc.). Built-inarithmetic capabilities using keyed data, constants and derivedvalues. Visual feedback for ease of forms design. Filescompatible with all CP /M -MP /M supported languages.Requires 32K CP /M 1195/125

Softwarewith /Manual

Manual Alone

GRAFFCOM

Ci PAYROLL - Designed in conjunction with the spec for PAYE0 routines by HMI Taxes. Processes up to 250 employees on

weekly or monthly basis. Can handle cash, cheque or banktransfer payments plus total tracking of all year to date figures.Prints amp master, payroll log, payslips and bank giros.Requires CBASIC-2 1475/135

O COMPANY SALES - Performs sales accounting function.Controls payments of invoices and prints sales ledger and ageddebtors report. Suitable for any accounting period.Comprehensive VAT control and analysis of all sales invoices.Requires CBASIC-2 1425)135

O COMPANY PURCHASES - Performs purchase accounting© function. Controls invoices, credit & debit notes. Prints

purchase ledger, aged creditors report and payment advices.Comprehensive VAT control and analysis of all purchases,Interfaces with the ADD system. Requires CBASIC-2

14251E35

D GENERAL ACCOUNTING - Produces Nominal Ledger, TrialC) Balance, P/L and Balance Sheet. Define your own coding

system. Interactive data entry plus optional data capture fromCompany Sales and Company Purchases. Requires CBASIC-2

1375/135

O STOCK CONTROLMaintains stock records, monitors stock levels to ensure

Q optimum stock holding. Details include stock desc., productcode, unit, unit price, quantity on hand on order/minimum,Stock analysis reports can be weekly, monthly, quarterly etc.Interfaces with Order Entry Invoicing system. RequiresCBASIC-2 £3251135

17 ORDER ENTRY Et INVOICINGPerforms order entry and invoicing function. Handles invoices

0 for services and consumable items, part orders and partquantities. Sales Analysis report shows sales movemets andtrends for user -defined period Interfaces with Stock Control.ADD and Company Sales systems. Requires CBASIC-2

1325/135

El ADD - Complete control of all your names & addresses© including suppliers, clients, enquiries etc. Assign your own

coding system and select all output via the report generator. Willprint anything from mailing labels to directories. RequiresCBASIC-2 £2251135

TIME RECORDING SYSTEM - Provides comprehensive(3 control over manhour expenditures by job or account. Expense

details can also be controlled. Up to 75 activities can be assignedand reports produced weekly /monthly showing movements andjob account totals to date. Requires CBASIC-2. 1375/135

O LEASE RENTAL Et HP SYSTEM - Designed to control© agreements and contracts that are payable at regular intervals by

fixed amounts. Handles lease, rental, HP or maintenanceagreements with payments by invoice, SO, or cash. Can beused with ADD and CSS for complete credit control system.Requires CBASIC-2. E375/135

Also available in bundles, contact us for details.

I 0 PRACTICAL COMPUTING May 1981

Softwarewith /Manual

Manual Alone

STRUCTURED SYSTEMS GROUP0 ANALYST - Customised data entry and reporting system.

User specifies up to 75 data items per record. Interactive dataentry, retrieval and update facility makes informationmanagement easy. Sophisticated report generator providescustomised reports using selected records with multiple levelbreakpoints for summarisation. Requires CBASIC-2, 24 x 80CRT, printer and 48K system £1251f10

LETTERIGHT - Program to create edit and type letters or otherdocuments. Has facilities to enter, display, delete and movetext, with good video screen presentation. Designed to integratewith NAD for form letter mailings. Requires CBASIC-2

f1051E15

NAD Name and Address selection system - interactive mail listcreation and maintenance program with output as full reportswith reference data or restricted information for mail labels.Transfer system for extraction and transfer of selected recordsto create new files. Requires CBASIC-2 £451f12

QSORT - Fast sort/merge program for files with fixed recordlength, variable field length information. Up to five ascending ordescending keys. Full back-up of input files created. Parameterfile created optionally with interactive program which requiresCBASIC-2. Parameter file may be generated with CP /Massembler utility E50/f 12

SOFTWARE SYSTEMS CBASIC-2 Disk Extended BASIC - Non -interactive BASICg with pseudo -code compiler and runtime interpreter. Supports

full file control, chaining, integer and extended precisionvariables etc £75/f10

MICRO FOCUSD STANDARD CIS COBOL - ANSI '74 COBOL standardCi compiler fully validated by U.S. Navy tests to ANSI level 1.

Supports many features to level 2 including dynamic loading ofCOBOL modules and a full ISAM file facility. Also, programsegmentation, interactive debug and powerful interactiveextensions to support protected and unprotected CRT screenformatting from COBOL programs used with any dumb terminal

f400/f 25

FORMS 2 - CRT screen editor. Automatically creates a queryC) and update program of indexed files using CRT protected and

unprotected screen formats. Output is COBOL data descriptionsfor copying into CIS COBOL programs. No programmingexperience needed. Output program directly compiled by CISCOBOL (standard) £1001£ 12

D APO/80 - Concise and powerful language for applicationQZ software development. Complex programming problems are

reduced to simple expresions in APL. Features include up to 27Kactive workspace, shared arrays of up to 8dimensions, disk workspact.OV-7..opy object library. The systemalso supports auxiliary processors for interfacing I/O ports.Requires 48K CP /M and serial APL printing terminal or CRT

E270/f20 PASCALIM - Compiler generates P code from extended

language implementation of standard PASCAL. Supportsoverlay structure through additional procedure calls and theSEGMENT procedure type. Provides convenient string handlingcapability with the added variable type STRING. Untyped filesallow memory image I/O. Requires 56K CP/M f1951f20

PASCALIZ - Z80 native code PASCAL compiler Producesoptimised portable reentrant code. All interfacing to CP/M isthrough the support library. The package includes compilercompanion macro assembler and source for the library. Requires56K and Z80 CPU. Version 3 includes all of Jensen /Wirth

£2051£ 15

O PASCAL/MT - Subset of standard PASCAL. GeneratesC) ROMable 8080 machine code. Symbolic debugger included.

Supports interrupt procedures, CP /M file I/O and assemblylanguage interface. Real variables can be BCD, software floatingpoint, or AMD 9511 hardware floating point. Version 3 includesSets, Enumeration and Record data types. Manual explainsBASIC to PASCAL conversion. Source for the run time packagerequires MAC (See under Digital Research). Requires 32K.

f135/f20E TINY C - interactive interpretive system for teaching

structured programming techniques. Manual includes fullsource listings E45/E30

O BDS C COMPILER - Supports most major features ofg language, including Structures, Arrays, Pointers, recursive

function evaluation, linkable with library to 8080 binary output.Lacks data initialization, long & float type and static & registerclam specifiers. Documentation includes "C" ProgrammingLanguage book by Kernighan & Ritchie £601E10

O WHITESMITHS' C COMPILER - The ultimate in systemsC) software tools. Produces faster code than Pascal with more

extensive facilities. Conforms to the full UNIX Version 7 Clanguage, described by Kernighan and Ritchie, and makesavailable over 75 functions for performing I/O, stringmanipulation and storage allocation. Compiler output inA -Natural source. Supplied with A -Natural. Requires 60K CP /M

f3251f20

O ALGOL 60 Compiler - Powerful block -structured language0 featuring economical run time dynamic allocation of memory.

Very compact 124K total RAM) system implementing almost allAlgol 60 report features plus many powerful extensionsincluding string handling, direct disk address I/O etc Requires580 CPU E110/f12

E 280 Development Package - Consists of 111 disk file lineg editor, with global inter and intra-line facilities; 121 Z80 relocating

assembler, Zilog Mostek mnemonics, conditional assembly andcross reference table capabilities:. 131 linking loader producingabsolute Intel hex disk file for CP/M LOAD, DDT or SIDfacilities (50/(12

PRACTICAL COMPUTING May 1981

Softwarewith /Manual

Manual Alone

ZDT - Z80 Debugger to trace, break and examine registersg with standard Zilog/Mostek mnemonic disassembly displays.

Facilities similar to DDT £20 when ordered with Z80.

Development Package £30/f7

O DISTEL - Disk based disassembler to Intel 8080 or TDL/XitanZ80 source code, listing and crow reference files. Intel or TDLXitan pseudo ops optional. Runs on 8080. E35/E7

DISILOG - As Distel to Zilog Mostek mnemonic files. Runs on(0 Z80 only £35/f7

TEXTWRITER III - Text formatter to justify and paginateletters and other documents. Special features include insertionof text during execution from other disk files or console,permitting recipe documents to be created from linkedfragments on other files. Has facilities for sorted index, table ofcontents and footnote insertion. Ideal for contracts manuals.etc. £751£3

DATEBOOK - Program to manage time just like an officeappointment book but using the speed and memory of acomputer. Keeps track of three appointment schedules (threedental chairs, three attorneys, etc.l at once. Appointmentsconsist of name, reason for Tintment, the date and time,and the length of the apaiVfient. System can be quicklycustomized for the individual user. Many helpful features formaking, changing, finding, and reporting appointments.Requires 48K CP/M and 180K bytes diskette storage. Notavailable for Apple CP/M (185/f15

O POSTMASTER - A comprehensive package for mail listg maintenance that is completely menu driven. Features included

keyed record extraction and label production. A form letterprogram is included which provides neat letters on single sheetor continuous forms. Compatible with NAD files. RequiresCBASIC-2 E85/110

O XASM-68 - Non -macro cross -assembler with nestedconditionals and full range of pseudo operations. Assemblesfrom standard Motorola MC6800 mnemonics to intel hex

£115/f15

O XASM-65 - As XASM-68 for MOS Technology MCS-6500series mnemonics El 151f 15

XASM-48 - As XASM-68 for Intel MCS-48 and UPI -41families E115/E15

O XASM-18 - As XASM-68 for RCA 1802 E115/E15

WHATSIT? - Interactive data -base system using associativetags to retrieve information by subject. Hashing and randomaccess used for fast resonse. Requires CBASIC £70/f15

XYBASIC Interative Process Control BASIC - Full disk BASICfeatures plus unique commands to handle bytes, rotate andshift, and to test and set bits. Available in integer, Extended andROMable versions.Integer Disk or Integer ROMable £165/f15Extended Disk or Extended ROMable £215/E15

SMAIJ80 Structured Macro Assembley Language - Packageof powerful general purpose text macro processor and SMALstructured language compiler. SMAL is an assembler languagewith IF -THEN -ELSE, LOOP -REPEAT -WHILE, DO -END, BEGIN -END constructs f40/f 10

O SELECTOR III -C2 - Data Base Processor to create andg maintain multi Key data bases. Prints formatted, sorted reports

with numerical summaries or mailing labels. Comes with sampleapplications including Sales Activity, Inventory, Payables,Receivables, Check Register, and Client/Patient Appointments ,etc. Requires CBASIC Version 2. Supplied in source code.

f 185/f 12

IBM/CPM Utility Package - has full range of functions tocreate or re -name an IBM 3741 volume, display directoryinformation and edit the data set contents. Provides full filetransfer facilities between 3741 volume data sets and CP /M files

E125/E7

O BASIC UTILITY DISK - Consists of Ill CRUNCH -14g Compacting utility to reduce the size and increase the speed of

programs in Microsoft Basic and TRS-80 Basic. 121 DPFUN -Double precision subroutines for computing nineteentranscendental functions including square root, natural log, logbase 10, sin, arc sin, hyperbolic sin, hyperbolic arc sin, etc.Furnished in source on diskette and documentation E30/E10

Softwarewtth /Manual

Manual Alone

0 THE. STRING BIT - Fortran character string handling.(0 Routines to find, fill, pack, move, separate, concatenate and

compare character strings. This package completely eliminatesthe problems associated with character string handling in

FORTRAN. Supplied with source E3Olf 10

BSTAM - Utility to link one computer to another also equipped(0 with BSTAM. Allows file transfers at full data speed Ino

conversion to hex), with CRC block control check for veryreliable error detection and automatic retry. We use it! It's great!Full wildcard expansions to send .COM, etc. 9600 baud withwire, 300 baud with phone connection. Both ends need one.Standard and M versions can talk to one another E75/f5

O BSTMS -. Intelligent terminal program for CP /M systems.9 Permits communication between micros and mainframes.

Sends character data files to remote computers under completecontrol. System can record c, -,d44 er data sent from remotecomputer systems and da,tIvAinks. Includes programs toEXPAND and COMPRESS binary files for transmission. Thissoftware requires a knowledge of assembler language forinstalltion. 0151110

O PLINK* - Two pass disk -to -disk linkage editor/loader whichcan produce re-entrant, ROMable code. Can link programs thatare larger than available mee"-M for execution targeted onanother machine. Full librz a-I:abilities. Input can be PSARelocatable Binary Module. UL Object Module or MicrosoftREL files. Output can be a COM file, Intel hex file, TDL ObjectModule or PSA Relocatable file £75/E15

RECLAIM -A utility to validate media under CP/M. Programtests a diskette or hard diskette whard disk surface for errors,reserving the imperfection.14.17visible files, and permittingcontinued usage of the remainder. Essential for any hard disk.Requires CP/M version 2. f401f5

STRING/80 - Character string handling plus routines for directCP/M BDOS calls from FORTRAN and other compatibleMicrosoft languages. The utilityrary contains routines thatenable programmes to chaietv..i. file, retrieve comand lineparameters, and search fir. directories with full wild cardfacilites. Supplied as linkable modules in Microsoft format.

f 501E12

STRING190 source code available separately E185/n.a.

O VSORT - Versatile sort/merge system for fixed length(0 records with fixed or variable length fields. VSORT can be used

as a stand-alone package or lOenti and called as a subroutinefrom CBASIC-2. When use," "l. VSORT maximizesthe use of buffer space by szVng the TPA on disk and restoringit on completion of sorting. Records may be up to 256 byteslong with a maximum of 5 fields. Upper/lower case translationand numeric fields supported. E105/E15

O CBS - Configurable Business System is a comprehensive setg of programmes for defining custom data files and applicationsystems without using programming language such as BASIC,FORTRAN, etc. Multiple key fields for each data file aresupported. Set-up program cuviwizes system to user's CRTand printer. Provides fast 14.1.,y interactive data entry and

Report generatorprogram does complex calculations with stored and deriveddata, record selection with multiple criteria, and customformats. Sample inventory and mailing list system included. Nosupport language required £185/f 20

O MAGIC WAND* - Word processing system with simple, easyto use full screen text editor and powerful print processor. Editorhas all standard editing functions including text insert anddelete, global search and replace, block move and library filesfor boiler plate text. Print reN4 nor formating commandsinclude automatic margins tiVination, heading & footings,centred and justified text. Also prints with true proportionalspacing, merges with data files for automatic form letters, andperforms run-time conditional testing for varied output.Requires 32K CP /M and CRT terminal with addressable cursor.

f185/f 20

T/MAKER - Powerful new tool for preparing managementreports with tabular data. Makes financial modeling projectseasy. Do you want a weekly profitability report? Set up the tableand compute. Just change the sets figures for next week andcompute. You have a new v$. T /MAKER includes a fullscreen editor for setting uprnies which pages left, right, upand down. Compute includes standard arithmetic, percents,exponents, common transcedental functions, averages,maxima, minima, projections, etc. Requires 48K CP /M andCBASIC-2 £1551£15

Orders must specifydisk type and format,e.g. North Star -Horizonsingle density.

Add 15% VAT toorders. Add (1 per itempostage and packing

All orders must beprepaid. Make chequesPOs etc payable toLifeboat Associates.

Manual costs aredeductable fromsubsequent softwarepurchase

EFFECTIVE JANUARY 1981

The Software Supermarketis a trademark ofLifeboat Associates.

Lifeboat Associates P.O. Box

-CP M and MP M are trademarks of Digital Research280 is a trademark of Zilog.UNIX IS a trademark of Bell Laborittes.WHATSIP is a trademark of Computer Headware.Electric Pencil is a trademark of Michael Shraver Software.TRS-80 is a trademark of Tandy Corp.Pascal M is a trademark of SorcimSoft Card is a trademark of Microsoft.Apple is a trademark of Apple Computer.PLINK is a trademark of Phoenix Software Associates Ltd.MAGIC WAND is a trademark of Small Business Application. Inc

() Modified version available for use with CP M as implemented onHeath and TRS-80 Model 1 computers.

0 User license agreement for this product must be signed and returnedto Lifeboat Associates before shipment may be made

125 London WC2H 9LU 01-836 9028/9 Circle No. 106

Wou.ld youinterview onlyone applicant

foranimportant

job?

12

CURRY'S MICRO SYSTEMS LTD., A MEMBER OF THE CURRYS GROUP OF COMPANIESOUR TERMS AND CONDITIONS OF SALE ARE DIFFERENT FROM THOSE SET OUT IN CURRYS LTD., STATEMENT OF TRADING STANDARDS BUT THEY EMBODY THE SAME PRINCIPLE.

MORE PROTECTION FOR YOU. OUR CUSTOMER, YOU WILL FIND FULL DETAILS OF TERMS OF BUSINESS ON THE REVERSE SIDE OF OUR INVOICES AND AGREEMENTS.

PRACTICAL COMPUTING May 1981

PRACTICAL COMPUTING May 1981

If you were filling an important job, nodoubt you'd make a short list.

Yet, surprisingly, many businessmenwill sign on the dotted line for a micro-computer after interviewing only one.

At Micro -C, we've put together a shortlist for you. Although each is different,they're all value for money. (Since we're partof Currys, that's not a promise we makelightly.)

Here are four brief C.V's:Commodore PetFor small businesses, it'll tackle book-

keeping, word processing and incompleterecords.

ITT 20 20 and Apple IIIf your business is slightly more in-

volved, we might talk about the ITT 20 20 orthe Apple II. They'll tackle book-keeping, in-complete records, word processing and,through Visicalc, fmancial planning.

National Panasonic - JD800, JD840and Micro -C 2000.For small businesses that want to be big

businesses, we'll suggest you look at ourmore sophisticated hardware. They'll do allthe others do but they'll also give you all thefmancial and management information youneed to grow.

However, before we talk about hard-ware or software, we'll talk about yourbusiness. (It's the only way we know to give

honest, unbiased advice.)

or woul

To Currys Micro -Systems Limited, 653 London Road,High Wycombe, Bucks HP111EZ0 Please send me an information pack on your service and products0 Please telephone to make an appointment

Name

Company

Address

TelephonePC3

At the same time, we'll offer any numberof ways to buy or lease starting from £35 aweek.

We'll also offer a one year guaranteewhile others are talking about 90 days.

At a little extra cost, we'll offer to servicemachines within one working day; and we'llhelp with staff training.

As for software, we test every packageand if they fail to come up to our standards,we won't stock them.

Come and see us for a free demonstra-tion. Or, if you prefer it, an interview with a

very hot short list.

we.

MICRO -C INSIDE CURRYS SHOPS AT: BIRMINGHAM TEL: 2331105 EXETER TEL: 213391 LEEDS ALBION STREET TEL: 446601 LUTON TEL: 0494 40262

NOTTINGHAM TEL: 412455 SOUTHAMPTON BARGATE TEL: 29676 INSIDE BRIDGERS SHOWROOMS AT: BRISTOL TEL: 650501 NEW MALDEN TEL: 01-949 2091

Circle No. 10713

MICROCOMPUTER PRODUCTSINTERNATIONAL LTD

LIP En TE rl PRI 5E 5EUROPE'S LARGEST SELECTION OF MICROCOMPUTER SOFTWARE, BOOKS AND MAGAZINES FOR THE HOBBYIST, EDUCATIONALIST, PROFESSIONAL AND RETAILER

BOOKS

BY OSBORNEIntroduction to Microcomputer SeriesVol 0: Beginners BookVol 1: BASIC ConceptsVol 2: Some Real Microprocessors (without binder)Vol 2: Some Real Microprocessors (with binder)Vol 2: Updating supplement set Nos. 1-6Vol 3: Some Real Support Devices (without binder)Vol 3: Some Real Support Devices (with binder)Vol 3: Updating supplement set Nos. 1-61 Binder (Specify for Vol 2 or 3)1 Updating supplement (Specify for Vol 2 or 31

PET and the IEEE 488 (GPIB) Bus6800 Programming for Logic Design8080 Programming for Logic DesignZ80 Programming for Logic DesignZ80 Assembly Language Programming6502 Assembly Language Programming8080A/8085 Assembly Language Programming6800 Assembly Language ProgrammingAccounts Payable and Accounts Receivable (C BASIC or Wang)Payroll with Cost Accounting (C BASIC or Wang BASIC)General Ledger (C BASIC or Wang BASIC)Some Common BASIC ProgramsPractical BASIC ProgramsRunning Wild80891/0 Processor HandbookZ8000 Assembly Language ProgrammingThe CRT Controller HandbookThe 68000 Microprocessor HandbookApple User's GuideCP/M User's GuideThe 68000 Handbook16 Bit Microprocessor Handbook6809 Assembly Language Programming

£5.95£8.25

£18.95£20.50E18.95E11.95E13.50£18.95£5.75£4.00

E9.95E6.30£6.30£6.30

E10.75£10.75£7.95£7.95

£13.15E13.50£12.25

£8.95E9.25E2.00E4.00

E13.50E4.50SBAETBAETBAETBAETBAETBA

GENERAL

See Magazines and Subscriptions(Microprocessors from Chips to SystemsMicroprocessor Interfacing TechniquesIC OP -AMP CookbookRTL CookbookCiarcias Circuit CellarBuyers Guide to MicrosoftwareCalculating with BASICComputer Programs that Work (in BASIC)Dr Dobbs Journal Volume 1Dr Dobbs Journal Volume 2Dr Dobbs Journal Volume 3Best of ByteScelbi BYTE PrimerBest of Creative Computing, Vol 1Best of Creative Computing, Vol 2Program DesignProgramming Techniques: SimulationNumbers in Theory and PracticePIMS-A Database Management SystemBest of Interface Age -SoftwareProgramming the Z8000CPM HandbookK2 FDOS8086 Book

Microsoft BASIC University Software Inc., Listings:Home and Economics ProgramsEducation and Scientific ProgramsSmall Business Programs

See Osborne Books!£7.00£9.95E8.95£4.2515.50E2.40£4.95£3.95

£13.95£13.95E13.95£8.95£8.95£6.95£6.95£4.25£4.250.50£6.50£9.95£7.95£8.95

£13.95E11.25

£15.00£20.95£29.50

FOR THE Z80

See Osborne Books!Z80 Instruction Handbook (Wadsworth)Programming the Z80 (Zacs)Z80 Software Gourmet Guide and Cookbook32 BASIC Programs for the TRS-80 (Level III 16K £10.10Introduction to the T -Bug (Guide to TRS-80 Machine Language Monitor) £4.5030 Programs for the Sinclair ZX80 E6.95

12.95E8.95£8.95

FOR THE 6800

See Magazines and Subscriptions!6800 Software Gourmet Guide and Cookbook6800 Tracer -An aid to 6800 Program DebuggingTiny AssemblerRA 6800 ML -An M6800 Relocatable Macro AssemblerLink 68 -An M6800 Linking LoaderMONDEB-An Advanced M6800 Monitor Debugger

See Osborne Books!E7.15£3.95£5.75

£15.35£5.50£3.50

CONCERNING LANGUAGEA Practical Introduction to PASCALBeginners guide to UCSD PASCALIntroduction of PASCAL (Including UCSD PASCAL)BYTE Book of PASCALSCELBAL-BASIC Language Interpreter (Source Code)Instant BASICBASIC BASICAdvanced BASICUsers Guide to North Star BASICMicrosoft BASIC (a guide)Secret Guide to ComputersFifty BASIC Exercises

£3.9517.50£8.70

£16.25£15.00

E6.95E6.50E6.00

E10.00E6.5014.0018.95

FOR THE 6502See Magazines and Subscriptions! See Osborne Books,

FOR THE 6502

Best of Micro, Vol 2 £5.50Programming the 6502 (Zacs) £7.956502 Applications £7.956502 Software Gourmet Guide and Cookbook £7.25The PET Revealed £10.0032 BASIC Programs for the PET E10.10First Book of KIM £7.00PET/CBM Personal Computer Guide £10.00Library of PET Subroutines £10.00

FOR THE 8080

See Osborne Books!8080 Hex Code Card £1.958080 Octal Code Card £1.958080 Software Gourmet Guide and Cookbook £7.158080/8085 Software Design £6.758080 Standard Monitor £9.958080 Standard Assembler £9.958080 Standard Editor E9.958080 Special Package: Monitor, Editor, Assembler £20.00BASEX: A simple Language and Compiler for the 8080 £5.50

FOR FUN

BASIC Computer Games £5.00More BASIC Computer Games £5.508080 Galaxy Game E6.95SUPER-WUMPUS-A Game in 6800 Assembler Code & BASIC £4.25Computer Music Book £6.75Computer Rage (a Board Game) E6.95Games, Tricks and Puzzles for a Hand Calculator £2.49Introduction to TRS-80 Graphics £5.75Take My Computer Please ... (Fiction) £3.25Introduction to Low Resolution Graphics for PET, Apple TRS-80 £5.50Starship Simulation £4.50Microsoft BASIC: University Software Inc., ListingsFun and Games Programs 1 £9.50Fun and Games Programs 2 £9.506502 Games E7.95

FOR THE NOVICE

See Magazines and Subscriptions!Getting Down to Business with Your MicrocomputerIntroduction to Personal and Business ComputingGetting Involved with Your Own ComputerHow to Profit from Your Personal ComputerMicrocomputer PotpourriHobby Computers are HereNew Hobby ComputersUnderstanding Microcomputers and Small Computer SystemsUnderstanding Microcomputers and Small Computer Systems

and Audio CassetteHow to Make Money with Your MicrocomputerFrom the Counter to the Bottom LineBuying a Business ComputerYou Just Bought a Personal What?

See Osborne Books!£5.50£5.50£5.50E6.50£1.95£3.95E3.95E6.95

E8.75E5.75

110.00£9.75£7.95

MAGAZINES

MAGAZINE SUBSCRIPTIONS (all processed within 3 weeks)

Micro 6502 Journal 112 issues)68 Micro (12 issues)Personal Computing (12 issues)Interface Age (12 issues).Dr Dobbs Journal (12 issues)Recreational Computing (6 issues)BYTE (12 issues)Creative Computing (12 issues)Kilobaud Microcomputing (12 issues)Compute for the 6502 (12 issues)80' Microcomputing (12 issues)S-100 Microsystems (for CPM users) (6 issues)

£14.50£18.00£18.00£25.50£16.00£11.50£33.00£22.00£26.00£22.00£25.00£1550

MAGAZINE BACK ISSUES

Micro 6502 JournalPersonal ComputingInterface AgeDr Dobbs JournalComputer Music JournalRecreational ComputingBYTECreative ComputingCalculators and ComputersKilobaud MicrocomputingCompute -for the 650268' Micro80-MicrocomputingOn ComputingS-100 MicrosystemsMagazine Storage Box (holds 12)

£1.75£1.95£2.95E1.95£3.75£1.95£3.25£1.95£1.95£3.25£2.25£1.95£2.95£1.95£1.95£2.00

BYTE NIBBLE REPRINTS:

a) A TMS-9900 Monitorb) BASIC Cross -Reference Generatorcl A Micro Word Processord) 'Tiny' PASCAL in 8080 Assembly Language )'e needed to use this)el A 'Tiny' PASCAL Compilerf) An APL Interpreter in PASCALg) Computer Assisted Flight Planningh) Computerized Wine Cellari) The Design of an M6800 Lisp Interpreter

£3.50£1.25£4.50

E13.00E13.50£13.00£2.35£2.00

£13.00

EnTERPRDE5 MICROCOMPUTER PRODUCTSINTERNATIONAL LTD.

8-11 CAMBRIDGE HOUSE. CAMBRIDGE ROAD. BARKING. ESSEX IG11 8NT, ENGLANDTelephone 01-591 6511 Telex: 892395

Microfocus Ltd. CIS COBOL version 4.3 E425/2SFORMS 2 £100/10

Byrom Software BSTAM-Utility to link one microcomputerWORD -MASTER 1.7 £70/20to another also using BSTAM E70/5 Micropro Inc.BSTMS-Utility to link a micro

to a mini or mainframe E95/10TEX-WRITER 2.6 05/15WORD -STAR 2.1 £240/35MAIL -MERGE 2.1 £70/10WORD -STAR with MAIL -MERGE £310/45

Compiler Systems CBASIC v2.06 E65/15 SUPER -SORT: Version 1 £120/20Version 2 E100/20

DATASTAR 1.1 £165/20Computer Plus FMS 80 (File Management System) £395/25

Microsoft Inc. BASIC -80 f175/17Computer Services Bidirectional driver for Diablo Hytype

printers for use on CPM & CDOS systems £65/10BASIC Compiler 5.2 E195/17FORTRAN -80 020/17COBOL -80 4.0 £355/17M/SORT £70/11

CP/M User Library 42 Volumes lone volume per disc) 8" E4/ EDIT -BO £45/1142 Volumes (one volume per 2 discs) 5" £8/ MACRO -80 £60/11Index £1/ MICROSEED 0184/20

MULISP fTBA/20MUMATH £140/20

Creative Computing CS -9001 BASIC Games 1 E12/ XMACRO-86 £165/11CS -9002 BASIC Games 2 £12/ XFORTRAN-86 £410/17CS -9000 BASIC Games 1 and 2 £22/CS -9003 ADVENTURE I.O. £12/CS -9004 BILINGUAL Original Adventure £12/CS -9005 BASIC Games 3 £12/

MT Microsystems Pascal MT 5.1 £145/20

CS -9006 BASIC Games 4 £12/CS -9007 BASIC Games 3 and 4 f22/ Northshare Multi-user system for Horizon Users 5.1 £40/5CS -9008 BASIC Games 1, 2, 3 and 4 £401

Digital Research (Most formats now available)MPM 1.1 £175/18CP/M 1.4 £65/18CP/M 2.2 f90/18 Software/Manual OnlyCP/NET £130/12SID E45/12

Osborne & Associates Accounts Payable &ZSID f55/12MAC f55/12 Accounts Receivable (disc only) £501TEX E45/12 General Ledger (disc only) 00/DESPOOL £30/5 Payroll with Cost Accounting (disc only) MO/PL/1 £325/25

Phoenix Software PLINK-Disc to disc link loader £65/15Information Unlimited WHATSIT (Database Management System) Associates PASM-Macro assembler £65/15

on North Star E59/on CP/M E75/on APPLE 2:48k (requires int Basic) 02/on APPLE 2:32k (requires int Basic) £59/on ITT 2020 (see Apple)

(For 280 only) PEDIT-Line editor with Macros £65/15BUG-Very powerful debug £66/15Package with all the above £175/30

Structured Systems Sales Ledger £350/15(All Converted to Purchase Ledger £350/15

KLH Systems Spooler for CPM systems E65/5 UK Standard) Nominal Ledger f350/15Stock Control 050/15Letteright 05/10Analyst (File management Reporting System) £115/10

MPI Ltd. Diablo driver runs 110 to 9600 baudfor CP/M or CDOS E30/5

NAD (Name and Address selection system) £50/10OSORT £50/10

Multiforth £65/20TDL Software Business Basic £801(Technical Design ZTEL (Text Editing Lang.) £35/Labs) MACRO II (280 Macro Assembler) £35/

Micah Inc. CP/M for CDOS Users: LINKER £35/Program to Expand CP/M system to becompatable with Cromemco CDOS software E59/5

DEBUG I) (for 8080/Z80) £45/

Tiny -C Associates Tiny -C language for 8080, 8085, Z80 systems E50/36Michael Shrayer Inc. Electric Pencil Word Processor £100/

SSII for tty etc £100/DSII for Diablo £1051 Supersoft Inc. DIAGNOSTICS 1 £35/5TRS-80 Cassette/disc £50/ TERM £66/5

Circle No. 10...8

ORDERINFORMATION

Software prices reflect distribution on 8" single de-nsity discs. If a format is requested which requiresadditional discs a surcharge of £4 per additional discwill be added.Please add £3.00 for postage, packing and insuranceplus VAT on ALL software items (including manuals)purchased. For overseas pleae add £4.50 per item.If required, DATAPOST D service is available for anextra charge of £8.50.Most software on this Advertisement is available fromstock and a 72 -hour return service is thereby offered onmost prepaid orders. When ordering CP/M softwareplease specify the format you require otherwise soft-ware will be dispatched on an 8" single density disc.For more information on any of these items, pleasephone, write or visit. (We are open during officehours).All publications are published in the U.S.A. and arestocked in Britain by L.P. Enterprises: M.P.I. Ltd.We aim to keep all of these books in stock and as a

result of this most mail orders are despatched by re-turn of post.

MAIL ORDER TELEPHONE ORDER VISITSend Cash, Cheque, Credit Card No Postal Order. IMOtoL.P. Enterprises: MPI Ltd., Room PC, 11, Cambridge House,Cambridge Road, Barking,Essex.IG11 8NT. UK.

All Payment must be in sterling and drawn against aUK bank.Subscriptions are processed to start with the next cur-rent issue, after the date of orderPlease add £0.75 for postage on ALL books ormagazines purchased.These details are all current as of December 1980Prices are subject to change without notice, due tofluctuation in the dollar rate.

Trade Enquiries welcome. Bulk Purchasers welcome.

OEMterms

available

System SpecificationsTwin Z80A's with 4MHZ Clock Frequency One Z80A (the hostprocessor) performs all processor and screen related functions. Thesecond Z80A is "down -loaded" by the host to execute disk I/O, Whennot processing disk data, the second Z80 may be programmed by thehost for other processor relation functions.8 bits10 microseconds register to register158All interrupts are vectored

350K (700K on QD model) total bytes formatted on two double densitydrives. Optional 20.96 megabyte hard disk storage is available directlyfrom Intertec.250K bits/second250 milliseconds. 35 milliseconds track -to -track.4'4 inch mini -disk300 RPM

32K bytes dynamic RAM. Expandable to 64K (socketed). 64K standardon QD model.256 bytes of static RAM is provided in addition to the main processorRAM. This memory is used for program and/or data storage for theauxiliary processor.1K bytes standard. Allows ROM "bootstrapping" of system at power -on. ROM storage is 2708 compatible and may be reprogrammed by theuser for custom applications.

12 -inch, specially focused. P4 phosphor, non -glare screen.25 lines x 80 characters per line.8 x 8 character matrix on a 8 x 10 character field.Light characters on a dark background. Blinking or non -blinking.20 MHZ.Reversed image (block cursor).

Memory -mapped at 38 kilobaud. Serial transmission of data at rates upto 9600 bps.Simplified RS -232 asynchronous. Parallel interface available.Universal RS -232 asynchronous. Synchronous interface optional.Printed circuit edge connector provided for connection of optional S-100bus adaptor. Adaptor features internally mounted cardguide for up toone S-100 type accessory.Enables display of all incoming and outgoing control codes.Choice of even, odd, marking, or spacing.Half or Full Duplex. One or two stop bits.Direct positioning by either discrete or absolute addressing.

SuperBrain users get exceptional performance for just afraction of what they'd expect to pay. Standard SuperBrainfeatures include: two double density mini -floppies with 350Kbytes of disk storage, 32K of ram memory (expandable to 64K)to handle even the most sophisticated programs, a CP/ MDisk Operating System with a high powered text editor,assembler, debugger and a disk formator. And, withSuperBrain's S-100 bus adaptor, you can add all theprogramming power you will ever need ... almost any type ofS-100 compatible bus accessory.SuperBrain's CP/ M operating system boasts an overwhelmingamount of available software in BASIC, FORTRAN, COBOL,and APL. Whatever your application ... General Ledger,Accounts Receivable, Payroll, Inventory or Word Processing,SuperBrain is tops in its class. And the SuperB rain QD boaststhe same powerful performance but also features a double -sided drive system to render more than 700K bytes of diskstorage and a full 64K of RAM. All standard!

_A

WIDELY USED IN U.K./FRANCE/U.S.A. AND ENGLISH SPEAKING COUNTRIES FOR ITS OVERALLFLEXIBILITY AS A COMPLETE BUSINESS PACKAGE.

Our New CompuStarTM 10 Megabyte Disk Storage System (called aDSS) features an 8 inch Winchester drive packaged in an attractive,compact desktop encldsure. Complete with disk, controller andpower supply. Just plug it into the Z80 adaptor of your SuperBrainand turn it on. It's so quiet, you'll hardly know it's there. But, you'llquickly be astounded with its awesome power and amazing speed.The secret behind our Compu Star DSS is its unique controller/multi-plexor. It allows many terminals to "share" the resources of a singledisk. So, not only can you use the DSS with your SuperBrain, youcan configure multiple user stations using our new series of Compu-StarTM terminals, called Video Processing Units or VPU'sTM.

The COMPUSTARTm Family ....VIDEO PROCESSING UNITSModel 10 VPU 64K Internal Memory

Integral CRT, CPU, & Keyboard Download programmableModel 15 UPU (Universal Processing Unit) 64K Internal Memory Same features as VPU, less integral CRT and keyboard Can be used as a remote printer or a terminal interface deviceModel 20 VPU 64K Internal Memory 350K Dual Disk Capacity

Integral CPU, Disks, CRT & KeyboardModel 30 VPU 64K Internal Memory 750K Dual Disk Capacity

Integral CPU, Disks, CRT & KeyboardModel 40 VPU 64K Internal Memory

1 V, MB Dual Disk CapacityIntegral CPU, Disks, CRT & Keyboard

DISK STORAGE SYSTEMS (All feature our 255 user controller)10 MB Winchester Shugart 8 inch mechanism Quiet, table -top operation Can be used with CompuStar or SuperBrain Video Terminals32 MB Control Data CMD

Cartridge Module Mechanism16 MB fixed /16 MB removable

Rack -mountable96 MB Control Data CMD

Cartridge Module Mechanism 80 MB fixed/16MB removalbe Rack -mountable

16 PRACTICAL COMPUTING May 1981

rINCLUDES INVENTORY, DATABASE MANAGEMENT, INVOICING, MAILING ADDRESSES, STATEMENTS, SALES/PURCHASELEDGER WITH OR WITHOUT AUTO STOCK UPDATE AND DOUBLE ENTRY JOURNALS INCLUDING NOMINAL LEDGER;

PLUS A'C RECEIVABLE AND PAYABLE MAKING AUTO BANK ENTRIES.

01 = ENTER NAMES AND ADDRESSES02 = SALES INVOICES03 = A/C RECEIVABLES04= PURCHASE INVOICES05 = A/C PAYABLES06= STOCK CONTROL07 = ORDER CONTROL08= BANK UPDATES09 = SALES LEDGERS10= PURCHASE LEDGER11 = INCOMPLETE RECORDS12= USER DATABASE AREA

WHICH OPTION

13= PRINT CUSTOMER STATEMENTS14= PRINT SUPPLIER STATEMENTS15= PRINT AGENT STATEMENTS16= PRINT TAX STATEMENTS17= RUN SEPARATE PROGRAMS18= CHANGE VOCABULARY19= PRINT YEAR AUDIT20= PRINT PROFIT/ LOSS ACCOUNT21 = DISK DIRECTORIES22= CASHFLOW FORECAST23 = PAYROLL (N /AVAILABLE)24= DISK SWAP/EXIT SYSTEM

DATABASE FEATURES ARE:WITHIN T HE LIMITS OF TWELVE FIELDS AND 256 CHARACTERS PER RECORD, ANY FILE ARCHITECTURE CAN BE DESIGNEDWITH COMPLETE FREEDOM OVER THE LINGUISTIC CONVENTIONS ASSIGNED TO EACH FIELD. THE FILE THEN CAN STORE32000 RECORDS WHICH CAN BE SEARCHED BY THE RANDOM ACCESS NUMBER (RETRIEVED IN LESS THAN ONE SECOND)OR SEQUENTIALLY COMPARING FOR LEFT FIELD PARTS, FIELD- INKEYS; OR PARTS OF RECORD, AND THEN CHANGED,

PRINTED, DELETED, SKIPPED.

GRAMA (WINTER) LTD/ G.W. COMPUTERS LTD. ARE THE PRODUCERS OF THIS PACKAGE WHICH IS UNEQUALLED FORITS LEVEL OF TOTAL INTEGRATION, LINGUISTIC FLEXIBILITY AND MAXIMISED DISK/MEMORY CONSERVATION.

AUTHOR TONY WINTER (M.D.; B.A.LIT; B.A.HON.PHIL; AND LECTURER)

RESTRICTED DEMONSTRATIONS ONLY BY APPOINTMENT AT ONE OF OUR LONDON ADDRESSES DUE TO LONG TERMCONTRACTUAL COMMITMENTS. WE EXPORT TO ALL COUNTRIES; TAKE AMEXCO, ACCESS AND BARCLAYCARD.CONTACT TONY WINTER ON 01.636.8210 OR 01.631.4818 AND IF UNAVAILABLE THEN LEAVE A CALL-BACK MESSAGE(CLEARLY STATING YOUR TELEPHONE NUMBER AND NAME) ON THE 24 HOUR ANSWER -PHONE; WE CALL BACK

ANYWHERE IN THE WORLD.

PRICE OF PACKAGE IS 975.00 (EXCLUDING MENU ITEMS 19,20,22,23) OR 1075.00 FOR THE FULL PACKAGE (23 AVAILABLEEND YEAR, 19,20,22 BEING CURRENTLY INCLUDED). REQUIRES MBASIC-80 AND RUNS ONLY ON HARDWARE ON OUR

PRICE LIST.L

WE EXPORT TO ALL COUNTRIES CALLERS ONLY BY APPOINTMENTCONTACT TONY WINTER ON 01.636.8210

89 BEDFORD COURT MANSIONS; BEDFORD AVENUE, LONDON W.C.1.NOTE!!! LEVEL 9 00 TOTALLY IN CORE PROGRAM LEAVES MASTER DRIVE FREE (SAVING OF 200 POUNDS HARDWARE)

IMPORTANT!!!. NO HARDWARE IS ANY VALUE WITHOUT THE SOFTWARE, AND OUR SOFTWARE IS UNEQUALLED.WE GIVE YOU A DISCOUNT TO SET YOU GOING. JUST DECIDE ON THE SYSTEM YOU INTEND PURCHASING, ANDTAKE 10% OF ITS VALUE OFF THE PRICE YOU WOULD HAVE TO PAY FOR THE SOFTWARE. YOU COULD GET THE

SOFTWARE FREE WITH THE HARDWARE IF YOU CHOSE THE BEST SYSTEM WE SELL.rSUPER BRAIN( + K + 320 K DISK64K + 700 K DISK64K + 1.5 M DISKEMULATOR TERMLINTERTUBE III TML16 MEG CDC H.DISK40 MEG CDC H.DISKCORDLESS PHONESSHUGART DRIVESTRACTORSSHUGART 5 MEG DSK

SYSTEM 164K + 750 K DISKCRT & S100 BUSIN 1 INTEGRAL UNIT

CBASIC 80CIS COBOLMAIL MERGEDATASTAR

SUPERBRAIN1850.002195.002795.00

495.00495.00

3950.004750.00

135.0095.00

150.001500.00

3750.00

150.00420.00

55.00190.00

COMPUSTAR COMPUSTAR64K MDL 10 VPU 1595.0064K MDL 15 PRNT 1495.0064K MDL 20VPU 2295.0064K MDL 30 VPU 2495.0064K MDL 40 VPU 2795.0010 MEG INTERTEC 2950.0032 MED INTERTEC 7950.0096 MEG INTERTEC 8500.00BUS PROGRAM 975.00BUS MANUAL 9.00S100 CONTROLLER 750.00

SYSTEM 264K + 5.3 M DISKCRT Et S100 BUSIN 1 INTEGRAL UNIT

FORTRAN -80PASCAL UCSDSUPER SORTBASCOMPILER

5550.00

200.00275.00120.00190.00

PRINTER * PRINTER * PRINTEROKI MICRO -80 395.00CENTRONIC 737 425.00EPSON MX80 395.00TEXAS 810 1395.00DIABLO 630 1595.00NEC 5530 1595.00NEC 5510 1695.00NEC 5525 1895.00QUME 5/55 1950.00SHEET FEED 750.00CP.M (TM) FREE.00

SYSTEM 364K + 10.6 MEGCRT Et S100 BUSIN 1 INTEGRAL UNIT

COBOL -80WORD -STARCBASICTEXTWRITER

7250.00

320.00195.0075.0075.00

OUR PRICE INCLUDES THE FOLLOWING FREE TRAINING SESSION (2 HOURS) DELIVERY 5/10/15/20 DISKS 'DEPENDINGON TOTAL SYSTEM' CABLES 6 MONTH WARRANTY 'MACHINE SWAP IF DEFECTIVE IN 3 WEEKS' 24/48 HOUR REPAIRSERVICE AT OUR OFFICES ALL ITEMS IN STOCK PAPER ' WITH PRINTER' 10% OF HARDWARE PRICE IN SOFTWARE ASFREE DISCOUNT RIBBONS Et THIMBLES WHERE APPROPRIATE. TROUBLE -SHOOTING PROGRAMS AND SELECTIONS OFMOST IMPORTANT CHIPS AVAILABLE FOR 50.00.IF YOU WISH TO MAKE THE WARRANTY TO 1 YEAR THEN ADD 5% OF HARDWARE COST. OTHERWISE NO MAINTENANCE

SCHEDULE, SIMPLE AD -HOC CHARGES AFTER WARRANTY EXPIRATION, SAME QUALITY SERVICE.

1

CALLERS ONLY BY APPOINTMENT AT ONE OF OUR LONDON OFFICES. TELS 01.636.8210 AND 01.631 4818 (TONY WINTER)

PRACTICAL COMPUTING May 1981

Circle No. 109

17

The quality of the newSCRIPTA

daisywheel printeris astonishingly good

-and so's the price from CPSA lot is written about the quality of daisywheel

printers, but how many people would be prepared to use

one to make up an advertisement ? **This paragraph was

actually printed on a SCRIPTA RO daisywheel printer for

reproduction in this advertisement.

lommillimimmoompb.Manufactured in West Germany by world renowned

Olympia International.The SCRIPTA RO (receive only) model and the

SCRIPTA KSR model which incorporates a full electronictypewriter keyboard, including auto corrector facility.

Both models are available with IEEE, RS232 Serialand Parallel Interfaces. So if you have a COMMODORE,APPLE, TANDY, SUPERBRAIN, NORTHSTAR HORIZON,CROMENCO, SORCERER, SHARP, 380Z etc. etc. CPShave a SCRIPTA printer for you.

* * Will your printer pass the CPS underline test?There is a choice of several different daisywheel type

styles and both printers use low cost carbon ribboncassettes.

The equipment comes with a 90 day warranty.CPS offer a full on -site maintenance contract.You can buy, lease or hire your SCRIPTA from CPS.

Accessories available:Rutishauser Tractor Feed £175+VATRutishauser Cut Sheet Feed f395 +VAT

Contact Nick Ashburner today at: -

(DATA SYSTEMS)LTDThird Floor, Arden House, 1102 Warwick Road, ocks Green,Birmingham B27 6BH. Tel: 021-707 3866

A member of the CPS Group.

18

1410rdP qUalitytS

rOcesso_nr. r frois-"vordy pal "I(ceil46'o,7241.404CrASI.F1447.

- a''-14,04°- sc8z07-48°0 qi

FREE Data Desk

Circle No. 110PRACTICAL COMPUTING May 1981

HOW READYIS YOUR

READY-MADEFACTORY?

Finding the right unit factory for YOU involves a lot more than square footage!What are you getting for your money? Will you have to pay for essential services?

In Northampton we've been designing for Industry for over 10 years and knowyour needs better than most. Our unit factories are designed and built to a highfinish and come complete with heating system, main services, offices & car parking.

All these features at rents around per square foot makeour 5000, 10 000 square feet and larger,unit factories, a shrewd choice if youneed to move or expand-now!

And why Northampton? Find the. Ml's junction 15 on your motorway

) . map for one very obvious reason.- The town's traditional, no nonsense

.11

454- ..t

ir4-1;.t :$ "*;

re

l` 414

;t31'approach to doing businessis another.

NORTHAMPTONContact Donald McLean on 0604 34734

Northampton Development Corporation, 2-3 Market Square, Northampton NN1 2EN

PRACTICAL COMPUTING May 1981

Circle No.111

19

East Computers Lid.SPECIALISTS IN MICROCOMPUTERS AND SOFTWARE119 JOHN BRIGHT STREET, BIRMINGHAM B1 1BETelephone: 021 -632 6458

7

QUANTITY

TRS 80 LEVEL IIGAMES - CassetteE Air Mail Pilot £8.50E Ball Turret Gunner

£8.50O Battleground £8.50E Cosmic Patrol

£12.50E Dare Devil E8.50E Dynamic Device

Drivers £16.50E Flight Path £8.50E Invaders £8.50E Investors Paradise

E8.50 Jet Fighter Pilot

£12.501 Night Flight £8.501-1 Othello £8.50F.1 Romrom Patrol/

Tie Fighter E8.50E Klingon Capture

£6.50r.-1. Space Trek IV £6.50G Skirmish 80 £8.50(1: Winners Delight

£8.50G Your Cribbage and

Checkers Partner£8.50

SCOT ADAMSADVENTUREINTERNATIONAL

Adventure Land£12.50

Our complete package offers you:Free initial discussion and adviceSoftware PackagesSupply and InstallationLeasing and Financing TermsMaintenance ContractsFull After Sales Service

AppleWe offer a full range of equipment from the "Home/Hobbyist" type to the

professional Business System. Ask about our "Starter packs". Prices from£700 . 00- £5000 . 00 .

SharpWe offer the full range of Sharp products from the PC -1211 Pocket

Computer to the 48k MZ-80K with Disk Drives and Printers, we will also bestocking shortly the New Sharp PC -3200 computer system. Prices from£100-£3500.00.

Delta SystemsA range of Z80 based Micro -computers starting at 64k with 1Meg of 8"

Floppy Disk Store, expanding to 512k with 34 Meg of Hard Disk Store andTape Back-up. Prices from £2500-10500.00.

THIS MONTH'S SPECIAL OFFERTELE VIDEO 912C TERMINAL

ANY £485.00 + VAT

softwleiN'' uKII DEALER ENQUIRIESINVITED1\10\N AV L"

Approved Business Dealers for:Apple II Plus Delta SystemsSharp MZ8OK Onyx Systems

As fully authorised Dealers for all the above equipment and as experi-enced computer professionals, we are the best people to assist you inchoosing your computer system.

Onyx SystemsThe C8000 series are a range of powerful small business computers from

Onyx Systems. This state-of-the-art computer system combines high speedprocessors, memory, Winchester disk and cartridge tape drive in oneefficient, compact package.

Industry -compatible versions of BASIC, COBOL, PASCAL andFORTRAN are available on several operating systems leg. CP/ M), along

with communications software, wordprocessing and business applicationpackages.

The C8000 series offers more features, better performance, higher qualityand greater reliability than any other unit for the price. Prices from £6500-£15000.00.

We also supply a full range of printers both dot matrix and daisywheel,connection cables and also media (diskettes and disks), stationery (listingpaper), ribbons etc. etc.

Contact us for all your requirements, write or telephone for full details andprice lists.

E Kid Ventures E12.50O Galactic Empire

£12.50E Ghost Train £12.50E Mission Impossible

E12.50 Mystery Fun House

E12.505 Pirates Adventure

£12.50E Pyramid of Doom

112.50 Slag £12.50El Star Trek 3.5 E12.50O Strange Odyssey

£12.50 The Count £12.50E Voodoo Castle

E12.50

EducationO IQ Test £8.50E Teacher £8.50E Vocabulary Builder

8. 50Video Speed -Reading

Trainer £8.50 Word Watch £6.50

UtilitiesEl BP A Basic

ProgrammingE12.50TRS 80 Utility

£8.50

TRS 80 Utility £8.50TLDIS 16K, 32K,48K E12.50The Disassembler16K, 32K, 48K £8.50

Home (Personnel)Use

Body Buddy E8.501 Energy Audit £40.50

Personal BillPaying £6.50

BusinessExecutive ExpenseReport Generator

£8.50Oracle 80 £61.50Sales Analysis

120.50Terminal 80 £20.50The Wordslinger

£24.50

Misc.Demo II £6.50Demo II £6.50TRS 80 Tests £8.50IRV £20.50

TRS 80 DisksUtilitiesO Disk EditorO Disk ScopeE DLDISO IRVE Oracle 93

(33.001E16.50£16.50£24.50£81.50

GamesScot AdamsAdventureInternational Adventureland/

Pirate's Adventure/Mission ImpossibleAdventure 13 pack)

£33.00D Galactic Empire

Galactic TrilogyE33.00

D Local Call forDeath £16.50

D Mystery FunHouse/Pyramid of Doom/Ghost Town13 pack) £33.00

E l Six Micro StoriesE12.50

Star Trek 3.5 £16.50O Two Heads of the

Coin £16.50E Voodoo Castle/

The Count/Strange Odyssey

133 00

SOLE UKDISTRIBUTORS!!

BusinessGalactic SoftwareLtd

Mail list (Model 1version) E81.50Mail list (Model2 version) £162.50

TRS 80 Level I & IIEducation

Grade Book £8.50Ham Package 1

ES 50Electronics 1 £6.50Typing Teacher

£8.50

GamesAir FlightSimulation £8.50Chessmate 80

£16.50Oil Tycoon £6.50Space Trek II

£6.50Santa PoraviaFiumaccio £6.50

Apple DisksGames

Air FlightSimulation £16.50

Apple Fun (16.50Golf £6.50Mimic £6.50Oil Tycoon £8.50Paddle Fun £16.50Santa Poravia andFiumaccio £8.50Sahara Warriors

£6.50Space Wars £6.50Super Shooters

£8.50Sky Bombers II

£16.50

Scot AdamsAdventureInternational

Adventure/ PiratesAdventure/Mission ImpossibleAdventure13 pack) £33.00Asteroid £16.50Mystery FunHouse/Pyramid of Doom/Ghost Town13 pack) £33.00Voodoo Castle/The Count/Strange Odyssey13 pack) £33.00

EducationMath Fun £16.50

7 Math Tutor I

G1 Math Tutor II£6.50

£6.50

Home (Personal) UseSolar (Energy)Home £33.00

BusinessAccountantsAssistant £6.50Finance andInvestment 116.50

PETEducation Ham Package 1

£6.50Electrical Engineer'sAssistant £8.50

UtilityE Pet Utility 1 £8.50

GamesE Trek X £6.50 Dungeon of Death

£6.50G Santa Poravia and

Fiumaccio E8.50

Instant Software Support SystemInstant Software offers a special support and reporting system to enable the users of our software to get the very best support and

advice on how to gain the maximum benefit from our products. Enquiries will be actioned promptly to provide a first class service."TRS-80 Trademark of Tandy Corp. CP/M Trademark of Digital Res.CBasic Trademark of Compiler Systems. Apple Trademark of Apple Inc. E&OE

Please use this page as an order form: Tick program required

Name

Address

Tel

Cheque/PO NoAll prices include VAT @ 15% packing & return postage to U.K. addresses.Send 50p. for descriptive Catalogue. PC5 81

LOBO'S NEW LDOS puts muscle In your TRSEICILOGO DRIVES' new LOOS' Disk Operating System is loaded with new outstanding

features that will enable you to realise the full power and potential of your TRS-80. WithLDOS, you can support up to eight drives 15" and 8" drives, double -sided drives, doubledensity drives, 80 track drives), including the new 8" and 5" Winchester fixed disk drives, inany combination.

Other LOOS muscle building features include:ISAM accessing techniques: keyboard typeahead; Graphic string packer: Dated files;

Marked files; File transfer by class; Built-in lowercase display drivers; Non -breakable AUTOand DO commands, and many, many more.

LOOS is the perfect operating system to use with your expansion interfaces and disksubsystems.'TRS-80 is a registered trademark of Radio Shack & Tandy Company.

SPECIAL INTRODUCTORY OFFER £99

20

Circle No. 112

PRACTICAL COMPUTING May 1981

Circle No. 113 0,

Since its introduction the Sharp MZ-80K has proved to beone of the most successful and versatile microcomputersystems around. Sharp now have a comprehensive range ofproducts ready to make the powerful MZ-80K with itsPrinter and Disc Drives even more adaptable.

Products include:- Universal Interface Card, MachineLanguage and Z-80 Assembler packages, CP/M* plus acomprehensive range of software.*Trade mark of Digital Research Ltd.

AVONBCG SHOP EQUIPMENT LTDBnstol, Tel: 0272 425338DECIMAL BUSINESS M/Cs LTDBristol, Tel: 0272 294591BEDFORDSHIREH.B. Computers (Luton) LtdLuton, Tel: 0582 416887BERKSHIRENewbear Computing Store LtdNewbury, Tel: 0635 30505BIRMINGHAMCamden ElectronicsSmall Heath, Tel 021-773 8240E.B.S. LtdBirmingham 1,Tel: 021-233 3045Newbear Computing Store LtdBirmingham 826, Tel: 021-707 7170BUCKINGHAMSHIREInterface Components LtdAmersham, Tel: 02403 22307CHESHIREChadesworth of Crewe LtdCrewe, Tel: 0270 56342Cash Register ServicesChester. Tel: 0244 317549Fletcher Worthington LtdHale. Tel: 061-928 8928Newbear Computing Store LtdStockport Tel: 061-491 2290CLEVELANDHunting Computer Services LtdStockton-on-Tees, Tel 0642 613021DERBYSHIRELowe Electronics LtdMatlock, Tel: 0629 2817DEVONCrystal Electronics LtdTorquay, Tel: 0803 22699

GET ITALLEXETERPeter Scott (Exeter) LtdExeter, Tel. 0392 73309DORSETSouth Coast Business M/CsFerndown, Tel. 0202 893040ESSEXProrole LtdWestcliff -on-Sea, Tel: 0702 335298GLOUCESTERSHIREGloucestershire Shop Equipment LtdGloucester, Tel. 0452 36012HAMPSHIREAdvanced Business ConceptsNew Milton, Tel 0425 618181Xitan Systems LtdSouthampton, Tel: 0703 38740HERTFORDSHIREKing Pin ComputersStevenage, Tel: 0438 59677KENTVideo Services (Bromley) LtdBromley, Tel: 01-4608833

LANCASHIREB & B Computers LtdBolton, Tel 0202 26644H.R. Control Systems LtdChodey, Tel: 02572 75234Sound ServiceBurnley, Tel: 0282 38481Sumita Electronics LtdPreston, Tel: 0772 55065LEICESTERSHIREArden Data ProcessingLeicester, Tel: 0533 22255Gilbert ComputersLubenham, Tel 0858 65894

Leicester Computer CentreLeicester, Tel: 0533 556268LINCOLNSHIREHowes Elect & Autom. Servs.Lincoln, Tel- Lincoln 32379Z. R. Business ConsultantsLincoln, Tel: 0522 680087LONDONBridgewater AccountingWhetstone, Tel: 01-446 0320Butel-Comco LtdHendon, Tel. 01-2020262Central Calculators LtdLondon EC2, Tel. 01-729 5588Digital Design & DevelopmentLondon W1, Tel: 01-387 7388Euro-Calc LtdLondon WC1, Tel: 01-405 3223Euro-Calc LtdLondon EC2, Tel: 01-729 4555Euro-Calc LtdLondon W1, Tel: 01-636 5560Keen Computers LtdLondon EC1, Tel. 01-248 7307Lion Computer Shops LtdLondon W1. Tel: 01-6371601Personal Computers LtdLondon EC2, Tel: 01-626 8121Scope LtdLondon EC2, Tel: 01-247 8506Sumlock Bondain LtdLondon EC1, Tel: 01-253 2447MANCHESTERSumlock Electronic Services LtdManchester 3, Tel 061-834 4233Sumlock Software LtdManchester M3,Tel: 061-228 3502

You'll find all the help and advice you need aboutthe MZ-80K at your Specialist Sharp Dealer in the list below.

If there is no dealer in your area, or if you require any furtherinformation write to: -Computer Division,Sharp Electronics (UK) Ltd.,Sharp House, Thorp Road,Newton Heath,Manchester M10 9BE.

Computers that talk your language.

SHARP

HEREMERSEYSIDEMicrodigital LtdLiverpool, Tel 051-227 2535Sota Communication SystemsLiverpool L14, Tel 051-480 5770MIDDLESEXCream Computer ShopHarrow, Tel: 01-380 0833NORFOLKSumlock Bondain (East Anglia)Norwich, Tel: 0603 26259NORTHAMPTONSHIREH.B. Computers LtdKettering, Northamptonshire,Tel: 0536 520910NORTHERN IRELANDO & M SystemsBelfast, Tel- 0232 49440

NOTTINGHAMSHIREKeen Computers LtdNottingham, Tell 0602 583245Mansfield Business M/C LtdMansfield, Tel 0623 26610OXFORDSHIREOxford Computer StoreOxford, Tel: 0865 4 51 72REPUBLIC OF IRELANDO'Connor Computers LtdGalway, Tel: 0009 61173Tomorrows World LtdDublin 2,Tel: 0001 776861SALOPComputer CornerShrewsbury Tel: 0743 55166SCOTLANDA & G KnightAberdeen, Tel 0224 630526Business and Electronics M/CsEdinburgh, Tel: 031-226 5454

Micro CentreEdinburgh, Tel: 031-556 7354MicroforthDunfermline, Tell 0383 34954Moray Instruments LtdElgin, Tel: 0343 3747Pointer Business Equipt LtdGlasgow, Tel 041-332 3621Robox Data Systems LtdGlasgow, Tel 041-221 5401Tyseal Computers LtdAberdeen, Tel: 0224 573111

SOMERSETNorsett Office Supplies LtdCheddar Tel 0934 742184SOUTH HUMBERSIDESilicon Chip CentreGrimsby, Tel 0472 45353SOUTH WALESCity RadioCardiff, Tel: 0222 28169STAFFORDSHIREW. B. Computer ServicesCannock, Tel: 0543 75555SUFFOLKC.1. R. Microtek Co. LtdIpswich, Tel: 0473 501 52SURREYPetaled Electronic ServicesWoking Tel: 04862 69032R.M.B. LtdCroydon, Tel: 01-684 1134Saradan Electronic ServicesWallington, Tel: 01-669 9483T & V Johnson (Microcomputers)Camberley, Tel: 0276 20446SUSSEXM & H Office EquipmentBrighton, Tel: 0273 697231

TYNE & WEARP.M.S. LtdSunderland.Tel: 0783 480009WALESLimrose Electronics LtdWrexham, Tel: 097 883 5555Morriston Computer CentreSwansea, Tel: 0792 795817Sigma Systems LtdCardiff, Tel: 0222 21515WARWICKSHIREBusiness & Leisure MicrocomputersKenilworth, Tel 0926 512127YORKSHIREBits & P.C:sWetherby, Tel. 0937 63744Datron Micro -Centre LtdSheffield, Tel: 0742 585490Huddersfield Computer CentreHuddersfield, Tel. 0484 20774Neecos (D.P.) LtdDarlington, Tel: 0325 69540Quadraphenia LtdSheffield, Tel 0742 77824Ram Computer Services LtdBradford, Tel 0274 391166Yorkshire Electronic Servs.Leeds, Tel- 0532 522181

Erase Eproms in 8 minutes

for under £100

The high speed, high capacity model UV8 sets newperformance and price standards.

Cuts typical erasure times by a factor of 5 8 MINUTE SOLID STATE TIMER Capacity up to 14 EPROMS 2708 type erased in 4 to 7 minutes High intensity 254 NM UV source Safety interlock automatically starts timing sequence Audio tone signals erasure cycle complete Internal switch to extend erase time.

MICRODATA Computers Ltd, Belvedere Works, BiltonWay, Pump Lane Industrial Estate, Hayes, Middlesex.

Telephone (01) 848 9871 (6 lines) Telex 934110

Circle No. 114L.

THE COMPLETE DATA ENTRY ElRETRIEVAL AND UPDATE SYSTEM

FOR YOUR MICRO

DataStar mTakes the drudgery of outdata -entry programming!

Use DataStar to generate screen layouts, validate datainput and update files.

DataStar has horizontal and vertical scrolling facilitiesfor large forms, and performs search/retrieval and arith-metic operations. Produced by MicroPro International,the company that created the famous WordStar word-processing software.

DataStar is the complete data entry and retrieval packagefor £180; manual available for £29, refundable againstpurchase of software. Runs on Z80/8080/8085 microsunder CP/ M or CP/ M compatible operating systems.

CONTACT US TODAY!

HELISTAR SYSTEMS LTD.150 WESTON ROAD, ASTON CLINTON,

AYLESBURY, BUCKS HP22 5EP.

III

III

I

Circle No. 115

A- c_t I&J COMPUTERS UisooRs. ,,,,-°'

3 CRUNDALE AVENUE, KINGSBURY NW9 9PJ 01-204 7525

THE "PET" SPECIALISTS

NEW LOW, LOW, 'PET' PRICES!! SOFTWAREAs well as a full range of Petsoft and Commodore Software, wehave some highly reliable "Home -Brewed" programs available.STOCK CONTROL Et INVOICING £60(Handles up to 500 items - 32K) (180 on 16K). Stock depleted oninvoicing, search etc. Cassette, disk (Et print option).CASH BOOK £90Enter daily/weekly amounts - printout and totals, weekly/monthlyanalysis, totals and balances.MACHINE HIRE Typewriter 8- Plant Hire Firms. £420STOCK TAKING Cuts out all the hard work £230OUTSIDE SERVICES (For Mini -Cabs Etc) £220Sae for free software booklet

Pet 8K (Large keys) £420*16K £499*32K £630*

Ext cassette decks) + counter) £ 55*PET Friction Feed printers £350*

TRY US!YOU WILL NOT BE

DISAPPOINTEDAVAILABLE FROM STOCK + V AT SUPERPETS NOW EX -STOCK'PrintersDisc Drives SundriesPET 3023 PET 3040 Tool kits: library casesPET 3022 Compu 400K Disks: C12 CassettesCentronic 779 Compu 800K Paper (roll Et tractor feed)Spinwriter Interfaces Labels: Dust covers

SPECIALS FOR THIS MONTH:PETMASTER SUPERCHIPS - UPGRADE YOUR PET EVEN MORE)A FEW ONLY: Brand New CENTRONIC 779 t/f printers £590*

Brand New PET 2023 f/f printers £320 Commodore Business ProgramsSpecialists in: Bristol Trader, Item 8- Monitor

Superpay Word ProcessingTHE "MUPETs" ARE HERE!3 TO 8 PETs ONLY NEED 1 DISK DRIVE . . .

Daily demonstrations: Ring for details.SPECIALISED SOFTWARE APPLICATIONSUNDERTAKEN. RING FOR DETAILS

°ow.. 17'3zarnI COMPLETE SYSTEMS

ANN. -- FROM £1700!!- a----- _.

2 FOR JUST OVER THE PRICE FOR 1!We now have limited stock of NEWCASSETTE DECKS, with built-inCOUNTER + SOUND BOX FOR PETS.AT ONLY £65* EACH.Orders dealt with in strict rotation

THE SYSTEMS WE SUPPLY Et INSTALL ARE COMPLETE:ESTIMATES GIVEN FREE WITH NO HIDDEN EXTRAS:

FULL BACK-UP: GUARANTEED EXPERTISE.lit PRICES DO NOT INCLUDE VAT

PERSONAL SHOPPERS WELCOME ALL GOODS SENT SAME DAY WHEREVER POSSIBLEPhone & Mail Orders accepted. LARGE S.A.E. FOR LISTS ETC.

VISA

22

Circle No. 116

PRACTICAL COMPUTING May 1981

TIU 1011 electronics48 JUNCTION ROAD, ARCHWAY, LONDON N19 5RD 100 yds FROM ARCHWAY STATION ft 9 BUS ROUTES

TELEPHONE 01-263 9493 263 9495

YOUR SOUNDEST CONNECTION ,I N THE WORLD OF COMPONENTS AND COMPUTERS

8N BK RAM

16N 26K RAM

32N 32K RAM

CASSETTE DECK

£399

£499

£599

f55

343K Twin Floppy Disk£695

PETS Et SYSTEMSNEW32K with 80 col ScreenTwin Disk Drive 950K

£825£895

All with new keyboardand green screenFriction Feed Printer

£375Tractor Feed Printer

£425

MEMORY EXPANSION KITSuitable for UK101, Superboardexpansion using 211 4's each boardhas 16K ram capacity kit contains* On board power supply* 4K Eprom expansion* Fully buffered for easy expansion

via 40 pin socket* 8K kit* 16K kit

Printed Circuit Board40 pin - 40 pin header plug

COLOUR BOARD1 ---Available at long last.

Please write or phonefor details. £84.95

E79.95

f106.95f29.95

f8.50

CASESAvailable forU.K. 101, SuperboardNascom,Appx. DIM. 1 7" x 15"435 x 384 mm

PRICE £24.50Post Er Packing £1.50

I1

NEW SHOPNEXT DOOR

"WOOLLIES'

(NORTHERN LINE)ARCHWAY

STATION

JUNCTION ROADA400

UPPER HOLLOWAYL MR & ER STATION

UK101 P.P.I.BUILT Es TESTED. INTERFACES TX80PRINTER DIRECT, CAN BEPROGRAMMED TO OPERATE RELAYS,MOTORS, VARIOUS OTHERPERIPHERALS 'CENTRONICSCOMPATABLE' PLUS INTO IC SOCKET.RED I 11111 DISPLAY LED BINARY DISPLAYFULL DOCUMENTED £29.95

PRINTERS

EPSON TX80 £295EPSON MX80 £359

Dot-matrix printer with Petgraphics interface: Centronicsparallel, options: PET, Apple and

serial.

St JOHNSWAY

O

VIDEO GENIEbased on TRS80

Utilises Z80, 12k level II Basic,Integral Cassette Deck, UHF 0/P.16k RAM,

all TRS80 features

£289

UK101£179 IN KIT FORM£229 READY BUILT

& TESTED£255 COMPLETE

IN CASE4K EXPANSION(8 x 2114)now only £14.00No extras required* Free sampler tape* Full Qwerty keyboard* 8K basic* Ram expandable to 8K

on board (4K inc)* Kansas City tape interface* NEW MONITOR ALLOWS FULL EDITING & CURSOR CONTROL

£22.00

Please add VAT 15% to all prices. Postage on computers, printers and cassette decks charged at cost, all other itemsP&P 30p. Place your order using your Access or Barclaycard. (Min tel order £5). Trade and export enquiries welcome,credit facilities arranged. \k, wcloolx

PRACTICAL COMPUTING May 1981

Circle No. 117

23

LONDON COMPUTER CENTREEPSON MX80 FT £395

WITH

DUAL PRINT MODES+ ROLLER ATTACHMENT

CORRESPONDENCE QUALITY AND STANDARD DOT MATRIX IN ONE LOW COST UNIT

LETTER LIKE PRINT QUALITY

3 -WAY PAPER HANDLING1. Letterheads or A42. Fanfold3. Paper Rolls

LOW NOISEThe quietest dot Matrix Printer132 COLUMNS PER LINEDirectly replaces big, expensive printers, eg:Texas 810, Centronics 700HIGH RELIABILITYPrecision engineered by Shinshu Seiki asubsidiary of Seiko Watch Co. of JapanDial 01-388 699112For fast action and serviceFOR A DEMONSTRATION CALL INTO:

43 GRAFTON WAY, LONDON W1P 5LA (Opposite Maples)Tel: 388 699112 OPENING HOURS: 11-7 MON-FRI 12-4 SAT

24 hour answer phone: 01-388 5721 Circle No. 118

OVewBearBETTER PRICES!BETTER DELIVERY!WIDEST RANGE OFSOFTWAREFor the best dealfrom the largestsharp dealerphone Newbear(0635) 30505

Many unique productsZen/Listings/Word Proc.

SHARP

AppleII plus

licIPPie

For ex -stock delivery12 months warranty

Computing Store Ltd

ACORNPROM PROGRAMMERS

PROM ERASERS

KEYBOARDS

51, AND 8"DISC DRIVES

WIDEST RANGEOF BOOKS IN U.K.

and Bear careBear Bargains

NORTHSTAR

* HORIZOInstalled on your site with full fieldservice anywhere in U.K. fully C.P.M.compatible. Chosen by Newbear forits reliability and performance.64K Dual Drive Quad £1995.00North Star HorizonNewbury Laboratory 7009 terminal £795.00Citoh8300 R.M. Printer £499.00CPIM 2.2. f95.00

EPlease send urgently:Sharp El ANorth Star Horizon 0 Cat. 0Booklist 0 CitohE N.L. Terminals 0Please contact me 0 Phone NoNameAddress

24

8!

NEWBEAR 'COMPUTING STORE LTD. (HEAD OFFICE)40 BARTHOLOMEW STREET, NEWBURY, BERKSTEL. (0635) 30505 TELEX 848507 NCSFIRST FLOOR OFFICES, TIVOLI CENTRE, COVENTRY ROAD.

BIRMINGHAM. TEL. 021 707 7170220-222 STOCKPORT ROAD, CHEADLE HEATH, STOCKPORT.TEL. 061-4912290

Circle No. 119

PRACTICAL COMPUTING May 1981

PROFESSIONAL

SUPERBRAINSOFTWARE

COMPILERS Et UTILITIESMicrofocus CIS COBOL:- Standard compiler £425- Forms -2 utility £100NB We are the sole UK distributors of Microfocus products on theSUPER BRAIN .

Microsoft:- MBASIC interpreter £155

BASIC 80 compiler £200- COBOL 80 compiler £390- FORTRAN 80 compiler £260- MACRO 80 assembler £ 85Micropro:- WORDSTAR (word-processing) £230- Mailing list merge for above £ 65- DATASTAR (data management) £160- SUPERSORT £130The Micro Solution Ltd:- REPORT GENERATOR £100

(this superb data management tool allows you to produce inter-actively a COBOL program to select records from a file and printthem in your layout)

- BSTAM (inter machine Transfer)... £ 75

APPLICATIONS SOFTWAREThe Micro Solution Ltd:- Integrated Accounting System £750- Stock Control System £400- Bill of Materials System £400These three modules interlock as required tomake a superb total business system.Half day free training is included in the aboveprice for each module.The Accounting system includes:- Sales/Purchase/Nominal Ledgers + VAT- Final Accounts/ Profit 8- Loss/ Bal sheet- Invoicing- Open Item or Balance ForwardThe Stock Control system includes:- Order processing/Auto. Reordering- Picking List productionOthers:- Television Rental system £800- Estate Agents' system £475- CP/ M Specials (Auto Load etc) . . . POA

SUPERBRAINS AVAILABLE FROM STOCK,

FROM £1600 Subject to exchange rate fluctuation

ADD VAT AT STD. RATE TO ALL ABOVE PRICESPOSTAGE AND PACKING WILL BE ADDEDDELIVERY NEXT DAY FOR STOCK ITEMS

** CASH WITH ORDER - DELIVERY FREE

DEALER ENQUIRIES WELCOME

111MTINVItt.tAti NFSf

YCltM

101.1, KAM!

Contact:Park Farm HouseHeythropChipping NortonOXFORDSHIREOX7 5TW

telephone:CHIPPING NORTON (0608) 3256ask for: Bill Whaley

Or

Bede Dunlop

PRACTICAL COMPUTING May 1981

Circle No. 120

25

CRYSTAL ELECTRONICSCC ELECTRONICS

SHARP FAZSOKFor the latest competitive

PRICEContact us

Before you accept discounts elsewhere.GIVE US A TRY

CRYSTAL ELECTRONICS is the home of XTAL BASICACCLAIMED BY MANY

Bi-directional serial board for your SHARP RS232compatible ' <150 Baud to > 2400 Baud adjustable.'5,6,7.8 Bit words. plugs into MZ80 I/O £99.50 plus VAT

MZBOK owners-are you XTAL followers?NO! Then please read on.XTAL BASIC (SHARP)

Takes 5K less memory, has all the features of SHARP BASICPLUS Multi dim strings, error trapping, logical operators,machine code monitor, more flexible peripheral handling,improved screen control, increased list control, auto run, If..then.. else-and it doesn't stop there-it grows. You canextend the commands and functions at will -10K, 12K, 16K,BASIC?.

SHARP to XTAL BASIC conversion program is included.£40 plus VAT

Members of Computer Retailers Association & Apple Dealers Association

Shop open 0930-1730 except Saturday & Sunday40 Magdalene Road. Torquay. Devon. England Tel 0803 22699

`AcceTelex 42507 XTALG

N.011 011ssand Barclaycard welcome. imjro,

COMPUTERSAND

COMPONENTS

Circle No. 121

FROM LEADING MANUFACTURER

2732

£11.00

COMPLETEEPROM SERVICE

110 COPYING

No ERASING3110 CUSTOM PROGRAMMING EG TWO 2708

INTO ONE 2716 and ADDRESS CHANGESETC (all prices subject to VAT p + p 60p)

BE fill (itgiSiirg) LTA.307 New Kings Rd., London SW6 4RF.

Tel. 01-736 550314

Circle No. 122

gpoR6555gmagaT005030======p300=3000YuuToa====,4;245,%04p*,:,'400555655555EMS51,M56555517:5P,,k7 " 5par -,,, , g IF,ak '.7-,-1,r,- riot .5,.:.4 4, -rouRvitwalia-' 4,4564

1

544 Cl, ,1 u 1 4,...40...4,,P1/4 ,,4) -047C til 1 qiiVrigpkg p g04=a"300"

ER54,515450gAMEgh#1551d4 ,,,q kgri40-4-10 I"ftitttuffttuttiitttittuttutttttttttt======titEttt45qtM'PAPtttttP !,1 AdttgA

PP4

1, Montague Street,London WC1B 5BP

Telephone: 01-580-9792Telex: MTW 888941 LCCI G

DRAMATIC SPEED INCREASEfor CP/M systems

Is your system painfully slow? Is it forever disk -bound? Do the alternatives look prohibitively expensive?Is 64K of RAM insufficient? At last there is a neat, cost effective solution -

THE SILICON DISK SYSTEMThis remarkable, innovative software package from J.K. Systems Research Ltd., with the addition ofstandard RAM, enables your microcomputer to challenge the performance of many minicomputers.Furthermore, this can usualy be done without making any changes to your existing applicationsoftware.THE SILICON DISK SYSTEM will run on most CP/M and MP/M systems. It allows additional RAM tobe controlled in such a manner as to appear as a super -fast additional disk drive. This memory isorganised using the standard CP/M file structure and therefore can be accessed by programe like anyother disk drive.This form of memory management gives rise directly to:(i) Extended Memory Addressing Capability - up to 8 megabytes of RAM!

(ii) Very fast file accessing - typically 500 times as fast as floppy discs!Sorting and searching long index files, lengthy compilations, database assessing and many other ofthose disk -bound activities which take too long on floppy or even hard disk systems can now becarried out at processor speed. Users of MP/M or CP/NET will find the benefits especially attractive.

ALL THIS FOR ONLY £295Too good to be true? Seeing is believing.Ask your dealer to demonstrate itor contact Microcosm direct. Dealer enquiries also welcome.

Circle No. 12326 PRACTICAL COMPUTING May 1981

HAPPINESSis knowing you have spentonly £259* for your Epson printer

Standard CentronicsInterface make it idealfor your Apple, TRS80 etc.

The MX70 comes with only a Centronics Interface, yet it offersHIGH RESOLUTION GRAPHICS and has a speed of 80 cps !!!We certainly believe we can claim the MX70 is the WORLD'SLOWEST COST 9'/2- TRACTOR PRINTER.And with the name EPSON on it - a subsidiary of the SEIKOWATCH CO of Japan - you can rest assured of its reliabilityand quality.

*80 cps *Uni-directional *Easy to read 5x7 dot matrix*High Resolution Graphics (480x8 dots) *Enlarged Printing*4 National Character Sets *Optional Interface - TRS80,Apple II Plus, Nascom *Top of Form *Self Test *£ sign*Programmable Line Feed *Backspace

THE EPSON DISTRIBUTOR

micro Paelpharals61 New Market Square,Basingstoke, Hampshire RG21 1HW

Tel : 0256 56468 (4 lines) Tlx: 858575Ring Ian for up to the minute prices andtechnical information on a whole range ofJapanese Micro Products

The MX70" price excludes

VAT anddelivery

charges

HIGH RESOLUTIONGRAPHICS - fitted as standard

.1. , /e

4- -41 I -i;12

,e4 ,r1

HIGH RES PRINTOUT WITH MX70 & APPLE

To: Micro Peripherals, 61 New Market Square, Basingstoke, Hants.

Please send me full details of the EPSON range including printout.

Name Position

Company

Address'

(BLOCK CAPITALS PLEASE)PC5A

.1

PRACTICAL COMPUTING May /981

Circle No. 124

27

SUPERBRAIN PLUSINTERTEC DATA SYSTEMS* INTRODUCEDTHE REMARKABLE SUPERBRAIN AT THESTART OF 1980now ENCOTEL SYSTEMS LTD.

introduces SUPERBRAINAll THE STANDARD FEATURES* 64K RAM * DUAL Z8() A's *

DUAL RS -232 COMMUNICATIONS PORTS*CP/M 2.2 OPERATING SYSTEM *

+ 800K DISC CAPACITY STANDARD(STD QD MIC 700K)

+ 1.5 MB OPTIONAL+ FAST DISC ACCESS - FIVE TIMES FASTER THAN STANDARD MACHINES+ KEY REPEAT

+ OPTIONAL TELEX BOARD

SUPERBRAIN + 800K1500K

HARD DISCS 10MB32MB96MB

* (allows up to 255 COMPUSTAR users)6 month warranty - 1 years maintenance agreement £200

£2450£2800£2640£7900£9900

** SOFTWARE **THE BEST RANGE OF SOFTWARInew* 6502/6800/8080/8085/Z80 ASSEMBLER

8048 ASSEMBLERTHE CREATOR BASIC PROGRAM WRITERTHE REPORTER BASIC FILE REPORTERSPELLBINDER WORD PROCESSING

* Demonstrable IBM 3780 EMULATOR (3270 soon)* A DBMS WHICH SURPASSES CODASYL DBMS REQUIREMENTS

GRAHAM DORIAN BUSINESS SOFTWAREBASIC, COBOL, FORTRAN, PL/I, PASCAL (APL soon)DATA ENTRY SYSTEM AND DATA ENTRY TOOL £75 EACH

* ASYNC TERMINAL SOFTWARE £75

WHY ARE SO MANY LARGE COMPANIES COMING TO US?because WE OFFER fast DELIVERY, PROFESSIONAL SERVICE

IBM COMMUNICATIONS EMULATORS, SOUND ENGINEERING ANDSOFTWARE EXPERIENCE, COMPETITIVE PRICES and backup

"c)e

xcc

\) -e'

,4; IS ONLY AVAILABLE FROM THE ENCOTEL DEALER GROUP

TERODEC MICROSYSTEMS LTD Reading, Berks (0734) 664345/6 WORKFLOW LTD Cowden, Kent (034286) 35;BOYD MICROSYSTEMS LTD Bushey; Heath, Herts (01) 950 0303 D D M LTD Brentwood, Essex (0277) 214168 or 229379MAP COMPUTERS LTD Oldham, Lancs (061) 633 3084 ENSIGN LTD Swindon, Wiltshire (0793) 42615MAP COMPUTERS LTD Leeds (0532) 445234 KING PIN COMPUTERS LTD Stevenage, Herts (0438) 59677MAP COMPUTERS LTD Glasgow (041) 204 1297 ISIS COMPUTER SERVICES Henley on Thames, Oxon (04912) 77735DIOLOGUE TERMINALS LTD London (01) 660 0119 NICOMTECH LTD Plymouth, Devon (0752) 669801SYSTEMS MICROS LTD Telford, Staffs (0952) 460 214 ORCHARD MICROBYTE LTD Rayleigh. Essex (0268) 741271MICROMANAGEMENT LTD Ipswich, Suffolk (0473) 4592 BUSINESS CONTROL & DEVELOPMENT Cheltenham, Glos Eves ham (0386) 831969RED VALE COMPUTERS LTD Bury St Edmonds, Suffolk (095381) 316 LABTRONICS COMPUTERS LTD London & Kent (09592) 2872OCEANIC LTD London (01) 488 97.51 I.R. INSTRUMENTS Sanderstead, Surrey 1011 657 7646

Encotel Systems Ltd530 - 539 Purley Way, Croydon, Surrey Telephone: 01-686 968718 Telex 265605

* WE ARE OFFICAL INTERTEC DISTRIBUTORS Circle No. 125

BLACK WHITEORGREENTHE CHOICE ISYOURS.

Black Et White model £85.00 + VAT + £4.50 car.

Green model £95.00 + VAT + £4.50 car.

OVM Video Monitors:-Precision engineered VideoMonitors, with a 9" screen,accepting standard 1.4V P -Pinputs at 75 ohms or highimpedance.

Metal cased, solid state andreliable, white or green.

The choice is yours.

LOWE ELECTRONICSCHESTERFIELD ROAD, MATLOCK, DERBYSHIRE DE4 5LE TEL 06294995

TRADE ENQUIRIES WELCOME

11.

E

Circle No. 126

PRACTICAL COMPUTING May 1981

Val'ead eekieftateitSo65 e.9. Sewer, Eclefeoevte,Weicaz

Ofteg71to.c-'7u 9-530Sat 9.30-5'30

5,11161PaEtWA5E

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NE046912TE PC20856

kk P2 0XCE551416W140/CWG- GOY itILL

dorsilab,

51-00' cavrox/NIESP41140N PORkrYAZ

Tel 01- 952 0526

NEW Pea PE16

CA1432K £69500GSM 3040 flOPIN 1695 00OM 3012 iff NCR 1415 00

NEW W80E00414/

579(16 14-1289500

NEW 1 At& 01.5C

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OWE WOKSd4/5( /51/TERE2115 00

Pinkfhop

OUR SYSTEMS ARE MASTERPIECES -CONE AND SEE THEM!

Circle No. 127

EMG MICRO SYSTEMSEMG 01-688 0088

We are specialists in complete installationstailor made for your business requirements:

WORD PROCESSING SYSTEM £1999INVOICE AND CUSTOMER SYSTEM £2999LEADS AND SALES SYSTEM £2999INSURANCE AGENT SYSTEM £2999ESTATE AGENCY SYSTEM £2999COMPLETE BUSINESS SYSTEM £3999

We are MAIN LONDON SORCERER STOCKISTS

Sorcerer Systems Desk, Mains Stabilisation,Cooling Fan, Memory Upgrades, Servicing

RENTALPlug-in 315K Disk Drive £4.31 per weekVideo Disk Unit £ 5.59 per weekDaisywheel WP System £14.99 per weekWP Correspondence Course, Link your Sorcererto a mainfram or other Sorcerer

Full software list on request

6 COPIES OF SOURCE MAGAZINE ONLY £5

Write to Dept PCA, EMG Microcomputers Ltd,30, Heathfield Road, Croydon, Surrey.

Circle No. 128

29

NASBUS COMPATIBLE

NEWSMore great deals from 6 Nascom Dealers

A NASCOM-2 BASED SYSTEM FOR £1549 +VATThe proven Nascom-2 microcomputer can now Gemini Dual Drive Floppy Disk System.The CPUbe bought as a complete system from £1499 + and RAM boards are also available built - theVAT. For this price you get the Nascom-2 kit, 16K additional cost is availableRAM board kit, Kenilworth case with 2 card frame, on application.Centronics 737 printer, 10 inch monitor,and the

GEMINI G805 FLOPPY DISKSYSTEM FOR NASCOM-1 & 2It's here at lastA floppy disk system and CP/M.

CP/M SYSTEM.The disk unit comes fullyassembled complete with one or two 5k"drives (FD250 double sided,single density)giving 160K per drive, controller card, powersupply, interconnects from Nascom-1 or 2 tothe FDC card and a second interconnect fromthe FDC card to two drives,CP/M 1.4 ondiskette plus manual, a BIOS EPROM and newN2MD PROM.All in a stylish enclosure.Nascom-2 Single drive system. £450 + VATNascom-2 Double drive system £640 + VATNascom-1 Single drive system. £460 + VATNascom-1 Double drive system £650 + VATAdditional FD250 drives £205 + VATD -DOS SYSTEM. The disk unit is alsoavailable without CP/ M to enable existingNas-Sys software to be used.Simple read,write routines are supplied in EPROM.The unitplugs straight into the Nascom PlaSingle drive system £395 + VAT(please state which Nascom the unit is for)Certain parts of the CP/ M and D -DOS disksystems are available in kit form.Details available on request.

KENILWORTH CASEFOR NASCOM-2The Kenilworth case isa professional casedesigned specifically for the Nascom-2 andup to four additional 8' x 8" cardsithashardwood side panels and a plastic coatedsteel base and cover.A fully cut back panelwill accept a fan, UHF and video connectorsand up to 8 0 -type connectors.The basic caseaccepts the N2 board, PSU and keyboard.Optional support kits are available for 2 and 5card expansion.Kenilworth case £49.50 + VAT2 -card support kit £7.50 + VAT5 -card support kit £19.50 + VAT

GEMINI EPROM BOARDThis Nasbus compatible EPROM boardaccepts up to 16,2716 or 2708 EPROMsIt has a separate socket for the MK36271 8KBASIC ROM for the benefit of Nascom-1 users.And for Nascom-2 users, a wait state forslower EPROMs.The board also supports theNascom Page Mode Scheme.EPROM Board (kit) £55 + VATEPROM Board (built & tested) £70 + VAT

CASSETTEENHANCING UNITThe Castle interface isa built and tested add-on unit which lifts the Nascom-2 into theclass of the fully professional computer.ltmutes spurious output from cassette recorderswitching, odds motor control facilities,automatically switches output betweencassette and printer,simplifies 2400 baudcassette operating and provides true RS232handshake.Castle Interface Unit £17.50 + VAT

A -D CONVERTERFor really interesting and useful interactionswith the outside world' the Milham analogueto digital converter is a must.This 8 -bitconverter is multiplexed between fourchannels - all software selectable. Samplingrate is 4KHz.Sensitivity is adjustable.Typical applications include temperaturemeasurement,voice analysis, joysticktracking and voltage measurement.lt issupplied built and tested with extensivesoftware and easy connection to the NascomPIO. Milham A -D Converter

(built and tested)._ £49.50 + VAT

PROGRAMMER'S AIDFor Nascom ROM BASIC running under Nas-Sys.Supplied in 2 x 2708 EPROMs. Featuresinclude:auto line numbering; intelligentrenumbering;program appending;linedeletion; hexadecimal conversion;recompression of reserved words;auto repeat;and printer handshake routines.Whenordering please state whether this is to beused with Nas-Sys 1 or 3. Price £28 + VAT.

DUAL MONITOR BOARDA piggy -bock board that allows N 1 users toswitch rapidly between two separate operat-ing systems. Price (kit) £6.50 + VAT.

NASCOM-2 Microcomputer Kit £225 -VATNASCOM-1 Microcomputer Kit £125 + VAT

Built & tested £140 + VATIMP Printer. Built & tested £325 + VAT

CENTRONICS 737MICRO PRINTERA high performance, low price, dot-matrixprinter that runs at 80cps (proportional) and50cps (monospaced).This new printer givestext processing quality print,And can printsubscripts and superscripts.lt has 3 -waypaper handling and parallel interface asstandard.Serial interface is optional. Price£425 VAT.Fanfold paper (2000 sheets)£18 VAT.

GEMINI `SUPERMUM112 x 8 piggy -back board for Nascom-1offering five -slot motherboard, quality 5Apower supply and reliable buffering with resetjump facility. Price £85 - VAT.

BITS & PC's PCG5 x 4 board which plugs straight intoNascom-2.0perates on cell structure of 128dots, producing 64 different cells.Oncedefined, each cell may be placed anywhere,any number of times on screensimultaneously.Max screen capacity:768cells. Dot resolution:384 x 256 98304.Many other features including intermixing ofalpha -numeric characters and pixels.Price(kit) £60 VAT.

GEMINI 64K RAM BOARDNewly developed Nasbus compatible boardthat can accommodate up to 64K of RAMincluding Page Mode facility. Prices:£110 (16K),£130 (32K),£150 (48K),£170 (64K).Add VAT to all prices.

An prices are correct at time of going to pressand are effective 1st May 1981

All the products are available while stocks last from the Nascom dealers below.(Mail order enquirers should telephone for delivery dates and post and packing costs.) Access & Barclaycard welcome.

BITS & PC'S4 Westgate,Wetherby,W.Yorks.Tel:(0937) 63774.BUSINESS & LEISUREMICROCOMPUTERS16 The Square, Kenilworth, Works.Tel:(0926) 512127.

ELECTROVALUE LTD.680 Burnage Lane, Burnage,Manchester M19 1NA.Tel:(061) 432 4945.28 St Judes, Englefield Green,Egham, Surey TW20 OH B.Tel: (0784) 33603. Tlx:264475

TARGET ELECTRONICS16 Cherry Lane, Bristol BSI 3NG.Tel:(0272) 421196INTERFACE COMPONENTS LTD.Oakfield Corner, Sycamore Road,Amersha m, Bucks.Tel:(02403) 22307.Tlx:837788.

DISKPENThe powerful text editor written for theNascom is now available on a 51 inch floppydisk with a number of new features.PrIce£43.25 VAT.

PORT PROBEAllows monitoring of input and output ofNascom PI 0.This board can generateinterrupts and simulate handshake control.Price (kit) £17.50 VAT.

HEX & CONTROL KEYPADSHexadecimal scratchpad keyboard kit forN1/2:Price £34 + VAT.As above but including (on the same board)a control keypad kit to add N2 control keys toNI .PrIce £40.50 -VAT.

BASIC PROGRAMMER'S AIDSupplied on tape for N1/2 running Nos -Sysand Nascom ROM BASIC.Features includeauto line number,full cross-reference listing,delete lines,find,compacting command, plusa comprehensive line re -numbering facility.Price £13 + VAT.

GEMINI EPROM-PROG.2708 (multi -rail) and 2716 (single -rail)EPROM programmer kit controlled by N1/2PIO.Supplied with comprehensive softwarefor use with Nos -Sys. Price £35.95 + VAT.

HENRY'S RADIO404 Edgware Road, London W2.Tel:(01) 402 6822.Tlx:262284 (quote ref:1400).

ark

==1:1

30

Circle No. 129PRACTICAL COMPUTING May 1981

Discover the full professionalpower of Hewlett-Packardspersonalcomputer.

Now you can extend the HP -85'spower simply by plugging in high-performance printers, plotters andflexible disc systems.Power where you need it.

The HP -85 puts professionalproblem -solving power wherever youneed it. There's a video display withhigh resolution and editing capability.A whisper -quiet thermal printer forhard copies of display graphics andalphanumerics. A magnetic tape unitwith up to 217 K of storage percartridge. And a complete keyboard,including eight keys you can defineyourself. Powerful, easy -to -usefeatures, thanks to HP's extendedBASIC programming language.

Decide the peripherals you need.HP's Interface Bus (HP-IB/IEEE-

488) lets you add up to 14 peripheralsor instruments. No need to write specialoperating programs- HP's peripheralROMs do it for you.

New HP enhancement ROMs andmodules give you access to 80 K bytesof operating system, withoutsignificantly reducing user memory.The HP 2631B printer means high-speed, high -quality printing. And theHP 7225 Graphics Plotter gives youhigh -resolution, publication -qualitygraphics on paper or film.

For extra memory storage, use theHP 82900 series of 51/4" flexible discdrives. Each drive gives you about270 K bytes of formatted storage ondouble -sided, double -density discs.The operating system is in the MassStorage ROM, leaving the HP -85 mainmemory free.

Behind the HP -85 computingsystem is the strength of Hewlett-Packard. Continuous commitment toquality. One -source service and support.

1111111111111111111111.111111111111111111111111111

For more details or ademonstration, contact your nearestHP Dealer shown below.

VEIHEWLETTPACKARD

Contact your nearest dealer for a demonstration. Aberdeen Tyseal Typewriter Services, Tel: 29019; Belfast Cardiac Services, Tel: 625566; Birmingham Anglo American Computing, TelColeshill 65396; Taylor Wilson Systems, Tel: Knowle 6192; Bournemouth South Coast Business Machines, Tel: Wimborne 893040; Brighton Office Machinery Engineering, Tel: 689682;Bristol Decimal Business Machines, Tel: 294591; Cambridge Cambridge Computer Store, Tel: 65334; Chelmsford Automatic & Electronic Calculators, Tel: 69529; Dublin Abacus Systems,Tel: 711966; Edinburgh Business & Electronic Machines, Tel: 226 4294; Holdene, Tel: 668 2727; Glasgow Robox, Tel: 221 5401; Leeds Holdene, Tel: 459459; Leicester Sumlock Services,Tel: 29673; Liverpool Rockliff Brothers, Tel: 521 5830; London Automatic & Electronic Calculators, Tel: 2471886; Euro Calc, Tels: 739 6484,636 8161, 405 3113; Sumlock-Bondain, Tels:2500505, 626 0487; The Xerox Store, Tel: 629 0694; Manchester Automated Business Equipment, Tel: 432 0708; Holdene, Tel: Wilmslow 529486; Newcastle Thos Hill Group, Tel: 739261;Newport Micromedia Systems Ltd, Tel: 59276; Reading CSE Computers, Tel: 61492; Sintrom Electronics, Tel: 85464; Royston (Herts) El ectroplan, Tel: 41171; Southampton South CoastBusiness Machines, Tel: 22958; Sunderland Thos Hill Group, Tel: 42447; Tunbridge Wells D J Herriott, Tel: 22443/4; Wallingford Midas Advisory Services, Tel: 36773; Watford Automatic&Electronic Calculators, Tel: 31571; Woking Petal ect Electronic Services Ltd, Tel: 69032; Worthing Office Machinery Engineering, Tel: 207292; Channel Islands: (Guernsey) ProfessionalBusiness Systems, Tel: 26011, (Jersey) Professional Business Systems,Tel: 75611.

PRACTICAL COMPUTING May 1981

Circle No. 13031

PCS L TUSCAN BASED COMPUTER SYSTEMSWE - SUPPLY SYSTEMS FOR BUSINESS APPLICATIONS USING THE

"TUSCAN" S100 CP/M* MICRO -COMPUTER WITH 5 1/4" OR 8"DISCS.

WE - ADVISE AND CAN WRITE ANY SOFTWARE PACKAGES FOROUR SYSTEMS.

WE - ALSO PROVIDE STANDARD SOFTWARE FOR ESTATE AGENTS,INSURANCE AGENTS, BUSINESS ACCOUNTING AND WORDPROCESSING.

WE - INCLUDE IN OUR PRICES THE DELIVERY, TESTING ANDCOMMISSIONING AT YOUR PREMISES OF COMPLETESYSTEMS FOR 7 DAYS.THEREFORE WE CAN ONLY GIVE THIS SERVICE WITHIN 50MILES OF NEWBURY.

WE - CAN DELIVER HARDWARE, SUCH AS TUSCAN IN ASSEMBLEDFORM TOGETHER WITH DISC DRIVES ETC. TO ANY AREA.

FOR FURTHER INFORMATION PHONE OR WRITE, GIVING DETAILS OF YOUR APPLICATION.

'Reg. trademark.

PURLEY COMPUTER SYSTEMS LTD.21 BARTHOLOMEW STREET,

NEWBURY, BERKS.TEL: 0635 41784 Day Acts

Circle No. 131

KEMITRON ELECTRONICS LTD

The Complete Business SystemThe KEMITRON K3000 Disk Based System is an all BRITISH microcomputer suitable for all Business andEducational applications. The basic unit consists of two 8" floppy disk drives, processor (Z80A), RAM,communications interface and supporting hardware.

Its unique modular design allows the simple addition of more memory or input/output interfaces as andwhen required. This powerful facility can also be applied to the addition of extra disks (up to four).The computer is supported by the CP/M disk operating system which provides all communication betweenthe disks, terminal and printer and includes several utility programs. CP/M is the industry standard and assuch can utilise a wide variety of well supported software which is both readily available and reasonablypriced.

APPLICATIONS* WORD PROCESSING* FINANCIAL PACKAGES* STOCK CONTROL* INVOICING* PAYROLL* ASSEMBLY LANGUAGE. DEVELOPMENT" EDUCATIONAL & LABORATORY COMPUTER* PROGRAM DEVELOPMENT

TECHNICAL DETAILS* Z80A Based - runs at 4 MHz* 32-48 or 64K RAM - Dynamic* Twin RS232 ports - more if required* Twin 8" single sided single density disk drives* Supports CP/M

from £2,300+ VATCHESTER 21-23 CHARLES STREET

COMPUTING - Ring or write for further details HOOLE, CHESTER CH2 3AY

CENTRE TEL: (0244) 21817

32

Circle No. 132

PRACTICAL COMPUTING May 198

WE'RE MAKING ANOFFER YOU CAN'T REFUSE

HARDWAREApple 16K 695.00Disk Drives 299.00Controller 3.3 84.0016K Add-on RAM 56.00Full Colour System 435.009" High Res B/W Monitor 148.009" Black/White Monitor 127.0012" Black/White Monitor 189.00Cable for Monitor 9.0012" Green/Black Cable 166.00

ACCESSORIESSpeech Lab 122.00Speechlink 2000 168.00Pascal Language 299.00Applesoft Card 116.00Integer Card 116.0080 Col Card 162.00Apple Juice 157.00Black/White Modulator 14.00Clock/Calendar Card 168.00Supertalker 179.00Rom -Plus Board 127.89Romwriter 106.00Copyplus Rom 30.00Music System - Complete 312.00Apple Pilot 104.00

INTERFACE CARDSProtype Cards 15.00Parallel Printer Card 104.00Comms Card 130.00Serial Card 113.00Centronics Card 130.00Controller Card 45.00Eurocolour Card 113.00IEEE Interface 212.00

BUSINESS SOFTWAREVisicalc 125,00Desk Top Plan 75.00CCA Database 75.00DMBS Database 100.00Information Master 100.00Data Master 100.00Stock Systems from 100.00Integrated Ledgers 855.00Invoicer 140.00Payroll 375.00Word Processing from 42.00Apple Post 27.00Mailing List 70.00

MISCELLANEOUSDOS Tool Kit 3.3 42.00Animation Pack 42.00Verserwriter 149.00Graphics Tablet 462.00Joy Stick 44.00Revolving Tables 42.00

GAMES. THIS MONTH'S SPECIAL 48K APPLE FOR £695.00WAR OTHER ADVENTURE SHOOTINGBismark 29.95 Monoply 12.00 Invasion Orion 18.00 Wild Western Gunfighter 16.00Ambush 29.95 Olympic Decathlon 20.00 Star Fleet Orion 18.00 Battleship Commander 16.00Napoleonics 29.95 Apple Bowl 9.00 Temple of Apshai 22.95 Bill Budge Space Album 34.00Conflict 29.00 Tranquility Base 20.00 Apple Invaders 12.00 Super Star Base Gunner 18.00Air Combat 22.00 Trilogy 26.00 Moorlocks Tower 18.00 Super Space Invaders 22.00Galactic Trader 22.00 Head -On (Car racing) 22.00 Adventure 24.00 Star Cruiser 22.00Galactic Revolution 22.00 Typing Tutor (Cassette) 14.00 Asteroids in Space 15.00 Bloody Murder (Knife:Throwing). 14.00Galactic Empire 22.00 Gammon Gambler 15.00 Akalabeth 24.00 Hyper Space War 23.00Flight Simulator Bridge Partner 14.00 Hell Fire Warrior 22.95

Cassette or Disk 29.95 Baseball 16.00 Datestones of Ryn 18.00Sargon Chess 30.00Animation Package 44.00

P.D.S. ROAD SHOW IMPORTANT NOTICEP.D.S. will shortly be launching their 1981 road show in the North West On exhibition will be micro and mini Continuing their competitive policy P.D.S. are now offering short and longcomputers, with word and data processing capabilities, memory typewriters and plain paper copiers. Please term rentals for clients in the North West. Ring for details. Our Mail Orderphone for imitation card. Forthcoming venues April 16th Crest Suite, Crest Hotel. Bolton. fith May Buckingham dept. is now open to service all the U.K. If you know your requirements ringRoom, Saxon !no, Blackburn 930am-8pm. for our price.

SUBSTANTIAL DISCOUNTS FOR CASH PURCHASERSWE NOW OFFER ONE FULL YEARS WARRANTY ON ALL APPLE EQUIPMENT

- rofe55tonal Data -Qp5tent5.CARNE HOUSE, MARKLAND HILL, CHORLEY NEW RD, BOLTON. dir2

0204 topple(ALL PRICES SUBJECT TO VAT) 493816

ALL PRICES CORRECT AT THE TIME OF GOING TO PRESS

PRACTICAL COMPUTING May 1 98 1

Circle No. 133

33

eirs,*a Pete & Pam Computerspito Microcomputer hardware & softwareSpecialists in Applefore

Peter & Porn Fisher

WE DISTRIBUTE FOR MICROSOFT, HIGH TECHNOLOGY, STONEWARECOMPUTER STATION, CALIFORNIA PACIFIC, DAKINS, BRODERBUND,STARCRAFT, SUB LOGIC AND MIR ENTERPRISES. DEALER ENQUIRIESWELCOMED.

APPLE --16KEXPANSION BOARDS

At last - Apple users can obtain additionalmemory without the expense of buying alanguage system. Fully compatable withPASCAL, Integer BASIC as well as MicrosoftSOFTCARD. VISICALC owners can also useadditional memory.

Microsoft Ramcard £109.95Andromeda Expansion Board £109.95

(can be changed to allow use of more than one board)

Z-80 SOFTCARD - £169A Z -80A Microprocessor for Apple. ProvidesCP/ M and MBASIC-5. Allows use of COBOL80 - £299.FORTRAN 80 - £109.95 - Basic Complete£195NEW Wordstar, the Prince ofWordprocessors, on APPLE formatted CP/ Mdisc - £250.

THE MILL 6809 BOARD - £169A 6809 processor for APPLE Allows joint useof 6502 and 6809 processors.Coming soon - PASCAL, Patcher - todouble the speed of APPLES UCSD Pascal.

VISICALC - £75A must for every APPLE owner - soon to beenhanced by being linked to INFORMATIONMASTER CCA DATAM Management system£49.95

80 Column BoardsSup -R -Terminal - £195

Videx - £179Apple Pie 80 Column Word Processor

for above -£75

PLEASE ADD 15% VAT TO YOUR ORDERPOSTAGE AND PACKING FREEASK FOR OUR FULL CATALOG

IF YOU KNOW WHAT YOU WANT AND DON'T WANT TO PAYAN INFLATED PRICE

GIVE US A CALL - WE SELL ALL SORTS OF THINGS FOR APPLETEL 01-877 2062124HRS1 7 DAYS A WEEK98 MOVSER ROAD LONDON SW16 6SH

POST OFFICE GIRO NO 585 6450

Circle No. 134

34

UNIVERSITY OF MANCHESTEREXTRA -MURAL DEPARTMENT

Learn Basic Practical BasicA residential course, Sunday evening, 2nd Augustto Friday afternoon, 7th August, 1981, at HollyRoyde, Manchester.All computers use a high level language. Mostmicrocomputers off BASIC as a standard highlevel language. Anyone can learn BASIC!This is for those with no previous experience ofBASIC and probably no programming experience.The whole emphasis of the course will be aleisured approach to the writing of well structuredprograms and the teaching will be as practical aspossible.The fee will be £125 which includes full board andtuition.

Advanced Programming for the PETA residential course, Saturday morning, 19thSeptember to Sunday afternoon 20th September,1981, at Holly Royde, Manchester.A two-day intensive course suitable for peoplewith previous programming experience and aknowledge of BASIC. It will cover writing fasterprograms - writing more efficient programs -introduction to machine code - communicatingwith peripheral devices - peeks and pokes.The fee will be £70 which includes full board andtuition.For full details of both the above courses please contact:

Mrs. Sue EdenDepartment of Extra -Mural Studies,

The University, Manchester, M13 9PL,or telephone 061-273 3333 ext 3076.

Circle No. 135

. FEATURESted

floating cursor edit with Add,- Change, Math, Print and Preview

Autominatcil

st:elrtclienhngatreadc,-

modes. Single key cursor control

ter, Word and Line insertion Forwardand Backward scrolling Automatic on

screen tabbing Auto paragraph indent N., Character Word and Line deletion Block copy,PQQ. save and delete Advanced file handlingGlobal

(multi -file) search and replace Column decimalalignment justification Automatic pagination 6 06' printer tab controls Li ne Centering On -screen

42' zes lower case with Data Shift Adapter (Paymar also suppor-ted) Split -Screen allows editing two portions of a file

simultaneously built In 15 digit floating point calculatorperforms on -screen calculations, column totals and verifiesnumeric data In statistical documents.Maximum file size

20,049 characters. Automatic file linkage (Autolink) provides un-limited file size,Preview a file exactly as It would print. The previewmode carries Autolink operations allowing Inspection of large docu-ments. uses any printer which will Interface with an apple computerPrinting features Include; underline, bold face, superscript, subscript.Complete Software with Full Documentation and Binder £145.00Plus VAT) (Requires 48k Apple II or Apple II plus).

ADDRESS BOOK (Mailing List)In our opinion, the BEST mailing list programme for apple!Stores700 addresses per disk, select by record contents for viewing,labelprinting or may be used in conjunction with Super -Text II.(Requires 48K Apple II or Apple II plus) £49.95 + VAT.

/.1DATA SHIFT (Lower case Adaptor) j4 i...4 -,This ROM simply plugs into your Apple 4c

1l!to display upper and lower case characters .. /./ /

on screen. Data Shift carries a full 96 7"b'k/4., t,,/ )1Character ASCII set £35.75 + VAT. /1,,- ! ,,,,,

See these products at our stockists: I 1 1 .5.,,,..4, q Y

BARNSLEY: Wharncliffe Business Systems Tel(0226) 86819BRISTOL: Decimal Business Machine Te1(0272) 214093 ,6040,,,BRISTOL: Dataforce (UK) Ltd. Tel(0272) 279016 ,e,ve",,,5"CARDIFF: David Porter Office Equipment Te1(0222) 496785 .);.0 ,), q 0 ,ST. HELENS: Page Electronic Developments Te1(0744) 21030 "' 4k 0 .,A;t4 \ ,0 ;(. .1.,WEST BROMWICH: H&H Business Systems Te11038-48312363 ...i... c.,\>,q`, (),-,

oF . c4 4, 44

Circle No. 136

PRACTICAL COMPUTING May 1981

_A ATM;RAM AND EPROM NEW LOW VAT INCLUSIVE PRICES

2716 5v Rail £9-50 4116 200 NS 16KX1 DYN.2716 3 Rail £8-50 2114L-3 300 NS 1KX4 ST.2708 450 NS £4-50 2102L-3 650 NS 1KX1 ST.2708 Ex Equip £2-25 TMS4030JL 300 NS 4KX1 DYN

All devices full spec. and guaranteed. Bulk enquiries welcome.

8 forf19-958 for f22-508forf 5-508forf 9-95

NOW OPENMONDAY-SATURDA

9.30-5.30In stock now test equipment, microprocessors,

to

transformers, power supplies, scopes, sig. gen's,

equipment, I.C.'s, tools, components, vassema

bhriacs, e

ke

transistors, microswitches,V.D.U's sub -

other stock lines. Just a mere fraction of our vast

displayed below: 100's of bargains for callers.

TELETYPE ASR33 ICL TERM IPRI NTER SCOOP PURCHASEI/O TERMINALS 300 BAUD TERMINALS 12"VIDEO MONITORS

k

From £195 + CARVAT

Fully fledged industry standard ASR33 data ter-minal. Many features including: ASCII keyboardand printer for data I/O, auto data detect circuitry,RS232 serial interface, 110 baud, 8 bit paper tapepunch and reader for off line data preparation andridiculously cheap and reliable data storage. Sup-plied in good condition and in working order.Options: Floor stand E12.50 + VAT

Sound proof enclosure £25.00 - VAT

EQUIPMENT CASESGIVE

YOURM.P.U.

A HOMEONLY£9.95

as ppSuperb professional fully enclosed, made for theG.P.O. to the highest standard, offered at afraction of their original cost they featurealuminium sides, hinged removable front panel.which can be secured by 2 screws to preventprying fingers. All are finished in two tone G.P.O.grey and although believed brand new may haveminor scuff marks/scratches due to bad storage.Dimensions 16-13 x 6 "H x 14.4"W

NATIONAL MA1012 LEDk 0

vl

PRICESREDUCED

ONLY£295

CAR+ VAT

Made under licence from the world famous GE CoThe ICL Termiprinter is a small attractive unit withso many features it is impossible to list them in thespace available! Brief spec. as follows; RS232serial interface, switchable baud rates 110, 150,300, (30 cpsl, upper and lower case correspondence type face, standard paper, almost silent running, form feed, electronic tab settings, suited forword processor applications plus many morefeatures. Supplied in good condition and in working order. Limited quantity.

CONNECTDIRECT TOYOUR MICRO

Made by the "BALL MIRATEL" CORPORATION USAthe CD12 is a self contained, mains powered chassisprofessional monitor. All controls are inbuilt on asingle PCB with exception of the brightness controlwhich can be brought out for external use. Manyfeatures such as composite video, quoted bandwidthof 19 Mhz, superb linearity arid definition make this amust far any MICRO/CCTV application.Brand new and boxed only+ carriage £7.50 + VAT. f97.50+ VATInput harness, brightness pot and connector £2.50+ VAT. Dimensions 9"H x 11"D x 11 ON

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ONLY f170 +"."-+ VAT Send E197.50pNote: When order ing please give the address and telephone number where the Tanteladaptor is to be used, we will arrange all details with the Post Office for installation of the

jack socket (normally within 7 days)

*12 HOUR* ALARM* 50/60 HZThe same module as used in most ALARM/CLOCKradios today, the only difference is our price! Allelectronics are mounted on a PCB measuring only3" x 1k" and by addition of a few switches and 5/16volts AC you have a multi function alarm clock at afraction of cost. Other features include snoozetimer, am pm, alarm set, power fail indicator, flash-ing seconds cursor, modulated alarm output etc.Supplied brand new with full data onlySuitable transformer £1.75. £5.25

SEMICONDUCTOR'GRAB BAGS'

Amazing value mixed semiconductors, includetransistors, digital, linear 1. C.'s. macs. diodes, bndgerecs. etc. etc. All devices guaranteed brand new, fullspec. with manufacturers markings, fully guaranteed

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DISCOUNTDue to our massive bulk purchasing programmewhich enables us to bring you the best possiblebargains, we have thousands of I.C.'s, Transistors,Relays, Cap's., P.C.B.'s, Sub -assemblies, Switches,.etc. etc. surplus to our requirements. Because wedon't have sufficient stocks of any one item toinclude in our ads., we are packing all these itemsinto the "BARGAIN PARCEL OF A LIFETIME"Thousands of components at giveaway prices!Guaranteed to be worth at least 3 times what youpay plus we always include something from our ads.for unbeatable value!! Sold by weight

2.5Ids f 4.75+pp f1.25 5Ids f 6.75+pp f1.8010Ids f11.75+pp f2.25 20Ids £19.99+pp £4.75

JUST INSecondhand chassis 9" Blue -best mains powered videomonitors, composite videoinput with inbuilt 5v 3 amp DCP.S.U. Tested, but unguaran-

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MATRIX PRINTERSThis must be one of our greatest bulkdeals, this fabulous printer is listed atover £1800 and judging by theconstruction we are not surprised.Made under license from theLOGABAX Co. the DMZ180 is anexceptionally sturdy high speed 180 cpsmatrix printer, capable of printing up to132 characters per line on standard "Fan Fold" sprocket fed paper. Aprecision 7 x 7 matrix head using ruby bearings, gives a clearconcise type font. Many other features include internal buffer forhigh throughput, standard ink ribbon, software controllable formand tab functions, standard "CENTRONICS" ASCII parallel interfaceetc. etc.Optional extras Floor Stand £30.00 + VAT, Paper Stand £18.00 +VAT

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ELECTRONICSDept. PC. 64-66 Melfort Rd., Thornton Heath, MAIL ORDERCroydon, Surrey. Tel: 01-689 7702 or 01-6896800 INFORMATIONUnless otherwise stated all prices inclusive of V.A.T. Cash with order. Minimumorder value £2.00. Prices and Postage quoted for UK only. Where post andpacking not indicated please add 60p per order. Bona Fida account ordersminimum £10.00. Export and trade enquiries welcome. Orders despatchedsame day where possible. Access and Barclaycard Visa welcome.

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Straight from the U.S.A. made by the world ftVP600 Series of cased freestanding keyboaments of the most exacting user, rightUtilising the latest in switch technology. Out5 million operations. The keyboard has a heincluding full ASCII 128 character set, u

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VP601 7 bit fully coded output with delstrobe, etc.VP611 Same as VP601 with numeric pad.VP606 Serial, RS232, 20MA and TTL output,6 selectable Baud Rates.VP616 Same as VP606: with numeric pad,Post, Packing and Insurance.ORDER NOW OR SEND FOR DETAILS.

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5v D.C. POWER S PPLIESFollowing the recent "SELL OUT" demand for our 5v3 amp P.S.U. we have managed to secure a large quantity of ex -computer systems P.S.U.'s with the followingspec.; 240 or 110v A.C. input. Outputs of 5v @ 3-4amps, 7.2v @ 3 amps and 6.5v @ 1 amp. The 5v and7.2v outputs are fully regulated and adjustable withvariable current limiting on the 5v supply. Unit is selfcontained on a P.C.B. measuring only 12" x xThe 7.2v output is ideal for feeding "on board" regu-lators or a further 3 amp LM323 K regulator to give aneffective 5v @ 7 amp supply.Supplied complete with circuit at only £10.95 +£1 .75pp.Believed working but untested, ungua anteed.

PRACTICAL COMPUTING May 1981 Circle No. 137

35

ELECTRONIC GAMESATARI

SPECIAL PRICE

£86 + VAT

SPACEINVADERS

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Available August 1980This is the most advanced TVgame in the world.Expandablenext year into a fullmicrocomputer.COLOUR CATALOGUEAVAILABLE WITHDETAILS ON ALL THECARTRIDGES

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* 16 Colours or shades of Grey -.1111111=* Multiple High Resolution Graphics Modes(64 x 71, 129x 159, 255 x 335)* Character mode (60 x 24)* Split Screen Modes* Full ASCII Upper Et Lower Character Set* Unique graphical - Sound Commands forSmooth Music, random frequencies Er - . - , i.

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SUPERBRAINSuperBrain's CP/ M operating systemboasts an overwhelming amount ofavailable software in BASIC, FOR -TRAN, COBOL, and APL. Whateveryour application. . . General Ledger,Accounts Receivable, Payroll, Inven-tory or Word Processing, SuperBrainis tops in its class.

320K £1850 700K £24001.5Mb £2750

PRINTERS * RS232 1/F

EPSON TX£30B (inc. 11F Er

cable) £359EPSON MX80 £425ANADEX DP8000 £495ANADEX DP9500 £895ANADEX DP9501 £995PAPER TIGER £585

All as Standard

at only + VAT£595MICROLINE 80 £359IBM GOLFBALL £595CENTRONICS 737 £425NEXOS PETAL £1195

ACULAB FLOPPY TAPEThe ideal graduation from Cassettes for all

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TEL BATH 102251334659AF TER HOURS 10761)33283

36

Circle No. 139

PRACTICAL COMPUTING May 1981

Circle No. 140

INTEGRATED SMALLBUSINESS SOFTWARE

ISBSISBS -FA totally Integrated Small Business Systemdesigned for single user floppy disk basedsystems. ISBS-F is already being used bymany Businesses and Professions throughoutthe UK. Each package can be used asstandalone or can be built into anintegrated system depending on userrequirements. All packages are fullysupported and maintained, and aresupplied with easy to follow ReferenceManuals. ISBS-F is easy to install and ideal forthe first time small Business user with noprevious computer experience.

ISBS -WA Hard disk or Winchester disk basedIntegrated Business Software system which isupwards compatible with ISBS-F. This systemis ideal for the small to medium size userwhere data storage and processing speedexceeds the capabilities of floppy diskbased systems. Choose from anycombination of modules and add others ata later stage if required. The system featuresmany facilities found in minicomputer andmainframe business packages. All modulesare fully supported and maintained andcomprehensive documentation is suppliedwith each installation.

STOCKCONTROL

CONTROL

COMPANYCOMPANYPURCHASES

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ISBS has been designed for most popular 8080/Z80 Microcomputer disk systems running under CP/M'ISBS-F: 48k & 2 floppy disk system, VDU, 132 col printer, CP/M* 1.4 or 2. xISBS-W: 64k & Hard disk(s) system, VDU, 132 col printer CP/M 2 x or MP/MCurrent installations on Rair Black Box, Northstar, Heath, Cromemco, Altos, Superbrain, IMS 5000/8000,Dynabyte, Micromation.For further details and prices contact your nearest dealer or call us direct.

CP/M, MP/M trademarks Digital Research.

araS.MMeriMSYSTEMS GROUP 52 Shaftesbury Avenue London W1 01-734 5970

If this ad. doesn't convince youthat Epson produce the worlds'best low cost quality printers...- the FREE printout samples will!!THE MX 80 FT/1- both single sheet (friction) and continuous

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with up to 3 copies. *Systems Flexibility - full range of optional interfaces andgraphics ROM's. *International Versatility - internally selectable characters UK, USA,

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Please send me full details of the EPSON range including printout. .

Name Position -

Company

Address

PC5/8 1

(BLOCK CAPITALS PLEASE)

38

Circle No. 141

PRACTICAL COMPUTING May 1981

ATHE LOW COST

WAYTO EXPANDYOUR MEMORY

FOR

CIPPIdCOMPUTERS

Apple is a trademarkof Apple Computer Inc.

Pre -testedOne yearwarranty

Available now

16K RAM -£35.0032K RAM -£65.00

Inclusive of VAT and carriage

Please write for order form now

MICROTECHBox 76, World Trade Centre,

Europe House, London El 9AA

Circle No. 142

PRACTICAL COMPUTING May 1981

Trouble with computersupplies?Poor quality!

Delivery delays!Suppliers lack

product knowledge!

Try usA.W. Hawkins & Co. Ltd.We can supply a wide range of:

RibbonsListing PaperDaisywheelsFloppy Disks

From stock atcompetitive prices.

A.W. Hawkins & Co. Ltd.1-5 Clerkenwell Road

London EC1

Tel: 01-253 0768

Circle No. 143

THE. WEST LONDON

microcentre6 Pavilion Parade, Wood Lane, London W12 OHQ Tel: 01-743 9000

`Apple means businessIf you think a microcomputer might help inyour business - perhaps you should betalking to us.

We take care of our customers.

We are geared to provide a complete range ofmicrocomputer services. If you wish, we can:- tailor the hardware to suit your exact needs- find you the right programs- provide all consumables- train your operators- maintain your hardware

And we stay in touch to answeryour questions and sort out anyproblems.

All this at prices you can afford.Even the most expensivesystem is unlikely to costmore than £5000.

Leasing terms are available

01-743 9000 liappia o

Circle No. 144

39

Is it time you hadan Electronic Assistantin the office?

The micro chip has broughtaffordable computing to thesmall business and professionalpractice, as well as to individualsand departments in largeorganisations. Desktopcomputing is now a practicalreality for a host of tasks thatwere too expensive orimpractical on big computers.The microcomputer has becomean Electronic Assistant in theoffice.

Number CruncherAn Electronic Assistant can

help collect, store, calculate andanalyse numerical data.Microcomputers are aidingaccountants, actuaries,administrators, analysts andarchitects. Budgeting, pricing,costing and estimating are just afew practical applications.

Word ProcessorChange the disc and your

Electronic Assistant becomes aword processor. It will help withproposals, contracts, reports,documents, price -lists, mailingand all those other wordy officetasks.

Information RetrieverYour Electronic Assistant will

keep a file of personnel, pupils,properties, patients. Find whatyou want, when you want it.Match people to jobs, children toschools, buyers to houses,patients to treatments. Retrievefiles and print information at thetouch of a button.

Business MinderAnd of course your Electronic

Assistant will help mind yourbusiness. Send bills, keep

, r

) 47/ %iii/11

Digitus specialises in microcomputing, communications and the elec-tronic office. The Company provides complete systems for the smallbusiness, professional practice and large organisation. Costs vary be-tween £3,000 and £30,000 per system depending on facilities. Weacquire software packages and equipment from all over the world tosatisfy requirements and have the capability to put machines andsoftware together, adding the special features you need.

40

accounts, process orders, takestock. Give you time to look at thebusiness information you'venever had time to analyseproperly.

Micros Can Growon You

Microcomputers are cheapenough to add a secondmachine as jobs grow Replicatethem to perform similar tasks indifferent locations. Link themtogether in a local network.Program them to talk to bigcomputers.

Ask Digitus to advise you andsupply an Electronic Assistant tosuit your present and futureneeds.

Call: 01-405 6761 or write forinformation to: Digitus Limited,9 Macklin Street, Covent Garden,London WC2.

DIGITUS - ELECTRONICASSISTANTS IN THE OFFICE

Circle No. 145PRACTICAL COMPUTING May 1981

Editorial

Financing the futureTHERE ARE two sides to the micro business: the fun and thrills

of making machines do things no-one in their right mindswould even consider and there is the small matter of stayingalive while you do it. It is accepted on all hands that Britain'ssalvation is to be found through microelectronics, andthat it is the prime duty of government and industry tofoster this delicate plant.

There is an impressive list of organisations willing - nay,anxious - to fund the micro entrepreneur. There is theNational Research and Development Corporation, NRDC,the National Enterprise Board, NEB, the Industrial Com-mercial Finance Corporation, ICFC, Department ofIndustry's software support scheme, and the Departmentof Industry itself. The clearing banks have "start-up"schemes for small businesses. Elaborate and expensivecommittees look into the situation and regularly reportthat there is no shortage of money for investment - rather,there is a shortage of projects.

The micro business is very like the Wild West, and, as in anyfrontier town, the sheriff - your genial editor - is apt alsoto be the local seed merchant. Thus it is with us. As well asrunning this delightful magazine, I have a software publishingbusiness. What concerns us here is the light my experiencesheds on the way the micro industry is actually funded.

We start at Christmas 1979 with a list of projects and a wayof doing business. We go to NRDC who say yes; the wholeproject looks interesting, the products seem sound,bothtechnically and from the marketing point of view. Theywant to become involved in the micro business and theywill think about it - urgently. We are still waiting foran answer to the letter asking for support, dated November1979.

ICFC: they think it's a topping idea - well, kind words costnothing - but they are not really interested in researchand development. Perhaps a little later on? A little downthe road? Yes, fine, fine. Nice to see you. Do come back- when you do not need us.

NEB: prostrate from the INMOS deal, there seemed littlepoint bothering them with a request for a few pifflingthousands. Your friendly local bank is advertising easyfinance for small businesses; bank manager says he doesnot know much about software, but will think about it.Thinks and advances nothing but the neat idea that if we putup £15,000 cash, the bank will match it with a two-year loanat 21 percent - repayments to start immediately.

At last, a gleam of light in the gloom. At the Departmentof Industry - whose Information Technology Divisioncontains some patient people who clearly want to be helpful- mention is made of the Software Products Scheme,SPS, which is managed for them by the National ComputingCentre. Haven't you heard of it? It's just what you need.

The SPS gives approved products marketed by approvedcompanies a choice of support: you can have 25 percentof your projected costs as a gift, or 50 percent as a loan,repayable as a percentage of gross income. Better still,the SPS is intended to help with marketing as well asdevelopment.

It sounded too good to be true. I spend a great deal of timethinking how much it might take to sell the two productswe have finished, and then to finish and sell two moreproducts which were in embryo. It is rather like guessingthe length of four expensive pieces of string. Finally, theproposal is sent to Manchester. After the usual silence,back comes the answer, no.

Why not? Long telephone conversation with a frank andhelpful man. Firstly, SPS is designed to help small softwarehouses.

PL: You can't get smaller than us. We haven't even got a dog.

SPS: Ah, you misunderstand me. When I say small, I meanturning over, say, £60,000 or less. With accounts for onlyfive years.

PL: But the whole micro industry is less than three years old.SPS: Ah, well, there you are. There is another difficulty.

Two of your products are finished, you say?PL: Yes, you can see them running.SPS: Well, the SPS is not really designed to support marketing

alone.PL: But surely it's better to put public money into something

which works rather than something which might work?Less, how shall we say, risky?

SPS: That may well be so, but it's not how the Treasurysees it.

PL: So, if we had been going five years and hadn't done anywork, you might help?

SPS: Not so fast. How many full-time employees have you?PL: Thank God, none. Everyone works on a royalty. Like

a book author.SPS: Well, that puts the lid on it. You must have three full-

time technical employees.PL: That's £40,000 a year.SPS: And anyway, I don't see in your accounts that you

have the money to match what you're asking us to give you.PL: Of course we haven't. If we had any money we wouldn't

be going through these loops.SPS: You have to convince us that you can put up your

75 percent or 50 percent of the money your firm needs.PL: We can't, but what about this? You agree in principle

that certain expenses qualify for support under the SPS.When we've paid a bill in one of those areas, we'll sendit to you and you give us 50 percent. In that way, it doesn'tmatter that we don't have the money now. We must havefound it because the bill will be paid before you see it.

SPS: That would be retroactive financing. The Treasurywould never hear of it.

PL: Thank you so much for your time.Some of the wisest words ever printed in this magazine were

these: "When we first started, we believed that if we hadsubstantial backing, we could have made a fortune veryquickly. In retrospect, we simply would have lost all themoney. We might still have come in the right directionbut our mistakes would have cost money rather than justtime. I don't think that in the long term, if you are deter-mined to make a business work, backing on a large scaleis worth it, especially if you do not have a good deal ofbusiness experience". Mike Fischer on the start of ResearchMachines, Practical Computing April 1980 page 84.

True enough for the individual small company. Yet noticethe trade-off between time and money. Time is what Britaindoes not have very much of. Our rivals are putting a greatdeal of money into the microelectronics industry. They areforging ahead, in their fields, at an impressive rate.

It happens that our microsoftware industry is - potentially,at least - spread among many people who work in backrooms. What we need is some way of giving them smallamounts of money while accepting the risk that only one in10 will pay off. What is £5,000 or £10,000 put into 100 smallfirms compared to the umpteen billion hurled daily andirretrievably into heavy industry?

If microelectronics is going to produce a new cottage industry,we have to be willing to support people in cottages with talentbut no capital - not in the crumbling palaces of dyingindustries. If this frightens the Treasury, we will be able tocongratulate ourselves on having expired in completefinancial rectitude.

Had we but world enough and time.This coyness, Minister, were no crime.

PRACTICAL COMPUTING May 1981 41

Feedback

Our Feedback columns offer readers the opportunity of bringing their computingexperience and problems to the attention of others, as well as to seek our advice orto make suggestions, which we are always happy to receive. Make sure you useFeedback-it is your chance to keep in touch.

Friend or foe?WITH Boris Allan as a friend, who needsenemies? Though I tend to agree with hisargument, I found his article confusing -December 1980 issue. For a more directexample, this program contains both arecursive, FNF, and iterative, FNG,method of determining the factorial of agiven number. As can be seen, they giveidentical results on the HP -3000.FACT

10 LONG A20 INPUT "FACTORIAL ",A30 PRINT FNF(A)40 PRINT FNG(A)50 GOTO 2060 DEF LONG FNF(LONG N)70 IF N=0 THEN RETURN 180 ELSE DO90 IF N<0 THEN RETURN 0

100 ELSE RETURN N*FNF(N-1)110 DOEND120 FNEND130 DEF LONG FNG(LONG N)140 LONG R150 R=1160 IF N=0 THEN RETURN 1170 ELSE DO180 IF N<0 THEN RETURN 0190 ELSE DO200 FOR I=1 TO N210 R=I*R220 NEXT I230 RETURN R240 DOENb250 DOEND260 FNEND

>RUNFACTFACTORIAL 36. 000000000000000L+006. 000000000000000L+00

FACTORIAL 302. 652528598121911L+322. 652528598121911L+32

FACTORIAL 503. 041409320171338L+643. 041409320171338L+64

FACTORIAL*CONTROL -Y BREAK IN LINE 20 IN FACT

Now, I doubt that anyone could suggestthat either solution is the better one, interms of aesthetic appearance. Both aresimple, and both reflect the algorithmadopted. However, FNF uses a methodwhich is a step removed from thenormally -used definition of a factorial -as used in FNG - and it is this extra stepwhich makes the program more difficultto follow.

Personally, if I had to use the factorialin a program - and, in 17 years ofcomputer work, I have used recursion nomore than three or four times, and thefactorial never - I would use the recur-sive method because of its conciseness.However, it is extremely wasteful withstack space, and on smaller machines, Imight be forced to use the iterativeapproach.

Paul Farrell's letter, Feedback, February1981, on the other hand, gives a perfect

42

example of recursion being used in itsproper place. Unfortunately, the outsideworld of commercial computing is not sowell-defined, and I fear that most com-puter people's experience is similar tomine - recursion is one of the hundredsof techniques we have in our armoury butwhich is rarely used.

Doug Scott,Maidstone,

Kent.

Liverpool MuPetIN CASE Pet users are rushing out to buythe MuPet multi-user system, followingyour highly favourable review, February1981, may I add two points of caution.

First, our MuPet has the most discon-certing habit of hanging -up in operation.The cause is unknown but the effect isdisaster, for the whole system, includingthe Pets, is frozen and the only remedy isto power -down and start again. If two orthree users are in the middle of programdevelopment work, the result is anger andchaos. As an add-on re -set switch isavailable for the MuPet in the U.S., itsuggests that this particular problem is notuncommon.

Second, and of great importance tosystems set up solely for package jobrunning, is our MuPet's total inability todo batch printing. Thus, if two or morePets are running print -output jobs, theprinting is inter -leaved. This is inevitable,as the Print statement in Pet Basic closes -down the printer channel after executionand leaves it available for further calls. Ifthe next call is from another Pet -perhaps while the original Pet is doingsome processing - interleaving of printruns is the result.

Despite the claims that no programchanges are necessary to run on theMuPet, the only way to overcome theproblem is a complete re -write of all ourprograms to ensure that all print state-ments are placed together thus forcingdomination of the channel.

GSP Thomas,University of Liverpool.

Sorcerers' covenWHEN THE Sorcerer was first introduced inearly 1979, two separate user groups werestarted. One, based in Woking, Surrey,never got off the ground. The othergroup, started in June 1979, has been incontinuous production ever since.

This second group was started at a timewhen there was a great shortage of soft-ware for the Sorcerer and so one of itsmain aims in those early days was tospread programs within the group. For

this reason, the group name Sorcerer Program Exchange Club, SPEC, was chosen.

It soon became apparent that there wereproblems involved in distributing cassettetapes. These problems were technical, log-istic and not least legal. Therefore, it wasdecided to play down the programexchange part of the group and to con-centrate on the newsletter side.

In view of the misleading nature of thetitle SPEC, it was decided late last year tochange it to something more suitable. Thegroup's membership is very widespreadwith members in Australia, New Zealand,Hong Kong, U.S.A., Canada and everycountry in Europe with a particularconcentration in the Netherlands.

Because of this mainly European ratherthan British membership, we decided torename the group the European SorcererClub - or ESCape as it has becomeknown within the group. Incidentally, thereason for the predominance of Dutchmembers is due to the Dutch TV servicerunning a computer course which used theSorcerer as the preferred machine. Theybeat the BBC by about 18 months.

For further details write to me, ColinMorle, 32 Watchyard Lane, Formby,Near Liverpool L37 3JU. Telephone 070-48-72137. Subscription costs £5 perannum if you live in the British Isles and£7 for elsewhere in Europe; outsideEurope, the cost is £12. Colin Morle,

Formby,Merseyside.

Teaching qualityTHE ARTICLE by M P Thorne in PracticalComputing, January 1981, on poor -quality mathematics software evokes agreat deal of sympathy. It was satisfactoryto note that the programs which werepraised were from good educationalbackgrounds.

When other aids to learning, such asbooks, are produced, authors' names aregiven. Teachers rightly view withsuspicion any materials for which noeducational sources are given; thiscertainly applies to computer programs. Isuggest that the following points be lookedfor when buying educational software: The material should have sound educa-

tional origins based on teachingexperience and on sound educationaltheory and practice. Full explanationsshould be given in teachers' notesand student leaflets.

The computer program and documen-tation should be written by someonewith experience in writing educationalsoftware - or under such a person'sguidance. (continued on page 44)

PRACTICAL COMPUTING May 1981

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43

Feedback(continued from page 42) Both teacher originators and program-

mers should have the backing ofsome group or organisation fordiscussion in the early stages.

The whole unit should be edited,preferably by someone - or somepersons - with considerable ex-perience of teaching the subjectmatter and of computer education.

The unit should have been on schooltrials and revised in the light ofcomments received.

The names of the teacher originator(s),programmer(s), editor(s) and of thegroup organising discussion trialsand production should be given.

Programs from the Schools Councilproject, Computers in the Curriculum,director R Lewis, the leading producer ofeducational software for secondaryschools in this country, and from otherprojects such as ITMA will be found tosatisfy these criteria.

It is not meant, in any way, todiscourage teachers and their computingfriends from producing their ownprograms to meet specific needs, nor fromexchanging such programs with theirfriends. Such authors would do well tonote some of the snags which Thornementions, and also to consult the projectpapers produced by the Computers in theCurriculum project. Especially relevantare paper 17 on guidelines for authors andpaper 14 on the project's aims andmethods in producing materials inmathematics.

Donovan Tagg,Lancaster.

Statistical errorsTHE PROGRAM described in the article,Statistics on a micro, Practical ComputingFebruary 1981, is very interesting andingenious but unfortunately contains anumber of errors. To save anyone whowishes to run the program the trouble ofdebugging it, here are the errors which Ihave found.

Lines 15, 35 and 915 can be deleted asthey only duplicate other lines. Lines 640and 660 apear to have some charactersmissing. These lines should read:640 IF NA = 0 THEN Z = 1 : GOTO 740660 IF TA > TB THEN U = UA:M = NA:GOTO 680

In line 550 the subscript for SB shouldbe NB and not MB as shown. Perhaps theworst error occurs in line 2000. Not only isthe program incorrect but the error hasbeen repeated in the text describing it. Themaximum value of the last element in Qshould be N - 1 and not M - 1 as stated.

For those whose Basic does not have theIf Then Else form of decision statement, Iwould suggest that subroutine 2000 berewritten as follows:2000 IF Q(M-1) = N-1 THEN RETURN2010 Q(M-1) = Q(M-1) + 12020 GOSUB 40002030 GOTO 2000

With these corrections, I have run theprogram successfully on a Pet. The only

44

further changes required were the deletionof line 10 and references to the strings Aand B made in the conventional form ofA$ and B$.

J Halliday,Port Talbot,

West Glamorgan.

Solid adviceI HAVE been repairing radar and electronicinstrumentation for some 20 years now, soam reasonably sure of my soldering. I

bought myself a computer kit, regularlyadvertised in your pages.

Had I had problems with bad joints orduff components there would have beenno problem. However, the plated throughholes in the board were intermittent. Allcomponents in the kit were guaranteed, ofcourse, but in the case of the board, oncemy iron had made the first joint thesupplier could and would say that I haddamaged it.

A repair service was offered, but havingspent the best part of a month's wages,another £25 was throwing good moneyafter bad - especially as the nature of thetrouble was such that I could see thecomputer commuting between Derby andLondon for months on end.

So, my recommendation to anyonebuying a kit, is this: pay the extra for aready -built machine, preferably from asupplier who has enough confidence in hisproduct to give a year's guarantee. Makesure you have some protection.

I would go further and say: treat it asroughly as possible, short of visibledamage, to try and show up any incipientopen circuits.

J Bland,Derby.

Old -ROM updateIN FEEDBACK, February 1981, I wroteabout the updating of old -ROM Pets tothe newer Basic 2 versions. Since my letterwas published I have had a letter from thesales manager of Commodore U.K. whichsays that I have my facts wrong. I hadobtained my facts from Commodore U.K.at Euston Road, London.

The facts given in the letter from theCommodore U.K. sales manager are asfollows: Machines with 901447 series ROMchips require a set of four ROMs toupdate, these are and always have been£38 the set. Machines using 6540 ROM sets requireseven chips to update. They are £104 theset. However, as a gesture to good cust-omer relations, Commodore is nowmaking these ROM sets available for £38- all prices exclusive of VAT. OfficialCommodore User Club members canobtain these ROM sets free if they buy adisc drive.

It would seem sensible for anyone con-templating updating an early 8K machineto purchase ROM sets now - the currentprices may not last for ever and at £38,

they are being sold at below cost price.J A Banks,Loughton,

Essex

Micro leasingIN THE March issue of PracticalComputing, in your article, Is it worthleasing a Micro?, you quoted mycompany's bureau charges as £100establishment fee, with weekly charges of£110. I must point out that this figurewould reflect the average monthly cost tomaintain a sales ledger of roughly 100accounts.

Our weekly charges are based on a runcharge and then prorata, based on inputand output volumes. When one considersthat the fees also embrace on-the-jobtraining for our users, our charges becomethe most cost-effective way of imple-menting a computer system.

Malcolm Harvey,West One Computer Services

London Wl. In case it was not clear from the March1981 article on leasing micros, MalcolmHarvey and Roger Martin both workedfor CSC when they were in Nigeria.

Electronic accountingI WAS interested to read the comments ofG D Herbage of Gnomist InternationalLtd, March 1981 Feedback, on the needfor a business accounting packaged basedon the well-known Kalamazoo system.

In collaboration with B & D Steels Ltd,Altrincham, Cheshire, we have developedjust such a system, based on the TRS-80with 48K of RAM and four mini -floppies.It has now been in operation for morethan a year. The system was run in parallelwith the Kalamazoo cards for one monthonly - the changeover was so smooththat it was felt that the cards could besafely dispensed with after that time.

According to Robin Lucas, chiefaccountant of B & D, the ease of thetransition was largely due to the fact thatthe entry procedures closely followedthose of the Kalamazoo system, withwhich they were already familiar.

George Sassoon,JZK Electronics,

Warminster,Wiltshire.

Kalamazoo's answerIN MARCH 1981 Feedback, G D Herbagereferred to the need for a ready -to -gomicrocomputer package capable ofreplacing the Kalamazoo or similaraccounting method and costing less than£5,000.

Readers with similar interests to thoseexpressed by Herbage may like to knowthat Kalamazoo will shortly be launchingjust such a package for use with a newrange of microcomputers.

P J Rex,Kalamazoo Ltd,Birmingham.

PRACTICAL COMPUTING May 1981

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Circle No. 150

45

ZX-81 lower price forhigher performanceA PERSONAL computer fromSinclair Research launched toreplace the popular ZX-80 ispriced at only £69.95 and isnow in production at theTimex factory in Dundee.Based on an innovatory four -chip design, the Sinclair ZX-81also sells in kit form at £49.95- the mains adaptor is anextra £8.95.

At the launch of the newcomputer, its designer, CliveSinclair, claimed that in theU.K., his ZX-80 is nowoutselling all other personalcomputers put together and heconfidently predicted that by

The ZX printer.

the end of 1981, SinclairResearch will exceed theproduction volume of anyother personal computermanufacturer in the world.

The key design achievementin the ZX-81, which is con-structed in thick black plastic,is a new master -chip custom-built in the U.K. by Ferranti.It replaces 18 chips in the ZX-80and adds some new features.The ZX-81 has a Z -80A micro-processor and an 8K BasicROM which allows floating-point arithmetic and gives fullscientific functions.

The new computer embodiesall the main features of itspredecessor including single -stroke key word -entry, auto-matic checking of every state-ment line and a display of 24lines by 32 characters.

New features, in addition toa print -drive facility, includethe ability to operate in twosoftware -selectable modes, fastand normal - fast is fourtimes the speed of normal. Innormal mode the Sinclair ZX-81 will compute and displaysimultaneously and allows

46

continuous moving, flicker -free graphics.

A 40 -key, touch -sensitivemembrane keyboard gives theequivalent of 81 keys usingfunction mode and single -presskey -word systems. The graphicsmode enables an additional 20graphical and 54 inverse videocharacters to be entered directlyfrom the keyboard.

Programs can be loaded andsaved on a conventional homecassette player and re -selectedfrom the computer keyboard.The cassette -interface facilityhas been improved toovercome some of the ZX-80'sloading problems and programsare given names so the ZX-81can search through a tape forthe required program. There isalso a new 200 -page instructionmanual.

The new 8K Basic ROM usedin the ZX-81 will shortly beavailable to ZX-80 owners as adrop -in replacement chip, sup-plied with new keyboard tem-plates and operating manual. Itwill enable the ZX-80 to offerall ZX-81 features exceptflicker -free graphics.

Sinclair has also announcedthat a printer for the ZX-80/81

Sinclair's ZX-81.

computers will be available inJune for around £50. It willoffer full alpha -numericsacross 32 columns and includesa command, COPY, whichprints out exactly what is onthe TV screen.

In the first nine months sincethe ZX-80 was launched inFebruary 1980, 50,000 of thecomputers were sold - abouthalf of them in the U.K. Sincethen, the units have been soldat the rate of about 10,000 permonth with 30 percent goinginto the U.K. market. Produc-tion of the ZX-81 began inMarch at the rate of 10,000 permonth.

Health hazardof VDUsIN RESPONSE tO a call from aconference on the health andother hazards associated withthe use of VDUs, a researchproject has been initiated bythe Institute for ConsumerErgonomics.

The conference was entitledHealth hazards of VDUs, andwas held by the HusatResearch Group, ofLoughborough, Leicestershire.It was the widespread concernvoiced by delegates at theconference which promptedthe research.

The project is to be fundedby the EEC coal and steelcommunity, and will be carriedout in those industries. Certainothers will participate bycontributing financially or byallowing access to sites.

It is intended to research intothe incidence and severity ofthe various types of discomfortand fatigue caused by theseunits, and in certain cases, tospecify the ergonomic require-ments necessary for theoptimisation of VDU use withregard to the existing con-straints.

The Institute for ConsumerErgonomics would be pleasedto hear from companiesthinking about VDUs and theiruse, and anyone else involvedin similar research.

Pet displays its multi-lingualprowess with Cytek deviceCYTEK (U.K.) Ltd of Man-chester has launched a devicewhich enables the Pet todisplay multi-lingual text on itsscreen. The device, Multi -font, works in conjunctionwith the Wordcraft word-processing system. There arefive main versions of Multi -font; scientific, legal, com-mercial, European multi-lingual, non -European multi-lingual. Each version canformat the special charactersrelevant to its application.

Multifont is used in con-junction with any 32K Pet, andany version of the Wordcraftprogram and the Qume Sprint5 series of daisywheel printers.The operator can see the effectof using different print -wheelswithout printing anything.

2r10111k2./1=...1114LMMAIr1 4111 ,-ai VICAMEMEM101...n../11..1.11,11VM11

fiCP111:111111ryl.:.., ..,1111,,

This is achieved by matchingthe characters within thecomputer to those on a spec-ified print -wheel.

Up to four separate fontscan be stored in the computerat any one time - the first isthe standard Commodorebusiness set. Multifont doesnot occupy any of the Petmemory, so the operation ofthe computer is not affected.

A total of 73 fonts are

available for the Qume printerand 29 keyboard sequences.The Multifont fonts corres-pond to these sequences, andsince one sequence may beused by several different type-faces, the four available fontscould cover many print -wheels.Keyboard overlays are availableto enable the operator to ident-ify quickly and easily all thecharacters in the sequence andlocate the appropriate keys.

Cytek can create Multifontsets to user's own specifica-tions if required and groupingsother than the main five can beprovided. Multifont is availableas an add-on to Wordcraft at£172 + VAT and a completesystem is £4,200. For inform-ation telephone Cytek on 061-872 4682.

PRACTICAL COMPUTING May 1981

Printout

EducationalgrantA GRANT of £60,000 has beenmade by the Council forEducational Technology aspart of a micro electronics educ-ation programme. Initially,the project will take the formof a course to be run at andby the Thames Polytechnic forteachers in such subjects asbiology, geography and econ-omics.

The course lasts 10 weeks, isattended by teachers onsecondment from localauthorities and it is specificallyaimed at those teaching insecondary schools.

Acorn picked to make newmachine for BBC series

ACORN COMPUTERS has landedthe job of building the newBBC microcomputer - andthe projected BBC -TV seriesFirst Byte will use an extendedform of Atom Basic in itsinstructional material.

Acorn describes the newmachine, which will retail forless than £200 and should beready by the end of 1981, as "acondensed version of theforthcoming Proton". Itsspecification was devised by aBBC team which included

Pet users involved in mechanical data logging and positioncontrol may find this shaft position encoder from CetronicLtd of use. Recently added to the Commodore -approvedproduct list, the C030C absolute optical shaft encoder willenable a Pet computer to communicate with mechanicalsystems in the real world using a specially designed inter-face. The encoder will be capable of resolving mechanicalrotation into 256 eight -bit words, utilising grey code toincrease the reliability of the readings. An interface/decoderboard is supplied to convert the grey code to binary and feedit to the Pet via the input port. Cetronic may be contactedat Hoddesdon Road, Stanstead Abbotts, Ware, Hertford-shire SG 12 8E), telephone 0920 871077.

Charles Sandbank, head ofBBC Research, RichardRussell of BBC Designs, whostyled the exterior and JohnColl, president of MUSE.Other consultants includedRay Kernow, John Sweetonand Peter de Bono.

The specification of the newmicro is for 16K of RAM asstandard, with the potential forexpansion to 96K; add-onteletext receiver at a cost ofaround £100; add-on Prestelinterface; high -quality movingkeyboard "with a positiveaction like a top -class electrictypewriter"; ultra high -resolution graphics in blackand white - 640 horizontalpoints - a feature which it is

claimed can be found only onmicros costing more than£1,000; colour graphics at alower level of resolution; andpotential for networking withother computers or peripherals.

Initially, the requirementwas for a Z-80 processor,teletext capability and CP/Msupport, but intensive dis-cussions throughout theindustry showed that it was notpossible to have a machinebuilt in Britain within the timelimit. The Z-80 requirementwas scrapped but Acorn hasbeen able to meet the otherswithin the time limit. A newBBC Basic to be called ABCwas to have been developedbut this too was dropped forlack of time.

Not all within the industryare, however, agreed that the

Texas 16 -bit TMS-9995 winsadded operation speedTEXAS Instruments hasdeveloped a 16 -bit micro-computer in a 40 -pin packagewhich includes the 6MHz clockgeneration, 256 bytes of fastRAM, an interval timer andthe necessary circuitry forhandling prioritised interrupts.

The device, called the TMS-9995 to indicate its generic linkwith the 9900 family, wasdesigned and developed byTexas Instruments at itsBedford location. The genericlink with the TMS-9900, TMS-

9980, and SBP-9900 family ofprocessors gives it completesoftware compatibility, so thata range of component softwareis already available.

However, the TMS-9995 hasa significantly superior per-formance. The instruction setis that of the TMS-9900 withthe addition of four new com-mands which enhance its abilityto perform numerical tasks.There are also two new systeminterrupts, one of which, thearithmetic overflow, helps

speed maths operations byhandling overflow conditionswithout resorting to extrasoftware.

An evaluation board willsoon be available for the TMS-9995 which contains a monitorfor program assembly, editingand execution. The hardwarecontains two data links.

The TMS-9995 is fabricatedusing NMOS and operatesfrom a single + 5 volt supplyand will cost £23 for quantitiesof 100 plus.

BBC tried hard enough forwhat it wanted. Clive Sinclair,at the launch of the ZX-81,indicated that he could havebuilt such a machine for a priceof £110 at the point of sale -sales will be by the manu-facturer under licence to theBBC and marketed on behalfof the BBC by mail order froma box number.

Sinclair tells PracticalComputing: "We did quotefor it. We had a specificationfrom the BBC but it wasn'tvery full and there were someambiguities in it. We said wecould build it for £110 but itwas clear our bid wouldn'tcome to anything. We had toput in a bid to protectourselves.

"We feel that the BBCshould have talked more to theindustry and made the spec-ification better known. Wethink it's crazy. Here we aretrying to compete with theworld's industry and our ownnational broadcasting system isoperating against us".

Charles Sandbank of BBCResearch disagrees: "The BBChas taken advice from a greatmany people with experienceof the micro industry", he says."As an employer of engineers,I think it's a worthwhilemachine but it's a very difficultdecision. The BBC has goneinto it very carefully and hasdone all the right things andhas gone for the solution whichseems to have the highestprobability of doing what itwanted".

Acorn Computers will alsosupply some of the software,which will be written in AtomBasic, adapted for compat-ibility with Microsoft Basic.Proposed programs includehow to plan your electricity usemore economically, work outyour tax liability, learn maths,spelling or typing, managebusiness accounts or run anoffice. There will be hobbyprograms to interest theamateur astronomer, musicianor photographer.

A 30 -hour course will be runby the National ExtensionCollege at Cambridge to tie inwith the TV series, and severalcourse books are planned.

PRACTICAL COMPUTING May 1981 47

Three good reasons whyprofessionals pick Apples

1. In researchApple desk top computer systems helpyou collect, store and analyse data asfast as you can load and execute aprogram. There are many softwareprograms for Apple which enable youto manipulate your data in thecomputing world. If you need specialprograms you can now use any ofApple's development languages -Basic, Fortran, Pascal, Cobol andPilot.

2. In engineeringApple desk top computer systems letyou define models and refineprototypes. Do you want to studycause and effect of several variables?Apple can compute new resultsinstantly and display them incolourful, easy -to -read graphs, chartsor plots on a video monitor.

Please send me full information on the Applecomputer, the Apple software booklet and mynearest Dealer. I am interested in how Apple canhelp me in:El Science E Research O EngineeringO Production Management E Business

Name:

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Post Code:

Telephone Number.

Profession.PC5

48

3. In productionmanagementApple desk top computer systemsmake it simple to gather data, analyseproductivity, measure yields andfacilitate all phases of productioncontrol. Do you want to speed uprepetitive tasks? You can rely onApple's word processing capabilities towrite, edit and print your reports anddata.

Apples grow with youWhichever system you choose, Applenever locks you into a singleconfiguration. You can use up toeight I/O accessory expansion slots toadd an IEEE bus, Apple's Silentype-printer, a modem or a Graphics Tablet.You can add up to 64K bytes and 51/4in.disc drives without adding anyoverhead. For support, service and thebest extended warranty in the industry- Apple is the answer. If you have anyother questions about why Apple ischosen by professionals in engineeringand science, see your nearest AppleComputer Dealer.

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Price exclusive of VAT and correct at time of goingto press.* Apple is a trademark of Apple Computer Inc, Cupertino,California, L'SA.

Circle No. 151

PRACTICAL COMPUTING May 1981

PrintoutTHE LATEST product rangefrom Alf Ltd will turn anordinary Apple II computerinto a sophisticated musicalinstrument. Two music boardswhich plug into the Appleexpansion socket, and someassociated software includingan ear -training package and acollection of Albums areavailable on cassette or disc.

The MC -1 music card hasnine independent channels orvoices. Each voice is mono-phonic - it can play like a one -fingered keyboard player. Theuse of more voices means thatchords can be formed or thecomputer could use a voice toprovide its own accompani-ment.

Three voices provide the leftstereo output, three the rightand the remaining three play

How you and your machinecan make beautiful musicthrough both speakers toprovide the middle. The voiceshave individual control overpitch, envelope, and volumeand one voice from each of thethree stereo positions can beused to create white noiseeffects. This would be of greatuse to users synthesising per-cussive effects such as cymbals,etc.

The MC -16 music board issimilar but provides only threevoices on one output channel.This reduction in voices is com-pensated for by the inclusionof some extra features; a range

of 63 half -tones as opposed toMC -15, more volume controllevels and an ability to havetwo channels with variablepulse -width mode; the freq-uency is controlled by the thirdchannel.

The software provided withthe boards is comprehensive,will provide the user with acolour graphic display of themusic being played. Songs caneasily be entered from sheetmusic and the display showsthe music on the screen.

When you enter music, amenu of available notes is

Keeping school-leavers in the pinkand micro firms in the blackON THE one hand, we have thetypical micro firm and on theother, an impending tide ofschool-leavers who have allplayed with computers andlook forward to exciting jobsin the microrevolution.

The problem - to bring thetwo together without breakingthe banks of one or the heartsof the other. One solutionmight be the Youth Oppor-tunities Scheme, YOP. Thecentral idea of YOP is tointroduce out -of -work school-leavers, 16-18, to the world ofwork. The Government's partis to pay them a tax-freeallowance of £23.50 a weekfor six months - the sponsor'spart is to have them around theplace and show them, in areasonably humane and con-structive way, how the realworld earns its bread - andperhaps butter. One hopes thatby the end of the six months,or sooner, they will be souseful they are offered a full-time job.

It seems possible that theremight be places in microbusinesses for such youngpeople, especially if theyalready have some idea ofprogramming.

To get this scheme off theground, the Manpower Ser-vices Commission has to bepresented with a draft schemeof activities which will be ap-proved centrally and then

PRACTICAL COMPUTING May 1981

passed to local Job Centres foraction. Our suggestion for sucha program might be: Introduction to company

and what it does. Basic office procedures:

keeping records, filing cor-respondence, liaising withcustomers/clients.

Computing: keeping rec-ords, making back-ups ofprograms and data, simpleapplications programming.

The scheme's main stipula-tions are: The company must have

three full-time employees

but it may employ more. The young people on the

scheme must not replaceany full-time employees.

Their work must conformto health and safety reg-ulations.

They must not work nightsor Sundays.

Anyone interested shouldwrite to us with suggestions.Literature about YOP isavailable from Miss J Trenor,Manpower Services Com-mission, Selkirk House, 166High Holborn, London WC1V6PF.

Software is neither cheap nor indestructible. Discs left lyingabout in offices seem to attract tea and other spills or areknocked to the floor - before you know wher you are, nextweek's payroll data is corrupted. The new data storage aidfrom Rexel has been designed to make the storage andretrieval of floppy discs a simple matter. The storage aidsare in the form of binders, with pockets made of toughNyrex material to hold the discs. The system will alsoconsist of labels to help identification. Further details from0296-81421.

displayed and an arrowindicating the selected note ismanoeuvred by the paddle.The other paddle is used toposition the note on the stavewhich is also displayed on thescreen. A subroutine facilityenables the user to call-uppassages which need to berepeated and there is also anediting facility. The MC -1 cardcosts £91 and the MC -16 £114and both are available fromApple dealers.

Apple sees tothe lightingAN AUDIO -visual system whichuses an Apple II computer asits base is now being intro-duced to the U.K. The Super-star multivision computersystem can be used to programthe batteries of slide projectorsand ancillary equipment usedfor multi -projector slidepresentations.

The "professional" multi -vision production market hasso far been dominated by

The system in action.

dedicated microprocessorsystems. The Apple -controlledsystem could also be used torun standard Apple software.

The Superstar system con-sists of an Apple computer,twin disc drives, a 9in. VDUand a Universal Interfacewhich allows disolve units,slide projectors and auxiliariessuch as lights, motorisedcurtains and film projectors tobe driven from the computer.

The system was developedby Clear Light in Florida anduses its own high-level languagefor programming the light seq-uences. Details in the U.K.from Myriad, 01-240 1941.

49

Printout

Gateway is Prestel's routeinto new teletext territoryPRESTEL is to offer a new ser-vice later this year. Mysteriouslyknown as Gateway, it will per-mit Prestel users to accessthird -party databases. Based ona system already operating inWest Germany, with softwaredeveloped by Systems Designersunder contract to Aregon Inter-national, Gateway is expectedto enlarge greatly the scope ofPrestel when it is fully imple-mented in 1982.

Key to the system is the so-called Gateway frame whichleads the user from the Prestelnetwork into a privately -ownedcomputer, all of whosefacilities may then be enjoyedby the user, assuming, ofcourse, that he is in possessionof the relevant password.

A demonstration at theLondon Prestel headquartershosted by Prestel boss RichardHooper, showed Gateway in

Triumph -Adler microsenter the fieldTHE Triumph -Adler group,owned by the West Germanindustrial giant Volkswagen,has finally made its move intothe small-business microcom-puter market with the launchof its Alphatronic range ofsystems.

The Alphatronic is based onthe 8085A microprocessor chiprunning at 3MHz. There aretwo basic configurations of thesystem: the standard P1 at£1,550 which includes theprocessor, VDU, an integraldouble -density floppy disc unitand full documentation writtenin clear English; the P2 has afurther floppy disc drive and adot-matrix printer and costs£2,345.

The outstanding feature ofthe Alphatronic is the largeamount of applications soft-ware already available for thesystem, including programswritten by larger softwarehouses. Among the software isa payroll program called Flexi-pay, written by Compuserve.There is also a business soft-ware package which consists ofseveral modules; payroll, sales,

Microsense isboughtMICROSENSE Computers ofHemel Hempstead, Hertford-shire, the sole distributor ofApple Computers in the U.K.has been purchased by Applefor an undisclosed sum. Thetransition is expected to becompleted by the autumn.

Microsense will become asubsidiary of Apple.

50

purchase ledger, nominalledger, and stock control witha sales invoicing option. Theprogram is written by Tridataof Birmingham.

Microtrend has produced acomplete range of software forthe system, including a word-processing system, a data -management package whichapparently has helped to sellmany Alphatronics already,two user-friendly commercialaccounting packages and Basicteach -in, a computer -aidedlearning program designed toteach beginners MicrosoftBasic. Adler Business SystemsLtd, 27 Goswell Road, LondonECIM 7AJ. Telephone 01-2501717.

action live from West Germany,whose Bildschirmtext is closelymodelled on Prestel althoughthere are as yet only two com-puters.

There were two shortdemonstrations, one of acustomer -account enquiry andone of a conversion fromsterling into U.S. dollars. Thiskind of networked inform-ation retrieval and processingis nothing new, of course; butit will be the first time this typeof access has been feasiblethrough Prestel.

Gateway's advantages,according to lain Chisholm,who is in charge of marketing,are fourfold: It puts far greater process-

ing power in the hands ofa user who already hasaccess to Prestel.

There is great flexibilityin security arrangementsfor different categories ofinformation - even asingle page can have itsown security password.

It makes keyword searchesavailable.

Interactive transactions viaPrestel are now a possi-bility. At present you maysend a message via Prestelbut there is no acknowledg-ment that the messagehas been received andacted on.

Paper TigertrioTHERE ARE three new Tigerprinters on the market,replacing the old Tiger 440.They are distributed throughMicrosense and the nationwidenetwork of more than 400Apple dealers. At the bottomof the range is the Tiger 445, animpact printer with a full 96 -character upper- and lower-case set, a choice of eight user -selectable character sizes,graphics option, tractor -feedand multiple -copy capability.The 440 can print at speeds ofup to 95 characters per second.

Next in the range is the 460which because of an unusual

The Paper Tiger family.

matrix head will print denser,higher -quality characters. It isbi-directional and can print atspeeds in excess of 150 cps. Atthe top of the range is the Tiger560, a 132 -column matrixprinter with graphics and anexpanded buffer. It is intendedfor data- and text -processing.

The prices for the range are;445, £545, 460; £795, and 560;£995.

Sophisticated Micromodellerto be distributed by ACT

ACT Microsoft - one of twoBritish computer companiesquoted on the Stock Exchange- has become the sole U.K.distributor of an importantnew software package designedto run on micros.

The product is called Micro -modeller and is a low-costfinancial -modelling packagefor the Apple II, developed inBritain and U.S. by Intelligence(U.K.) Ltd. David Low, man-aging director of ACT com-ments: "Each year, two orthree software packages of realsignificance emerge - Micro -modeller is one of these".

ACT is already the sole dis-tributor of VisiCalc, the best-

selling program in the worldlast year, and envisages Micro -modeller emulating its success.Its main appeal will be to thesmall -to -medium-sized busi-nesses and the middle layer ofmanagement in larger concerns.

Micromodeller represents afraction of the yearly bureauxfees a comparable facilitywould cost, plus it has theadded advantage of being apersonal system - at less than£4,000 a system, everyone in acompany needing the facilitycould have a personal system.

Like VisiCalc, the programis user-friendly - the com-mands are in plain English. Ithas a menu and is supported

locally by the dealer andnationally by a hotline. Finan-cial functions are built-in, andreports are generated automat-ically to the user's own specif-ications. Summary reports canbe displayed on the screenbefore any printing is per-formed.

An attractive feature ofMicromodeller is the slide -show presentation, which usescolour graphics to presentinformation in a graphicalform.

This useful facility will, nodoubt, help to sell the packageto those people whose jobentails disseminating financialinformation.

PRACTICAL COMPUTING May 1981

BLACK BOX IIIMICROCOMPUTER

SOLUTIONSConventional microcomputers canhave problems - too little memory, /-not enough storage, poor com-munications, no expandability.RAIR's Black Box III range

3

51

high-speed hard disk,16 simultaneous users, andshared -resource multi -computer networking, the only

thing micro about the Black Box III is the price.Call your nearest Dealer for details.

provides all the solutions. With up to512K bytes of memory, 200M bytes of

21 Single mini -disk system 2 Dual mini -disk system3 Single mini -disk plus 5" hard -disk system 4 Single 8" hard -disk system5 Add-on 8" hard -disk

Healey Of Unit 7, Westfield Industrial Estate, Portsmouth Road, Horndean, Hants Tel: 0705 597555Digitus Lt. 9 Macklin Street, Covent Garden, London WC2 Tel: 01-405 6761 Hallam Computer Systems Ltd 1 Berkeley Precinct,Eccleshall Road, Sheffield SH 8PN Tel: 0742 663125 lialdene Lo: Manchester Unity House, 11-12 Rampart Road, Leeds Tel: 0532 459459Lion Micro Cc 227 Tottenham Court Road, London WI Tel: 01-636 9613 and 21 Bond St Brighton Tel: 0273 601838Micrcrnedia 5 Seymour House, 14-16 Chepstow Road, Newport, Gwent Tel'. 0633 59276 NSC Computer Shop: 29 Hanging Ditch,Manchester Tel: 061-832 2269 T & V Johnson (Microcomputers Johnson House, 75-79 Park St Camberley Tel: 0276 20446 also148 Cowley Road, Oxford TeL 0865 721461 and 48 Gloucester Road. Bristol BS7 8BH Tel: 0272 422061

Rair Limited, 30-32 Neal Street, London WC2H 9PS Tel: 01-836 4663 Circle No. 152

52_

WOULDN'T YOU LIKE ANOSCAR

FOR A SUPERB PERFORMANCE

To a casual glance, we must admit that there are severalother computers which superficially resemble OSCAR.However, if you peek under the stylish structural foamhousing, with its separate keyboard for betterergonomics, you'll notice the differences.

S100 SYSTEMOSCAR has a 6 -slot motherboard, housed inside theVDU housing, with proven IDS S100 cards to inter-national standards for a flexible, easily maintained,system.

4MHz Z80A PROCESSOR CHIPPossibly the most powerful m.p.u. chip in its class,running at full speed, makes OSCAR more powerful thanmany mini -computers.

64K DYNAMIC MEMORYA full sized system for your full sized applications.

DISKETTE OR HARD DISKThe options are yours, starting with twin floppies at400KBytes per drive or an 11MBytes Winchester locatedinside the VDU housing.

Maximum size? We're not saying, as we keep onincreasing it, but it's unlikely to be too small.

CP/MTM OPERATING SYSTEMUse of the industry standard CP/MTM Operating Systemmeans that a wealth of applications software will run onyour OSCAR.

VISUAL DISPLAY UNITWith the green phosphor recommended by opticians forlow eyestrain, the VDU also has a bonded face -plate forextra safety. There is a full character set with realdescenders on the lower-case letters. There are 24 lineseach of 80 characters.

KEYBOARDSeparate keyboard with full QWERTY and numeric padfor fast entry.

PRINTER OPTIONSA range of printers is available. Your dealer can help youselect the appropriate one for your requirements.

APPLICATION PROGRAMS FREESales, Purchase and Nominal Ledgers plus Stock Controland Payroll are available from your dealer and to avoidthe problems of pirating, all you have to pay for are themanuals and the media. If these packages do not suit,your dealer will be able to offer alternatives, although,these are unlikely to be free!

NATIONAL SERVICE NETWORKIt's no good owning the best system if you can't get itmended, so IDS have arranged for a National ServiceNetwork to offer maintenance contracts on your OSCAR.

PRICEAn OSCAR with twin floppies costs from £2,495.00(excluding VAT and printer)

NOWCut along this line, complete and post for further details.

Designed and manufactured in the United Kingdom by: -

INTERACTIVE DATA SYSTEMS LTD.14 Heathfield, Stacey Bushes, Milton Keynes MK12 6HP

Buckinghamshire, EnglandTelephone (0908) 313997

Please send details of OSCAR and your other S100 products to:

Name

Position

Address

CompanyPC5/81

Circle No. 153

Circle No. 154

CE Tim cs

SPECIAL PRINTER OFFER £375JARD FEATURES

10 CPI 16.5 CPI100 characters/second 165 characters/second

80 characters/line 132 characters/line10 CPI or 16.5 CPI selectable by software command.Expanded character selection for both 10 and 16.5 CPI. 3 -way paper handling: A4 cut sheet, paper roll and fanfold. 7 x 7 dot matrix 96 character ASCII plus five selectable European character sets Microprocessor electronics Undirectional print at 10 IPS 6 LPI vertical .

Centronics colours and logo

Centronics Parallel (Standard) RS 232/V24 Serial (Option)

RIBBON SYSTEMContinuous ribbon 9/16" (14mm) wide, 20 yards (18.3 meters) longMobius loop allows printing on upper and lower portion on alternatepasses.

OPERATOR CONTROLSPower on/ofReset switch - allows disabling of printer without dropping AC

DATA INPUT7 or 8 bit ASCII parallel, TTL levels with strobeAcknowledge pulse indicates that data was received.

ELECTRICAL REQUIREMENTS60 Hz; 115VAC, + 10%/-10% of Nominal50 Hz; 230VAC, + 10%/-10% of Nominal

PHYSICAL DIMENSIONSWeight:Width:Depth:Height:

less than 10 lbs./5 kg14.5 inches/37cm11.0 inches/28cm4.89 inches/13cm

Dimensions exclusive of roll paper holder.

4TUREOperating: 40° to 100°F (4.4° to 37.7°C)Storage: -35° to 140°F (-37.2° to 60°C)

Operating: 20% to 90% (No Condensation)Storage: 5% to 95% (No Condensation)

FORMS HANDLINGRoll Paper: 8.5 in. x 5.0 dia. with 1 in. core

maximum dimension.3.5 in. wide with .38 in. core minimumdimension

Fan Fold: 9.0 in./22.9cm wide pin to pin9.5 in./24.1cm wide overall

Up to 3 ply paper with 2 carbons (total thickness not to exceed.012 inches)Cut Sheet: Maximum width 8.5 inches

Pctiona1 Computcr,s timitcc194-200 Bishopsgateondon EC2M 4NR

Telephone: 01-626 8121

AccountingBusiness Systems

The cream foryour apple.Within the space of a few short months, TABS has

rapidly become established as the best accountingsoftware on the market for APPLE II.

Our unique modular accounting system, developedfor the APPLE II microcomputer, has been designedspecifically to meet an increasing demand from the smallbusiness.

The fully integrated system enables modules to beused independently or together so that as businessexpands so does the system simply by adding a newmodule.

To ensure that our low cost accounting system*is fully understood, TABS offer a full support service,through our national dealer network, that includestraining courses, consultancy and free seminars.

Modules include: Purchase Ledger, Sales Ledger,Nominal Ledger, Payroll, Stock Control, Job Costing,Word Processing, Training, Support, ManagementAccounts, Invoice Compiler, Fast DataEntry, Sales Order Processing, Mail List.

Each module costs an astonishingly low

*The minimum system required to run the TABS modules is:Apple 48K, Disk with controller, Disk without controller, Silentype printer, TABS Firmware card, total cost £2056

Expanding Dealer Network

LONDON Eurocalc Ltd 01-405 3223 Lion Computers 01-636 9613 Marchessa Ltd 01-726 4809. Micro Control Ltd 01-402 8842. Time & PeopleLtd 01-242 4706. AVON C & G Computer Group Ltd 0934 417724. Datalink Micro -Computer Systems Ltd 0272 213427. BERKS. HexagonServices 0753 21998 BUCKS. Chiltern Computers 0296 32642. Chiltern Office Efficiency Ltd 02405 72777. CAMBS. Top Mark Computers 0480212563. CHESHIRE Systems Integration 061-928 5784. CORNWALL Diskwise Ltd 057-93 3780. ESSEX Compuskill 0708 751906. Meclec03708 5047 GLOS. Casa Management Consultants Ltd 045383 4551. William John & Co 04536 70109 HANTS. Access Control Systems Ltd0730 5274. Grist Business Services 0703 39061. Logan Electronics Ltd 0425 619761. HERTS. H G Services 0727 30129 Lux Computer Services0923 29513 HUMBERSIDE Computer Facilities Ltd 0724 63137 KENT Microlen Computers Ltd 0732 845412. Microspot 0622 858753. LANCS.K C Business Systems 0254 676077 Lancaster Computer Services Ltd 0772 31030. LINCOLNSHIRE Estate Computer Systems 0529 305637MANCHESTER Shannons Radio Ltd 061-748 2339. MERSEYSIDE Micro Digital Ltd 051-227 2535. Rockcliffe Micro Computer Division051-521 5830. MIDDLESEX Microsolve Computer Services Ltd 01-951 0218/9/0. W. MIDLANDS Micro Business Centre Ltd 0902 725687.Westwood Computers Ltd 021-632 5824 NORFOLK Anglia Computer Centre 0603 29652 Carlton Computers Ltd 0493 58897 NORTHANTSCo -Compute Ltd 0604 33767. OXFORDSHIRE Courtland Electrical 0865 779282. SALOP. Cressage Computer Services 0743 69009 STAFFS.Abel Computer Systems Ltd 0827 50804 SUFFOLK Bh/th Computers Ltd 050-270 371 SURREY Ramm Computer Services 0284 64045 Aerco-Gemsoft Ltd 04862 22881. Ferguson Computer Services 09323 45330. SUSSEX Ilexford Ltd 0273 23020. Datex Micro 0903 39290. I D TComputers 044-483 370 Oval Computer Systems 0903 501355. Supabeam Computer Services 0403 61647 STAFFS. Britannia Computers Ltd0384 233433. WORCS. Capricorn Computer Systems Ltd 0905 21541. Mike Dennis Associates Computer Systems 0386 48240 S. YORKS.Hallam Computers 0742 663125. EIRE Teletone Ltd Dublin 715954. N. IRELAND Medical & Scientific Computer Services Ltd 08462 77533.SCOTLAND Scotbyte Computers Ltd 031-343 1005. Gate Microsystems Ltd 0382 28194

If you are interested in TABS low cost Accounting Business Systems,please tick box(es) and return this coupon to us.User enquiry

Please send me an invitation to a free seminar.Please send me the TABS User ManualI enclose £5 (postage and packing included)

Dealer enquiryPlease send me details of your Dealer Plan

NAME

ADDRESS

Tel. No.PC5/8

TABS Ltd, The Old Rectory, Blackford, Wincanton, Somerset.Telephone: North CatLury (0963) 40164 TABS,

Software review

Low-cost Wordease fits the billfor office applicationsTHE GREATEST weakness of Wordease liesin its documentation. Written with thecomputer buff in mind, the documentationfor this otherwise extremely usefulprogram is guaranteed to frighten awayanyone unfamiliar with computer termin-ology. It is written using a wealth of tech-nical jargon, it does not contain workedexamples which might at least have madeWordease a little easier to use and it con-tains a few minor inaccuracies.

I do not consider myself a computerwhizz -kid, but at the same time, I think Iknow enough about the subject to be ableto have a commercial program up andrunning as quickly as the next person. Yetby the time I had unraveled the vectoringto my existing print routines and had per-suaded the program to read my standardkeyboard, it had taken me four hours toload and run Wordease.

Another four hours passed before I wasable to use it to any real purpose afterwhich I was on the learning curve whichshould have been reached after a singlereading - or, at most, two readings - ofthe manual. The typical user of the pro-gram, say, typist or secretary with nospecial computer knowledge, mightabandon the program because the initiallearning hump is just too steep. Thatwould be a shame because when used at itsbest, Wordease is a print formatter parexcellence, comparing well to manymodern typesetting machines.

So what is Wordease? It is described asa text editor and text processor and its useis clearly divided into these two separatefunctions. As a text editor I found itinferior to Naspen - the only Nascom-based competitor in the same price andsize range, reviewed September 1980 -but that as a pre-print processor, it is ex-tremely versatile and capable of producingcomplex multi -page documents easily andto a very high standard.

Available controlsAssuming a memory already full of

text, the more obvious controls are easilyavailable. Scrolling -up and down throughthe buffer, inserting and deleting, findingand replacing pre -defined strings - allwith full on -screen cursor mobility - isstraightforward and a bytes -remainingdisplay is available although it is updatedonly occasionally when text is processedbut not during normal entry.

The speed, incidentally, of such actionsas insertion or replacement is particularlyimpressive and is achieved through the useof a "playground" area - an interestingand useful way to increase text processing

PRACTICAL COMPUTING May 1981

. Circle No. 155

Nick Laurie analyses the strengths and weaknesses ofWordease, the word-processing package for Nascom.

speed. For further details read Wilkes:Scroll editing, IEEE transactions on com-puters volume 19, number 11, November1970.

The find command is also capableof handling wild characters embedded asasterisks in the find string. There is, how-ever, a serious disadvantage - it is a line -based editor with all the action exceptentry taking place on a single edit line -line 8 on the screen - and the text is re-flected on to the screen exactly as itappears in the buffer.

Blank linesThere is no tidy -up routine so that

words wrap around from one line to thenext. It is essential, therefore, to hitnewline at the end of each screen line fortidiness - fine for touch typists but hellfor two -finger Peek and Poke types.Insertions and deletions have an un-nerving habit of leaving blank lines andodd word -breaks permanently insertedinto the text.

The general untidiness is cleared -up inthe processed output but not in the bufferand it makes editing of text on the screeninto a very disjointed affair and reallyprevents Wordease from being usedextensively for original writing. On theother hand, when large blocks of the textare standard as is often the case inbusiness letter writing, the program reallysaves time.

By using the so-called macro com-mands, it is possible to store up to 10 textsections which can be called up byreferring to them by number in the bodyof the text. They will be inserted and for-matted automatically leaving, forexample, only the names and addresses ofa standard letter to be defined by the oper-ator.

Two such macros are dedicated to pro-viding the page headings and footings andcan include automatic page numbering aswell. Very useful when a multi -page reportis being prepared. A macro can contain anembedded instruction to call up anothermacro - and so on to the full depth of 10- so allowing considerable versatility.

As well as these normal editing features,there are a number of commands availablefor use in a direct mode. `U' and 'D'followed by a number will cause thescreen display to scroll -up or down by asmany lines as required while 'T' and 'B'put the top or bottom lines respectively on

to the edit line. A software shift lock isavailable.

Text on the edit line can be marked andnew markers - maximum of two, todefine a single block of text - adjustthemselves automatically to point towardseach other so that, as new markers areadded, the nearest old one is deleted andthe new one points towards the remainingone. Marked areas can then be copied toany required line or killed.

Again, the fact that the editor is line -orientated may mean that some fineshuffling is needed to place text at exactlythe right spot. A save command feeds themarked area direct to cassette or disc insome systems and the saved text can bereplayed direct to the edit line as though itwere from a keyboard. Misread charactersare displayed as `?' to allow easy recog-nition. The KILL command is the onlycommand that has to be spelt in full -just as well since it is not possible torecover killed text. 'Q' or quit returnscontrol to the system monitor.

The final command as far as the editoris concerned is `P' for process and it leadsus to the second and, to my mind, farmore impressive face of Wordease.

Format and outputThe purpose of the processor is to

format and output the contents of the textbuffer to one or more of the three ports.Each of the ports is a vector to a user -defined - and user -supplied - outputroutine. Typically, port 1 would be sent tothe screen to provide a view of the generalappearance of the formatted text while thesecond might be directed to a printeroperating routine with the third going to atape or disc system. All three ports have tobe vectored by the user so that any outputroutine can be used.

Unfortunately, the manual againassumes that the user is used to fiddlingabout in individual memory locations inmachine code and keeps explanations ofprocedure to a minimum while theoccasional inaccuracy in the memory mapprovided does little to help find the properlocation. Each vector is followed by acontrol word which can be set to any ofthe following options:

I . Character delay feature on or off2. Use Nascom I carriage return code3. Inhibit line feeds4. Force upper-case - capitals

(continued on next page)

55

Software review(continued from previous page)

The control word, inserted by the userin Hex, can be the sum of any of theseoptions to give different controls ondifferent ports. The required port orcombination of ports is selected byentering the command `Pn' where 'n' isthe port number followed, if required, bya `Dn' command which sets the pre -codedport delay factor to control the characteroutput speed while `Pn' defines the pagenumber of the first page output in multi -page documents.

Text is processed from the buffer as asingle continuous string and is justifiedautomatically whether you want it so ornot. I consider this to be a fault since, if aline is to be printed unjustified, it isnecessary to insert a specific commandinto the text each time this format isrequired.

With the current ubiquity of wordprocessors, there is a tendency for every-one to produce tidy, justified output onany three -by -two dot-matrix printer andthis tends to give an appearance on a parwith the resprayed banger or the gildedstinging nettle.

On poorer -quality word processors, thejustification routines can lead to a gappyappearance and the overall result is thatthe style of computer -generated wordoutput is becoming very recognisable -and not for its better qualities either.There are times when one would like topretend that a letter has been hand -typedand at such times, the forced justificationis a positive disadvantage.

Error messageDuring the processing it is possible, or

even probable, that errors caused by theuse of inappropriate or conflictingcommands will occur. An error message isdisplayed and a jump made to a vectordefining your machine's "bell" routine -very useful if you want to leave yourmachine during processing. If no bell isavailable, the Hex command C9 isinserted in the bell vector and the errormessage is displayed silently.

While most of the error messages areself-explanatory, the fact that they are notexplained in the manual is a fault whichdoes nothing to help the slope of thelearning curve. Processing is halted whenan error occurs and the offending line ofbuffer is placed on the edit line.

Unfortunately, the precise spot atwhich the error was found is not markedand, bearing in mind that there may be 12of more commands embedded in a line oftext, it can call for a good deal of studyingto find the mistake. That again is not afault exclusive to the system but onewhich I have encountered on othermachines costing upwards of £15,000.

The formatting commands consist of 14very comprehensive codes which can beinserted into the body of the text to tell theprinter exactly what to do when they areencountered. Imagine you have writtenand edited your text, you have pre -defined

a number of macros for your standardparagraphs and it is now time to thinkabout printing.

Going through the text line by line, youinsert commands into the text at eachpoint where the printer has to do some-thing other than print justified words - itcan do that with no commands beyond adefined line length. Insertion of control`C' - an up-arrow, 5E Hex - indicatesto the processor that the followingcharacter is a command - which will not,of course, be printed - at which point theprocessor interprets the next characterand controls the printer accordingly.

These characters are which is usedto set the line length. Here and in allcommands using a numeric suffix, 'n' is adecimal number which defaults to 1 and isto the command character. Beware,though, of numbers which are part of thetext to be printed; if they follow acommand, a separating space must beused to avoid confusing the system.

`13' and 'S' set the line spacing to single -or double-spaced, 'I' sets an indentcausing printing to start at column n on alllines until the command is cancelled usingILO, while 'T' for tab causes a once -onlytabulator to column 'n'. 'N' prints a newline while `E' for eject prints new linesuntil the end of the page, whose length isinitially defined using `Pn', is reached.

A very clever conditional eject 'Cn',operates the multiple line feed only ifthere are fewer than 'n' lines left on thecurrent page and would, for example, beused before a chapter heading to avoidprinting it at the foot of the page.

The last few commands complete thesystem: 'F' for finish which outputs newlines to the end of the page and then haltsthe printer; an 'H' simply halts the printeruntil any key is pressed allowing the userto change the sheets in a sheet -fed printerand it would normally be included in thefoot -of -page macro which is referencedwhenever a page has been completed.

This same macro would usually containthe 'X' instruction to print the currentpage number - three digits, leading zerosuppression. 'Un' is a user commandallowing decimal 'n' to be output to theprinter for special-purpose control codessuch as a printer on/off switch. Onehandy feature of the commands is thatthey can be entered in upper- or lower-case which helps to avoid errors.

In spite of the apparent complexity ofreading the text buffer once it has beenpadded out with commands, one can growused to it very quickly with regular use.With practice, it is possible to read a pieceof text, visualise the finished appearancerequired and then insert the control codesto produce it. Many a sub -editor would beable to master the machine - given adecent manual - in minutes.

A trial run formatting to the screen isessential to check that everything youwanted happened and it is a shame thatthis output is, in effect, lost once it hasscrolled off the screen. Ideally, it should

replace the existing buffer string with theprocessed string to allow further editing totake place.

Once satisfied with the format the printprocess command is given and manuals,books, circular letters can be churned outad nauseam. The 'Wordease manual isproduced on Wordease and is a model oftidiness - visually, if not in terms ofcontent.

In large volumes, it is still far lessexpensive to typeset and print usingslightly less modern techniques than to useimpact printers and photocopying. That isbecause the area of paper required fortypeset material is far less than it is fortype -written material and on a 30- or 40 -page manual, the reproduction costs of amass of paper far outweigh the savingsmade by avoiding professional type-setting.

I have used Wordease to format andprint a number of experimental pieces andfound that with practice - and, prefer-ably, some familiarity with modernphotosetting techniques - it is invaluablein the preparation of complex reports andstandard letters although practicallyhopeless for original or creative writing.

The ideal user for Wordease would bethe small business involved in the con-tinuous generation of similar but non-identical material such as an estate agentor mail-order company. Such a firm mightwell consider dedicating a Nascom andprinter solely to this purpose at a very lowcost indeed. A copywriter or an authornot requiring the powerful processing onoffer but needing detailed and tidy editingfacilities would go out of his creative mindin a very short time.

The fact that this editor seems to begeared for report writing and standardletter writing rather than to creation oforiginal material gives Wordease theappearance of either having been builtspecifically for a particular job and thenmarketed as an afterthought or of simplybeing another half -completed programrushed on to the market ahead of time.

Wondering which answer was correct Ihad a word with Program Power whodistribute it and I was put in touch withthe author, TR Harris of Vader Systems inPortsmouth who confirmed that he wroteit with a view to satisfying his own needs- mostly for standard letters - and thatthe marketing followed when variouspeople expressed interest. Hence thedocumentation and low cost - £25.

Conclusions Wordease is very much a purpose -designed program and while it may beunsuitable for many people, those whoseinterests lie in the production of standardletters, complex multi -page documentsand short runs of things like instructionmanuals will find it superb. It is at its worst for creative writing. It does everything it is supposed to doand does them well, but it may not doeverything you would like it to do.

56 PRACTICAL COMPUTING May 1981

AWord Processor,Report Writer,Mailing System,Data Base Manager,andaComputerall for £1995Yes,we are offering all this with ourSERIES 5000 5" floppy -disc systemfor the incredibly low price of k1995.*

Not only do you get a powerfulZ -80A system on the S-100 bus built tohigh quality standards by IndustrialMicrosystems, one of the longest -andbest -established companies in themicrocomputer industry,andsupported by Equinox,specialists.inmicrocomputers and multi-usersystems.

You also get thepopular CP/M

Operating System(from Digital Research),

a 12 -slot bus for easyexpansion,a Z -80A CPU for powerfulperformance,2 serial and one parallelinterfaces,64KB of dynamic RAMwith in-built error detection capability,

and dual 5" double -density drives withthe option of a third drive (or quadcapacity drives in place of double -density) in the same cabinet.Additionally,there is the Turbochargeroption providing both enhanced disccapacity,disc performance anddiagnostics.And if even greater storageis required we can supply 8" floppy

drives and cartridge disc drives.A powerful system for thecomputer -user and systemdeveloper - and one witheventual access to OS/2000,the Industrial Microsystems

networking system.And for the office or

business user we areincluding as standard a

powerful Word -Processingpackage (Wordstar),a Mailing and

Letterwriting package (Mail -Merge)and the Datastar Data Base Manager.All these packages are widely acceptedand professionally written byMicropro International.

Being CP/M based,the system withsuitable configuration will also run thebusiness software developed by (forinstance) Graffcom,Peachtree,Paxton,etc.

It will also run a wide range oflanguages - Basic,Cobol,Fortran,Pascal,APL,Algol,C.Lisp,and Forthand will support a wide range of add-on S-100 devices,such as floating pointprocessors,Prestel interfaces,speechsynthesisers,digitisers and plotters,etc.

And just to make certain that youget full use out of your system,nationwide field service support isavailable at a modest extra cost.

*add VAT and the terminal and printer ofyour choice at the costs shown.

Series 5000 with 64KB Dynamic RAM,dual 5" double density drives, CP/MOperating System, Wordstar, Mail -Mergeand Datastar L1995

The same system with quad drives inplace of the double density drives £2230

Add-on double density drive £290Add-on quad drive £405Peripherals:Televideo 912C VDU £595Elbit 1920X VDU with WordstarkeyboardOKI Microline 80 printer 595Texas 810 150cps printer 450NEC Spinwriter RO Wordprocessing printer £1850

All prices exclude VAT,carriage,training and installationand are subject to our standard terms and conditions.

OEM dealer and educational enquiries welcome.

UINOXCOMPUTER SYSTEMS LIMITED

Kleeman House,16 Aiming Street,New Inn Yard,London EC2A 3HBTel:01-739 2387/9 & 01-729 4460

Circle No. 156PRACTICAL COMPUTING May 1981 57

Business computing combinationof Equinox and MVT-Famos

EQUINOX Computer Systems Ltd is a Britishcompany based in London and was estab-lished three years ago, in July 1978. Thatwas at the height of the initial wave ofenthusiasm about microcomputers. Atthat time, most suppliers were selling com-puters for the hobbyist and educationalmarkets.

Many companies were supplying microswithout the peripherals necessary to makea complete system. The customer was ex-pected to buy the components separatelyand build-up a system, rather like a stereoenthusiast and, like the stereo enthusiast,he would run into the attendant problems- how to select compatible equipment,and how to store the equipment so that itis not just a mess of boxes and wires.

Equinox was set-up with the aim ofsupplying complete systems - the com-puter, VDU, printer and disc drives. Ithas a staff of 12, including eight technicalstaff involved in setting -up and testing theequipment before it is sent to customers.It supplies many of its systems through theOEMs, own equipment manufacturers.

This is a term in the computer trade re-ferring to companies which buy equipmentfrom other manufacturers and add otherhardware or software to it before sellingthe complete system to the customer.

Recently, it has often been used to referto systems houses which buy the hardwareat a discount and provide applicationsprograms either in the packages orcustomer -written software. Equinox has anetwork of about 30 such dealers aroundthe U.K., particularly in the south, south-west, East Anglia and the north-west.

Its first two products were a systembased on the North Star Horizon and theEquinox 300. The North Star Horizon is a

by David Wattwell-known Z-80 system sold by severalother suppliers with a maximum 56K ofmemory and two 5 'Ain. floppy discs in anintegral cabinet. The Equinox 300 is a 16 -bit multi -tasking multi-user system using achip set manufactured by the WesternDigital Corporation.

The system features a minimum48Kbytes of memory with dual floppydiscs, up to a maximum 512Kbytes ofmemory and a variety of hard discs, froma 10Mbyte system with 5Mbytes fixedstorage and a 5Mbyte removable cart-ridge, up to the CDC Phoenix disc whichhas a 16Mbyte removable cartridge andmay have from 16 to 80Mbytes of fixedstorage.

In autumn 1979, Equinox announcedthe IMS 5000 and 8000 systems, and in thesummer of 1980, the Equinox 200. Aswith the 300, the systems may have from48Kbytes to 512Kbytes of memory, usingbank switching, and a range of disc drivesfor mass storage. The 5000 and 8000 aresupplied directly by IMS, Industrial MicroSystems of Orange, California, with5 1/4in. mini floppy and 8in. floppy disk-ettes respectively.

The 5000 may have from one to threedisc drives, and the 8000 up to four discdrives. Both types of disc may be suppliedin single -density, double -density ordouble -sided, double -density formats,giving a maximum of 1Mbyte on-linestorage with the 5000 and 4Mbytes withthe 8000. The Equinox 200 is more suit-able for multi-user applications - it issupplied with the same discs as theEquinox 300, the Ampex 448 10Mbytedisc manufactured by the Ampex Corpor-ation, or the CDC Phoenix disc providingfrom 32 to 96 Mbytes of on-line massstorage. The same processor is used in the5000 and 8000 and is supplied by IMS.

Equinox supplies a variety of operatingsystems, program languages and twoword-processing packages for use with itssystems. For single -user systems, it has the

58 PRACTICAL COMPUTING May 1981

Review -2

ubiquitous CP/M from Digital ResearchInc, complete with Microsoft MBasic orBasic -80, Fortran -80 and Cobol -80. CIS -Cobol is also available from the Britishfirm, MicroFocus - it is one of the mostacclaimed Cobol compilers availablefor eight -bit microcomputer systems.Wordstar may be used for word-processingapplications.

Multi-user systemsAlso from Digital Research is MP/M

for multi-user systems. It is compatiblewith CP/M so any of the languages men-tioned may be used on a MP/M system, ascan Wordstar. Omnix is also a CP/M-compatible multi-user operating systemfrom a U.K. firm, 1500 Systems Ltd.MP/M and Omnix are useful for upgrad-ing to a multi -terminal system wheredifferent applications will be run on eachterminal, especially when those applic-ations have been developed under CP/M.Unfortunately, MP/M has no means ofpreventing unauthorised use of files.Many multi-user operating systems allowfiles for a single user to be grouped to-gether which may then be protected by apassword.

From CAP, one of the largest computer

system houses in the country, the CAP-MicroCobol business operating system isavailable. Various applications packageshave been developed to run with Micro -Cobol, including sales ledger, purchaseand nominal ledger, Autoclerk, a filemaintenance utility for creating,amending and inspecting business datafiles, and Autoindex, a database indexingsystem for fast storage and retrieval ofdata.

Finally, from MVT MicrocomputerSystems Inc is another multi-user, multi-task operating system called MVT-Famos.Famos is an extremely powerful disc oper-ating system for eight -bit microcomputersfeaturing multi-user security and usespasswords to allow access to selected pro-grams and files.

Memory may be bank -switched up to512Kbytes with tasks dynamicallyallocated to individual memory banks. Ifthere is sufficient space, two or more tasksmay use the same bank. Applications pro-grams may be written in assembler usingASMZ, a Z-80/8080 macroassembler, orin MVT-Basic. MVT-Basic consists of are-entrant compiler and run-time module.The compiler produces re-entrant objectcode, so if several operators are runningthe same program, only one version of the

program need be loaded in memory.For the purposes of the review, I exam-

ined the Famos operating system on anIMS 8000, with twin double -sided,double -density 8in. diskettes and a Hazel-tine 1500 VDU. The benefits of Famoswould be more noticeable on the hard -discEquinox 200 systems, but as the IMS5000, 8000 and Equinox 200 arecompatible with identical processor andmemory, it was easier to examine the8000. I received a good deal of advice inthe use of Famos from Microtek Com-puter Services, an Equinox OEM, basedin Orpington, Kent.

Central processorThe central processor unit, CPU, used

in the IMS 5000, 8000 and Equinox uses aZ -80A processor chip and is mounted on a12 -slot S-100 motherboard. The systemsmay be configured with a minimum of56K and a maximum of 512Kbytes ofrandom access memory, and they willsupport up to 20 terminals using RS232serial interfaces. Two parallel ports areprovided for devices such as printers.

The IMS systems, the 5000 and 8000may be provided as desk -top models orsuspended beneath a desk -top, to give awork -station configuration. The Equinox200 series are rack -mounted, again in acabinet 22in. wide by 32in. deep and 34in.high for the 10Mbyte system and 42in.high for the 32Mbyte system. The stand-ard motherboard for the Equinox 200 has19 slots giving more space for extramemory and interface boards.

The 200 series may be configured withthe Ampex 448 10Mbyte disc with5Mbytes on a removable cartridge, or theCDC Phoenix drive which has a 16Mbyteremovable cartridge and from 16 to80Mbytes of unformatted fixed disc stor-age - when formatted the storage isslightly reduced. In addition, floppy discsmay be provided with the system as in thesmaller models. This is particularly usefulfor the easy transfer of programs and files- particularly when applications pro-grams are being developed.

Various peripheralsEquinox supplies a variety of other

peripherals to complete the system,including Televideo 912C, Hazeltine 1500or Elbit 1920X VDUs and OKI Microline80 printer, Texas Instruments 810 150 cpsprinter, or NEC Spinwriter - a word-processing -quality printer.

Starting the system is a simple matter ofswitching on the computer and all peri-pherals and inserting the boot disc in drive0. The operating system is loaded intomemory automatically. There is a springloaded re -set switch on the front of thecabinet above the red power switch to re-load the operating system in the event of asystem crash. The power switch alsoserves as a "power on" indicator and

(continued on next page)

PRACTICAL COMPUTING May 1981 59

(continued from previous page)lights -up whenever it is switched -on.

The hard disc drives have additionalcontrols, a stop/start switch, ready light,fault light and write -protect switches forthe cartridge and fixed discs. The10Mbyte drive also has an active lightwhich flashes on and off indicating discactivity.

Once the Famos operating system isloaded the operator may sign on to thesystem by typing "Q" at the terminalwhich will cause a message to be displayedindicating the version of Famos beingused. No other character will have anyeffect so it is important to make sure yourkeyboard is set for upper-case input, orlike me, you could find yourselfwondering why nothing happens when the"Q" key is pressed. All system commandsmust be typed in upper-case or they will berejected by Famos.

Famos may be supplied without user -accounting for single -user systems, inwhich case the system will displaySSREADY, which is the standard promptindicating the system is ready to execute atask. However, with the user -accountingversion, a user name, up to eightcharacters, must now be entered followedby the password associated with the username. The password is not echoed on thescreen when it is typed -in, making itharder for unauthorised people to learnpasswords and gain access to the system.

Restricting accessBesides restricting access to the system,

user -accounting also permits file accessfor a user to be restricted to the files in hisown account. File names may be up to 15characters long. When user -accounting isin operation, all file references made bythe user have a three -character prefixtagged on to them automatically - theprefix is the first three characters of theuser's name.

It is invisible to the user except whenusing certain system commands, such asMAP which displays the list of files on adisc and it means if two users specify thesame file name, they will access twodifferent files unless they have the samefirst three characters in their user names.

File -name prefixing is optional. If it isdisabled, any user can access any file.Also, file -name prefixing does not occur ifthe user name begins with "X", or the filename begins with "C". User namesbeginning with "X" are designated assystem accounts and can access any file onthe system and similarly file namesbeginning with the letter "C" aredesignated as common files which may beaccessed by any user.

In addition to user account passwords,another level of security is provided byallowing individual files to be protected bypasswords. Passwords are specified byputting a comma and the password afterthe name of the file - the whole string isup to 15 characters long. The passwords

are not normally displayed with the filenames, but whenever a file name isspecified for processing, the passwordmust be specified as well.

There are four types of files handled byFamos, types A, B, C and E. Type A is forprint spool files, data files or programsource files, type B indicates compiledBasic programs, type C indicatesassembler programs and type E,temporary edit files created by Word -flow, the MVT word-processing system. .

The device on which a file resides maybe specified by prefixing the file namewith a colon, followed by a unit number.Up to 16 units may be referenced in thisway. Unit numbers may be in the range 0to 9 or A to 0 with the numbers 1 to 9being equivalent to A to I. Devices may berandom, i.e., discs, or serial such asprinters. Serial devices are indicated byusing the special character " < " in placeof the file name in the file specification.

When the operator has signed on to thesystem, his terminal is under control ofSuperselector, the re-entrant commandprocessor. This issues the promptSSREADY and waits for the operator toinput a command. Superselector allowsthe user to queue an assembler program asa task for execution, suspend a task,resume a task, resume a task attached tothe terminal so that the task may displaymessages or receive input from theterminal, end a task deleting it from thesystem, or end all tasks currently initiatedby the terminal and sign the user off thesystem.

In addition to these commands, varioussystem functions which are part of theoperating system may be executed just bytyping the name of the required function.

Sample hardware pricesI . Horizon System.

56K RAM,two 51/4in. double -sided, double -density disc drivesHazeltine 1500 VDUOKI Microline 80 Printer

2. As for I but withElbit I 920X VDUNEC Spinwriter

3. IMS 500064K RAMthree 5'/in. double -sided, double -density disc drivesElbit VDUNEC Spinwriter

4. IMS 800064K RAMtwo 8in. double -sided, double -density disc drivesElbit VDUNEC Spinwriter

5. Equinox 200-1064K RAM10Mbyte disc driveElbit VDUTexas 810 150 cps printer

6. As five but with192K RAMfour Elbit VDUsone Texas printerone NEC Spinwriter

7. Equinox 200-32256K RAMsix Elbit VDUstwo printers

£ 4,200

£ 5,450

£ 5,650

£ 5.900

£ 9.750

£15,500

£20,500

These functions allow the user to create,delete, copy and merge files, display filesand file names, edit, compile and runBasic source files, display various systemstatistics and control the operation of thesystem.

Famos does not allow the operator totype -ahead - that is to continue enteringcommands or data while the system isprocessing previous commands. I foundthis rather inconvenient. If one attemptsto type -in data before the system is ready,the input is rejected and the terminalmakes a beep.

The Superselector will accept a string ofcommands and parameters input in asingle line of up to 66 characters. Eachcommand must be separated by a "/",parameters by "[", and the firstparameter for a command must bepreceded by a dot.

Command sequenceThis is useful for inputting sequences of

commands which might take a com-paratively long time to execute and forwhich all the required parameters areknown, for instance, when compiling andrunning a Basic program. Alternatively,new system functions may be set-up whichconsist of a set of the existing commands,or systems programmers can createentirely new system functions usingexisting commands.

A special editor, MCOMM, is used tocreate the function in a type C file. Thecommands to execute the function areinput as described for command lines butonly one command and its parametersmay be input on each line.

Although these facilities, particularlythe ability to set-up special functions, areuseful, I found it was very easy to forgetto type a dot before the first parameter ofa command with the result that the systemmisinterpreted the command. With type -ahead, the operator does not have to learnany special characters for inputting thecommands.

Some special control codes can be usedto correct commands before they areinput to the system. Control "X" cancelsall input on the line as a new commandcan be typed. Control "G" and Control"H" move the cursor right and leftrespectively so that characters can bechanged by positioning the cursorcorrectly and typing the new characterover the existing character. Characters canbe inserted by using control "I".

Control "X" does not cause thecancelled input to be cleared from thescreen, or give any other visual indicationthat it has been entered. Control "I"causes the character under the cursor to beduplicated and the display is not changeduntil the cursor is moved along, so it canbe confusing to use both these characters.

There are two other special charactersused by Famos. Control "T" is used togenerate an interrupt when a program isexecuting a Wait statement, and ESCAPE

60 PRACTICAL COMPUTING May 1981

Review --------which may be used to suspend a task andreturn to the Superselector. The task maythen be resumed or terminated by theSuperselector.

If the task requires no operator inter-vention and does not require any operatorinput, it may be suspended after beinginitiated by pressing ESCAPE, and thenresumed. This frees the terminal for useby another task.

Another facility available only withuser -accounting versions of Famos isbatch processing. Programs may be rununder control of the batch processorwhich accepts commands and data from aspecial file called job file, as though theywere being typed in by an operator.

Job files may contain job control linesor terminal input lines. Job control linesallow terminal output to be routed to aspecial file or device, user -account namesand passwords to be specified, terminalinput to be echoed on the terminal outputfile, and for the current task to wait untilits sub -tasks are complete.

Terminal -input lines are lines of data tobe input to the programs being executedby the batch processor and appear exactlyas they would if typed by an operator.Batch -processing tasks are controlled bythe batch monitor which is a specialprogram which is treated by Famos as adummy user. That is why it is availableonly with user -accounting versions. Thebatch monitor maintains a queue of tasksawaiting execution which can be examinedand manipulated by a batch controlprogram.

Job displayedBCONTROL allows the operator to

display the jobs awaiting execution andthe current job being executed, to abortthe current job, or all jobs, to delete thecurrent job -file name and to bump jobsup the queue so they will be executedsooner.

Batch processing is a very powerfulfacility because it allows non -urgent tasksto be queued for processing as required,freeing the terminals to be available forinput and enquiry and other tasks requir-ing a good deal of operator intervention.

Efamos, the E stands for extendedmemory, allows systems to be configuredwith up to 512Kbytes of random accessmemory. The memory is allocated in32Kbyte banks - the first bank is used bythe operating system and remaining banksare available to user tasks.

Terminals are assigned to banks eitherexplicitly via a bank -assignment table, orbanks may be allocated dynamically, inwhich case a user is assigned to the bankwith the least number of other users. Thebank assignments can be changed by usingthe ASSIGNB system command. They arenot fixed when the system is initiallygenerated as they are in many other oper-ating systems.

At present only Basic and assembler areavailable for writing application pro-

grams, although Cobol is reputedly underdevelopment. MVT-Basic consists of a re-entrant run-time package and compiler.The compiler produces semi -compiledobject code, which also re-entrant. Usinga compiled language, it is less easy todevelop and test programs than using aninterpreter, but a compiler usually pro-duces more efficient code, so thatprograms execute more quickly. MVT-Basic certainly seems to be acceptablyfast. Except in the case of transcendentalfunctions like SIN, COS and LOG.

The review system performed approx-imately 83 operations per minute of asimple loop containing a SIN and a LOGfunction. I asked Paul Ringer at Microtekabout it and he said MVT did not writethem very efficiently because anassumption was made that they are notused very frequently in business data pro-cessing. That is true, but when they areused, the same calculation may need to bedone on hundreds of records in a file.Microtek solved this by designing its ownroutines for the function it needed.

The Basic contains all the usual verbsand expressions. Variable names may beup to eight characters long and stringvariables up to 55 bytes long. The size maybe defined by the Size statement at thebeginning of the program. It is good prac-tice to define the size of all string variablesused in a program. Otherwise, strings willdefault to a size of 80 bytes which iswasteful of program space.

The precision of floating-point vari-ables is determined when the system isgenerated. The default size is six byteswhich allows numbers to be held to 10decimal digits of accuracy. Multi-dimensional string and numeric variablearrays are supported by Famos. Theredoes not appear to be a limit on thenumber of dimensions which may be spec-ified but the total number of elementsmay not exceed 255.

There are two methods for input from aterminal, the Input statement and theGBYTE function. The Input statement

allows one or more variables to be inputseparated by single spaces. Commas arenot treated as delimiters and may beincluded in string variables. GBYTEallows a program to receive the next char-acter input from the keyboard. There isno Input Line statement in MVT-Basic toinput a complete line of data terminatedby line feed or carriage return.

Fixed -length strings may be input usingthe FLD function which allows spaces tobe input as part of the string. If a stringlonger than the length specified is typed,the string will be truncated. If the string istoo short, the input will be rejected andthe program will re -execute the wholeInput statement - as it does in the eventof any error.

Input statementIn general, I found the Input statement

rather inflexible, particularly for input ofstring data. I believe it is better to use theGBYTE function and the FLD functionwould have been much more useful if itaccepted short strings.

The Print and Print Using statementswork in a similar fashion to M -Basic andother versions. The Print Using statementallows data to be output in specific for-mats and is also similar to M -Basic. TheTab function may be used for positioningthe cursor anywhere on the screen andmay have one argument specifying thenext print position on the current line, ortwo arguments specifying a line andcolumn position, which is very useful forinputting or displaying screen formatteddata.

Basic has facilities for handling files intwo ways. Type I access is primarily forsequential ASCII files, while type II,internal format, is used for mainlyrandom access data files, although filescan, in fact, be accessed by either method.ASCII files are used for print spool filesor job files to be used in batch processingand are treated in a similar fashion to

(continued on page 63)

PRACTICAL COMPUTING May 1981 61

We believe the North Star Horizon isthe only microcomputer which hasquality and reliability necessary forthe serious small business user. Wesupply the Horizon with a Hazeltine1420 terminal and an Epson MX80 DotMatrix printer or optionally with aVulcra-Craig terminal and Diablo630 letter quality printer.ACCOUNTSComplete accounting software for theabove system suitable for the smallmanufacturing company. It ischaracterised by extreme ease of useand security of data. It uses only threedisks thus preventing all that confusiontypical of so many accounts systems. Thesoftware is designed to be very fast wheninteracting with the user. Included in thepackage are facilities for fast search,ledger inspection, aged debt analysisand management accounting summary.The latter provides a completebreakdown of overhead expenditureand all trading parameters and is an

NETWORKINGOffice Administration, Data logging and ComputerAided Manufacture (CAM) all tied together with thisZ80 based micro network utilising low cost hardware I

and proven software. This can be built up from astand alone word processing system at £2,800 to fullnetwork systems starting from £7,750. Governmentassistance available for CAM applications. Freefeasibility studies undertaken by MAP consultants.Contact Peter Krueger for more information.

IA Systems (Intelligent Artefacts)Cambridge Road, Orwell,Royston, HertfordshireTel: (022020) 689

I

I

I

I

I

I

From a single system to a networksupporting 250 users

extremely powerful tool for managementaccounting in todays small business.Passwords and other safeguards make itvirtually impossible to make mistakes oneexample of which is the back up facilityin which it is impossible to accidentallycopy from the back up disk,to theworking disk.

INVENTORY CONTROLThis program links to the accounts systemthrough a special sales module so thatsales from stock are automaticallyentered into the accounts. You can evensell directly from stock generating aninvoice on the spot and even inspect yourstock whilst in the middle of generatingan invoice. The system gives warnings oflow stock levels notifying re -order pointsand will also analyse sales by stock itemgiving total margins on each item. Thisextremely powerful system is ideal forcompanies or shops selling from stock.

r Please send me details of the IAI Networking System

Name.

Address

Company

Position

IA Systems, Cambridge Road,Orwell, Royston, Hertfordshire.Tel: (022020) 689,

PCS 81.1

Circle No. 157

62 PRACTICAL COMPUTING May 1981

Review(continued from page 61)the terminal input/output methods.

MVT-Basic treats type I files as contain-ing variable length fields delimited byspaces or "Escape" characters.Alternatively, fixed lenith fields can bereferenced using the FLD function.

For type II files, data:is input using theGet statement and output using the Putstatement. Both statements have the sameformat consisting of file number, recordsize and record number parametersfollowed by a variable list.

If the record size parameter is zero, therecord number parameter may be used tomove the file pointer, which indicates thecurrent position in the file, backwards orforwards a specified number of bytes.Data is held on the file in a fixed formataccording to type.

Numeric variables occupy six bytes andstring variables the length of the string asdefined by the Size statement plus twobytes. There appear to be no restrictionson having variable length records in a filebut obviously one would have to be verycareful how one accessed such a file so asto keep track of the file pointer.

Disc -file integrity is Maintained by theoperating system. Allocation of file stor-age space is managed by, using a bit -map.That is common to many operatingsystems, but Famos keeps the bit -mapconstantly up-to-date. When Famos needsto refer to the bit -map:, it is read into aspecial buffer. It is amended as necessaryand then written out ithmediately. Thatensures the bit -map alivays reflects thestate of the disc, although it obviously willslow file accessing.

Bit -map updateThe time taken to write 100 256byte

records on the IMS 8000 system was 50seconds, compared with five seconds toread the same records. Many othersystems, 'particularly thope designed to usehard discs, hold the bic-map in memorycontinually and only update the map onthe disc just prior to; the disc beingremoved from the system or the systembeing shut -down.

If the bit -map is not written back beforea disc is removed, in the 'event of a systemcrash the bit -map is not updated and willnot indicate the true state of the disc. Ifthe bit -map is not recovered at the earliestopportunity, data can be lost orcorrupted. The file system also preventstwo tasks accessing the same record simul-taneously by automatically providingrecord lock -outs.

The physical block size used for disc fileaccessing is 256bytes for; both floppy andhard discs. However, loical records maybe any size from one to 65,536bytes.Lock -outs operate on physical blocks, soif there are multiple records to each blockin a particular file and ohe record is beingaccessed in a particular block, other taskswill be prevented from accessing anyrecords in the block until:the first record is

PRACTICAL COMPUTING May 1981

released. For cases where records spanblocks, Famos provides a method forsetting long locks.

GETR and PUTR should be used in-stead of Get and Put for records whichspan blocks. These statements control thesetting of long locks. There is also a state-ment ULOCK which forces the removalof long locks from a file although it doesnot affect the normal block locks.

There are two functions for use witheither type of file: POSI allows the pro -

Software PricesMVT-Famos run-time system £ 475MVT-Famos Development system

including Wordflow £ 1,350MVT-Wordflow £ 250CAP-MicroCobol E 2,650CP/M £ 95MP/M £ 395Omnix £ 495

gram to position the file pointer to thestart of a specified block, and CHGFallows a file to be expanded or contracted.

Both assembler and Basic subroutinesmay be called by a Basic program. Theformat for Call is similar in both cases. Acontrol code may be specified in the call.For assembler routines the control codejust allows the program to load, retain,release or call routines, as required.

For Basic subroutine calls, the controlcode allows the routine to be executed andthen return to the calling program, or toact like the Chain statement in most otherversions of Basic, which transfers controlto the new module releasing the callingprogram. The Call statement for Basicsubroutines also has a parameter specifyingwhich variables are to be used for passingvalues to the subroutine and which arereceiving return values.

The Basic subroutine may then havetwo special statements, a PARM state-ment listing the variables to receive datafrom the calling program, and a Returnstatement listing variables to be returnedto the calling program. This last isdifferent from the normal internal sub-routine Return statement.

This facility is very powerful - partic-ularly in being able to call Basic sub-routines. Despite the format being similarfor Basic or assembler calls, there is nodanger of confusing the two because thecontrol code for assembler calls is in therange 0 to 4, while for Basic calls, it mustbe 10 or 11.

For indexed -sequential file access, anassembler program called ISM2 isprovided with Famos. It uses a hash indextable to locate keys which gives very fastaccess times when keys are random. Thehash index table is held in a key filetogether with the keys. ISM2 uses aspecial algorithm to calculate hash values.Each key in the file is pointed to by anentry in the hash index table.

That means the keys can normally befound by using only two reads of the keyfile. This may be compared to tree -structured index files where keys are

stored in successive levels, each level indic-ating the position in the level below wherethe key might be found, until one arrivesat the lowest level where the keys point tothe actual data file.

In this type of structure, it normallyrequires as many reads as there are indexlevels to locate the data record. Hashindex tables are fine unless there areseveral keys with the same hash value,when they can become inefficient.

Since new keys are added to the end ofthe key file rather than being inserted inorder, it can be inefficient to producereports in key order. To sort key files intoorder, a utility called SUPSORT has beenprovided. It is claimed to be very fast. TheBasic manual quotes 20,000 to 50,000 keysper hour on a hard disc, depending on theordering of the file and key length.

There is a comprehensive set ,of devel-opment tools for producing assemblerprograms, including a macro assemblerASMZ, debugging program DBUG, andlinkage editor LKED. ASMZ is compat-ible with 8080 or Z-80 code. DBUG allowsthe programmer to test assembler pro-grams by setting breakpoints, display andset memory contents, and read and writesdata to disc or the terminal.

Word processorThere is also a word-processing package

available for use with Famos. CalledMVT-Wordflow, it consists of a screeneditor and a print program. The editorallows up to three document files to beprocessed in the same session. Wordflowis very versatile - it features commandsfor setting rulers, cut and paste of textfrom one file to another, or within thesame file, insertion of control codes to setunderlining, boldface, printing of super-scripts or subscripts.

Composite characters can also becreated and there is a facility for listingprocessing. Rulers allow the setting oftop, bottom, left and right margins, para-graph and word-wrap indenting. Alsotabulators can be set which allow left- orright -alignment, or text strings can bealigned on a particular character. Socolumns of numbers can be printed withthe numbers all aligned on the decimalpoint.

I found the editing commands them-selves relatively easy to use, although mostof the commands required two controlcodes to be entered, rather than one. Forinstance Control D Control C is used todelete a character, and Control V ControlB to go to the start of the file.

Some commands are even more com-plex, but this is not a criticism as they arefor special operations like search and re-place, or for specifying fields to be in-serted when performing list processing. Astext is entered or edited, words are oftensplit on the right margin and the displaybecomes confusing to read. If you want tosee the text correctly formatted, Control

(continued on next page)

63

Review(continued from previous page)X is the key which must be pressed.

The output program is used to bring thedocument inserting fields like the date anddata from list processing files which mustbe in a special format.

The documentation provided withFamos was all produced by MVT-Micro-computer Systems. It consisted of aFamos Users' Manual, Wordflow Users'Manual, Program Development Manual,a Basic Programmers' Guide and a MVT-ASMZ Programmers' Manual. On thewhole, they were comprehensive and rela-tively easy to find one's way round,although the programming manuals werenot as easy to follow as the user manuals.I noticed some omissions, particularly inthe Basic Manual.

The format for the use of GETR andPUTR was not given, for instance. Alsosome of the manuals would have bene-fitted from the inclusion of indexes at theback - especially the Program Develop-ment Manual and the ASMZ Manual.Also, the Wordflow manual did not havean index, although it had useful lists of allthe commands.

Operational configurationSo that I could see an Equinox 200 in

operation, Microtek introduced me to oneof its customers, Chemical Bank Inter-national which has a 32Mbyte system withfive Elbit VDUs, a Tally 1602 serialprinter and floppy discs for data transferto an IBM system 32.

The system has 224Kbytes of RAM,32K for use with each VDU, 32K for useby the system and 32K for use by thebatch monitor. Four VDUs are used forenquiries and one for entering file up-dates.

The system is designed to handle trad-ing in Eurobonds, which are types ofsecurities issued by large multi -nationalcorporations and traded in by banks andother financial institutions. Like otherforms of dealing in securities or commod-ities, this involves a good deal of intenseactivity at certain times of the day.

During peak dealing times, there mustbe no appreciable degradation in responseto enquiries. Up to 1,000 securities may beheld on the system, which is designed tohandle up to 350 deals per day, and arecord of the previous 28 days dealings ismaintained on the history -monthly file.

In a demonstration of the system capa-bilities selecting all deals for a customer inthe past month, it took 21 seconds tolocate and display 12 records from 9,800on the history file.

At about 5 pm each day, the end -of -dayprogram is run to update the daily profitand loss fields, and up to four yields foreach security on file. This process takes anaverage of 12 seconds per security. Thecalculation of yields, in particular, is verycomplex as the method used is an iterativeprocess requiring successive approxim-ations to reach the final value.

The technique is to make an initialguess at the answer to the problem and usethis value to calculate a new value which iscloser to the required result. When theresults of two successive approximationsare close enough together, within somemargin of error, the last value is taken asthe correct result. The end -of -dayprogram also updates the history -monthlyfile with the day's dealings, prints variousdaily reports and performs the file securitycopying.

It is a 32Mbyte system becauseChemical Bank International required thefaster response available, even though ithas only 4Mbytes of data. Therefore, ithas all its files on the fixed disc and usesthe cartridge to copy data.

All that is run under the control of thebatch monitor. The bank is lucky inhaving a night shift operating its main-frame who switch -off the Equinox systemwhen the end -of -day processing is finished,although there is no reason why com-puters should not be left on 24 hours aday. Indeed, in many cases, leaving acomputer on continuously can improvethe life of a system.

The bank decided to buy the Equinox11 months ago, when it had already beenwaiting six months for an IBM system 38.At that time, it knew there was still a six-month wait for the IBM system andbusiness pressures forced it to look atmicrocomputer systems. The Bank lookedat several systems, including Cromemco,Zilog and DEC 11/23 systems.

The Equinox was the only system whichmet its criteria, which were to have amulti-user system with a Basic compiler.Having decided on using Equinox equip-ment in June, 1980 the Bank bought anIMS 8000 system complete with applic-ations package in August. In September,1980, the Bank decided to upgrade to ahard -disc system and re -designed applic-ations software, which it received onNovember 15. The staff were very pleasedwith the Equinox and with Microtek'sservice and support, and are consideringenhancing the system to link into theGeisco time-sharing network.

Conclusions Equinox has a wide range of systems,ranging from small, single -user systems tomulti -terminal, hard -disc systems. The Equinox 200 systems are compat-ible with the IMS 5000 and 8000 becausethey use the same processor. With a max-imum configuration of 20 terminals, twoprinters, up to 96Mbytes of hard -discmass storage and, say, 256Kbytes ofmemory, which allows 32K for eachterminal plus 32 for the operating systemand 32 for a batch processor, it is a verypowerful system. I believe there have been some prob-lems with the S-100 bus on the hard -discsystems recently, but they have since beensolved. Equinox also supplies a wide range of

operating systems and support software touse with its hardware. None of thesoftware is actually developed byEquinox. Both the CAP-MicroCobol businessoperating system, and MVT-Famos aresuitable for multi-user business systems.MP/M can also be used but has no file -protection or security features as standard,and neither does it have automatic recordlock -outs; these facilities would have to bebuilt-in by the programmer. MicroCobol seems rather expensivecompared to the other operating systemson offer. Famos is an extremely powerful andversatile operating system well suited tomulti-user systems; the user accountingsecurity and file security systems are veryuseful: Famos has been designed to main-tain file integrity as much as possible whileallowing multi-user access to files anddynamic file extension and contraction. The batch -processing and multi -taskhandling features of Famos are bothextremely useful and I would advisehaving the user -accounting version ofFamos even with a single -terminal systemso that it is possible to use batch pro-cessing; also, the single -user version hasno protection against unauthorised peopleusing the system. MVT-Basic seems to be a reasonableimplementation of Basic. Being compiled,MVT-Basic programs run faster thaninterpreted programs. Transcendentalfunctions are rather slow but they arerarely used in business data processing. I found terminal input awkward to usein Basic; for many applications, theGBYTE function looks more appropriatethan the INPUT statement. I think anInput Line command would have been auseful addition. File input/output is very flexible but itmust be used with caution as ASCII fileaccess and internal format can be used onthe same file and also record or byte posit-ioning. Because of the points described, Famosis not a system for the inexperienced pro-grammer: if you are an inexperienced userwho just requires a business system it isbest to have the applications programs, orpackage, provided by an OEM systemshouse. That is true of most interactivemulti-user systems because of the carewhich must be taken to prevent users up-dating the same record at the same time,and also to allow those users adequateresponse. To a large extent, Famosprevents the first problem by using theautomatic record locks, but it can stilloccur if PUTR and GETR are not usedfor records which overlap blocks. Wordflow is a useful word-processingpackage, but I did not like the double -character control codes, and I would havepreferred to see a correct display at alltimes. However, it is a powerful package.The list processing facility is particularlyuseful for producing multiple copies ofletters with different addresses.

64 PRACTICAL COMPUTING May 1981

I II II = II

MultiVariable

Task ...System Software for Micros

Multi-user Micro Power throughFAMOSTm

from MVT Microcomputer Systems, Inc.

THE ONLY 8080/Z80 MULTI-USER SYSTEMFOR HIGH END -USER PRODUCTIVITY

RELIABILITY - Owing to efficient design andlong (3 year) period of stabilization.

DATA BASE INTEGRITY - FAMOS file systemis only micro program supporting automatic filesystem integrity maintenance. File record lockoutsare automatically provided by the file system.

DEVICE INDEPENDENCE - Table controlledrandom and serial file I/O. One microcomputer cansimultaneously support several hard disks, floppydisks, drum storage and even core memory, alloperating synchronously.

FLEXIBLE MEMORY MANAGEMENT - Bankselect on fixed boundaries (16 and 32 KBytes) andextended address mapped memory. Up to 3 MBytesof memory can be used with each user having hisown 32 KByte bank.

THROUGHPUT - Optimizing BASIC compilerand fast run-time provide unmatched throughput in amulti-user environment.... 6-30 times faster thancompeting systems.EFFICIENT LARGE DATA BASE SUPPORT -Multiple key ISAM provides rapid access to recordsin files to 16 MBytes. Random files can be any size.ENVIRONMENTAL FLEXIBILITY - FAMOS isthe only software system supporting a true batchmonitor. Any combination of foreground,background and interactive operations aresimultaneously supported. This includes concurrentdata and word processing, program developmentand communications.USER ACCOUNTING WITH MULTI-USERFILE SECURITY - File protection is providedthrough: passwords, filename prefixing and codeprotected flag protects.

FAMOS, the logical system of choice:By the Manufacturer . prolongs sales life for Z80 based systems. FAMOS 6MHZsystem will outperform 16 bit systems.By the System House ...lower maintenance, vertical customer base, migration path(16 bit run-time system will be available when timely).By the End -User . . high productivity, lower cost per work station, no obsolescence,minimal down time.

SINGLE SOURCE SYSTEM SOFTWARE ... Multi -tasking DOS, Optimizing BASIC Compiler,8080/Z80 macro assembler, Relocating Linkage Editor, Multi-user word processing system, List process-ing system, Disk SORTs, Core SORT, User Accounting, Multi -key ISAM, BASIC DBUG facility, Diagnosticroutines, Spooler, Forms facility, BATCH processor, Command line interpreter, BDE utility, Communica-tion software, BASIC SYSGN utility, Over 225 system routines, variables and utilities .. . and more.

HARDWARE SUPPORTED... CROMEMCO, IBC, IMS5000, IMS 8000, NCR 8130, NCR 8140,PCC 2000, MICROBYTE, ARTEC, SSM, SYSTEMS GROUP and others. Hard disk subsystems includeKONAN SMC-100, XCOMP and Century Data.

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- I-1-PRACTICAL COMPUTING May 1981

Circle No. 158

65

Sharp's cut -above-averageMZ-80K hardwareThe Sharp MZ-80K computer was first marketed in theU.K. in 1979; before that, it had been available only as akit in Japan. In the 18 months the machine has been onsale in Britain, the price for a model equipped with 20KRAM has fallen substantially to £380.

THE SHARP MZ-80K is advertised widely,often with an emphasis on its suitabilityfor business or office use. It is also usedfor laboratory and industrial processcontrol by firms such as 3D Digital Designand Development. Three units areavailable as part of the MZ-80K package;an input/output interface unit, a dualfloppy disc drive and a tractor -feed dot-matrix printer.

The commercial reputation of Japanesefirms is based very largely on often cleverprecision engineering and high -quality

by John Dawsoncontrol during production. The ability ofthe Japanese to write ingenious softwareis, however, less certain.

The high -quality engineering in, forexample, the MZ-80K double -track discdrives may suggest that the Japanese havesought hardware solutions to compensatefor their software failings.

The dimensions, weights and powerconsumption for the review equipment areset out in table 1. The review MZ-80K hadbeen fitted with a Xtal CP/M adaptation.The machine consists of four printedcircuit boards: the main CPU board, taperecorder, keyboard, and visual displayunit/audio frequency amplifier. The CPUboard is the largest and is mounted insidethe base of the steel case with the otherboards mounted on the upper section ofthe case.

The power supply is enclosed within aventilated metal case and is mountedbeside the CPU board. Power is suppliedthrough a two -pin connector which isstandard for all the units in the system atthe rear of the computer and there is asecond opening, with a screwed metalcover, which allows access to a 50 -pinScotchflex connector. The CPU bus isbrought out to the connector and is thesole signal input and output pathway tothe computer - the 50 lines are showndiagrammatically in figure 1.

The MZ-80K has a three -octave soundgenerator and a real-time clock which isre -set when the machine is switched -on.There are pre-set controls for the VDUand the volume of the internal loud-speaker mounted on the front edge of theprinted circuit board below the VDU. TheCPU board has vacant connections for are -set switch.

The steel case of the computer isstrongly constructed with a piano hingeconnecting the upper and lower sectionswhich are normally secured by fourscrews. The strut supporting the uppersection of the computer when it is openedhas a retaining thumbscrew on the lowerleg which can be screwed -in to prevent the

Dimensions WeightMZ-80K 4IW 47D 28H I 3kg.MZ-801/0 20 32 13 5MZ-80FD 20 32 20 7.9MZ-80P3 41 38 19 10

Software serial numbersSharp/Xtal monitorSharp tape BasicSharp disc BasicXtal CP/MXtal CBasic

SP 1002SP 5025SP 6015Version 2.21Version 2.061

Dimensions are quoted in centimeters andexclude cable -bending radii. Total power con-sumption for the four units is given as 2I5VVatts.

Table I . Equipment dimensions.

upper section of the case collapsingaccidentally.

The visual display unit produces awhite -on -black image 40 characters wideby 25 lines deep in an eight -by -eightformat. A wide range of graphicscharacters are available including elec-tronic symbols for drawing circuitdiagrams on screen and a good number ofgames and general-purpose shapes. Thelower-case letters have true descendersand there is a pseudo -high -resolutiongraphics capability which will display 50by 80 pixels.

Both the stability and definition of thedisplay are excellent, although there wassome pin -cushion distortion in the picturesymmetry on the review machine, whichmeant that the last six characters on theright-hand side of the bottom line werealmost illegible because they had curvedoff the screen.

This fault is not apparent on two othernewer MZ-80K machines where thepicture symmetry is good - good enoughfor you to take direct photographs of thescreen and use them as slides in lectures.

The cassette tape recorder in the MZ-80K uses a pulse -width modulationrecording technique and transfersinformation at 1,200 bits per second. Amechanical tape counter is fitted and the

recorder is controlled both by mechanicalkeys and the system software.

The tape counter is fitted in the cassetterecorder and programs or data on thecassette tape can be located accurately andreasonably quickly using the fast forwardand rewind controls with the counter. Thedata -transfer rate for the recorder isimpressive - it allows the 14 kilobyteSharp Basic tape to be loaded in about 1.5minutes.

On microcomputers, the keyboard andthe visual display unit are the interfacebetween machine and user. The level ofambient lighting in an office environ-ment, the reflections from a VDU screenand the angle at which it slopes, the abilityto separate the keyboard from the screenso that a typist or operator can becomfortable are all important consider-ations in designing a machine which willallow a user to operate it for long periodswithout fatigue or unnecessary strain.

Similarly, a considerable amount ofwork has been done on the ergonomics ofkeyboard design and this is apparent nowin both computers and word processorsfrom firms like IBM and Logica at oneend of the scale to more modest machinessuch as the Tandy TRS-80 at the other.Those who use keyboards as part of theirwork develop strong preferences and thisallows room for variations such as theextended front on the IBM 5120 machineon which an operator can rest the palm ofhis hand. These variations are made,however, within well-defined limits ofgood design.

The keyboard of the MZ-80K ismarkedly at variance with the rest of themachine, is outside any concepts of gooddesign and surely can be neither intendednor used for serious typing. The spacingof the keys is the same as an ordinaryoffices typewriter - 0.75in. from keycentre to key centre - but the relativepositions of the keys are non-standardalthough the board uses a normalQWERTY lay -out.

In particular, the position normallyoccupied by the space bar contains thecursor control, carriage return and insert/delete key in addition to a small space key.The key -tops are transparent plastic capsmarked with graphics characters as well asthe alpha -numeric characters. The mainalpha -numeric markings do not stand outclearly enough which makes identificationof a particular key more difficult.

Under the original Sharp monitor, thekeyboard also has non-standardfunctions. Lower-case letters are pro-duced after the SML/CAP key has beenpressed but the comma and full stop keysthen produce characters with umlautaccents. This is an infuriating idio-

66 PRACTICAL COMPUTING May 1981

Review

STOCK PEOISTRATV,STOCK Arkt44MEN,

ENOU:Ry

V.,OH,i'N

,JTST.A(ThTrLIEP:. FILE

E,IT FR.6.km

The Sharp MZ-80K.

Sharp's MZ-80 P3 dot-matrix printer.

syncrasy whenever text is being entered.The MZ-80P3 printer is a tractor -fed

dot-matrix printer capable of handlingpaper widths from four to 10in. Thenormal characters are printed in a six -by -seven dot format and there are nodescenders on lower-case letters. Theprinter will produce double -widthcharacters in a 12 -by -seven format and theprint -head is driven across the paper by apeg in a slotted drum. This has theimportant consequence that the print -head must complete a full line's travelhowever short the line printed. In otherwords, a line -feed character still requires

the print head to traverse the full width ofthe paper and return.

The print -head prints in one directiononly and will produce 80 characters perline on 10in. paper. The printer acceptsparallel eight -bit ASCII data and willproduce 255 ASCII and graphicscharacters. There is an 80 -character printbuffer inside the MZ-80P3 and it ispossible to lose the last line of print undersome circumstances in which case it maybe output, disconcertingly, at the top ofthe next print run.

The MZ-80FD floppy disc unit containstwo 5 1/4in. single -sided, single -density,

double -track disc drives, storing 143kilobytes per disc. The disc drivemechanisms are very smooth and wellmade. the 70 -track format is unusual andnon-standard in the U.K. and means thatsoftware which might otherwise beregarded as standard, e.g., CP/M-basedprograms, is not directly transportablefrom other machines to the MZ-80K.

Like all the peripheral units formingpart of the MZ-80K system, the MZ-80 I/Ounit is housed in a smart steel case,containing a five -slot mother board and adiscrete power supply unit. The motherboard uses double -sided connectors with30 pins on each side. The pitch of theconnector appears to be 0.125in. -a non-U.K. standard. The I/O interface unit isconnected to the MZ-80K by approx-imately I8in. of shielded 50 -way ribboncable.

Part of the MZ-80K configuration is areal-time clock which starts counting fromzero when the machine is switched -on.The clock can be synchronised with GMTand could be used to control externaldevices. If personal computers are tocontinue their present penetration into thehome market, it will be because they areseen to have a useful function around thehouse.

Machine durabilityThe computer will have to run con-

tinuously - with tighter electrical -engineering and safety requirements - if,for example, it is to operate a burglaralarm, deal with incoming telephone calls,process the family budget, and act as afacsimile transceiver for letters and mail-order catalogues. The MZ-80K and itsperipherals ran continuously for threedays during the review period withoutsigns of overheating or distress in any ofthe units.

Software has two important parts; theprogram itself and the accompanyingdocumentation. Good documentation isnot the myth it often seems to be andcompanies such as Hewlett-Packard, IBMand Rockwell produce excellent writtenexplanations to support their products.The U.K. armed forces also understandthe importance of clear, simple andconcise English in their instructionmanuals.

Comment on the CP/M manualssupplied with the Xtal adaptation for theSharp should start on a long rising note ofhysteria and frustration. The abundanceof jargon and virtual absence of workedexamples throughout the CP/Mdocumentation made the system almostwholly obscure for a user without accessto a source of CP/M folklore.

Moreover, the CP/M 2.21 version fittedto the MZ-80K is still cluttered withsediment from the past. CP/M origin-ated, for example, with machines whichused Teletypes for input and output.Consequently, the delete key on the Sharprepeats characters entered on a line in

(continued on next page)

PRACTICAL COMPUTING May 1981 67

(continued from previous page)reverse order, erasing them from the linememory at the same time. To correct amistyped letter in the word MUSACBOX,you must either delete the whole line ordelete and type the following:

MUSACBOXXOBCAICBOXwhich is then entered as MUSICBOX.The Research Machines CP/M version 1.4has a patch which simply erases a letterwhen the delete key is presed and I wonderhow this anachronism has survived intothe 2.21 version offered by Xtal.

More seriously, the assembler/dis-assembler included on the CP/M disc isan 8080 -based program which demandsthat the user should learn a new set of

Figure 2.

DDT OERS 2.2

-L12AA

12A0 CALL 1E:D

1203 MUI C,0112A9 CALL 1BC91208 LXI 8,1DF7120: DAD1200 SHLC' 1C3F120 NOP121A LXI H,06A41213 MUI A,FF1215 XRA 11

1216 MOO M,A-L

1217 JMP 0705121A HOP121B NOP121C HOP121D HOP121E NOP121F NOP1220 ??= '2A

1221 RUB 81222 HOP1223 MnV B, E:

-L

24121225

HOP??= AR

122A L; :, H, 921017,29 ??= 1A122A LXI H,4212122D mnu C B1 Li HOP122F DAD El

123A ??= 1A1231 STAX 81232 MOO B,B

68

mnemonics, also denying the use of theadditional Z-80 specific instructions,many of which are particularly powerful.When the disassembler is used to list Z-80code, it produces the results shown infigure 2 in which the double questionmarks presumably indicate instructionsbeyond the scope of the disassembler.

Research Machines, once again, haswritten a Z-80 assembler called ZASM forits own CP/M package. I found theeditor program difficult to use and, whenI was unable to make one instructionperform any function at all, the manualcompounded my confusion.

One good feature in the CP/M adapt-ation to the MZ-80K made by Xtal is itsmodest claim to have made "what weconsider to be some standardisations andimprovements on the . . . keyboard". TheSML/CAP key toggles between upper -and lower-case and lower-case charactersare given their normal ASCII value. Fullstops and commas can be typed normallyin both upper- and lower-case mode and,as far as is possible by altering software,the keyboard is greatly improved when themachine is running CP/M.

Xtal supplies the Rodney Zaks CP/Mhandbook with Xtal CP/M discs andmanuals. Although the book provides analphabetic list of CP/M commandspresented consistently, the text is often aparaphrase of the original manuals ratherthan a complementary overview andintroduction to the system.

Tape BasicThe Sharp tape Basic is supplied with

the machine so the main question in areview must be whether the additionalcost of the Xtal Basic is worthwhile.

Without sacrificing any instructions orsuffering any loss of speed, the XtalBasic occupies 5K less RAM. There aremore than 12 additional commandspacked into the reduced interpreterincluding the following:DEEK DOKEPRINT @ ON ERR GOTO/GOSUBWAIT SPEEDPOP POSAND OR and NOTIF THEN ELSE

The Xtal Basic works with six signifi-cant figures instead of eight, but has anextended exponential range. The PRINT@ command in the Xtal Basic allowsgraphs and tables to be plotted easilyon screen and is accompanied by less snowthan the more primitive Sharp POKEcommand. A disadvantage for someprospective buyers will be the lack of anyprinter routine in the Xtal Basic.

The documentaticn with the Xtal Basictape consisted of a printed pamphletdescribing the general features of thelanguage and its application to theNascom computer and a photocopiedbooklet setting out modifications specificto the Sharp version.

There are instructions for adding to theBasic instruction set in the originalNascom booklet and the conversion

A I B

AI S I. G

A14 2 INT

A13 3 G

AI 2 4 MREQ

All S G

A10 6 IORQ

A9 7 G

A8 8 RD

A7 9 G

A6 10 WR

AS II G

A4 12 MI

A3 13 G

A2 14 HALT

Al 15 G

AO 16 RESET

G 17 G

D7 18 G

D6 19 G

DS 20 G

D4 2i G

D3 22 G

D2 23 G

DI 24 G

> DO 25 G

MarkBus Connector Detail

Figure I . MZ-80K connection details for the50 -way system bus.

leaflet supplied with the tape has someinformation about port numbers, relevantmemory locations and an example of aprinter subroutine. A major advantage ofthe Xtal Basic is the additional program- Xtalbug - which allows machine -codemodifications and insertions to be madeto the Basic interpreter. The facility ispowerful, well worth having, and acomplete contrast to the jealous approachtaken by Sharp, which prohibits the userfrom taking even a security copy of themaster tape, both in writing and in thesoftware.

Also on the second side of the Xtal tapeis a conversion program for translatingprograms recorded in Sharp Basic to XtalBasic. The program worked successfullyalthough the one command not trans-lated - GET - required some syntaxchanges in the converted program. Thereare suggestions for modification in theXtal manual.

The major improvement in disc Basic isthat it permits sequential and random-access storage of data on disc andcontains two commands - CHAIN andSWAP - which allow whole programs tobe called from a disc, with execution andexisting variables transferred to the newprogram. The SWAP command returnsthe first program to the CPU at thecompletion of the second, and the firstprogram continues its execution.

The error handling of the disc Basic isenhanced greatly in comparison to thetape version. There are one or twoadditional instructions but no PRINTUSING command or IF THEN ELSE,both of which might have been expectedin a disc version.

PRACTICAL COMPUTING May 1981

Review

Conclusions The MZ-80K is mechanically andelectrically well designed and constructedwith the exception of the keyboard. Particularly at discount prices, themachine offers an impressive specifica-tion. Although the machine has no inherentinput/output capability, the Sharp bus iswell buffered and is readily available forproprietory or home -built expansionunits. The machine needs a re -set switch forassembly language and machine -codeprogramming as there is no way out ofloops or Halt (76H) instructions otherthan by switching the machine off, whenthe RAM contents are lost. A volume control on the outside of thecase would improve the usability of thecomputer. The MZ-80K, floppy disc, printercombination can be locked up in toomany ways; for example, if by accident,there is stored in a disc directory twoquotes without an intervening space, "",attempting to save any file by any namegives error 42, i.e., tried to register underan existing name. The price/performance ratio of theSharp peripherals is not in the same classas the MZ-80K itself. The MZ-80 I/Ointerface unit is expensive for what it doesand although the floppy disc unit is wellmade, it also looks expensive in com-parison with other reputable units.

The MZ-8FD floppy disc unit.

The printer matches the system both inits graphics set and styling but is definitelynot in the van of equipment. There is often much to be said forusing a well -tried and reliable designrather than a bug -ridden designer's dreamand in those terms, the MZ-80P3 is asuccessful, hard-working printer but assuch, its price is high. The Xtal Basic tape is good value formoney, releasing RAM and offering anenhanced instruction set. When Xtal incorporates a standardprinter routine into its tape Basic, I hopeit will include a command to print thecontents of the VDU screen - a com-paratively rare but valuable facility

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Circle No. 159PRACTICAL COMPUTING May 1981

lacking in both the Sharp versions ofBasic. The Sharp Basic manuals are badtranslations but offer many examples toillustrate individual instructions and pro-gramming techniques. The service manuals for the MZ-80Kand printer are excellent - a starkcontrast - containing fault locationflowcharts, test programs and waveformillustrations for various test points as wellas the usual circuit diagrams. The Sharp machine language manual isgood apart from poor -quality translation. The Basic Sharp system back-up is notthe worst of its kind but it is far fromadequate and cannot match in any waythe documentation supplied with, forexample, the Apple II. The keyboard prohibits the use of theMZ-80K in any environment where typistswill switch from a normal typewriter tothe computer and back again. A word-processing package for theMZ-80K would appear a wasted effort asthe machine does not seem suitable forbusiness use of this kind. On the other hand, the bus is wellbuffered and the computer stronglyconstructed, and with the addition of D -Aand A -D converters of the kind producedby 3D Digital Design and Developmentamong others, the MZ-80K offers goodhardware value for laboratory workerswho wish to control experiments and forengineers, most of whom will be unable totouch type.

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Circle No. 161PRACTICAL COMPUTING May 1981

ReviewVERSAWRITER II is a low-cost - about £150- add-on peripheral for the Apple II.It consists of a perspex sheet attached towhich is a pivoted arm and cursor point.The arm is connected via a ribbon cable tothe games input/output socket inside theApple. In addition to the hardware, thereare two floppy discs containing thesoftware routines for sensing and drivingthe drawing tablet. The product requires a48K Apple with two floppy disc drives andROM -based Apple -Soft. A 12 -page man-ual is provided.

Versawriter reproduces the movementof the cursor on the perspex tablet on tothe screen under the control of the Apple

by Mike McDonald

using high -resolution graphics mode. Thecursor movement is translated by the xand y movements which are detected bytwo potentiometers mounted in the pivotsof the cursor arm.

Apart from just drawing pictures on thescreen, shapes may be defined and storedaway in shape tables and may be recalledat will to be used to assemble a picture ordiagram.

On loading the master program fromdisc a main menu offers the followingfunctions: I . Draw with Versawriter

2. Calibrate system3. Recall a stored picture4. Catalogue this disc5. Add text to picture6. Calculate area and distance7. Electronic drawing8. End session

Our first job was to calibrate thesystem. A calibration chart is providedand had to be mounted on the tablet - ithas a transparent cover sheet under whichdocuments may be placed - and thecalibration program prompts for a seriesof alignment movements with the cursorarm.

The parameters of the alignment arestored on the master program disc forfuture reference. We were then able toselect the "draw with Versawriter" optionfrom the menu. This option caused aprogram to be loaded offering thefollowing functions:

P point cursor - draw lineS scale of drawingT transfer picture to discR recall picture from discC centre on screen current pointF smoothing factorE erase screenZ colour closed figure in current colourD draw with brush or editM make a shape tableI inspect shape tableL list of commandsQ quit programColours: W white0 orangeG green0 blackB blueV violet

If you hit any key, the screen blanksand displays a tiny flashing pixel -picture element - to represent theposition of the cursor. Any of the

PRACTICAL COMPUTING May 1981

Versawriter II: aninexpensive linein graphics drawing

commands given, may then be enteredthrough the keyboard to. affect thedisplay. If left in its default mode, thecursor flashes and follows any movemententered via the cursor on the tabletassembly.

If a colour key - i.e., the letterrepresenting the colour - is hit anymovement is then reproduced as a solid linein the appropriate colour on the screen. Asolid line will continue to be produceduntil the P key is hit to release thatfunction. The scale of the movement maybe magnified through the "S" option anda scaling factor between 1 and 5 may beentered. Movements are then multipled bythis on the screen.

The smoothing factor is a dampingeffect which reduces any jerkiness of

movement or sudden change in direction.Having drawn a few random patterns onthe screen, one option is that closedshapes may be filled with colour automat-ically. This is achieved by placing thecursor point in the area to be filled andselecting option "Z". The user is thenprompted for a colour number andoffered a test fill or reversed -out back-ground before proceeding. The facilityseemed to work well except that veryirregular shapes were not filled completely.

The draw with brush allows a brush sizebetween I and 5 to be defined and resultsin a pulsating blob which can be movedaround, depositing any selected colour asit goes. Once a picture has been produced,it may be saved on disc - this did not

(continued on next page)

71

Review(continued from previous page)work very well in our case - andsubsequently recalled. The screen is erasedby entering "E" and confirmation thatyou want to blank all efforts.

Shape tables may be created and usedand this is where Versawriter becomes amore viable proposition for commercialapplications. A number of shape tablesis provided on disc, including electricalshape, electronic shapes, geographicshapes, chemical symbols, chemicalapparatus, landscape shapes, plumbingshapes, and so on.

A picture may be formed up on thescreen of a series of specific shapes oritems while in the drawing mode. Oncecomplete, the items may be compiled oneby one for storage into a shape table. Theshape table may then be accessed and willallow the user to step through the storedshapes and dump each shape on to thescreen wherever the cursor is positioned.

Hence, from the electronic shape table,we were able to produce reasonablysophisticated circuit diagrams at highspeed with little or no drawing ability. Theapplications here are endless for any pro-fession or discipline which utilises drawingsor diagrams.

We loaded an electrical shape picture anput a series of shapes into a table. Thescreen is cleared and the table recalledwith the I function. The bottom of thedisplay shows the following options:

S scale = 1D drawing number 1 or CTRL DX fix S Y fix Y U undrawR rotate

When you call a shape table on to ablank screen, the first shape stored isflashed on the screen continuously at thepresent cursor location. By pressing thespace bar, it may be deposited in itsposition as a drawn object. Otherwise,some of the options may be used to alterits characteristics.

The scale may be increased although wefound that irregular shapes lost qualityonce enlarged past double their table size.If R is pressed, the shape rotates through45 degrees and will continue to do so if Ris held down. D causes the system to moveon to the next shape in the table in asequential fashion or control d allows theuser to go directly to a specific shapenumber.

Either an X axis or Y axis may be setand fixed with the X and Y function keys.That is very useful if creating regularshapes and diagrams and produces a neatpicture. Once an axis is set, cursormovement will be possible only along it. Nreturns the user to normal movement.

There is also an undraw or U optionwhereby a mistakenly -placed shape maybe removed by placing the- same shapeover it and pressing U. This masks theoffending part of the diagram. You mustput the blanking shape exactly on the oldversion to obliterate it completely.

Three shape tables on the master discwhere English, Greek, and Electronic

shapes. The English and Greek werealphabets which could be used to labeldiagrams. Hence the system could be usedfor foreign -language character generation.Once the shapes have been accessed andused to form a picture, the user may re-turn to the normal free -hand mode ofdrawing to make additions, amendments,or deletions. The resulting picture maythen be stored on the disc.

In addition to using a text shape table toput letters on diagrams, there is also an"add text to picture" function whichallows the user to type directly in throughthe keyboard labels of varying size andcolour, again positioned with the cursor.

There was a very interesting routine onone of the discs which produced standardshapes for drawing i.e., triangles, squares,rectangles, rhomboids, trapezoids, and soon. Each shape was defined by selecting aletter and the cursor was then placed atthe start position and end position.Versawriter would do the rest.

We were able to create some amazingmulti -dimensional diagrams with verylittle effort and the feature is a dreamcome true for those who have ever had toproduce an isometric drawing of acomplex shape in engineering drawingclasses.

Another facility of the package is acalculate area and distance function. Thisroutine allows the operator to draw apicture or recall a picture on to the screenand then proceed to map the formthrough scaling calculations.

A scale is calibrated in terms of the twoextremes of movement of the cursor onthe screen and the user is prompted for ascale factor and the units of scale, forexample, 10m. Any subsequent cursormovement is measured and a display givenof distance - or perimeter in the case of aclosed object - and an area calculationmay be requested to produce a squaremeasurement of an enclosed shape.

Demonstration programs are providedwith the package and produce someamazing pictures someone surely spentyears producing.

Conclusions Versawriter would appear to be an ex-tremely useful facility for the educationalmarket and possibly the commercial mar-ket if there were some way of producingan enlarged hard -copy print of the screen. With the several versions supplied toPractical Computing, we had difficultystoring a picture on disc and retrieving itagain intact. The programs also suffered from alack of consistency which, was somewhatirritating at first. The screen graphics are certainly of agood quality and some very complexdiagrams and pictures can be producedwith a little patience and a good deal ofpractise. Notes are provided for those interestedin producing their own programs for usewith the drawing tablet.

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72 PRACTICAL COMPUTING May 1981

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PRACTICAL COMPUTING May 1981 Circle No. 162

73

THINKING SYSTEMSDrawing on examples which range from thelaws of supply and demand to sociology, BorisAllan shows how mathematical techniques canbring feedback into computer programs.

MY SUBJECT matter is not easily specified.Consider what Thinking Systems couldmean: Systems which think Thinking using a systems approach Thinking about systems Thinking systematically

Then, are many meanings to the wordsystem and this quotation from Jorge LuisBorges highlights the abstractness of thesemany ideas of system.

A system is nothing more than the subord-ination of all aspects of the universe to anyone such aspect. Tion, Uqbar, Orbis Tertius.The way in which I approach the topic

means learning by doing; and I hope tostress the integrity of the approach byshowing how graphs, mathematics, paths,and programs all say the same things. I

shall look in detail at two examples, and

Figure I . A demand curve.

show how we have to reduce the universeto the system we are studying. Followingthe examples, I give definitions andexplanations of some system concepts.

We shall start with an example whichappears in the teaching of economics at alllevels, from CSE upwards. Consider thefollowing hypothesis: The less a commodity costs, the greater

the number of items of that commoditywill be desired.

or, the lower the price of a retailer'smicrocomputers, the more people will buyfrom him. However, there is a limit to thenumber of, say, TRS-80s people can use,even if they are given away. We show thisin economics by a demand curve withprice on the y axis and the quantity ofitems demanded on the x axis. The curveis one which slopes down from top left -high price, no demand - to bottom right- low price, high demand. A specimendemand curve is shown in figure 1.

The next hypothesis to consider is: The greater the price at which a com-

74

modity can be sold, the greater thenumber of items which will be produced

or, the greater the price that computergames for the Pet fetch, the greater thenumber of computer games for the Petproduced. That can also be shown on agraph: a supply curve with price on the yaxis and the quantity of items supplied onthe x axis. Figure 2 shows how the curveslopes upwards from bottom left -minimum price, no supply - to top right- high price, high supply.

A classical French economist Le Sayformulated a law about supply anddemand. Economists, being of an orig-inal turn of mind called it Say's Law: Supply creates its own demandor, if you swamp the market with uselesssoftware, there is a price at which somefool will buy some.

If we look at these two curves in con-junction, we begin to see the operation ofa market. Say's Law suggests that if wesupply a large number of items, the pricecharged for those items will be the onegiven for that number of items on thedemand curve. The two curves are amal-gamated in figure 3.

Suppose that S(0) items are produced -because the producers think the items willeach fetch a price of P - then "as supplycreates its own demand" the number ofitems sold will be D(0) where D(0) = S(0),but the price for each item will be P(0) andnot P. As P(0) is less than P then the sup-pliers have done less well than they pre-dicted. This is the story told by figure 3.

Continuing a little: the producers willonly produce S(1) items at a price of P(0),but the demand (D(1) = S(1)) for this

Figure 2. A supply curve.

number of items is such that the price eachfetches is P(1) - and P(I) is greater thanP(0), so the suppliers have done better

than they expected. This continues untilthe point of intersection of the curves isreached - that point is the equilibriumprice for those supply and demand curves.

At one time, the supply -and -demandmechanism was thought to assure a fair,i.e., equilibrium, price for all goods. Thatis, subject to random fluctuations, or theshapes of the curves changing over time.For our purposes the key, and erroneous,conclusion from graphs such as figure 3

Figure 3. Supply and demand curves.

was that the path of price and supplychanges always spiralled in to the equil-ibrium point.

An astute reader will see that this is notnecessarily true, and the program, Say'sLaw, is designed to investigate just thisphenomenon. First, however, some com-puter use is demanded.

To gain some practical experience ofsupply and demand before we learn moreabout its theory, we shall use theprogram, Say's Law. It is written inApplesoft Basic for the Apple II, andthough such commands as HOME, i.e.,clear screen and GET, i.e., input a char-acter from keyboard, without echoing,are not common to all Basics, the logic isclear, and the REMarks copious. If themulti -statement lines are too long for, say,Pets, space out the statements - I haveleft 20 between line numbers.

The Say's Law program is a simulationof what the classical market is supposed tobe - the equations, as programmed, tryto copy what happens under the classicalscheme or model.

When you run the program, in responseto the first query set, your maximumdemand to 100. You will then be told thatthe demand equation is

D(T) = 100 - l*P(T)and you will have to wait for the next sub-section to discover what that means. Youwill then tell the machine that the SupplyGradient is .2. The supply equation will begiven as

S(T) = 10 + .2*P(T-1)

PRACTICAL COMPUTING May 1981

Programming

Multiplier = -.2

Time Price Supply0 50.00 50.001 80.00 20.002 74.00 26.003 75.20 24.804 74.96 25.045 75.01 24.996 75.00 25.007 75.00 25.00

Table I. ()trick convergence to equilibrium.

with some mysterious quantity called theMultiplier being equal to (.2)/(-1) or-.2. You will have set up two lines: thesupply curve, and the demand curve withthe equations given. These two lines willintersect at a certain equilibrium pointand you will be informed that theEquilibrium Supply is 25. The next stagein your ride comes when you are askedhow much is sold in year zero, to whichyou should answer 50.

A table under three headings is formed.The first heading is Time, period, the nextPrice, at which items are sold, and thirdheading is Supply - of items. This simul-ation starts at Time 0, Price 50, andSupply 20; and at Time 2, Price is 80, andSupply - based on the price of 50 in thelast time period - is 20.

To continue output of results,.hit anykey, except F. F stops output of that seriesand the user can re -run using differentvalues. When Time period 7 has beenreached, the Price has stabilised at 75, andthe Supply has stabilised at the equil-ibrium supply of 25 - see table 1. Theclassical economists would be satisfiedwith this result.

If the programmaximum demand

is re -run with aof 100, a supply

gradient of .8 - giving a multiplier of

-.8 - and a supply in year zero that isnot 50 - because 50 is the equilibriumsupply - then, even after 30 time periods,the supply and price are still not quitestable. I show this in figure 4, whichgraphs Supply against Time. A supplygradient of .95 is even longer in reachingequilibrium - try it.

For fun, try a supply gradient of 1 -still keeping the maximum possibledemand at 100 - with an initial supply of80. Supply alternates between 80 and 30,with price alternating between 20 and 70- our spiral has become a rectangle. Notso re -assuring for the classical economistsas our earlier simulations.

When the supply gradient is 2, theequilibrium supply is 70 - for amaximum demand of 100 - the multiplieris -2. If we start with a near -equilibriumsupply of 72, then after five time periods,the supply should be 134 which exceedsthe maximum possible demand - whichis 100 - a highly unstable result whichwould not please the ancients.

Try various combinations of maximumdemand, supply gradient, and initialsupply, to see if you can discover whatmakes a system stable or unstable. Indoing so, you will be studying a phenom-enon which in economics is called thecobweb model, and is called negativefeedback in other fields.

As we are dealing with quantities whichvary over time, we emphasise the depen-dence on time by indexing our variables:P(T) is the price at which items are sold attime T; S(T) is the number of itemssupplied at time T; and D(T) is thedemand for items at a price of P(T) -Say's Law postulates that D(T) mustequal S(T).

The demand line shown in figure 1 has

the following equation which demonstrates1. D(T) = DMAX - DCOEFF*P(T)

with DMAX being the maximum possibledemand, and the gradient DCOEFF beinggiven by

DCOEFF = DMAX/DPRICEwhere DPRICE is the price at which de-mand is zero. The supply line stretchesupwards without any clear limit, unlikethe demand line. The supply equation is

2. S(T) = SPRICE + SCOEFF*P(T-1)with SPRICE being the price at whichsupply is zero, and SCOEFF is thegradient of the supply line - see figure 2.P(T-1) is the price level of the previous

75

70

J°

i

Iiiii* .Tim

! y y r

IDrr) _ la) I* HT)sch lo 84tP, T.AIn[bw -,L,pc,i7 10 70

Figure 4. Reaching equilibrium.

period which influences the present levelof supply.

If we add the further equation D(T) =S(T), equation 2 becomes

3. D(T) = SPRICE + SCOEFF*P(T-1)and when equation 1 is re -arranged weproduce

P(T) = DMAX/DCOEFF - D(T)/DCOEFFso that..P(T-1) = DMAX/DCOEFF -D(T-1)/

DCOEFF

(continued on next page)

100 REM110 REM *********** ***** *******120 REM130 REM140 REM SAY'S LAW150 REM160 REM A SIMULATION PROGRAM170 REM180 REM190 REM BY200 REM210 REM C J BORIS ALLAN220 REM230 REM240 REM250 REM260 REM THIS PROGRAM IS ONE OF270 REM THE SET TO ACCOMPANY280 REM290 REM300 REM T H I N K I N G310 REM S Y S T E M S320 REM330 REM ALL RIGHTS IN THIS340 REM PROGRAM ARE RESERVED.350 REM360 REM (C) G J B ALLAN, 1980370 REM380 REM390 REM400 REM410 REM1000 DEF FN E(X) ( INT (100 * X + 5)

/1020 DIM S(30),P(30): REM 'S' IS THE SET OPOUANTITIES SUPPLIED, AND 'P' IS THE CORRESPONDING PRICE. BY ASSUMPTION - SAY'S LAW - DEMAND ALWAYS EQUALS SUPPLY

1040 DPRICE = 100:SPRICE = 10: REM DPRICE IS PRICE AT WHICH DEMAND IS ZERO AND SPRICE IS PRICE AT WHICH SUPPLY ISZERO

1060 HOME GOSUB 1840: PRINT "WHAT IS THE MAXIMUM POSSIBLEPRINT "DEMAND (BETWEEN 100 AND 10000) INPUT DMAX

IF DMAX ) 10000 THEN 10601080 IF DMAX ( 100 THEN 10601100 GOSUB 1840:DCOEFF DMAX / DPRICE: PRINT "DEMAND EQUAT

ION IS :": PRINT : PRINT TAB( 5):"0(T) = ":DMAX:" -DCOEFF;-* P(T)-

1120 GOSUB 1840: PRINT "WHAT IS THE SUPPLY GRADIENT": PRINT"(GREATER THAN ZERO) "I; INPUT SCOEFF

1140 IF SCOEFF ( 0 THEN 11201160 COSUB 1840: PRINT "SUPPLY EQUATION IS :-: PRINT : PRINT

TAB( 5);-S(T) ";SPRICE:" + ";SCOEFF:"* P(T-1)": GOSUB1840

1180 GOSUB 1840: PRINT "MULTIPLIER = (";SCOEFF:")/(-";DCOEFF:") ": - SCOEFF / DCOEFF: GOSUB 1840

1200 GOSUB 1840: PRINT "EQUILIBRIUM SUPPLY IS -:(DMAX - SPRICE) / (DCOEFF + SCOEFF) SCOEFF + SPRICE: GOSUB 1840

1220 PRINT "HOW MUCH IS TO BE SOLD IN YEAR ZERO ?": PRINT "

(REMEMBER THE MAXIMUM POSSIBLE": PRINT "DEMAND IS ";DMAXI") -:: INPUT S(0)

1240 IF S(0) ( = DMAX THEN 12801260 GOSUB 1840: PRINT -SUPPLY IS GREATER THAN MAXIMUM": PRINT

"DEMAND, SO -;3(0) - ('MAX;" ITEMS ARE NOT U,,ED-: GOTO 1220

1280 P(0) = (DMAX - S(0)) / DCOEFF: REM PRICE AT TIME ZEROASSUMING ALL THE SUPPLY IS TAKEN

1300 IF P(0) SPRICE THEN 13401320 GDSUB 1840: PRINT "THE PRICE (";P(0);") IS LESS THAN "

: PRINT "THE MINIMUM SUPPLY PRICE (";SPRICE;")": PRINT"SO THE MARKET COLLAPSES ": GOTO 1220

1340 COSUB 1840: PRINT "TIME","PRICE","SUPPLY": PRINT1360 PRINT 0, FN F(P(0)), FN F(S(0))1380 FOR T = 1 TO 301400 S(T) = SPRICE + SCOEFF * P(T - 1): IF S(T) ( = DMAX THEN

1480: REM CALCULATE THE NEW LEVEL OF SUPPLY1420 GOSUB 1840: PRINT "SUPPLY EXCEEDS MAXIMUM DEMAND": PRINT

"BY -;S(T) - DMAX:- ITEMS, THUS MARKET COLLAPSES": PRINT"DO YOU WANT A RE -RUN (Y/N)?": GET A$: IF A$ = "Y" THEN1040

1440 IF A$ "N" THEN 18001460 GOTO 1420

(continued on next page)

PRACTICAL COMPUTING May 1981 75

Programming -(continued from previous page)

which, on substitution in equation 3, givesthe result

4. D(T) = (SPRICE + DMAX/DCOEFF)- (SCOEFF/DCOEFF)*D(T-1)

This is fundamental: equation 4 showshow demand at time T can be exactly pre-dicted at time T-1, and how a variablefeeds back on itself to alter its own futurevalue, though perhaps indirectly as in thiscase. We can also notice the key elementin this fundamental result - the size ofthe multiplier, i.e., (SCOEFF/DCOEFF),would seem to be crucial.

Those who have tried the program willrecognise the importance of the multi-plier. I am using the names of the variablesin the program in this mathematical sec-tion, as far as is possible, so that directcorrespondences can be made.

If equation 4 is true, equation 5 must betrue:5. D(T-1) = (DPRICE + DMAX/DCOEFF)

- (SCOEFF/DCOEFF)*D(T-2)and a combination of equation four withfive produces an interesting result

D(T) - D(T-1) = - (SCOEFF/DCOEFF)*(D(T-1) - D(T-2))which explains many things. The left-handside of this last equation equals the differ-ence between successive values of thedemand (D); and, if we define DDIFF(T)

to be D(T) - D(T-1), then suddenly6. DDIFF(T) = -(SCOEFF/DCOEFF)*DDIFF(T-1)or, successive differences in the values ofdemand are in a constant ratio-(SCOEFF/DCOEFF). So: if the multi-plier is between 0 and -1 in value, theseries converges to a fixed value. If themultiplier is less than -1, the seriesdiverges - and at -1 the series alternatesbetween two values. The justification forthese assertions lies in mathematicalanalysis work concerned with the sums ofpower series.

Equation 6 defines negative feedback: Negative feedback occurs when a

change in value over one period pro-duces a change in value in the reversedirection for a later period - for someseries of values.

and from our investigations in practice,and in theory, we are able to define Simple stable negative feedback gener-

ally occurs when the multiplier forsuccessive differences is between - butnot equal to -0 and -1 for some seriesof values.

Simple unstable negative feedback gen-erally occurs when the multiplier forsuccessive differences is less than -1for some series of values.The term negative feedback does not

mean adverse feedback, or stable feed-back: negative feedback is defined by thesign of the multiplier, and the conse-quences are ours to evaluate.Consider the three following cases:A. A pupil, D, is perceived by her teacher,

0, to be of above normal intelligence.0 expects, therefore, more from D, andthis affects the way he acts towards D.The result of O's behaviour is that D isencouraged in her work, does better, andthus begins to appear relatively moreintelligent. This apparent increase inability by D reinforces O's belief in herintelligence, and so he encourages Deven more - and so the story continues.This case is so common in schooling thatit has been given the name, the self-fulfilling prophecy, by sociologists -that is, if you act as if someone is intelli-gent then frequently the person begins toact more intelligently.

B. People in the industrial society, D's,have many, too many, illnesses. Ad-ministrators and politicians, Os, perceivethe illness of the Ds, and the Os decideto increase expenditure on technologicalmedicine. Unfortunately the result ofthe increased amount of technologicalmedicine, e.g., more large hospitalswith centralised facilities, at the expense

(continued on page 78)

(continued from previous page)

1480 P(T) = (DMAX - S(T)) / DCOEFF: IF P(T) ) SPRICE THEN 1600: REM PRICE AT NEW LEVEL OF SUPPLY

1500 GOSUB 18401520 PRINT "NEW PRICE AT A SUPPLY LEVEL": PRINT "OF "; FN F

(S(T));" PRODUCES A DEMAND AT A": PRINT "PRICE OF "; FNF(P(T));" WHICH IS LESS THAN": PRINT "THE MINIMUM PRICEFOR SUPPLY": PRINT "OF ";SPRICE;" - THE MARKET COLLAF'SES"PRINT "DO YOU WANT A RE-RUN (Y/N)?";: GET AS: IF A$ ="Y" THEN 1040IF A$ = "N" THEN 1800GOTO 1520PRINT Ts FN F(P(T)), FN F(S(T)): GET A$IF AS < "F" THEN 1700GOSUB 1840: PRINT "DO YOU WANT A RE-RUN (Y/N) ?";: GET

AS: IF A$ = "Y" THEN 1040IF A$ = "N" THEN 1800GOTO 1640TCOUNT = T: REM 'TCOUNT' CAN BE USED IN GRAPHICS ROUTINES, ETC.NEXT T1161_JB 1840:

A$: IF A$ =IF A$ = "N"GOTO 1740GOSUB 1340:*******-:

TINE CAN BE'TCOUNT'

1820 END1840 FOR 19 = 1 TO 3: PRINT : NEXT 19: RETURN

1540

15601580160016201640

166016801700

17201740

176017801800

PRINT "DO YOU WANT A RE-RUN (Y/N) ";: GET"Y" THEN 1040THEN 1800

GOSUB 1840: PRINTGOSUB 1840: GOSUB 1840:INSERTED AT THIS STAGE,

"******* PROGRAM ENDSREM A GRAPHICS ROUUSING 'S't 'F", AND

76 PRACTICAL COMPUTING May 1981

TOTALLY FLICKER FREEAbsolutely no flicker. You don't need to press any-thing for the display to move!

3 LEVELS OF PLAY IN EACH GAME

From easy to dangerously difficult - you'll find ithard to resist the challenge time after time!

MOVING GRAPHICSNo hardware modifications required for these excitingmoving graphics games! Just follow the instructions forcassette loading and off you go - no need for new ROMor extra memory.

MACHINE LANGUAGE

These programs are written in the computer's ownlanguage - only this way is it possible for continuous,flicker free action to occur.

ALL PROGRAMS ON CASSETTELoads just like any other program on cassette. Eachtape contains instructions on how best to load thecassette.

FITS IK BASIC MACHINEAmazing as it is, all these moving graphics programsfit into your basic IK Sinclair!

SUPER ZX80 INVASIONSUPER ZX80 INVASION is the moving graphics machine language game youand your Sinclair have been waiting for. Cruel and crafty invaders have beenspotted in battle formation ready to attack with your ship just below them!Quickly and skilfully you shift right and left as you carefully fire your lasersat them. But watch out - they are accurate! 3 levels from easy to almost im-possible to beat. Added bonus each cassette also has more sophisticated 2Kversion which will automatically reset and challenge you for hours!

DOUBLE BREAKOUTciting moving graphics game fit into your IK Sinclair ZX80! Try your skill onthe easiest level because even with the most skilful! bat control you'll find ithard to catch at the fastest level! Breaking through the first barricade is easybut don't be fooled for a second - it's much harder than you think! Two ballangles and curved bat will keep the excitement going for hours! Superbgraphics!

You'll be amazed to see how difficult it is for you to break through theZX80 DOUBLE BREAKOUT - and even more astonished to see this ex -

PLUS ASTEROID LANDER

PING PONG AND

***er****

PRACTICAL COMPUTING May 1981

£8

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Circle No. 163

77

(continued from page 76)

of small neighbourhood, cottage hos-pitals, is to increase illness of the Ds.This increase in illness of the Ds leadsthe Os to increase expenditure on thehigh-technology medicine - which infact produces illness. This is a con-densed version of a series of argumentsabout medicine and health care in indus-trial society. These arguments are oftenphrased in terms of social iatrogenesis,medical nemesis, small is beautiful,etc.

C. A group of young people, Ds, are per-ceived by some police officers, Os, to bebehaving suspiciously - the Ds arelabelled as potential or actual delin-quents by the Os. The Ds react towardsthis perceived antagonism of the Os bybecoming more delinquent. The increasein deliquency by the Ds produces, ofcourse, an increased level of harass-ment and surveillance by the Os. I donot think I need continue the story calledin sociology deviance amplification,or the cycle of deviance.What can we say about these three

cases, other than that they are systemicallyalmost identical? All three show thatsocial behaviour can contain intrinsicconflict - whereas the economic modelassumed an equilibrium state at the end,these cases all seem to point towards anunstable end.

In cases B and C, the result is contraryto that originally intended by the Os: in Billness is increased rather than decreasedas a result of the action of the Os -though many dispute this. In C, delin-quency is increased rather than decreasedfor this group of Ds - though in othercases, the action of the Os will have thedesired effect.

In society in general, this conflict ofexpectations, and actions, is far morecommon than one would think despite theemphasis one finds in the relevantliterature on negative feedback at theexpense of positive feedback.

Nothing is that simple. We saw withnegative feedback that we could have veryunstable systems, and so we find with thecycle of deviance that stability can bereached - and it is the system multiplierthat matters. Before you go any furtherjust think back to Say's Law.

Deviance amplificationWe have isolated two elements, the Ds

and Os, and have seen how the value ofsome characteristic of the Ds, and thevalue of some characteristic of the Os, aremutually dependent; what are relevantelements and characteristics for the simplemarket? Details of how the program,deviance amplification, is structured canbe seen from the REMarks, and themathematical analysis I shall give.

The program uses the general termdeviance for what in the examples A, Band C were different things - perhapsthat is why one side was always called D?

In A, the deviance might be measured inIQ points above some norm. In B, thedeviance might be measured in terms ofsome compound health index greater thansome idea of what would be an acceptablevalue for the health index.

Finally, in C, the deviance might bemeasured in terms of some compoundquantity made up of age, colour of skin,number of convictions, and type of neigh-bourhood. Most of our deductions fromthese models are qualitative, and the ideasare more important than the numbers.

In the program, we have "other(s)"who have a social reaction to deviance -called Os in the examples. For A, the reac-tion can be measured in some form by anindex of teacher encouragement above theaverage. In B, the reaction can be meas-ured in terms of extra, i.e., above thebasic, money spent on medicaltechnology. For C, the reaction could begauged by the number of times the policearrest or pick up on suspicion.

When we run the program and areasked what is the effect of deviance onsocial reaction, we enter 1. The programresponds by giving the information thatthe multiplier DR = 1. Next we enter theeffect of social reaction on deviance, 1,

and find that multiplier RD = 1. Thesystem multiplier, SM, is given as RD*DRand is 1.

A little story is then told about thedeviant(s). We assume that the deviant(s)are perceived to be different by 100 arbi-trary units. The reaction by the other(s) tothis deviance is 100*DR units of reaction-= 100*1 = 100.

This level of reaction increases the levelof deviance by 100*RD units - that is,100*DR*RD = 100*SM - the new levelof deviance is thus 100 + 100 = 200 units ofdeviance. The program stops at this stageso that you can digest what has happened,and to continue any key is pressed.

The levels of deviance and of reaction,are then calculated for 30 time periodsand an F stops the output at any point.For the values DR = 1 and RD = 1, bothdeviance and reaction steadily rise to 3100- an explosive situation. Running theprogram with values of SM > = 1 willalways lead to calamitous outcomes, but ifwe try DR = 0.5 and RD = 0.5, SM =0.25, stability is reached resonably quickly- deviance is stable at 166.67, and reac-tion is stable at 133.33.

The key is, again, the size of the multi-plier, SM. Stability is reached if 0 < SM< 1- so to suggest that positive feedback

cannot, by itself, produce a stable systemis incorrect. All depends on the multiplier.

Before I discuss the mathematics, onefinal point you may care to consider; inthe program there is a function TNT'defined in line 1040, set it equal to

1040 DEF FNT(T) = EXP(-T)and re -run some of your earlier values ofDR and RD. FNT is the 'boredom' func-tion, it tries to give some way of allowingthe other(s) to get bored with thedeviant(s). There are many other

functions you could try, e.g., FNT(T) =K/(K-1 +T) where you chose the valueof constant K.

As in the analysis of Say's Law, we indexby time, and, as in the case of Say's Law,we will use the same names for the vari-ables in the Basic program as we use inthis mathematical analysis.

D(T) is the absolute level of deviance attime T, R(T) is the absolute level of reac-tion at T. The change in deviance fromT-1 to T, i.e., D(T) - D(T-1), isshown as DD(T), and the correspondingchange in reaction is shown as RD(T).

We start with an initial level of devianceD(0) = 100, and DD(0) = 100 - as weassume that D(-1) = 0: the change indeviance, not the absolute level, producesa change in reaction given by the formula:

1. RD(T) = DD(T-1)*DRwhich in English, says that the change inreaction is proportional to the earlierchange in deviance. The change in devianceat time T comes from:

2. DD(T) = RD(T-1)*RDwhich says an equivalent thing aboutdeviance being proportional to reactionchange at an earlier time. Note that RD byitself is just a multiplier. An amalgam-ation of equations 1 and 2 produces

3. DD(T) = DD(T-2)*SMso that we can see how the change indeviance feeds back on itself at a later time,SM = DR*RD. By a little thought wecan see that

RD(T) = RD(T-2)*SMwhich shows the importance of the multi-plier SM. It is very easy to show that if SM< 1, assuming SM is positive, then theseries will always converge to some fixedvalue. Compare equation 3 to the earlierequation 6 and consider the differencesand similarities.

In a sense, equation 3 defines positivefeedback Positive feedback occurs when a change

in value over one period produces achange in value in the same directionfor a later period - for some series ofvalues.

Simple stable positive feedback gener-ally occurs when the multiplier forsuccessive differences is between - butnot equal to -0 and 1 for some seriesof values.

Simple unstable positive feedback gen-erally occurs when the multiplier forsuccessive differences is 1 or greater forsome series of values.If equation 1 is compared to the corres-

ponding equation in line 1320, we findthat the program the equation is given asthe equivalent of

RD(T) DD(T-1)*DR*FNT(T)The extra function TNT(T)' is a func-

tion of time - set normally to unity, line1040 - so that as the value of Tincreases, we can make the value of themultiplier relatively smaller. In this way,we can see that with boredom setting in,e.g., women's lib excites people less andless, most systems with positive feedbackend up in stability, given time.

78 PRACTICAL COMPUTING May 1981

Programming

To finish off the mathematical analysis,I will suggest two books which have beenfound to have good sections on the mathe-matics used so far, i.e., linear graphs, andpower/geometric series. The first book isdirected towards A -level mathematicsstudents; Sherlock et al., 1979: 1-35, espec-ially 24-27; 126-155, especially 139-146.The second is for applied mathematicscourses at degree level; Green, 1964: 1-32.Both books are well written: Sherlock etal., 1979, is excellent in this respect andthough Green, 1964, is more demanding,an A -level student should have little diffi-culty with this text. For any reader whowould like to be slowly introduced tomathematical thinking, Northrop, 1948, isunsurpassed.

I have not defined a system yet, though which you can exercise your critical facul-we have looked at four systems, and my ties:definition of feedback has been very Negative feedback is inherently stabilisingmathematical. Feedback has become avogue word: it is in all the best, and

because it decreases the error while positivefeedback is inherently destabilising and theerror gains explosively in magnitude. Entry

worse, books. In one, we read a confusion on feedback, Stafford Beer in Bullock andof negative feedback with feedback, and Stallybrass, 1977: 230.positive feedback being confused with nofeedback:

I still have not defined system.

As a result, even if Germany had won thewar - which it should have done on paper -it is hard to see how it could have survivedthe peace. If an organisation denies feedback,it becomes unrealistic and unstable, apt to

References

Bullock A and Stallybrass 0, 1977, The FontanaDictionary of Modern Thought, Fontana/Collins:

break up into rival dogmatic factions. If itallows feedback, it eventually has to placateso many rival interests that it becomesmotionless and no threat. Laurie, 1980: 270-

London.Green J A. /964. Sequences and Series. RKP: London.Laurie P. 1980, The Micro Revolution: A change forthe better or for the worse? Futura Publications:London.

271. Northrop E P, 1948, Riddles in Mathematics, PenguinI finish with one other example on Books. Harmondsworth.

100 REM110 REM120 REM130 REM140 REM THE CYCLE150 REM160 REM 0 F170 REM180 REM DEVIANCE (1)190 REM200 REM210 REM A SIMULATION PROGRAM220 REM230 REM240 REM BY250 REM260 REM G J BORIS ALLAN270 REM280 REM290 REM300 REM310 REM THIS PROGRAM IS ONE OF320 REM THE SET TO ACCOMPANY330 REM THE SERIES340 REM350 REM T H I N K I N G360 REM S Y S T E M S370 REM380 REM ALL RIGHTS IN THIS390 REM PROGRAM ARE RESERVED,400 REM410 REM (C) G J B ALLAN, 1980420 REM430 REM440 REM450 REM1020 DEF FN FIX) = ( INT (100 *

X + .5) / 100): REM FORMATTER

1040 DEF FN T(T) = 1: REM THISLINE CAN BE CHANGED TO ACCO

UNT FOR DIFFERENT EFFECTS OFTIME, EG FN T(T)=EXP(1-T)

1060 DIM D(30),R(30),DD(30),RD(30): REM 'D' IS ABSOLUTE LEVEL OF DEVIANCE, 'R' IS THE ABSSOLUTE LEVEL OF SOCIAL REACTION, 'DIP IS THE CHANGES IN LEVEL OF DEVIANCE, AND 'RD' IS CHANGE IN LEVEL OF REACTION

1080 HOME : GOSUB 1580: PRINT "WHAT IS THE EFFECT OF": PRINT"DEVIANCE UN SOCIAL REACTION

: PRINT "(THE DEVIANCE TOREACTION-: PRINT "MULTIPLIE

R.) "1: INPUT DR: PRINT : PRINT"MULTIPLIER DR = -:DR

1100 GOSUB 1580: PRINT -WHAT ISTHE EFFECT OF": PRINT "SOCJAL REACTION ON DEVIANCE PRINT"(THE REACTION TO DEVIANCE":PRINT "MULTIPLIER.) -:: INPUTRD: PRINT : PRINT "MULTIPLIER RD = ":RD

1120 GOSUB 1580: PRINT "THE SYSTEM MULTIPLIER (SM) IS ":,SM =

0**********************

***********************

***********************

RD * DR: PRINT FN F(SM): PRINT"(SM = RD * DR)"

1140 GOSUB 1580: PRINT "PRESS ANY KEY TO CONTINUE-:: GET AS:GOSUB 1580: PRINT "IF 0 (ZE

RO) IS 'NORMAL', AT": PRINT"TIME ZERO THE OTHER(S) F'ERCEIVLS": PRINT "THE DEVTANTIS) TO BE 'DIFFERENT' BY": PRINT"100 UNITS."

1160 PRINT : PRINT "THE REACTIONBY OTHER(S) TO A"; PRINT "D

EVIANCE OF 100 UNITS, IS AN-: PRINT "PERCEIVED REACTIONOF 100*DR UNITS,": PRINT "THAT IS, THE REACTION fq ": FNF(100 * DR))" UNITS."

1180 PRINT : PRINT "THIS IN TURNINCREASES THE": PRINT' "LEVE

L OF DEVIANCE BY -: EN F(100* DR):"*RD-: PRINT "= ": FN

F(100 * SM):- UNtrS: THIS PRODUCES ": PRINT "A NEW LEVELOF DEVIANCE OF EN F(100 *(1 + SM)):- UNITS -

1200 PRINT : PRINT "PRESS ANY KEY TO CONTINUE":: GET AS

1220 HOME : GOSUB 1580: PRINT -TIME-,"DEVNCE-,-REACTN-

1240 DD(0) = 100:D(0) = DDIco:RE(0) = DD(0) * DR:R(0) = RD(0)

REM INITIALIZATIONS

1260 PRINT : PRINT 0,D(0),R((i)1280 FOR I = 1 TO 301320 DD(I) = RE(I - 1) * PEoD(I'

- 1) + DD(I)Rnef. uu(

I - 1) * DR * FN T(I):R,T) ,

- 1) +

1340 PRINT I. FN I :D(I)), 7N FIR(I))

1360 GET AS: IF AS < ) "F" THEN1140

1380 PRINT PRINT -DO WANT A RE-RUN (Y/N)?":: GET AS: IF A$= "Y" THEN 1080

1400 IF AS = "N" THEN 15401420 GOTO 13801440 020UNT = I: REM 'ICOUNT' CA

N BE USED IN GRAPHICS ROUTINES, ETC.

1460 NEXT I1490 GOSUB 1580: PRINT "DO YOU W

ANT A RE -RUN (Y/N)?";: GET A5: IF AS = "Y" THEN 1080

1500 IF AS "N" THEN 5401520 GOTO 14801540 GOSUB 1580: GOSUB 1580: PRINT

"****** PROGRAM ENDS ******"GOSUB 1580: GOSOD 1580: REM

IT IS POSSIBLE TO INSERT GRAPHICS ROUTINES AT THIS STAGE

USING 'D',AND ',COUNT'.

1'-)60 ENDFOR 19 = 1 TO 3: PRINT : NEXT19: RETURN

PRACTICAL COMPUTING May 1981 79

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Tel

Education

Program angled to deal withclass-room trigonometryFOR MANY YEARS the computer has been used in a variety of ways in education, but even with thearrival of the microprocessor, the cost is still prohibitive for most schools. To make any significantcontribution to the learning process, several terminals would be required and this immediatelyraises the price beyond the reach of a school budget. Many schools, however, now possess oneterminal, run from a micro and soon many more will be similarly equipped. It is the aim of theBasic program which follows, to offer the teacher an opportunity to make more efficient use ofsuch as terminal, not as a learning machine, but rather as a teacher's auxiliary.

It performs this function in two ways: firstly, by supplying an unlimited number of randomexamples - and answers if required - for the teacher's use; and secondly by making availableindividual examples for each pupil, who, on entering a personal code number, is offered a choice ofproblem. The answer is filed under the same code number, by means of which the pupil can checkhis own result later.

In this way a whole class can be accommodated, some individually at their own speed, othersfrom specific examples on the black -board - but all quantities supplied when required by thecomputer. Most teachers would agree that in the subject of maths, few books supply a sufficientnumber or variety of questions; so the program fills a gap here, too. It will continue to churn outdifferent sets of values as long as required, limited only by the random function of the Basicinterpreter in use.

This month we offer a program in trigonometry, suitable for third -and fourth-year pupils andwhich supplies examples requiring a knowledge of the sine and cosine rule. Similar programs havebeen arranged to deal with other maths topics and a school with a library of these would be able toclaim that the micro had more than justified its cost - especially as there is a bonus. The use of apersonal number code appears to promote a greater interest in finding the correct answer and eventhe dispirited are inspired. Robert Ferguson.

0010

0020

0030

0050

0060

PRINT " CLASS TRIGONOMETRY"PRINT

PRINT

PRINT "CODE NUMBERS ARE RESTRICTED"PRINT "TO VALUES FROM 100 TO 140"

0220

0230

0240

0250

0260

X=0

IF P$ -"SIN" THEN X=1

IF PS="COS" THEN X-2IF P$="NO" THEN X=3IF X=0 THEN 385

0062 PRINT 0265 P(N)=X0063 PRINT 0270 ON X GOTO 500,850,13000070 P$(1)="SINE RULE'?" 0275 PRINT " ... AND RETURN WHEN YOU HAVE'0075 Ps(2)="COSINE RULE?" 0280 PRINT TAB(10);"THE ANSWER"0080 P$(3)="UNITS" 0285 PRINT0085 P$(4)=" (FOR THE COSINE)" 0290 PRINT0090 P1=3.14159265 0295 PRINT TAB(11);"NEXT PLEASE"0092 P2=180/P1 0300 PRINT0095 T$="ABCDEFPORXYZ" 0305 PRINT TAB(8);"WHAT IS YOUR CODE?"0110 DIM P(41),R(41),U(41) 0310 GOSUB 4000120 PRINT " IDENTIFY YOURSELF" 0312 PRINT0130 PRINT 0315 IF P(N)=0 THEN 1600140 PRINT " TYPE IN YOUR CODE" 0320 IF P(N)<0 THEN 13500145 PRINT 0325 PRINT0150 GOSUB 400 0335 PRINT "THE RESULT OF YOUR EXAMPLE IS'0160 PRINT " WELCOME, ";N$ 0345 PRINT TAB(5);R(N);" ";F'$(U(N))0170 PRINT " IF YOU PREFER EITHER" 0352 PRINT0180 PRINT " THE SINE OR COSINE RULE" 0355 PRINT TAB(8);"ANOTHER EXAMPLE?"0190 PRINT " TYPE SIN OR COS" 0360 PRINT TAB(7);"TYPE YES OR NO"0200 PRINT "IF NO PREFERENCE, TYPE NO" 0365 INPUT OS

0210 INPUT P$

(continued on next page)

PRACTICAL COMPUTING May 1981

. Circle No. 164

81

(continued from previous page) 0994 PRINT

0368 PRINT 0995 GOTO 2751000 S-INT(RND*10+1)0370 IF OWYES" THEN 11001010 S$=MID$(7$83)0375 IF OWNO" THEN 1400 , ,

1020 FOR I -I TO 30380 PRINT "TYPE YES OR NO ... RE-ENTER"1030 WI)=MID$(S$,I,1)

0381 INPUT 0$1040 NEXT I

0382 GOTO 3701050 RETURN

0385 PRINT "TYPE SIN COS OR NO"1100 IF P(N)=3 THEN 170

0388 PRINT "RE-ENTER PLEASE"1105 PRINT TAB(5);"STILL THE ";PW(N))

0390 GOTO 2101110 PRINT TAB(5);"TYPE YES OR NO"

0400 INPUT N$1115 INPUT R$

0410 IF ASC(N$)<>49 THEN 4501120 IF R$="YES" THEN 1180

0415 V=VAL(N$)1130 IF R$ -"NO" THEN 1160

0420 IF V<100 THEN 4501140 PRINT "TYPE YES OR NO ... RE-ENTER"

0425 IF V>140 THEN 4501150 GOTO 1115

0430 IF VOINT(V) THEN 4501160 PRINT TAB(6);"WHICH THIS TIME?"

0435 IF LEN(N$)>3 THEN 4501170 GOTO 190

0438 N=V -99

0440 RETURisl1180 X=P(N)

0450 PRINT "I DO NOT RECOGNISE YOU" 1185 PRINT

0460 PRINT "CHECK YOUR CODE AND RE-ENTER" 1190 GOTO 270

0470 GOTO 400 1200 U(N)=31210 X1=INT(RND*200+300)/100500 GOSUB 10001220 Y1=INT(RND*200+300)/10

0510 X1=INT(RND*200+300)/t01230 Z2=INT(RND*1600+100)/10

0520 Y2=INT(RND*1400+100)/101236 PRINT

0530 Z2=INT(RND*300+100)/101240 PRINT "IN TRIANGLE ";S$;","

0535 PRINT1250 PRINT S$(1)+S$(3);" = ";Y1

0540 PRINT "IN TRIANGLE ";S$;","1255 PRINT S$(2)+S$(3);" = ";X1

0550 PRINT S$(2)+S$(3);" = ";X1 1260 PRINT "ANGLE ";S$(3);" = ";7.2;"DEGREES"0560 PRINT "ANGLE ";S$(2);" ";Y2;" DEGRFFc" 1270 Z3=Z2/P20570 PRINT "ANGLE ";S$(3);" ";7.2;" DEGREES" PRINT0580 PRINT 1280 PRINT "FIND THE LENGTH OF ";S$(1)+S$(2)0590 U(N)=3 1285 PRINT0600 X2=180-Y2-Z2

1290 R=SOR(X1*X1+Y1*Y1-2*X1*Y1*COS(Z3))0610 X3=X2/P2

1292 R(N)=INT(R*100+0.5)/1000620 Y3=Y2/P2

1295 GOTO 2750630 R2=X1*SIN(Y3)/SIN(X3)

1300 B=RND(0)0635 R(N)=INT(R2*100+0.5)/100

1310 X=10640 PRINT "FIND THE LENGTH OF ";S$(1)+S$(3)

1320 IF B(0.5 THEN X=X+10645 PRINT

1330 GOTO 2700650 GOTO 275

1350 PRINT "WELCOME BACK, ";N$0670 IF FWNO" THEN 285

1360 PRINT "I THOUGHT YOU HAD FINISHED"0850 GOSUB 1000

1370 PRINT0860 A.RND(0)

1380 GOTO 1700870 IF A<0.4 THEN 1200

1400 P(N)=-10900 X1=INT(RND*200+300)/10 1410 PRINT0910 Y1=INT(RND4,250+300)/10 1420 PRINT TAB(6);"HAS EVERYONE FINISHED?"W0920 Z1=INT(RND*200+300)/10 1430 PRINT TAB(OTYPE YES OR NO"0925 PRINT 1435 INPUT F$0930 PRINT "IN TRIANGLE ";S$;"," 1440 IF FWYES" THEN 14800935 PRINT S$(1)+9$(2); "=";Z1 1450 IF F$="NO" THEN 2850940 PRINT S$(2)+5$(3);"=";)(1 1460 PRINT "TYPE YES OR NO ... RE-ENTER"0950 PRINT S$(3)+S$(1);",=";Y1 1470 6010 14350960 PRINT 1480 STOP0970 U(N)=4 1490 REM R.E.L.FERGUSON0980 PRINT "FIND THE VALUE OF ..." 1500 REM ABERDEEN 19790990 PRINT " THE COSINE OF ANGLE ";S$0992 R1=(X1*X1i1,1*71-Y14M/2/X1/71 READY

0993 R(N)=INT(R1*1000+0.5)/1000 #run

82 PRACTICAL COMPUTING May 1981

ApplicationsWHAT BUSINESS manages to combinetravel to exotic places on stockfindingmissions, the daily handling of beautifulproducts - each with a detailed andcharacteristic history - a retail outlet inLondon's King's Road at the forefront ofthe fashion scene, and a mail order andwholesale business which exportsthousands of products every month?

The answer, for those who have notalready guessed, is beads. Peter andKarina Sterry opened their shop Hobby

by Cathy LaneHorse 10 years ago, at the very start of the1970s' crafts boom. As the business de-veloped, though, they gradually droppedtheir other craft lines to concentrateon their best-seller.

Today Hobby Horse stocks 1,000 kindsof beads, and most of them are sold in 10or 12 colours. For the last four years,Sterry has been riding a boom, expandingsales at a zooming 80 percent a year orthereabouts - for 1980 Hobby Horse isexpecting a turnover above £500,000.

Beads are big business. Says PeterSterry: "Fortunately for me beads aremade in places like Africa, the Far East,India, South America. I have to go onbuying trips quite frequently, and I'malways on the lookout for new lines".Regular customers for the beads includethe toy manufacturers and the rag trade.

"In the last few years the jewelleryboom has helped us considerably", saysPeter, homing in on one of the key factorsfor his recent success. "Many of our retailcustomers make up ear -rings andnecklaces and sell them on market stalls; Isee our beads everywhere. Bo Derek'shairstyle in the movie Ten did us a greatdeal of good, too, and the U.S. Indianfashions last autumn worked for us as well- beaded moccasins in particular haveresulted in huge orders from shoemanufacturers".

The shop in Chelsea and the warehousejust around the corner are both Aladdin'sThe staff of Hobby Horse's Chelsea shop.

PRACTICAL COMPUTING May 1981

Peter Sterry and the Hobby Horse Pet.

Pearls of wisdomfrom Londonbead businesscaves of glitter and colour. Sterry seems tolike the aesthetics of his business: certainlyhe has a deep-seated dislike of bureau-cracy and paperwork: "I have one leverarch file which will hold all my corres-pondence for a year, and that's about it".

At present, the total office staffingconsists of one part-time bookkeeper -the 10 other employees are dividedbetween the retail shop, the wholesaleside, and packing for the mail orderbusiness.

For just 12 people to produce £500,000is a reasonable ratio of sales to staffing,one that many stocking and sellingoperations would envy. So, what is thesecret?

"We've only been able to do it because

of the computer, though", says Sterry."For instance, if I hadn't bought the Petearlier this year, I would have had to takeon four or five extra invoice typists bynow".

Yet he is not just saving on new staff -that is a visible and quantifiable aspect ofthe case - but Hobby Horse is winningsome equally important benefits in otherdirections, notably in increasing the speedand reducing mistakes in the invoicingand a tighter control of inventory.

The increase in the variety of beads soldand the problems presented by invoicetyping were the key factors in buying acomputer. Sterry admits cheerfully that heknew "absolutely nothing" aboutcomputers when he started lookingaround for one early in 1980: "I viewedthem very much as fun toys". Still, he hadambition: "My objective was to buy amachine and program it myself to do thestock control and invoicing. It didn't looktoo difficult. I was quite confident.Besides, it looked interesting".

After talking to a few programmerfriends, Sterry concluded that the Pet wasthe best buy at the low end of the market.It was widely available, tried and testedand generally well established, highly -rated by everyone, reportedly easy to use,and well supplied with ready-made extrasin the form of games, business programs,and add-on goodies if the requirement forthem were ever to arise in Hobby Horse'sfuture.

So for £800, Peter Sterry bought a32K Pet with a cassette unit but "the shopwas totally unhelpful, and as a result theygot no other custom from me".

(continued on next page)

83

Applications(continued from previous page)

The new Pet sat in Sterry's study forsome time, while he discovered veryquickly that he was not interested inprogramming it himself. At the time,however, he went as far as computerisinghis price list. "It wasn't too hard. All thebeads already had three -figure productreferences, so I wrote a simple programwhich used these catalogue numbers".

It may not have been hard, but it stilltook him four months. On the otherhand, it was a genuine and sensible use ofthe computer. The price list was intendedonly for reference use by staff in the shopand the business, not for customers, and itwas exactly the same as looking up theprices in a book as before. Hobby Horsehad previously handled price changes bycutting and pasting new information overthe old material in the catalogue. Auto-mating the price book produced a clearerand error -free reference.

Sterry may have been deciding that hewas no programmer, "but in fact, most ofthe delay in making the system work wasdue to the Commodore users' handbookfor the Pet. I found it particularly bad"

Invoicing systemMeanwhile, the invoicing system was

becoming a pressing problem on whichthe computer could usefully be employed.Sterry realised that this would necessitatebuying floppy disc drives - it is almostimpossible to implement a fast -accessbusiness computing system using the tapecassettes that he still had on his Pet.

He was however anxious to find a localsupplier. His bad experience of buying acomputer and the obvious advantages ofdealing with someone located con-veniently close prejudiced him strongly infavour of a neighbourhood trader.Fortuitously, Logic Box had just openedshop in the vicinity. Sterry was quick tobuy a printer, floppy disc drives and theready-made Trader package written by theBristol Software Factory.

Trader is a set of programs designedspecifically for stock -holding retailers andwholesalers. Peter Sterry liked it, thoughnot uncritically: "It is actually very good,but for me, there is one rather irritatingthing about it - it doesn't sort data at all.This means that only the original input isgrouped into product classifications. Allnew stock can't be entered into, say, theglass or bone bead group, but it does printour invoices very well".

Sterry reckons that if necessary hecould do without the computer, andcertainly he has not replaced the manualsystem. He does not depend on it 100percent. Yet it is clear that the Pet hasmade a considerable difference to therunning of his business.

That is the inventory question. Becausethe stock is so large and is expanding allthe time, it is impossible to obtain a stockvaluation without the computer. Thismeant that, in the past, Sterry neveractually knew whether he was making a

Hobby Horse employees in the wholesale and mail-order side of the business.

loss or a profit. The bank balance mightwell have been increasing, but his stockmight have been falling so fast that thecompany might really have beenapproaching bankruptcy.

Now the Pet tells him when stocks arelow, what the stock value is, and what theperiod sales have been. Previously, astock take would have occupied two fulldays, involved all the staff and then wouldhave taken Sterry a week of checking thecosts back to source. In theory, thecomputer can now do all that at the pressof a button. In theory, because Sterryqualifies its effectiveness: "It's neverquite accurate because things do slipthrough without being recorded. It shouldbe correct to within 10 percent - which,believe me, is a great improvement".

Sterry also finds that the Pet has vastlyimproved the company's public relationswhile helpfully doing something aboutreceivables: "All our debtors have aninvoice printed -out by the computer, thena statement, and they really seem to think,`He's really right on top of things now',and they pay more promptly".

Equally, Sterry can see who owesmoney more easily. In the pre -computerdays he would have had to go through theledger page by page looking for red ink todraw up any kind of a debtors' list.

The system does however have itslimitations, and he is keen to stress that hedoes not idolise it, but there have been noreally major disasters while he has beenusing the Pet: "We had a few discs whichwouldn't copy, and in the past, I've beenlazy about doing the back-up copiesproperly. But we've never lost more thana few days' work and at least we've alwaysknown what's been lost".

Not exactly the most rigorous approachto operating procedures for the computer,but at least it is clear that Peter Sterry andhis system have come to some kind ofunderstanding.

Apart from the price -list problem, theonly real complaint that Sterry has aboutthe software is the fact that it does notmaintain a complete ledger for eachcustomer - it only records details of thelast transaction. That produces, however,a useful audit trail, and it would bepossible to construct an automated ledger

from it if the Pet had more disc storage.After his initial interest in micro -

computing, Peter Sterry's views havematured somewhat into the kind ofapproach that typifies the first-timebusiness user: "I think that micro-computers should be like television sets. Iwant to be able to press button one andwatch BBC 1; I don't want to know howthe television set works, all I really careabout is receiving a good picture. Like-wise, I'm not interested in the ins and outsof programming, I just want a machinewhich will do the job for me with aminimum of problems.

"To do that comprehensively on mysystem is impossible at the moment,because there just isn't enough memoryfor programmers to produce the kind offail-safe programs that I would like to see,programs that do everything for you andwhich don't ever make mistakes. Theywould need far more memory than thecurrent generation of micros seems able tooffer. It's clear that the next generationwill have considerable advantages, andthey'll be able to be much more profligatewith memory".

Typical dayThe Hobby Horse computer is not

exactly overused. It deals only with stockvaluation, price lists, invoicing and state-ments: in a typical day it would do 12invoices, change a few prices, updatestock and record shop and mail ordersales. Sterry now employs a part-timeoperator for a few hours a day on threedays a week, for most of the input andanything very urgent he does himself.

"I think that I will eventually have toupgrade the system. Small systems areinherently less reliable and less flexiblethan bigger machines, and of course theycan't do'as much. Although I don't wantto expand the business physically, I dowant to continue increasing the turnover.

Sterry considers the costs he had borne- an outlay of some £2,500 for the Petincluding software - a reasonable priceto pay for the experience of learningabout computers in business.

"When I buy a new system to do thecomplete ledger, I won't be at the mercyof any experts".

84 PRACTICAL COMPUTING May 1981

Stock control -

Counting manual methodsout of the reckoningFOR MANY small firms, stock control is a tedious and time-consuming job. One way around that problem is to use acomputer to perform the task. You type -in on the computer theitems you have removed from stock and periodically ask it for alist of the stock items requiring re -ordering. This program doesjust that and several other things as well. When run, theprogram displays a menu on the screen and will wait for you totype a command key from A to G.

Key A is pressed to type the items you have removed from thestock. Each item has a number to identify it which must be input

by Tony Edgecombe

during this part of the program. The amount removed fromstock is entered. If the item was on the file, the program willcontinue to input the stock removals until all of the removedstock has been typed -in. If you make a mistake, however, andtype a stock number which is not on the file, the program willdisplay an error message and you will have to re -type theinformation.

The command key B is pressed to enter all of the stock that

has been re -ordered. If you make a mistake, the program willagain display an error message and the information will have tobe re -typed.

When new stock items are introduced, they can be added tofile using the command key C. Four variables have to be inputinto the system:

A Stock numberB Amount in stockC Minimum amount allowed in stockD Amount to be re-recorded when stock is too low

Once this data has been input, it will be printed on to the endof the file.

When a stock item has to be modified or will not be usedagain, it can be deleted by using the command key D. If the itemis not on the file the program will tell you so. Periodically, thestock will have to be re -ordered. By keying E, all of the stockrequiring ordering will be printed along with the amount to beordered.

For some reason, the operator may wish to examine thedetails of a particular stock item. That can be done by using thecommand key F. The final key, G, terminates the program andleaves you in Basic.

100110120

LET 11=10DIM A$(72>,8$(72),A(100,7)FILES A

560 GOTO 180570 PRINT "AMOUNT IN STOCK580 INPUT A(I,2)

130 READ %1 590 LET A(I,1)=A140 LET 1=1 600 PRINT "QUANTITY ON ORDER";1513 MAT P=ZER 610 INPUT A(I,3)160 IF END. 1 THEN 1813 620 LET A(I,4)=A<I,2)+P(I,3)170 MAT READ %1;I,ILI 630 PRINT "RE-ORDER LEWEL180 FOR I=1 TO 20 640 INPUT A(I,5)190 PRINT 650 PRINT "RE-ORDER QUANTITY ";200210

NEXTPRINT TAB(5);"STOCK CONTROL"

660 INPUT A(I,6)670 PRINT "SUPPLIER NUMBER ..;

220 PRINT TAB(5);" 680 INPUT A(I,7)230 PRINT 690 PRINT240 PRINT "1 INPUT NEW STOCK ITEM" 700 PRINT "ARE THERE ANY MORE NEW ITEMS (Y/N)";250 PRINT 710 INPUT A$260 PRINT PRINT DETAILS OF STOCK ITEM" 720 IF P$= "Y" 440270 PRINT 730 GOTO 180280 PRINT DELETE OLD STOCK ITEM" 740 PRINT290 PRINT 750 PRINT"PRODUCT NUMBER";300 PRINT TYPE REMOVED STOCK" 760 INPUT A310 PRINT 770 FOR I=1TOM320 PRINT TYPE STOCK ON ORDER" 780 IF A(I,1)=A THEN 810330 PRINT 790 NEXT I340 PRINT "6. TYPE STOCK RECEIOED" 800 GOTO 530350 PRINT 810 FOR J=17021360 PRINT PRINT ITEMS REQUIRING REORDERING" 820 PRINT370 PRINT 830 NEXT J380 PRINT FINISH STOCK CONTROL" 840 PRINT"PRODUCT NUMBER ";A(I,1)390 PRINT 850 PRINT"PHYSICAL STOCK ";A(I,2)400 PRINT 860 PRINT"QUANTITY ON ORDER ";A(I,3)410 INPUT I 870 PRINT"FREE STOCK ";A(I,4)4213 IF I(1 OR I>8 OR I<>INT<I) THEN 180 880 PRINT"RE-ORDER LEOEL ";A(I,5)430 GOTO I OF 440,740,930,1060,1160,1270,138071570 890 PRINT"RE-ORDER QUANTITY ";A(I,6)440 PRINT 900 PRINT"SUPPLIER NUMBER ";A(I,7)450 PRINT "PRODUCT NUMBER"; 910 PRINT460 INPUT A 920 GOTO 210470 FOR I.1 TO M 930 PRINT PRODUCT NUMBER";430 IF A(I,1)=A THEN 530 940 INPUT A490 IF A(I,1)=0 THEN 570 950 FOR I=1TOM500 NEXT I 960 IF WI,1)=P THEN 990510 PRINT "OUT OF SPACE" 970 NEXT I520 GOTO 180 980 GOTO 530530 PRINT 990 FOR J=I+1TOM540 PRINT "INCORRECT PRODUCT NUMBER" 1000 FOR K=1T07550 PRINT 1010 LET A(J-1,K)=A(J,K)

(continued on next page)

PRACTICAL COMPUTING May 1981 85

Stock control

(continued from previous page)

1020 NEXT K1030 NEXT J1040 LET A(J,1)=01050 GOTO 1801060 PRINT"PRODUCT NUMBER";1070 INPUT A1080 FOR I=1TOM1090 IF A(I,1)=A THEN 11201100 NEXT I1110 GOTO 5301120 PRINT"AMOUNT REMOVED";1130 INPUT A1140 LET A(I,2)=A(I,2)-A1150 GOTO 12501160 PRINT"PRODUCT NUMBER";1170 INPUT A1180 FOR I=1TOM1190 IF A(I,1)=A THEN 12201200 NEXT I1210 GOTO 5301220 PRINT "AMOUNT ON ORDER" 7

1230 INPUT A1240 LET A(I,3)=A(I,3)+A1250 LET A(I,4)=A(I,2)+A(I,3)1260 GOTO 1801270 PRINT"PRODUCT NUMBER";1280 INPUT A1290 FOR I=1TOM1300 IF A(I,1)=A THEN 13301310 NEXT I1.720 GOTO 5301330 PRINT "AMOUNT RECEIVED";1340 INPUT A1750 LET A(I,2)=A(I,2)+A1360 LET A(1,3)=01.770 GOTO 12501.780 FOR I=M -1T01 STEP -11790 FOR J=1TOI1400 IF A(J,7)<A(J+1,7)THEN 14601410 FOR A=1T071421 LET 6=A(J,A)1430 LET A(J,A)=A(J+1,A)1440 LET A(J+1,A)=81450 NEXT A1460 NEXT J1470 NEXT I

1480 PRINT "PRODUCT", "ORDER AMOUNT","SUPPLIER"1490 FOR I=1TOM1500 IF A(I,4)>A(I,5)THEN 15301510 IF A(I,1)=0 THEN 15301520 PRINT A(I,1),A(I,6),A(I,7)1570 NEXT I1540 FOR I=1 TO 100001550 NEXT I1560 GOTO 1801570 LET I=11580 READ %11590 MAT PRINTU;I,A1600 END

86

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Circle No. 165

88

New. Sinclair ZX8160 LET C

90 NE XT100 FOR I

70 FOR I80 LET 7

110 LET >120 LET130MIF Ti

Personal TtComputer. ;111 EF-rT

1E N GO TC

Kit: 149.25- completeReach advancedcomputer comprehensionin a few absorbing hours1980 saw a genuine breakthrough -the Sinclair ZX80, world's first com-plete personal computer for under£100. At £99.95, the ZX80 offered aspecification unchallenged at theprice.

Over 50,000 were sold, and theZX80 won virtually universal praisefrom computer professionals.

Now the Sinclair lead is in-creased: for just £69.95, the newSinclair ZX81 offers even moreadvanced computer facilities atan even lower price. And the ZX81kit means an even bigger saving.At £49.95 it costs almost 40% lessthan the ZX80 kit!

Lower price: higher capabilityWith the ZX81, it's just as simple toteach yourself computing, but theZX81 packs even greater workingcapability than the ZX80.

It uses the same micro-processor, but incorporates a new,more powerful 8K BASIC ROM -the 'trained intelligence' of thecomputer. This chip works indecimals, handles logs and trig,allows you to plot graphs, andbuilds up animated displays.

And the ZX81 incorporatesother operation refinements - thefacility to load and save namedprograms on cassette, for example,or to select a program off acassette through the keyboard.

Higher specification, lower price -how's it done?Quite simply, by design. The ZX80reduced the chips in a workingcomputer from 40 or so, to 21. TheZX81 reduces the 21 to 4!

The secret lies in a totally newmaster chip. Designed by Sinclairand custom-built in Britain, thisunique chip replaces 18 chips fromthe ZX80!

169.95complete

Kitor built -it's up to you!The picture shows dramatically howeasy the ZX81 kit is to build: justfour chips to assemble (plus, ofcourse the other discrete com-ponents) -a few hours' work with afine -tipped soldering iron. And youmay already have a suitable mainsadaptor - 600 mA at 9 V DC nominalunregulated (supplied with builtversion).

Kit and built versions comecomplete with all leads to connectto your TV (colour or black andwhite) and cassette recorder.

Proven micro -processor, new 8K BASICROM, RAM-and unique new master chip.

NewBASIC manual

30 FOR I35 LET37 PRINT4-0 LET P50 NE XT54 PRINT55 PRINT56 PRINT57 PRINT

Every ZX81 comes with acomprehensive, specially -writtenmanual -a complete course inBASIC programming, from firstprinciples to complex programs.

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New, improved specificationZ80 A micro -processor- new

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and scientific functions accurateto eight decimal places.

O G raph-drawing and animated -display facilities. Multi -dimensional string andnumerical arrays.Up to 26 FOR/NEXT loops."'Randomise function - useful forgames as well as seriousapplications.Cassette LOAD and SAVE withnamed programs.1K -byte RAM expandable to 16Kbytes with Sinclair RAM pack."'Able to drive the new Sinclairprinter (not available yet - butcoming soon!)"'Advanced 4 -chip design: micro-processor, ROM, RAM, plus masterchip - unique, custom-built chipreplacing 18 ZX80 chips.

ZX81Sinclair Research Ltd,6 Kings Parade, Cambridge, Cambs.,CB21SN. Tel: 0276 66104.Reg. no: 214 4630 00.

If you own aSinclair ZX80...The new 8K BASIC ROM used in theSinclair ZX81 is available to ZX80owners as a drop -in replacementchip. (Complete with new keyboardtemplate and operating manual.)

With the exception of animatedgraphics, all the advanced featuresof the ZX81 are now available onyour ZX80 - including the ability todrive the Sinclair ZX Printer.

Coming soon-the ZX Printer.Designed exclusively for use withthe ZX81 (and ZX80 with 8K BASICROM), the printer offers full alpha -numerics across 32 columns, andhighly sophisticated graphics.Special features include COPY,which prints out exactly what is onthe whole TV screen without theneed for further instructions. TheZX Printer will be available in Summer1981, at around £50 - watch thisspace!

16K- BYTE RAMpack for massiveadd-on memory.Designed as a complete module tofit your Sinclair ZX80 or ZX81, theRAM pack simply plugs into theexisting expansion port at the rearof the computer to multiply yourdata/program storage by 16!

Use it for long and complexprograms or as a personal database.Yet it costs as little as half the priceof competitive additional memory.

How to order your ZX81BY PHONE - Access or Barclaycardholders can call 01-200 0200 forpersonal attention 24 hours a day,every day. BY FREEPOST - use theno -stamp -needed coupon below.You can pay by cheque, postalorder, Access or Barclaycard.EITHER WAY - please allow up to28 days for delivery. And there's a14 -day money -back option, ofcourse. We want you to be satisfiedbeyond doubt - and we have nodoubt that you will be.

ro: Sinclair Research Ltd, FREEPOST 7, Cambridge, CB21YY. Ordei7IQty Item Code Item price

£Total

£

Sinclair ZX81 Personal Computer kit(s). Price includesZX81 BASIC manual, excludes mains adaptor. 12 49.95

Ready -assembled Sinclair ZX81 Personal Computer(s).Price includes ZX81 BASIC manual and mains adaptor. 11 69.95

Mains Adaptor(s) (600 mA at 9 V DC nominal unregulated). 10 8.95

16K -BYTE RAM pack(s). 18 49.95

8K BASIC ROM to fit ZX80. 17 19.95

Post and Packing. 2.95

Please tick if you require a VAT receipt O TOTAL £

*I enclose a cheque/postal order payable to Sinclair Research Ltd, for £*Please charge to my Access/Barclaycard account no.

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Applications

I

Micros find important role atheart of large-scale industryA MAJORITY of microcomputer applica-tions we see in use or whose softwarewe hear about is for small businesses.Large-scale heavy industry tends to havea great deal of computing power already,and full-time dp departments. Such micro -based equipment as they dispose of may beoutlandish to the amateur, who sees littleconnection between the desk -top machine

by Martin Haymanon which he plays Dungeons and Dragonsand the much -trumpeted robots of a Fiatassembly shop. Yet the micro can still beused, in a more or less standard fashion,to improve industry's profitability.

This much is shown by a visit I paidrecently to Marconi Space and DefenceSystems in Portsmouth, where systemsanalyst Des Breach has installed a multi-user Altos micro system with fourterminals to tidy up the running of thefactory's £5 million machine shop.Building and using machine tools has longbeen a field in which the British haveclaimed pre-eminence, though much ofthe equipment at Marconi is in fact U.S.-built.

It is, of course, precisely this area ofindustry which has received some of therecession's worst battering. High interestrates have made it very desirable to eithermaximise the productivity of existingplant or make intelligent and economicalplans for replacing it - preferably both.

Marconi is better placed than manysmaller concerns since it has manyGovernment contracts which were placedsome time ago and which are stillproviding work. Components for defenceequipment are still needed, since this isone area in which there have been fewspending cuts. The fear that all the fat hasbeen burned off industry and that it isnow losing its muscle does not seem to beshared by people I talked to at theMarconi Broad Oak Works.

Machine tools are generally operated bynumerical control, NC. Paper tapes aretyped on IBM typewriters with paper -tapereaders and punches. These tapes are fedto an optical reader which translates theminto machine instructions - move thecutter of a lathe so-and-so far along thelongitudinal axis of the workpiece, so-and-so far on the horizontal - and so on.This final stage, which in former times,before the introduction in this country ofNC, would have been performed by handby a machine operator, is now achieved byhydraulics and reciprocating ball screws.

That aspect of machine -shop workusually runs well, but machines breakdown and job priorities change mid -run,

PRACTICAL COMPUTING May 1981

An Altos multi-user system.

requiring that one machine be re-programmed for a different job, with adifferent paper tape. Obviously, once atape has been used and is effective for aparticular component, it is stored so it canbe used again in the future with amagnetic tape back-up copy.

Highly specialisedMany of Marconi's jobs are, however,

highly specialised and only a short run isneeded. What happens if a machinebreaks down in the middle of a job andthere is no tape for use on a differentmachine? The tape must be re -written fora different machine.

In the past, that had caused con-siderable delays at Broad Oak Works.It was not necessary to convert programsmanually, which would have taken anage, but the Transdata 4000 terminallinked by telephone to an IBM mainframeat Marconi headquarters in Chelmsford,Essex, was not altogether a satisfactorysolution. The IBM does indeed convertprograms, but was available only duringoffice hours, whereas the Broad OakWorks in Portsmouth functions on a shiftsystem, working from 6am to lOpm -there were bound to be breakdowns whenthe mainframe was not running.

There were also further inconveniences:new program development work requiredthe Transdata to drive a plotter. Some-times such work would be interruptedtwo or three times a day when a con-version routine required that the Trans -

data talk to the Chelmsford mainframe -time -wasting, since the run would have tobe re -started from scratch.

However, such are the economics ofthis kind of operation that it is judgedbetter to waste programmers' time thanmachine time, which on the largest millingmachines is costed at £28 per hour. Evenso, machine -floor downtime is calculatedat 15 percent.

Eventually, the IBM typewriters, onwhich the fundamental paper -tapedevelopment work was done became duefor replacement. An identical set-up wasgoing to cost around £9,000. Des Breachasked himself why a micro, or severalmicros, could not be bought for the samemoney and used to improve flexibility andfree his department from dependence onthe Chelmsford mainframe link and fromits attendant frustrations for programdevelopment. Micros would have betterediting facilities, would be less noisy, andwould offer a host of other advantages.

Breaking new groundAlthough Marconi is, of course, a micro-

processor manufacturer, its productstend to be for dedicated applicationsand it does not manufacture any kindof micro itself; and nor is there aground -level policy for microcomputeracquisition. Hence Des Breach foundhimself breaking new ground when heproposed to replace the IBMs with themachine which he had winnowed from the

(continued on next page)

91

Circle No. 167

Applications(continued from previous page)rest as the most suitable for the job. Hehad to go to headquarters to argue thecase for the Altos machines, which wouldbe paid for from the plant acquisitionfunds.

Why Altos? I asked Breach: "At thetime I started looking, at Compec twoyears ago, there wasn't a great dealavailable in the multi-user field; wewanted to keep compatibility with theTransdata, which had been installed bymy predecessor, but using mini -floppies.It also had to based on the 8080processor".

To a great extent, then, his decisionswere based on ensuring continuity with anexisting system which had been chosen forits IBM communications protocol to talkto the mainframe and had facilities forNC. This last feature, caused someheadaches with the Altos, which isinterrupt -driven; they had to be disabledto interface with the paper -tape writers,which need to be continuously driven.Yet, so far as he was concerned, it was allpart of a "reasonably, obvious way togo", shifting from dumb terminals tointelligent ones.

The Altos machines were supplied inthe normal commercial way, by the localAltos agent, Profac Computer Services inCamberley, Surrey. The Altos itself is aU.S. machine, the main agency for whichis held by nearby Logitek of Chorley,Surrey. Profac's Jim Reid installed thesystem which operated on MP/M 1.12,and wrote some of the software to adapt itfor the NC application, though DesBreach says that he had to tune it a littlebefore he could rely on it.

Ultimately, there is no reason that themicro should not control the machinetools directly, without the need for theintermediate paper -tape stage, but this issurely some way in the future. At themoment, each user can call routines froma common base of subroutines, which ismuch more efficient and less frustratingthan queuing for the mainframe.

Race of inventorsNeither Jim Reid nor Des Breach

seemed surprised that Marconi, as aBritish microelectronics manufacturer,should be buying micros from the States;they look at it in the same way as buying atypewriter or photocopier, which wouldequally likely be U.S.-built. "We are a longway behind the U.S. in terms of buildingmicros, but we can catch up in the area ofapplications and industrial control - weare, after all, a race of inventors", claimsJim Reid, who admits that he is very keento win the order from Marconi.

The Altos system is used for fourprincipal tasks: preparation and editing ofpaper tapes; conversion of tapes fordifferent machines; prior plotting ofcompleted tapes; and calculation of runtimes for costing purposes. The designprocess works .like this: a blueprint for anassembly arrives at the Broad Oak Works.

It is assigned to one of the drawing officestaff, who sits down at a board and withthe skill of knowledge and experience,calculates roughly how best the machinetool should make the passes over the billetof raw material.

These billets are usually of high-gradealloy, and extremely expensive. Theblueprints, along with materials' spec-ification are straight from the designoffice at Stanmore or from the Ministry ofDefence. Usually, there will be noindication as to what kind of componentit is, or to what machine it belongs. This isa curious aspect of the work at BroadOak, where everybody signs the OfficialSecrets Act.

After deciding what kind of machine -there are two types, milling machines andlathes - the drawing office engineermoves on to the paper -tape punch, or theAltos if he can program it, or if neither,then writes it all on a process form. Hemay at this stage be assisted by themainframe which will define the geometryof the part.

This stage of the work is usually done inAPT language and entered on to one ofthe Altos machines by the NC engineer. Itis stored on an Altos hard disc and sentvia Des Breach's own software to theTransdata 4000, configured as an internalterminal, and loaded on to its 8in. single -density floppies. This machine can thentalk to the IBM 3032 or 370 - at a price.As in many large companies, services areinternally billed, so there is an element ofcost -saving, too, in the processing powerintroduced by the Altos set-up.

There are two stages here: the inter-mediate processor, which defines thebasic geometry of the part, and the post -processor, "which does the frilly bits tointerface with each controller". Thedesign of a component can involveelaborate and lengthy calculations: forexample, the specification for the partmay require an elliptical external sectionand a wall thickness of such -and -such.Interpreting these criteria involves a gooddeal of computation since the internalsection will not in fact be elliptical.

When the paper -tape image is returnedover the line from Chelmsford, DesBreach's department sets to work to put inas many safety checks as possible. APTitself is a well -tried language and unlikelyto introduce errors but post -processorroutines can be prone to errors until theyare thoroughly de -bugged - in somecases this has taken as long as three years.They are long programs, usually suppliedby the machine -tool manufacturer butrefined in the light of experience.

The paper -tape routine so created isthen read on to the Altos which drives aHewlett-Packard plotter to give a physicalrepresentation of the passes a cutter willmake on a particular workpiece.

Here there is not substitute forexperience. It takes a trained eye to spotan abnormality in a plot, but in this kindof application there is literally no margin

for error. With a £3,000 billet of high-grade alloy flying around on a lathe, awrong routine which sends the cutter in atan impossible angle can cause grievousinjury to man and machine if the chuckbolts shear.

Even though every test is preceded by a"fresh -air pass", the proof of theprogram is in the slicing. "I don't thinkyou'll find any programmer who won'tadmit to a 50 percent increase in heart -rate every time at a try -out", Breach'scolleague Jim told me. "It might be six ornine months since you wrote the programthat the job is tried on the shop-floor, andit's a fraught moment. You know that ifyou've missed out a zero somewhere,something catastrophic could happen".In the background lurks the possibility ofa power failure: "A power cut is enoughto wipe out a RAM and if the processorgoes wild, so does the machine".

Spectacular time -savingsSome of the time -savings made by the

Altos are spectacular. Translatinginstructions for one machine for anotherinvolves re -sequencing blocks of com-mands; it may be one, several, or allthe blocks. One program searches for ablock and re -sequences the numbers.Where previously it might have taken amorning to re -sequence 400 blocks, it cannow be done at a rate of three minutes for1,000 blocks. Where a complete routineon the biggest milling machine, the ZIPmight take 9.5 hours to plot on theTransdata, it can now be done in 4.5minutes. Best of all is the low-cost time-sharing, where a plotter program cancontinue uninterrupted while the essentialconverter programs are run.

Des Breach says that, to his knowledge,it is the first application of a micro systemin this kind of numerical -control machine -shop. Others will doubtless disagree -I am told that Cincinnati Millicron in theStates does just this, though I've a feelingit probably uses a dedicated micro-processor rather than just an adaptedoff -the -shelf micro. What is especiallyinteresting about the Marconi install-ation at Broad Oalc Works is thatthe micro which is bought straight from aretailer can be used to improve radicallythe performance of heavily capitalisedplant.

After all, the first cost of the microsystem works out at something like 0.2percent of the machines on the shop-floor. It is vaguely disquieting, though,that these ideas must struggle up from thegrassroots, and that there exists no overallpolicy in a firm which specialised inelectronics, to use micros whereverpossible.

It is reassuring, though, that once DesBreach, had argued his case, this kind ofequipment has been approved for futureuse on other Marconi plants. Even if thehardware is American, at least theingenuity which brings it to life ishomegrown. (IJ

92 PRACTICAL COMPUTING May 1981

Networks

Ethernet or Cambridge Ring?THERE ARE fashions in communicationstechnology, as there are fashions inanything else. If you had said data com-munications in the mid -sixties, thetechnology gurus would have immediatelyresponded by discussing two problems,problems whose solutions they would thentell you were "just round the corner".The first was the high-speed transfer oflarge files, sited as remotely from eachother as possible.

The second problem was that of real-time interactive computing - a problemwhich was in practice of concern onlytd defence and airlines, for most ofcommercial computing was still largelybatch. Where there was interactive traffic,most of it was still low speed - about 300baud. The VDU was nowhere near soubiquitous; users in the main worked withTeletypes or Teletype -like terminals, andresponse times were slow.

By the late -sixties and early -seventies,the fashionable talk concerned networksand resource sharing, either nationwide oron a continental scale. It was the start ofthe era of packet switching and of theconcept of resource sharing. We wouldsoon, we were told, be able to sharecomputer resources irrespective ofdistance or manufacturer's name tag.

In the mid -seventies, the literature wassuddenly full of star networks andcommunications architecture was all therage: how did a manufacturer make itssystems talk to each other; what com-munications could it offer the market?

Satellite communicationsThat was followed rapidly by the

question of satellite communications.Satellite communications became acommon topic long before the majormanufacturers had arrived at suitablecommunications architectures.

The first ideas about satellite com-munications proposed star networks, withan orbiting central node. At first sight thismay seem odd. Is not after all one of themajor characteristics of a satellite thatwhen it broadcasts, any ground stationmay communicate with any other pointalso so equipped? That may be so, but itis not how the use of satellites was in-itially envisaged. It was looked at as amethod of high-speed, high -volumecommunications between headquarters,and outlying branches, plants and offices- a method of reinforcing centralcontrol.

That may, of course, have been areflection of the initial military com-munications uses to which satellitecommunications were put. However, withsatellites emerged a difference - theexperts were talking about the manage-ment of all communications. If you couldsend data, why not also voice, facsimile,and image.

PRACTICAL COMPUTING May 1981

Of course, as the initial satellite ground -stations were likely to be costly, we hadreturned to the area of shifting massvolumes. The larger the volumes, thebetter the economics looked.

Meanwhile, the fashion has changed yetagain. The next bandwaggon is the localcommunications network. Such is thepace of the bandwaggon that SBS hasalready stated that it will eventuallyprovide a service to link local com-munications networks via satellite.

Yet why such networks at all? Why notcontinue as we are doing now? Such

by Rex Malik

networks have their origins both intechnology and economics. In the tech-nology, because as solutions began to befound for the long-distance networkingproblem, it became apparent that many ofthe real problems were no longerconcerned with long-distance trans-mission, but with much shorter distances.

The concept of distributed computingwas beginning to take hold and evenwhere it had not, organisations now hadmany devices to link to each other or toCPUs. The problems needing solutionswere now the linking of devices locally toaccess the communications medium, andthe efficient use of that medium.

Now, a new discipline enters. It isknown as communications analysis andmanagement. That it exists at all is hardlyrecognised yet, but it can be seen moreand more particularly in large, inter-national operations, in technologically -aware companies and organisations.

It is the result of three pressures: costs,technology, complexity. Communicationscosts have been increasing, partly becauseof inflation, partly because of massiveinvestment programmes by post officesinternationally. Visible communicationscosts have, too, been increasing withcontinual substitution of machine powerfor man power.

The export revolution of the last 20years has meant that more and morecommunications take place and often overlonger distances. Thus 20 years ago,British industry only dabbled in the U.S.market, while the amount of trade withthe Far East was low.

Second, technology: the amount oftechnology in communications hasincreased. Then - 20 years ago - therewere only posts, telephone, Telex. Today,there are posts, telephone, Telex, data,facsimile. Direct -dialling internationallyhas arrived, and there are now a widevariety of services available within eachcategory, and an even wider range ofdevices.

Third, the result of this has been anincrease in complexity. Not five years ago,

even in the best -managed companies, thecommunications function was handled bya low-level manager. He negotiated withpost offices for data connections, tele-phone connections, and new Telexmachines. The rest was beyond hiscontrol. The content of communicationsdid not concern him, and neither did thefact that many of the devices for which heobtained links overlapped in function.

Now, mounting costs and new deviceshave given communications a newprominence in organisations which theynever had before and have created a newmanagement function; communicationsanalysis and management. At its best, thenew discipline tries to look at andquantify all forms of communication inan organisation and between thatorganisation and the outside world.

It measures the quantity and tries toassess the quality as well as investigatingthe costs. It is not just concerned withdigital technologies, but also oldermethods still in use - internal mail,messenger services. It deals, too, with thenewer technologies: how will wordprocessing, image processing, video beused? Do we need intelligent digitalexchanges? It deals with the future. Theplanning function has been added and itcan now become a serious managementjob.

Few surprisesCommunications analysis has pro-

duced surprises. Very few organisationsknew - indeed, many still do not know- how much they spend on communi-cations. This has been because com-munications bills were seldom identifiedand analysed before. Most costs wereusually subsumed under the title ofoverhead, with one or two clearly identi-fiable expenses - most noticeable was thetelephone bill.

As organisations have begun, howevertentatively, to identify where the com-munications budget is spent, so thecomposition of that budget has beenchanging. Postal systems and messengersdistributing paper around offices arebeing replaced increasingly by a need forcomputers, terminals, word processorsand other devices to intercommunicate,for remote files to be accessed on line, andfor printers somewhere in the organisationto output material.

The need to mix types of data if one isto build a local communications net whichwill provide solutions into the future, themainstream digital technology trends, thetypes of devices which are appearing onthe market, have all forced the networkdesigner to make use of packet switching.Packet switching, for those not familiarwith it, consists in essence of a techniquefor breaking data into packets of code,

(continued on next page)

93

Networks(continued from previous page)each of which carries an also codedaddress and other instructions.

Messages of whatever length arebroken -up into packets, cast on to thenetwork, and recognised by the device towhich they are addressed - it has aninterface - where they are collected andre -assembled into the full message or text.

Packet switching is, in principle, atechnology which is transparent as far asthe type of electronic communications isconcerned. It can be data, voice, picture.What determines whether it is any one orall three is the bandwidth available. Thereare various ways of achieving suchobjectives using packet switching.Currently the two leading commercialcandidates are the Cambridge Ring andEthernet.

Ethernet was originally the product ofXerox. Ethernet Mark One was developedby Xerox at its Palo Alto, Californialaboratory, and was under developmentfor seven years - with some use withinXerox - before it surfaced recently as acommercial product, the Mark Two, fromXerox, DEC, and Intel.

Image transmissionThe Ethernet Mark Two is a 10 megabit

per second data -rate system whereEthernet One was at three megabit. TheMark Two offers a capacity which will,in the relatively near future, permitimage transmission and eventually alsovoice transmission.

The three companies are not, however,just selling equipment: they are alsoselling a standard - a way of doingthings. They will be able to generate thevolumes between them to make theeconomics acceptable. Thus Intel will dothe basic LSIs, including that for thecontroller, while DEC will build thetransceivers.

The Cambridge Ring also had its originsin a research laboratory, the computerlaboratory of the University ofCambridge. It was devised to allow themto interconnect computers and similardevices, and by early 1979 they had inter-connected an experimental computer oftheir own, a PDP-7, two PDP-11s, aNova, and LSI-4, a free-standing plotter,and a number of Z -80 -based devices.

The Cambridge Ring has since beentaken up by Cambridge -based OrbisComputers which has already shipped atrial installation to ICI at Runcorn,Merseyside, a four -node ring to whichinitially were attached an LSI-4 and aPDP-11. It has also since been taken upby Logica VTS, the word-processing armof the Logica consultancy group. It isinterested in its use largely in the contextof office information systems.

So, how do Ethernet and theCambridge Ring differ? Firstly, theydiffer in basic architecture. The Ethernetconsists of a coaxial cable run through asite to which devices are then attached by

means of cable -TV -technology clampconnectors. There is no central control orswitching mechanism.

All the attached devices listen all thetime for passing packets. When the devicerecognises that a packet is addressed to it,it copies it into its own controller. Theconvention is that a packet with a zeroaddress is taken to be broadcast and alllinked devices then copy.

If a device wants to transmit a packet, itwaits until there is no passing traffic.Provision is made to alert devices if acollision between packets has taken place.The switching functions are performed bythe devices attached, leaving the Ethernetcable as a passive communicationsbackbone.

In topology, the Ethernet can bethought of an an unrooted tree: unrooted,because it can be extended from any onepoint in any direction. New stations cantap in at any point, yet one avoids multi -path interference - there is, of course,always only one path between source anddestination.

In terms of devices and parts, theEthernet has four components. The cableor Ether; the transceivers which drive thatEther; a device -specific interface whichdoes the packet switching calculations forthe device; and a controller, firmware orsoftware for sending the packets in andout of the Ether.

An example of Ethernet One at a veryheavily loaded site had 120 hostsconnected, including two time-sharingprocessors, a large number of personalcomputers, shared files, shared printers,and gateways to other sites. In a singleday, it carried about 300 million bytes ofdata - the majority of packets are about30bytes long - but the majority ofvolume is in much larger packets, about500bytes.

The Cambridge Ring consists of anumber of nodes connected cyclically toform a closed circuit. One part of eachnode is concerned with the regeneration ofincoming data signals for onward trans-mission. To maintain this function whenthe station is not switched on, 28VDC isdistributed around the ring from attachedpower supplies.

Ring cable in the Logica VTS version istelephone -grade, triple -twisted pair, withat present a maximum length betweenstations of 100m.

The Cambridge Ring is what is knownas an empty slot ring. In it, data travellingaround the ring is delayed -a delay canbe thought of as temporary storage ofdata in transit. The circulating storage isso marked that it can be recognised asempty. To gain access to the channel, astation finds a slot currently markedempty, grabs it, marks the slot as full landloads its data.

When data is transmitted, it reaches theaddressed receiver where it is copied. Thepacket with original data continuesto go round the ring, however, and thepacket is marked empty only by its

original transmitter. The receiver marksthe packet as it passes, either accepted orrejected because busy. Two response bitsare included in each packet which allowthe detection of a third stage, namely thatno station of that address was found.This stops packets which are wronglyaddressed from circulating for ever.

To prevent a station from hogging allthe empty slots on the ring, a round-robinscheme has been built into each station sothat a returning used slot must be passeddownstream and cannot be usedimmediately again by the same trans-mitting station. Provision has however,also been made for fast devices tocommunicate rapidly, while slow devicestransmit at a speed which matches theiroutput performance.

The Ring components are the stations- which include the repeater powered bythe ring - logic which provides the inter-face and controls transmission andreception, access logic which is individualto the type of device and matches itsinterface to the station interface, slavepower supplies, connectors, and amonitor. The monitor provides paddingvia a shift register of 40 bits. That isnecessary in very short rings where there isinsufficient cable and repeater delay toprovide even one circulating empty slot.

Logica VTS is to produce a number ofproducts which will include the ringcomponents and devices to be attached torings, including a ring bridge which willallow datagrams to be shipped betweentwo rings, and a ring gateway which willallow data to be interchanged between thering and X-25 networks.

It needs to be remembered that LogicaVTS is primarily in the business of inter-communicating word processors. Withcurrent technology, it would not be unfairto write that all ring systems suffer onedisadvantage: the usable packet length setagainst the size of the address and controlbits is small. It is no disadvantage whenconsidering the movement of computerdata only, clever engineering can fix that.

Long-term solutionThere is some doubt as to whether one

could expect a ring system to meet allcommunications requirements within asingle location. Ring systems are forsituations where a decision has been madeto concentrate most of the message trafficin digital computer -like devices. Or whereindeed a ring on its own will repay itsinvestment from the greater utility it givesto digital computer devices.

Not to be unfair, there is some doubt asyet as to whether Ethernet will provide thetotal answer. Or that if and when it does itwill be recognisably Ethernet as we knowit. All that we can say is that both arebrave attempts to answer at least part ofthe problem. The long-term solution inwhich one communications medium istransparent to all forms of communi-cation is still in practice some way away.Q

94 PRACTICAL COMPUTING May 1981

JOBOY YOY

TRS-80 SOFTWAREFROM THE PoROFESSIONALS

itWe are pleased to be able to announce the commencement of a new series of Adventure games. The series

named "Mysterious Adventures" is written in machine language by B. Howarth, an English author. The firstepisode is entitled "The Golden Baton". The scenario is that you have been sent by the ruler of your own land toa strange province with the mission of discovering the whereabouts of the legendary Golden Baton of Ferrenuil.King of the Ancient Elf Kingdom. The baton mysteriously disappeared several years ago and whilst others haveventured to the land in an attempt to discover it, none have returned to tell their tale!

The program follows what has become the normal structure for Adventure programs. Like the original mainframe Adventure, directions can be designated by just the first letter of the compass point and commands may beoptionally entered with just the first three letters of the appropriate word. As usual provision is made for savingthe game at any stage and such standard commands as Help, Inventory, Score and Quit are all available.Experienced adventurers will inevitably draw comparisons between this series and that of Scott Adams, so wewill leave it to them to make their judgements! The only comment that we will make at this time is that we find itquite invigorating to play an Adventure game by a different author as obviously they construct their storiesslightly differently. Mysterious Adventure 1, "The Golden Baton" is available on cassette for TRS-80 or VideoGenie machines of 16K or more and on disk for 32K up machines. It occupies a full 16K. The tape versions savetheir game to tape and the disk to disk.

Tape version £8.75 Disk version £11.00Both prices plus VAT and 75p P. & P.

TRS-80 & VIDEO GENIE SOFTWARE CATALOGUE £1.00 [refundable] plus 50p postage.

A.J.HARDING CNIOLIMERX71MOLIMERX LTD.

1 BUCKHURST ROAD & 28 COLLINGTON AVENUE,BEXHILL -ON -SEA, EAST SUSSEX.

TEL: [0424] 220391 TELEX 86736 SOTEX G

War/CARD

In3

PRACTICAL COMPUTING May 1981

Circle No. 168

95

COMPUTER

BACKGAMMONA COMPUTER program has beaten theworld champion backgammon player -the first time a computer has defeated aworld champion at his own game. Unlikeother strategic computer games, e.g.,computer chess, the backgammon pro-gram used positional judgment ratherthan searching algorithms. Writing such aprogram presents an interesting problemfor the hobbyist.

If you decide that you would like to usethe code of a working program as a start-ing point, or prefer just to play the game,a Basic program for Pet is listed. Theprogram is packed as tightly as possibleand just fits on an 8K Pet. We can giveonly brief ideas on backgammon strategy;a number of books have been written onthe subject and one of the most author-itative and readable is by Magriel.

Backgammon is a game for two playedon a board divided in 24 regions, knownas points, plus a central region, known asthe bar. Each player starts with 15 pieceswhich are moved round the board accord-ing to the roll of a pair of dice. Eventuallythe pieces are removed from the board al-together. The game is won by either forc-ing one's opponent to resign or being thefirst player to remove all one's pieces fromthe board.

The stake, i.e., a number of units, wonand lost for a single game may increaseduring the game, and if neither playerresigns, the amount won depends on thedistribution of the pieces of the losingplayer. Thus the objective of a game ofbackgammon is not just to win, but to winas many units as possible. The overallwinner is the player who emerges withmost units over a number of games.

Figure 1 shows a standard backgammonboard with the pieces in the startingpositions. The points have been numberedfrom 1 to 24 to aid description of therules. Player A's pieces are represented by and player B's by o. The bar is thecentral vertical region between points 6and 7. The general direction formovement of B's pieces is from point 1 topoint 24, whereas A's pieces go in theopposite direction - point 24 to point I.

At each turn, you are required toattempt to make either two separatemoves corresponding to the dice throws,or if the dice throws are equal, fourseparate moves. For example, supposeplayer B's throw was a six and a one in thestarting position. He can either move onepiece six places and another piece oneplace, e.g., a piece from point 12 to 18and a piece from point 17 to 18, or altern-atively, he can move one piece a total ofseven places - though this must be donein two moves, e.g., a piece from point 12

by Bob Snell andBarbara Colley

to 18 and then from point 18 to 19.Remember that if the dice throws areequal, you have four, and not just two,separate moves to make.

There is, however, the restriction thatyou must not move a piece on to a pointoccupied by two or more of your oppon-ent's pieces. This restriction will meanthat there will be times when you are un-able to make full use of your dice throws.The rules that apply in this situation are: You must make full use of the dicethrow if possible. If you can make only one move whentwo are normally required, you must usethe higher throw if possible.

If you move to a point occupied by asingle piece of your opponent, youropponent's piece is sent to the bar, whichis equivalent to going to a point beyondthe first point - 24 for player A or onefor player B. A single piece on a point iscalled a blot and if it is sent back to thebar, the piece is said to have been "hit".

When you have a piece on the bar youare not permitted to move any otherpieces on the board. It is essential, there-fore, to move your pieces from the bar assoon as possible. As far as player B is con-cerned, the bar may be treated as point 0,e.g., for a throw of three he may move topoint 3, assuming that point 3 is notoccupied by two or more of his oppon-ent's pieces. Similarly, player A can

assume that the bar is equivalent to the 25point.

Removing your own pieces from theboard is called "bearing off". To do it,you must first have all your pieces in yourown inner table, i.e., on your last sixpoints. For example, player B must haveall his pieces occupying point 19 or higher.To bear off, player B can assume that heis trying to move to point 25, player A topoint 0. Thus a throw of three will enableplayer B to bear off one piece from point22.

If you have a throw which would norm-ally enable you to bear off from a pointwhich is now unoccupied by your piecesand there is none of your pieces furtherout, you must bear off from the furthestpoint occupied. For example, if player Bthrows a three and all his remaining piecesare on points 23 and 24, he must bear offfrom point 23.

At the beginning of the game, the basicstake is one unit. Either player may, how-ever, before knowing his dice throw, optto double the stake. His opponent has thechoice of refusing the double, therebyconceding the game for the current stake,or accepting the double, in which case thegame continues. The stake may bedoubled again, but not by the player wholast doubled.

The stake may also be doubled on thefirst throw of the game - one die perplayer - which is used to determinewhich player has the first move, the higherscore earns this privilege. If the dice scoresare equal, the stake is automaticallydoubled.

If one player refuses a double, the unitswon and lost are equal to the currentstake. If the game ends because one playerhas borne off all his pieces, the units wonand lost may be higher. If the loser hasnot borne off any piece and still has oneor more pieces in his opponent's innertable - points 1-6 for player B, 19-24 forplayer A - the winner has backgammonedhis opponent and has won treble thecurrent stake.

If the loser has not borne off any piecebut the winner does not qualify for a

96 PRACTICAL COMPUTING May 1981

Games

backgammon, he has won a gammonwhich is worth twice the current stake. Ifthe loser has borne off a piece, he losesonly the current stake.

You can see from this that if you areheading for a gammon or backgammon, itis not prudent to offer your opponent adouble thereby enabling him to escapewith the loss of fewer units. A player mayresign only when a double is offered tohim.

The first consideration when designingan interactive program should be the userinterface - in this case, how the mech-anics of the game will be presented to theplayer. The player needs to know thecurrent position and requires a method toinput his moves, including the ability tooffer a double at a suitable time and toreply when doubles are offered by thecomputer.

He must also be able to decide whetherdice throws are to be generated automatic-ally by the computer or manually by theplayer. To the programmer, it seemsnatural to make the program generate dicethrows both for its own use and for theplayer. However, if the program is able tobeat a particular player consistently therecan be the doubt in the mind of the playerconfronted by a series of defeats that dicethrows are being fixed for the computer'sbenefit.

Perhaps the answer is to allow anoption at the beginning of the game sothat the player may choose whether hewants to enter the dice throws for eachmove himself or to allow the computer togenerate them.

With modern displays, it is possible touse eye-catching graphics to construct adiagram showing the current position ofthe pieces. However, we believe, like allserious game player -programmers, thatthe most important factor of a strategicgame such as computer backgammon ishow well the program plays rather thanhow good it is at telling you what it hasdone.

Pretty diagrams are all very well pro-viding that their construction does nottake perceptibly longer than a basic butadequate display, nor use valuableprogram space which otherwise would beavailable for improving strategy. What isacceptable depends on the size and capa-bility of the computer used - clearly it isnot the same for an 8K Pet and a 100KDEC -10.

A basic display, which can bereproduced on a printer, is shown infigure 2. The computer now takes theplace of player A and its opponent ofplayer B. One symbol is used for thecomputer's pieces and a second for theplayer's. Points are numbered for easyreference. Note that in theory, each pointmay contain up to 15 pieces. As shown infigure 2, if there are more than five pieceson a point, a digit is displayed. For repre-senting 10 pieces, A is used, for 11, B isused and so on.

Moves can be input and output using

XCOMPUTER

12 11 10 9 8 7 6 5 40 "X 0 X

"X 0 X"X"X"7

fl

3 2X XX X

DD BAR4 0

" 0 0 0 0 00 " 0 0 0 0 0

13 14 15 16 17 18 19 20 21 22 23 24OPPONENT

0

Notes: Doubling die - stake - is set to 4 and isin possession of opponent. Opponent has one piece on the bar. Computer has seven pieces on point 6.

Figure 2. Simple computer display suitablefor production on a Teletype.

point numbers. For the computer, 25 canbe used to mean the bar and 0 for bearingoff and vice versa for the player. In thisway, each move may be individuallyrepresented.

It is also vital for the program to ensurethat the rules of the game, which are pre-cisely defined, are obeyed. Some writersof commercial programs take the viewthat if the player wants to cheat byentering an incorrect move, it is up to him- the program will not attempt to check.We absolutely abhor this attitude.

Firstly, it is of no help to the playerlearning the game if he is allowed to makeillegal moves; in fact, even reasonablyexpert players are unaware of the applic-ation of the rules in certain cases, so eventhey can be helped. Secondly, the playermay have entered an incorrect move bymistake. In this case, a perfectly good

Table I. Recommended opening moves by first player.

Throw6-6

Move, computer Throw5-1

Move, computer13-8, 24-23 or 13-8, 6-5

6-5 24-18, 18-13 4-46-4 24-18, 18-14 or 24-18, 13-9 4-3 13-9, 13-10 or 24-20, 13-106-3 24-18, 18-15 or 24-18, 13-10 4-2 8-4, 6-46-2 13-7,7-5 or 24-18, 13-11 4-1 13-9, 24-23 or 13-9, 6-56-1 13-7,8-7 3-35-5 3-2 13-10, 13-11 or 24-21, 13-115-4 13-8, 13-9 or 24-20, 13-8 3-1 8-5, 6-5

or 24-20, 20-15 2-25-3 13-8, 13-10 2-1 13-11, 24-23 or 6-5, 13-115-2 13-8, 13-11 1-1

PRACTICAL COMPUTING May 1981

game could be ruined by the program'sinability to detect the error. It is vital thatall moves, including null moves, arechecked for validity and that doubling ispermitted only at the appropriate time.

To simulate dice throws, a pseudorandom -number generator is required. Itis often already provided for the pro-grammer by means of a function whichoutputs a real number between 0.0 and1.0. A number thus obtained needs to bemultiplied by six, truncated to an integerto which one is added to give a suitablethrow. If a random number generator isnot provided it is possible to write yourown by using arithmetic to overflowvalues - see Computer Simulation Tech-niques.

Given that we can now generate asequence of pseudo random numbers andhence dice throws, we still need to givedifferent values for each game. That maybe achieved by discarding some of therandom numbers to give a different start-ing point in the sequence. The number tobe discarded can be based on the currenttime, unless it is available on the computerbeing used, it must be input by the player.

The next item of software to write is themove generator. Given a particular dicethrow and position, the move generatorshould be able to generate every validmove. Obviously, this can be done only byconsidering the scores of both dice.

This piece of software is probably themost difficult to write because the pro-grammer must be certain that every poss-ible position and move is catered for. It

does not matter that the move generatorgives a particular move more than once,providing that it is not taking too longover redundant moves. It matters greatly,however, if it omits to find a particularmove. The move it omits could on someoccasions turn out to be the best move oreven the only move. Even worse thanallowing the player to cheat is allowing theprogram to cheat.

Having written the move generator, thedice generator and the user interface, theprogrammer has the fundamental ingred-ients of the program. It is then necessaryto write an algorithm which will choosethe best move from those available.Although on average there are about 20ways of playing a particular throw, therecould be more than 1,000 possibilities.Depending on the computer being used, itmay not be feasible to consider them all.

One way to write the program is toallow a certain number, variable betweenprogram runs, of move possibilities to beconsidered from those available. In thisway, a program run might be geared tosuit the level of competence of the player,e.g., the beginners' level might processtwo moves whereas the experts' levelcould allow up to 50 possibilities to beconsidered - even more if computerspeed permits.

The normal way for the computer toselect a move is for a value to be given to

(continued on page 99)

97

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Circle No. 110

PRACTICAL COMPUTING May 1981

Games(continued from page 97)each move considered; the move given thehighest value is the one adopted. Thisvalue is derived from several other valueseach of which reflect the assessment of themove and subsequent position accordingto various strategic factors.

Backgammon is a race and as such maybe likened to a middle-distance athleticsrace in which, during the early stages, theparticipants engage in tactical manoeuvresbefore finally sprinting to the finishingline. Yet in athletics, the length of the raceis known beforehand - not so the case inbackgammon. It is possible at any stage todetermine how far off the finishing line isby summing the number of points whichmust be traversed by each piece. This is

Player A ()

12 11 10 9 8 7 6 5 4 3 2 1

000

00

13 14 15 16 17 2 19 20 21 22 23 24Player B(0)

Figure I. Diagram of a backgammon boardwith the pieces in the starting positions.called the point count and is 167 at thebeginning of the game.

Knowing the point count for the playerand the computer, it is possible to deter-mine who is ahead in the race and by howmany turns since the average number ofpoints moved in one turn, assuming noneis wasted, is 81/6 - it is not 7 becausedoubles require a move through doublethe normal number of points. If contactbetween the two sides is still possible, thepoint count is able to rise because piecescan be hit; if contact is impossible, thepoint count can only decrease.

It is important to know whether youwish to maintain contact or not as thisaffects the assessment of whether part-icular moves are good or bad. Oncecontact has been lost, the race enters thesprint phase and the players are at themercy of the dice. If a player is suffic-iently far ahead and the distribution of thepieces means that a gammon or back-gammon is unlikely, he would be happy toenter this phase.

On the other hand, his opponent wouldgladly raise his own point count if thealternative was to lose contact and therebythe game. In that situation, he would tryto leave blots so that the tactical stage ofthe race would be prolonged with thepossibility that he could then hit back andthus improve his position.

However, he must be careful that hisposition does not deteriorate to such anextent that a gammon or backgammonbecomes a possibility; at some stage it

PRACTICAL COMPUTING May 1981

might be necessary to abandon all hope ofwinning and instead attempt to lose by aslittle as possible.

Hitting an opponent's piece increaseshis point count but also prolongs contact.It is of positive value unless you areanxious to avoid contact or unless you al-ready have a sufficient number of youropponent's pieces on the bar. The furtherback a piece is sent and the more difficultit is for your opponent to re-enter thebetter - because inner table points areunavailable.

Leaving blots is only a good move ifyou wish to be hit or if contact has beenlost, when it does not matter. Otherwise,it should be assigned a negative valuewhich takes into account the probabilityof being hit, how far back the piece wouldbe sent and how difficult it would be to re-enter. On a slow computer, we recom-mend evaluating the approximate probab-ility only.

Making points is the alternative ofleaving blots but becomes of positivesignificance when the point made is on theactive side of an opponent's piece. Notonly does it hinder his movement past thepoint, but it threatens him should he leavea blot without moving past. Clearly, notall points are of equal worth. At thebeginning of the game, the most import-ant points for the computer to capture, inprobable order of value, are: 20, 5, 21, 7,4, 22 and 18.

The hindrance value clearly increases asconsecutive points are made, up to six.When six consecutive points are made, itis called a prime and an opponent's pieceis unable to move past. Note that aseventh point adds nothing.

A builder point is one containing apiece which is in a position to move to adesirable point not already made, usingthe throw of one die should it be suitable.The piece should also be one the playerwould not mind moving. In figure 3a,points 10 and 8 are builder points withrespect to point 7, whereas in figure 3b,points 11, 10, 9 and 8 are builder pointsand therefore in this respect figure 3brepresents the better distribution.

During the end -play, where you arehoming in on your inner table and bearingoff, some further considerations regard-ing the distribution of your pieces arenecessary. First, the case where contacthas not been lost. If you are in the end-game, you must be ahead and thereforewish to play safely. Thus, you shouldavoid leaving blots and maintain contin-uity, two aspects already covered. In add-ition, to avoid leaving blots on futuremoves, you should try to keep spare pieceson the points furthest out and an evennumber on the last two points.

Alternatively, if you are trying to avoida backgammon, then obviously you moveyour pieces from your opponent's innertable as quickly as possible. To avoid agammon, maximise on cross-oversbetween tables and move your pieces intoyour own inner table as quickly as poss-

ible, if necessary piling them up on to the6 point. However, if there is a race to bearoff first and all your pieces are piled up onthe 5 and 6 points, you will not be in agood position to bear off easily.

Thus, when homing in, you should aimto distribute your pieces evenly withinyour inner table. It is also undesirable tostrip the higher points too early. Forexample, it is better to have one piece oneach point in your inner table than to havethree pieces on each of your three andfour points even though both distributionshave the same point count, i.e., both needa total dice score of 21. This is because ifa six is thrown in the second case, two ofthe dice score is wasted.

At first glance, it may appear that thebest policy to adopt is to play safe always;but you are unlikely to win many games ifyou do. Safe play is fine when you areahead in the race and do not want to letyour opponent back in.

Leaving blots means that you are morelikely to be hit, but also that you are morelikely to hit your opponent if he leavesblots. Furthermore, provided you can re-enter once hit, you then win the chance ofanother crack at him.

Having constructed a formula, a usefultest to apply is the set of opening movesgiven in table 1, which are generallyagreed by backgammon experts to be thebest. Of course, a look -up table can beused for them, but it is more satisfactoryto be able to demonstrate that you have

Figure 3. Builder points.

the best formula for the opening stageswithout recourse to a table.

Further formulae are necessary todecide when to offer a double andwhether to accept one if offered. Youshould offer a double when you have astrong advantage, but not one so greatthat it might lead to a gammon or back-gammon. You should accept a double ifyou consider that you have a greater than25 percent chance of winning.

That is difficult to calculate, exceptwhen there are few pieces left. The doub-ling formulae should normally be basedon the relative point counts and the lengthof the game plus an adjustment for thepotential of the current position.

ReferencesHans Berliner, Computer Backgammon, ScientificAmerican, June 1980, volume, 242, number 6 fordetails of the world champion's defeat.Paul Magriel, Backgammon, Hamlyn, 1976.Thomas H Naylor, Joseph L Balintfy, Donald SBurdick, Kong Chu, Computer Simulation Tech-niques, John Wiley & Sons, 1968.

(continued on next page)

99

Games

(continued from previous page)1 PRINT"72ACKGAMMON-61."2 PRINT"XWHAT LEVEL GAME (1-12i ".:INPUTH:H=F1.1-1,8=30 11=1 00=0 X=7,'1.3 '6=1.'93 DIMCP1(A),Z(2).9/.(4,21,11.(A).R1(A).RC2)4 FORI=ITOA 0A(I)=0 NEST 01(23)=167:01(A)= -167:F=255 0/1(1)=-2 01(12)=-5 011(17)=-3:01(191=-5 0/(24)=2 01(13)=5:01(8)=3 0/(5)=55 PRINT"7112 11 10 9 2 7 IS 1.1 5 5 4 3 2 1"

7 PRINT"KIKKOIMMIPMKOOKIMI3 14 15 16 17 16 IS 111113 20 21 22 23 241"C 1F14lTSF,O 18.. 1011=ITOIS FRINT"11 Ismer. NEXT FORL=IT024 G0SUB78 NEXT9 00521891 1=1140 -I 0=.,1

181013123 111NT"MY THFCW2(1)" YOUR THROW:7)2)11 I113,1,==)2JTNENOOSUD233 00101012 IF: I ) :2( 2,1110111=2 1 ) :2;11 ,=21( 2(2)=1 0010 2113 IF INT "my C,u WITH": I )" "2'. 21.00500 99: 1111-11"MY MOVES"14 1011.1Tort FF1t1,..;1: 1.1 " . 11EXT:5 303UP35 1101(27=15THEN005JD97 X=1 60102916 =1 0081.1009:11DWATHEN0OSUP95 GOT02117 1,05U0243 IFA$13"D001021113 00513043 60324E*7 110=100102019 FRINT"DOUDLE PEFUSED"-0=I 00103320 011=1 00KUD23821 FKINT"Y0191 GO WITH".211)" "252' 00514815722 113331THENFRINT"ILLEGAL MOVES - TRY AGAIN":00SUD96:00T02122 PRINT"YOLP MOVES":101I=1TOM,FRINTV/(1.11":"%;31(I.2,1 NEXT 1=FRE(0)24 C00131135 110.1,28)=-15THE4400544B97.X=0 00102925 C01.3U196 2=1 000.2' 110141000101326 1111167 110.=0150101327 001)9E247 1115="1"THENX=1 00101928 D14=-1 0051311238001013290=1 J=19-18*X;11211(27,X1-13000103330 0=2 IF011,11)13.0111E110=31301033Ti P0R1=JTOJ,5 I101XI,319TNEN0=332 NEXT5T ?=0D 11.1=ITHENPRINT"I": 00103534 FKANT"YOU"35 FRINT":YE 14544'S" 144411'. :IFY3ITHENPRINT"536 110=2THE44FRINT"(CANMO4l..",37 1111,3THENPRINT")013CKGAMMON38 Fl 1441 END39 F011=1102 2(1)=IN1(501413.1)+1)-HEXT:112(1)==(2)THENM=4 RETURN40 M=2 IFLX2),121:1,00104.241 IFC2OTHE14I=2,14 2)1)=2(2 2(2)=142 RETURN43 0=0 0080065;IFL15000104544 11011(1-'9).01(A,O3+1.,220>..40THEN0=145 1E11.446 GOSUB48:11110+2THEN0=147 RETURN48 1=0:0=0 FORI=IT024 1101(I.)30THEN1=1,121(INFI11IC(1-1)/4,1)49 I101(1)10THENC1=0-011(1)*I111((24-I)/4,1)50 NEXT :1=1,01(1).7 0=0-021,26)47 RETURN51 10=1 4=0:R(1)=K:11.2,=1. 11=C 1111(26110THENJ=252 FORI=11024 IFP1(I)OOTNENJ=253 11111(11(=0THENC=1:00105854 IFJ=2THENK=155 1111(1)=1THENC=1 00105856 E=55+5 -I IFE110REOX5THENE=157 1.(31=11.3)4E4C:C=C4.550 NEXT 1.1(2)+01(A)-11(A)..01*(P11(27)-01(27)) IFKOOTNENB=11,X14,R(1)+WK59 IFFC=OTHENRETURN60 1(1=11 1(2,=1.':FOR1=ITOLP 1111(PC2100106461 FORS=I102,L=1-64CS-1)FOR3=11.06 K=L-.1 IFK=OTHE4IK=-8 3=6 5=2 00106362 111,11(1000THENE1=8-R(S)*(1-I)63 NEXT:NEXT:IFK1OTHENIFP11(25)10THENB=B-11-10*)F-I)64 NEXT RETURN65 L=-01(81:11L301(29)THENL=01(23)66 RETURN67 0=0:003UB651FL>9900107763 J=1:1F01(28)-10THENJ=10069 111.15000107270 11=-01-1(29)-01(A)1141(<3*L+100)/400PN33541300107771 00107372 0054584811=0-1:11N(20RN)46*J00a07773 FOR1=1107,J=F-I:IF=D3OTHENJ=I:1=774 44EX1;IFJO7THEN0=1,RETURN75 11=0:10RI=JT012:3=1-I,IFQMD(-ITHENK=K+176 NEST:IFK<4THEN0=177 RETURN78 IFL=OORL=FTHENRETURN79 FRINT"4":3=011(L),P=ABS(J)80 IFLOI2THENPRINT"*001101MMNIM"SPC((L-12).3-2).:00.708231 FR1NTSPC((13-L)*3-2):82 IFL>18ORL17THENPRINTSPC(4)83 F0RK=ITO5 1111KTHENPRINT" MU". 00108984 113)=KANDK15THENPRINT"SAMI". 00108905 IFJC=-KANDKC5INENPRINT50Alr.100T08886 IFJ=KTHENPRIN1"6111r. 00108987 111=-1-THENPRINT"0411". 00T08988 PRINT"WRIGHTT3STR$(1).2)13 IFL:12THENFRINT"11",90 NEXTPETURN)1 FKI41T"460"SK(1.9:). 1=7-11111.01(FV2):J=1,071(1) R=7-I14T(-011(26):2)92 F=R -01..(26) FORL=IT015 PRINT" Aim"; :11L3PANDLC=JTHENFRINT"11/11",33 IFL)RANDLr1=KTHENPRINT"-W421111:94 NEXT FRINT"0":1ETURN95 FORI=ITOM L=V1(I.1) 0080E78 L=,)/. 1,2) 0051:$78 445141 005U831 RETURN96 COSUE250 FRINT"NIT RETURN WHEN READ..." 0051:M25137 00151250 FK14IT" 111111 1011=1T0698 FKINT" " NEXT FK1NT° 111111 RETURN99 M1=1 N=0 11=1 U=0 0=-399 FOR 1=1106 F1' 1:55 NEXT100 L1=14 .15=5..1,25 I14=0 I=2. 1 1.2(21 112( 11.17(2)THE4I1=1.2101 1=1-01.29 , -01(A.; IFI :; 3401' 23)* 350 ),'4000-1010,3102 .14 L1=13 X5=1 111=1

103 005U-1111 11141113010107104 14=1.1,1 1113:111141041=M0010107105 C5551451 IFS1=0ANDN=M10010103106 13----1 141=N 1011=11011 R.1(/),,11(1.1) R1(I=4)=V1.1,2. NEXT 0010103107 1011=110N -1)1.1.)=.1.1..1 WXI.2)=11(1+4, NEXT108 FOR1=ITC 11.1=01,I) NEXT109 11=1 FoP: 1=1101 A1=v111.1) A2=55(1,2) 005UB147 NEXT:111 1011=11.09 01.(I=111 I) NEXT RETUFNIII IF4A3010135112 1=.1113 11=1 11=314 r1111=1T011 11,I)=01.)1)-11EXT114 51=0 1755-:1. 1111-:31THE41IT=2)3-1.115 1111. fl=00010118115 4=F -IT 111%0:33-1001.0133117 1501. 1=1 V1.'(44.2;=1) 0011131118 1-0 4 01 J3511O1STE1-1 131=1 1111(3)1=000101211151 K=.1-11 IFF:=OTHEN1=1 J=1:00a0121120 1111 4 5>,-ITHENF55 J=1121 NEXT122 .W1=0001.0133123 111=100T0125124 V7:41,1.,=0 ouTuLA125 IF4.=OTHENK=.7125 IFK:::OTHENK=0,1

127 1=0 F011=11-024 1F11.(I)O0THE454=1 1554128 NEXT129 IFF=100T0133130 V1(N.1)=0 V1(11.2)=0131 9155"11(44.1::,32=N.2:VP=1 02:SU0147.1FN=M0OT0146131,-1 H=11+1'001.0114133 1245 '115,010145134 1F454 10010142135 N=N -1136 'FM11,1)=10010142137 1F'..':1' 14,2

133. 01",'I." 11.14-1 11811=00070134139 FORI=ITOA:13.(1)=011(1)-NEXT11=2(11:11N<31THENIT=21.0-1)140 K=N-1 IFK=00010118141 4.1=1 FORI=ITCC:111=V11(1.11, A35511. 1.2' NEXT 0010118142 IFM=40RR=20010144143 R=2 0010113144 N=I145 FORI=NTOMV1(1,1)=0-V1(I.2)=0:NEXT;N=N-1146 RETURN147 IFRI=1320010156145 L=(59-K1)'2:11(L)=111(L,,A2-A1,1FRI=OTHENF111(26)=11(261+1 0010152149 IFAI=FTNEN11(1)=11(1)-1:0010151150 111(91)=111(111)-2,1151 IF82=0THEN111(27)=111(277+1 RETURN152 IFA2=1THEN111(28)=P%)28)-1,RETURN153 11111(A2)10-4"PTHENP1(112)=N1182)+KP:RETURN154 1/1(A2)=KP L=55-L:11(0)=111(L)-KP:L=4.1111(L)=111(L)-132155 IFL=29THENK(L)=P11(L)+1156 RETURN157 FORI=ITOM:M1.1)=0:V1(I,2)=0:NE111158 D$"159 2.02140251,11118=CHR$(13)00T0164160 IF45$=CNRIC20)00T0165161 1=VAL(A$)111=0ANDR$13"0"THENR$="3"162 14=08+88163 PRINTA$11301.0159164 PRINT:001.0168165 B=LEN(14)-1,11B=OTNENPRI44TAC:0010 158166 110(10010159167 B$=LEFTS(B$,B):0010163168 0=1.514(85):K=01L=1:FORI=ITOM:101.1=1102169 K=K+1,I1 42)1THE441==20010174170 88=M10$03$.6.1),IFFI$CO"-"0010173171 IFL=10070169172 L=1:0010174173 V/(1.3)=V11(1,3)*10+VALCRS):L=0,0010169174 NEXT3.1.0=0:1011=I108T11(1).011(1):NEXT R(1)=2(11 :R(2)=2(2)175 FORI=ITOM411=W1(1.1) M2=V14(1.2).11M1<>M200T0192176 1111-A001:0182177 K=2(1) 0031:0223178 110=00010217179 IF:7(1)=2(2100T0M1130 4 =2(2) 0083E1223 110=10010108181 0010217182 455(3-3) 005U0223 110=0581021711521 112(3-313=72(3)00T0187184 1,=2(.1 1015=110A 11/(L)=N1(L) 11(121=Q1(L)'NEST185 00024E223 1010=110A P/(L)=R11(L)NEXT 1E0.1000218185 0010217137 111=MG010218188 0=0-J=1,1 1=0 FORT.=JTOM 11./1.4.. 1(2)1.'' K=M1.09190 111,-11301.0217191 3010213192 11111O0ORM13240010217193 11112,11ORM23F00T0217134 IFF11-1100010200135 'F11(26)3=00010217136 3=0 1012=1102 IFM2=2(K)THENJ=K197 NEXT 113=00010217138 V3=1/5512.1> 111.310010217199 0010215200 IFF3126)300111(111)0=0001.0217201 11M2=10010206202 3=11.) 115510010217203 12=412 -MI 111=2(1)TNENJ=1 6010215204 IF1=2)2/THENJ=2 0010215205 0010217206 R=F-N1 5=0 101:4 =1105 1111=12(J)THENS=1 K=2207 NEXT208 IF:1,00010217209 FORK=11018:1111(K):10THENS=0 4=14210 NEXT211 115=00010217212 111=2(310010215213 11=111-1 FORL=19TOK 1111(0110THENS=0 L=K214 NEXT 118=00010217215 541=M1 112=112:K1= -10052E147 IFM=211E55)3)=0216 0010219217 0=2218 I=M219 NEXT220 110=2111E442)1)=11) 2(2)=1(2) 6010222221 0=1 FORI=ITOA 1111(I)=11)I1:44EXT222 RETURN223 0=0:1111(26)=00070226224 1111(10520010237225 0010236226 5=0:FORL=11024:IFP1(L)3=00010229227 4,P=1_,11 IF4,F0241HE415=L5=2413010229228 11111(411311TNENS=-1 L554223 NE11.230 113=015010236231 IF5=-100T0237232 IFK.F=FTNENKI,18233 IFKFORTHENKP=S-1234 S=0 FORL=ITOKP 1111(L)COTHENS=1.L=K1235 4IE7IT, 118=00010237236 0=1237 RETURN238 PRINT"DOUBLE ACCEPTED"239 D=D+1,14=RIONT$(8TR$(D),21:FRINT"0"8155191"240 IFDIF9=0THENFRINT"WA$"121111P:241 PRINT"0441XNU116!MMOD6E6M "::IF1111,1)=OTHENPRINT"IOWAS"P"242 GOSU095: RETURN243 G00UB250 PRINT"HIT D TO OFFER DOUBLE ELSE HIT RETURN". 008140251244 1F8$="D"TNENRETURN245 IF54$=CHR$113)THENGOSUB97 RETURN246 FRINT"1". 13010243247 PR1NT"DOUBLE7 HIT A TO ACCEPT OR R TO REFUSE":00SUB251248 IFA$(3"A"AND54$2"R"THENPRINT"1". ,0010247249 RETURN250 PRI441"A6CAM6X0140101101401.40111014"1;RETURN251 GETR$AFA$= '3310251252 RETURN

READY.

100 PRACTICAL COMPUTING May 1981

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PRACTICAL COMPUTING May 1981

Circle No. 171

101

Duncan, a high-level interpreter

for Nascom 1, canrun three to four

times faster than aninteger Tiny Basicand just begs to beused for real-time

control applications.John Dawson

reports.PEOPLE making initial contact with com-puters should be aware that computerlanguages take many forms. They can bedesigned for special or general purposesand are nothing more than a way ofgrouping fundamental machine -codeinstructions into statements and com-mands which can be used more easily bysomeone wishing to program a computer.For example, a language called Unkle hasbeen introduced for possible use byBritish Telecom staff working withSystem X, while Mumps was developed byDEC specifically for medical informationsystems.

Common high-level languages are notwell suited to microprocessor -control pur-poses as each has an emphasis towards theenvironment of the original user. Com-mercial languages are distinguished bytheir ability to handle files, performdecimal arithmetic and manipulate textualinformation. Scientific languages areusually able to handle floating-pointnumerical calculations and arrays of data.

High-level languages do not producevery efficient machine -language programs- most versions of interpreted Basic, forexample, will execute only a few 100 in-structions each second. Conversely, ahigh-level language may produce a pro-gram listing which conveniently describesthe tasks the language will undertake. Farless time may be needed to write a pro-gram in a high-level language than in anassembler or machine -code -based system.

Command and controlCommand and control languages have

been developed for real-time processingon large computers - there is a languagecalled Ironman or ADA which has beendeveloped from a Pascal base for the U.S.Department of Defence and Coral 66 isclaimed to be a real-time, high-levelcompiler. Coral is not readily available onmicroprocessors but has a number of ex-tensions allowing bit manipulation andthe control of unusual peripheral devices.It has, however, no mechanism fordealing with interrupts and it is a hallmarkof real-time languages that they can

Figure I.

Duncan brings a neweconomical simplicityto Nascom 1 programsrespond to the asynchronous and unpre-dictable flow of information in the realworld.

Many microcomputer applications in-volve the reception of data and other in-formation from input devices and sendingdata and control information to outputdevices - figure 1. The circular path fromthe input sensor to the CPU, to the outputdevice and through the controlled processback to the input is an ordinary closedloop feedback system in which thecomputer, CPU, may switch the processon or off, or modify it according to thedata from the sensor. The CPU may scalethe input and may, for example, output alinear control signal on the basis of a log-arithmic input, or inject or remove hyster-esis from the system.

Robotics aspectsArticles on shaft encoders and other

aspects of robotics have been published inPractical Computing. Often the controland status information used in controlsystems is made up of a few binary digitswith very precise hardware -related mean-ings. In these conditions, a machine -codeprogram is attractive for its speed andability to compare and manipulateindividual bits in a byte of data.

We live mostly in a world of eight -bitaccuracy. For many purposes, an incre-mental scale of 255 parts is entirely suff-icient to describe the range of our exper-iences. We seldom need to know thetemperature of our environment to betterthan one degree Centigrade - 40 degreesC to + 40 degrees C is 80 increments - orthe time for which an egg has boiled toless than five seconds - one part in 48over a four -minute period.

Wind direction may be measured to twodegrees using 180 increments by meteorol-ogists and its speed to half a mile perhour, 250 increments. In amateur scientificapplications, eight bits can produce aresolution of better than 1/20in. in 10in.on a graph plotter, and will locate a robotto within plus or minus lin. of its target ina roof 20ft. square.

Duncan is a high-level interpreter forthe Nascom 1 computer written inmachine code and operating under the T4monitor. It contains instructions for theacquisition, logging and processing ofdata in addition to the usual arithmeticand logical operators. Unlike Basic,Duncan has no line numbers and shouldbe treated as a stream of source instruc-tions to the computer in which labels actas points of reference for jumps and sub-routine calls.

Duncan runs three or four times fasterthan an integer Tiny Basic. The languageis aimed at the control of external devicesand has many uses in schools, electronicservice workshops, model controlsystems, and the home.

Structural analysisA flowchart illustrating the structure of

Duncan is set out in figure 2. The programexecutes at OEFO; the program name isdisplayed and the entry table and aprompt are displayed on the next line. Theeight command modes are set out in table1 and they allow the creation of a newprogram, its subsequent printing, editingand execution, its storage and retrieval oncassette, and the storage and retrieval ofdata acquired during a program run.

The language occupies RAM from0050 - 1400 - 1968 bytes decimal -

102 PRACTICAL COMPUTING May 1981

Languages --which includes an area for the storage ofvariable values from 13C0 - 1400. Scratch -pad RAM is located at 13A0 - 13BF.Instructions are stored from 1400 - 15FFand the area 1600 - 17FF is used forlogging data. The program area is 512bytes in size and will overlay the data logarea if further instructions are entered.The existing memory allocation is,however, generous for the majority ofapplications.

The data log may be re -located on largesystems and can be adjusted to storevalues to fill whatever RAM is installed.Details of a memory expansion board forthe Nascom were published in PracticalComputing, November 1980.

Indispensable aidHard copy is an indispensable aid to

most computer applications and Duncanincludes subroutines to format and printdata on a teleprinter accepting CCITTfive -element code. The instruction set hasbeen designed for its mnemonic appealwithin the limitations imposed by thecharacter set available on Creed tele-printers.

Both the instruction mnemonics andtheir correlation with the equivalentprinted character can be altered easily.The hardware and software for a Nascom/Creed interface were described in Prac-tical Computing, July 1980.

Duncan works with 16 -bit unsignedintegers, 0 - 65535, and has I/O facilitiesfor eight -bit data values. The sign of theresult of a calculation is unimportant forcontrol tasks as a D -A converter can be setup to output 0 volts with an input value of128, swinging to the maximum positiveand negative outputs at 511 and 0 valuesat the input respectively.

Circuit diagramsThe Ferranti ZN 425 E-8 data sheet

contains practical circuit diagrams forboth D -A and A -D converters. This chipcan be connected easily to a PI/0 port onan unmodified Nascom 1.

Duncan allows conditional jumps to bemade and subroutines may be calledalthough nested subroutines are notallowed. Duncan uses reverse Polishnotation in which numbers are pushed upa stack and are brought down in thecourse of a calculation. The language usesnumber handling routines derived fromM5, which was described by RaymondAnderson in the Liverpool SoftwareGazette, November 1979.

The theoretical program illustrates thesimplicity and economy of a Duncancontrol sequence. The program should beread with the explanation of each step andin conjunction with the full instruction setwhich is listed in table 2. The program willturn off a dark room safelight, make anexposure in an enlarger after recoveringthe time in seconds from a keyboardentry, and then turn on the safelight.

The program assumes that D -Aconverters are connected to the Nascom

PRACTICAL COMPUTING May 1981

PI/0 and that the converters are used toswitch relays for control of the lights. Thesafelight is connected to port 4 and theenlarger to port 5:

0 =x 255 =z LAz S4 ? =t .

x S4 z S5 t W x S5JUA:

The following steps occur when the pro-gram is executed: 0 =x The CV, which is explained in

detail later, is set to 0 and this value isstored in variable x.

255 = z The CV is set to 255 and thisvalue is stored in variable z.

LA Label A - this is a reference pointin the program.

z S4 The CV takes the value stored invariable z (00255) and this value is et atport 4. The analogue voltage at port 4will go high.

? = t The program looks for a numberfrom the keyboard. The languagehandles 16 -bit unsigned integers, 0 -

65535. The last five numbers enteredare used, leading zeros are not requiredand the operation is terminated by anynon -numeric character, e.g., 773 new

Figure 2.

line is acceptable. The screen is scrolled -up one line and the cursor set to thebottomx4 left-hand margin.

z S5 The CV is set to the value storedin variable x, 00000, and this value is setat port 4. A similar process takes placeat port 5, 00255. The safelight has beenturned -off and the enlarger turned -on.

t W The CV is set to the value obtainedfrom the keyboard and previouslystored in variable t. W is a program-mable wait instruction and the computerwaits for the length of time determinedby t. 1W produces a wait of one second.

x S5 The enlarger is turned -off afterthe computer has emerged from the waitstate.

JUA The program jumps uncondition-ally to label A and the safelight is turnedon before a new number is requestedfrom the keyboard.

: Marks the end of the program.This program is very simple, it does not

set up the PI/0 ports as outputs, forexample, and could be made much moreconvenient. There should be no need for anew exposure time to be entered before

(continued on page 105)

OEF0

IC

Common = invalid commond or input

Quit Xecute Print Write Read Create List EditDUNCAN

entry table

Yes

/Programto

Creed

Executeprog am

instruction

/Data/program

Yes

/W itedata/

program

CallList

List 12

lines

Ins ruction

Q space

CommandI

IC

Quit Zero New line < > Delete nsert

Movecursor

Instructionand

close up

Instruction

end Yes

103

0 00 0 0 0

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Circle No. 172

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104

Circle No.173

PRACTICAL COMPUTING May 1981

Languages(continued from page 103)each print is made and the program couldbe modified to ask if a different time isnecessary. It demonstrates a controlsystem with a practical function andwhich uses only 32 bytes of programstorage discounting spaces which can beremoved from a practical version.

The current value, CV, is held in theregister pair DE in the Z-80 CPU. The CVmay be displayed at any time in the courseof a program by the instruction = ?. TheCV is altered in the following circum-stances: When a number is encountered in the

course of a program the CV is replacedby the number.

When a variable is encountered the CVis replaced by the value stored in thevariable.

The instructions I and D increment anddecrement the CV respectively.

After an arithmetic operation, the CVcontains the result. When a ? instruc-tion is encountered the program obtainsa numeric value from the keyboard andthe CV is replaced by the new number.The stack is lifted by the comma in-

struction `,' and the CV is pushed up thestack -a second comma will lift the stackagain pushing stack 1 to stack 2 and theCV to stack 1. The CV is unaltered by thelift instruction. The program sequence:

45 + + = ?will perform the following operations:

CV Stack 1 Stack 2xx xx xx

45

45

45

90

135

xx xx

45 xx

45 45

45 xx

xx xx

Screen displays

45

= ?00135

Similarly, the program sequence:6 = V , ? * = ?

will set the CV equal to 6, store the CV(6) in variable V, lift the stack, obtain anumber from the keyboard and place it inthe CV, multiply stack 1 by the CV, placethe result in the CV, and output the resultto the screen. The stack operations areshown below:

CV Stack 2

6 xx

6 xx

6 xx

Input (7) xx

42 xx xx

Stack I

xx

xx

6

6

6

=V

7

_7Screen displays 00042

Variables may be identified by anylower-case alpha character. Hence, Dun-can allows 26 variables and there is aspecial remainder variable - upper-caseR - which stores the overflow or under -

Ax

B

Cx

D

FxSxJcl

KHKS IKA

LxH

Pc

Acquire data from port x and place the value, 0 - 255, into the next sequential location inthe data log. CV is maintained intact.Bring back the value in the data log pointed to by the CV when the B instruction is entered.The CV is destroyed and replaced by the data value. 0 - 255.Clear the data log area, CD, or clear the screen, CS. Each location in the data log, CD,is set to zero and the log pointer is set to the start address - 1600 Hex.Decrement the CV by I .

Increment the CV by 1.Find the value, 0 - 255, at port x and place in the CV.Set the value in the CV, 0 - 255, at port x.Jump if condition c is satisfied to label I:

C - U

E

N

LG

UnconditionalCV = 0CV not = 0CV = stack ICV not = stack ICV less than or equal to stack I

CV greater than stack I

S Jump to start of programB Jump to Breakpoint and display Z-80 registers.

KH causes the program to scan the keyboard and jumps to Hold if any key is pressed.KS I causes the keyboard to he scanned and if a key is pressed the program will call at thesubroutine identified by label I . KA does not scan the keyboard but causes the low byteof CV - values up to 255 are entered correctly, larger numbers are entered modulo 255- to be placed into the data log at the next sequential location.Label followed by identifier x to which jumps and subroutine calls may be made.Hold program execution. Continue execution by pressing space bar. Press Q to quitprogram and return to the entry table.Programmable wait instruction. The program halts for a time defined by the value in theCV when the instruction is entered. One wait instruction, 1 W, lasts approximately onesecond.Prints the character immediately following the instruction. Special functions are executedby four suffixes:

S Prints the top 15 lines of the Nascom screen.L Prints the bottom line of the screen.

Prints carriage.return and line feed characters./ Prints a line feed character.

(t) Tekt t between brackets is displayed on the Nascom screen starting at the current cursorposition.Full stop - scrolls the Nascom screen up one line and places the cursor at the bottom left-hand margin.Comma - lifts each value in the stack and places the CV into stack I. The CV ismaintained intact.

$1 Program execution is transferred to the subroutine at label I. The CV is maintainedintact into the subroutine. There is no provision for nesting SRs.Return from subroutine. The CV is maintained intact.Obtains a number from the keyboard. Entry is terminated by any non -numeric character.The largest number that can be handled by Duncan is 216 or 65535 decimal. The valueentered becomes the CV.

=? Display the CV on the Nascom screen starting at the current cursor position. The CV ismaintained intact.

=v Replaces whatever value was stored in the variable v with the CV. CV is unaffected by theinstruction.

+ Arithmetic operator - adds the CV to stack I - the value at the top of the stack - andplaces the result in the CV. Overflow bits from the operation are lost.- Arithmetic operator - subtracts the CV from stack I and places the result in the CV.Underflow is not detected.Arithmetic operator - multiplies the CV by stack I and places the result in the CV.Overflowing bits are placed in variable R.

/ Arithmetic operator - divides stack I by the CV and places the result in the CV. Under -flowing bits are placed in the variable R.Colon - program terminator. Places three ASCII zero bytes in the program store andreturns from the Create mode to the entry table. This character may appear only at theend of a program and is forbidden inside bracketed text.

Table 2. Duncan instruction set.

flow bits after multiplication or division.Overflowing bits in addition and subtrac-tion operations are lost. The followingprogram illustrates how the R variableworks:

, ? / =? ( ) R =? :

9 3 Screen displays 00002 0000115 4 00003 00003141 12 00011 00009

Leading zeros are displayed. Thebrackets define text which is to be outputto the screen. In this case, the spacebetween the numbers and the R variablecontain the remainder of the divisionmodulo, the divisor.

The port identifier following the find,set and acquire instructions may be anynumeric character or upper -/lower-casealpha character. This allows the system toaddress 62 ports where port 0 = identifier0. Ports 6 and 7 address the PI/0 controlports and ports 4 and 5 are the I/Oaddresses. In extended systems port E, forexample, addresses port 21 decimal, 15Hex.

Error messages are displayed for faultsin program construction. Jump com-mands for which no label can be foundwill generate the message, JUMP

(continued on next page)

PRACTICAL COMPUTING May I981 105

Languages(continued from previous page)

ERROR, following which the programenters the edit mode, listing the programon the screen with the cursor pointing tothe incorrect jump label. The acquirecommand sets the PI/0 ports to inputdata and generates an error message if anattempt is made to address the controlports.

Programs running under Duncan maybe synchronised to external events byusing the principle of deliberate error. Thesynchronisation may either be to anexternal time signal or to some otherevent. The control program is set to finishits task deliberately ahead of the time atwhich a reference signal is expected.

The program then enters a loop inwhich the value obtained from a port iscompared to a value set in a program.When the reference signal occurs, thevalue obtained by the port is greater thanthe comparison value and the programjumps to the next phase.

Subroutine groupA standard Nascom 1 has no interrupt

facility, but Duncan can poll a number ofdevices to see whether or not an event hasoccurred which requires some action.After obtaining a value from a port, theprogram can be diverted to one or anotherof a group of subroutines depending onthe incoming reading. Although the sub-routine may be called from several pointsin a program, it is not necessary for thesubroutine to return to the instructionfollowing the call.

Because the program does not allowsubroutines to be nested, no problems arecreated when a jump is made from a sub-routine back into a different section of themain program. The return address for thesubroutine call is still available and will be

Table I. Duncan entry table.

P Prints the current Duncan program and re- turns to the entry table.

W Prompts for data, program or quit. Writesthe data log area or the program to cassetteand returns to the entry table. Quit returnsdirectly to the entry table.

R Reads either data or a program into thecorrect area for subsequent processing.Returns to the entry table.

Q Quits the entry table to the Nasbug T4monitor.

L Lists the current program. If the programoccupies more than 12 lines, the second pageis displayed by pressing the space bar. Q willquit the list mode either to the entry tableor. when list is called by the edit mode,back to the edit mode.

C A new program is created and overwritesany instructions previously stored. Thekeyboard functions normally with the excep-tion of the : (colon) which terminates thecreate mode and returns to the entry table.

X Causes the stored program to be inter-preted by Duncan and executed.

E Edit mode. The stored program is listedautomatically by the list mode and the editfunctions set out in table 3 may be carriedout. Q causes the termination of the Editmode and a return to the entry table.

106

Moves the cursor one position to the lefton the screen and one instruction towardsthe beginning of the program. The shift keyshould not be pressed as the < function isinterpreted directly by Duncan.

> Moves the cursor one position to the righton the screen and one instruction towardsthe end of the program. The shift key shouldnot be pressed.

Z Zeros the cursor to the first instruction inthe stored program. The character at theposition occupied by the cursor is displayedon the right-hand side of the top line of thescreen.

N Searches for the next new -line character andpositions the cursor at this point in theprogram. If the end of the program occursfirst, the cursor is placed on the terminatinginstruction.

D Deletes the instruction at the cursor position'and closes up the remainder of the program.

I Instructions may be inserted into a programby typing I followed by the new instructions.The keyboard may be used to enter anycharacter except a ':' which terminates thefunction and adds the instructions to theprogram.

Q Quits the edit mode for the entry table.

Note: It is possible to move the cursor from theprogram area and into the variable -storageRAM. Beware of inserting or deleting charactersif the cursor is not visible on the screen. The Zcommand will always return the cursor to thetop -left position of a listed program at the firstinstruction.

Table 3. Duncan edit mode functions.

destroyed and replaced when a new call ismade.

Hysteresis can be programmed into aswitching operation so that a process iseffected when the value obtained from anA -D converter exceeds one value, forexample 200 on a scale of 255 increments.A second section of the program may thenswitch the device off or effect some otherprocess when the value monitored by theA -D converter falls below 100 on the samescale.

Accurate meterThe Nascom 1 used with Duncan and a

simple Creed teleprinter can act as anaccurate digital printing volt meter usingthe hold and find instructions to measurea voltage when the space bar on the key-board is pressed. A simple program can bewritten to find a value which may bescaled and processed by Duncanaccording to the volt meter scale in useand will then print either the value or anexplanatory message followed by the volt-age that has been measured. A moresophisticated alternative is to use Duncanto prompt for each test point in a testroutine, print the expected voltage orother value and then print the valueobtained during the test.

The wait instruction has many uses.One wait state lasts approximately onesecond and a program may be set toacquire data or carry out some other pro-cess at any speed between filling the DataLog, 512 values, in less than a second tothe acquisition of one reading each day. Ifthe CV is 65535 when the wait instructionis entered, the computer will do nothing

for 18.2 hours before emerging to con-tinue the program. 12 hours is 43200seconds and the program sequence for a24 -hour wait is 43200 W W.

The acquire instruction stores incominginformation in sequential order ready forsubsequent retrieval by the bring -back in-struction. Data can be acquired from oneor a number of ports and can be inter-spersed with information such as timemarkers or values from calculations byusing the KA instruction.

Program sequencePutting the Ax instruction inside a pro-

gram loop can log data at regular intervalswhile the addition of a hold or KHinstruction to the loop will allow data tobe gathered under the control of the user.The program sequence:

= f LA ? KA f I = f,400 JGAwill put 399 values into the data log fromthe keyboard which can then be used as alook -up table for anything from playing atune through to displays of normal andabnormal electro-cardiogram recordingsfor training nurses and intensive therapyunit staff. Information can be retrievedfrom the data log either sequentially or ona random-access basis using the bring -back instruction.

Using a minimum system with a D -Aconverter on one of the PI/0 ports and anA -D converter on the other port, theNascom/Duncan combination can beused to measure easily a variety of para-meters in physical or electronic systemssuch as the signal characteristics of trans-istors or operational amplifiers, the effic-iency of small electric motors, or an echolocation display; either printing orplotting the results on a teleprinter.

Conclusions Duncan shows how a high-levellanguage can be developed for a particularpurpose. The structure of the language is diff-erent from Basic but is appropriate for thecontrol tasks for which it has been de-signed. Duncan is easy and satisfying to usewith even a minimum I/O capability onthe Nascom. Above all, Duncan provides an entryinto the intoxicating world of real-timecontrol of robots, laboratory experi-ments, electronic equipment and a diver-sity of domestic devices from model trainsto intelligent vacuum cleaners using a verysmall computer.

The listing for Duncan is too large to publish.However, a cassette with the program record inT4 dump or write format and back-up docu-mentation may be obtained from John Dawsoncare of Practical Computing. The packagecontains the cassette, a printout of a Hex dumpand an annotated, disassembled listing ofDuncan with additional notes on programreference points to help users who wish tomodify the program for their own purposes.The package costs £7.50 inclusive of postageand packing.

PRACTICAL COMPUTING May 1981

Languages

Raymond Anderson maintains that you should not develop tooheavy a dependence on Pascal because it will repay you by lettingyou down just when you need most programming support from it.Here are what he considers to be its cardinal deficiencies.

Prolonged use of Pascalcan seriously

damage mental healthPEOPLE learning Pascal after using Basicfor some time soon realise the advantagesa structured language can give them,become proud of their mastery of Pascaland seem keen to castigate those who stilluse Basic. Unfortunately, Pascal is farfrom ideal, and by the time people realiseit, they have to plod on as best they can toensure their investment in old software isnot lost - just as Fortran users have donefor 20 years.

My view is that it is better to learn alanguage which allows expansion withinitself as much as possible, so old invest-ment is not lost by providing more facil-ities, and portability is ensured. Algol 68is my personal choice, although ADAseems to have achieved this, and in theirown ways so have APL, Lisp and Forth.

Some software houses push Pascalbecause the compiler is reasonably easy towrite and easy to sell to somebody un-familiar with the language. Pascal pro-grammers push Pascal so more users willput pressure on software houses to sellbetter compilers, and compilers for moremachines. Some teachers push Pascalbecause it is easy to teach, and their pupilswill prefer a trendy language.

Burnt fingersAlgol 68 programmers worry that many

people will get their fingers burnt onPascal and lose faith in their climb up theAlgol tree. Pascal has some rather inter-esting features, such as subranges, setsand packed records which I feel are goodpoints, and many features which arecommon nowadays, and very useful suchas records, recursion, data types and soon. Pascal is useful as a first step towardsstructured programming, but you mustnot wait too long on the first step or youwill grow too weak to climb further.

Programmers in an applicationsenvironment find it useful if they can usea set of general-purpose routines providedby experts in some field. Examples of suchsets are the Gino and Ginograf graphicsroutines and the NAG subroutine libraryfor Fortran and Algol 68. There are alsomany cases where facilities are embeddedin languages to make certain activities

easier - for example handling databasesor laboratory equipment.

Unfortunately, such useful facilities arevery difficult to provide in Pascal. This isbecause a procedure which takes in anarray as a parameter can only take arraysof size fixed in the procedure declaration.A procedure written for integer arrays of100 elements could not be used witharrays of 101, 99 or 3 elements.

Even Fortran provides better facilitiesfor making libraries available - indeed,this is one of its main strengths in engin-eering and scientific fields. Algol 68allows new operator definitions for anydata types. APL users in business oftenuse a set of functions provided by pro-grammers so they do not need to concernthemselves with detail. This serious faultin Pascal was caused by an obsessivedesire to simplify storage allocation, butthe disadvantages are far too severe tojustify the simplification.

When a program has been written andthe algorithms checked using test data, itoften has to be used by untrained usersand on real data. Users will often feed incorrupt data - letters instead ofnumbers, blank lines, overlarge numbersor just gibberish, and a good program willgive some indication of the error and tryto continue to find more errors, ratherthan just bombing out.

Writing a robust program just to read anumber from a file is very difficult inPascal, because so many faults can occurwhich the program cannot sort out byusing the inbuilt routines to read aninteger. Consider some of the possibleerrors:

The file is empty The file is a line of blanks There are blank lines before the number The file starts with the letter X There are superfluous characters after

the number The number is too large or small to

hold an integer variable

The Pascal programmer has to forgetthe system routines, and write his ownnew ones to read character by character.More room for error and more work.Algol 68, Cobol, and PL/1 allow check-

ing on input, and Fortran 77 has a methodof trapping errors.

Pascal has no facilities for opening andcreating new files, and cannot enquireabout the status of files towhich it is con-nected except for detecting end of line,EOLN, and end of file, EOF. It is, in fact,so inadequate at file handling that almostall implementations have their own non-standard extensions, thereby reducingportability.

When Pascal was designed, it wasdecided that several restrictions would bemade to simplify compilation, and in-crease efficiency on the processors of theearly 1970s. One of these restrictions isthat the bounds of arrays had to be con-stants available at compile time.

Wasted spaceThat means that a program or routine

cannot declare the workspace it needs at aparticular time. Instead, it has to declarean array which is as large as it should everneed every time, thus wasting space onmost occasions. On microprocessors witha limited address space, a waste or space isworse than a slight reduction in speed.

Pascal requires that declarations of allprocedures, variables, and so on, aremade at the top of the main programbody, and at the top of each procedurebody. This is another example of how arestriction meant to make life slightlyeasier for the compiler writer is a problemfor the programmer, especially when he isworking on large programs. Once again,the result is a waste of space.

Suppose one block in the program usessome integers, and another uses somereals, and these variables are confined totheir respective blocks. If the variablescould be declared in their respectiveblocks, there would be re -use of store -saving space - no access to the variablesoutside their block - preventing errors -and the type of the variables is clear nearwhere they are used. There is no run-timepenalty, and hardly any increase incompiler complexity.

Procedures could be used in place of theblocks, but this can lead to a proliferation

(continued on next page)

PRACTICAL COMPUTING May 1981 107

Languages(continued from previous page)of small, 25 -line procedures, and markedloss of speed.

The Pascal For/Do loop is veryrestricted and often has to be replaced bysome open -coded equivalent using aWhile construct. There is no Step or Bypart, so the loop variable can go only upor down in steps of one. This petty restric-tion, supposedly for efficiency, is anotherarea where Pascal hinders straightforwardcoding and obscures intentions theloops may as well always start from 1.

A While part cannot be combined withthe Do loop, so an exit from the loop onsome condition - for example, the end ofa search - has to be by a Goto to somelabel outside.

The final oddity is that the loop vari-able has to be declared in the normalmanner at the top of the program or pro-cedure. Apart from slowing down coding,it has the undesirable effect of making thevariable accessible to code in the loop orin procedures declared "below it inscope" where it can be accidentallyaltered, causing chaos.

A useful feature of Pascal is its Caseconstruction which allows the selection ofone of several courses of action dependingon the value of a variable, or whichmember of a set it is. Unfortunately, thisfeature is marred by the lack of a Defaultor Out part which is a way of specifyingwhat to do if there is no relevant Caseaction.

Most Pascal implementations donothing if the selector is not catered for,but one usually wants to take some actionif an exception arises, and one has to usean If construction of some kind. This isyet another serious flaw in Pascal, which,this time, has no excuse.

Pascal does not provide access to theindividual bits in integers to allow packingof data, logical operations or shifts -often very important for systems pro-gramming.

Insecure areasPascal is a rather more secure language

than, say, Fortran, which means that notso many expensive runtime checks wouldbe required behind the scenes to preventaccidental or deliberate but dangeroustampering with data.

Unfortunately, Pascal becomes insecurein the areas which many programmersare already having difficulty thinkingabout what should be happening if allgoes well; the areas of variant, pointers,and heap storage.

Firstly, the mark and release scheme ofstorage management is completely un-checked, and allows easy corruption ofstore. Admittedly, a garbage collector is acomplex beast, but it saves the program-mer a good deal of work in storage man-agement, one of the major parts of manyproblems.

Secondly, a variant record can be estab-lished with one type, and then

assignments can be made to the fields ofthe record pretending it is some othertype, possibly one which occupies morestore, thereby corrupting neighbouringdata.

Thirdly, since a procedure parameterdoes not have a "type" associated with it,checking of the number of argumentsused by the procedure when it is calledinside another procedure are highly diffi-cult - perhaps impossible - at compiletime, and usually never made at compiletime. It is a similar problem to that en-countered in Fortran where it is imposs-ible to tell at compile time if subprogramsare being called with the correct numberand type of arguments.

Pascal has deficiencies in many areas,ranging from annoying omissions - Stepin Do -loop, Out in Case construct - toserious design flaws - fixed size of arrayparameters.

Those deficiencies do not mean that thelanguage is unusable, but they mean thatdifficulties arise just when the compilerand language should be helping most.

The insecurities mentioned in the finalsection mean that as things grow harderand harder to monitor, data corruptionscan occur causing faults in unexpectedplaces, and storage becomes more difficultto manage.

By all means use Pascal if you need astructured language quickly, but keeplooking for a longer -lasting tool andinvest in it as soon as you can.

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Circle No. 174

108PRACTICAL COMPUTING May 1981

Z-80 Zodiac

Reverse Polish codeTHE subroutine described converts a fully -parenthesised expression in algebraic formto its reverse Polish equivalent, writes DElworthy of Wilmslow, Cheshire. It is re -locatable, and should run on any Z -80 -based system which uses ASCII codes forA to Z, full stop and parentheses.

The expression must end in a full stop.All other characters are treated as oper-ators except "(",")" and A to Z. In brief,the subroutine works by transferring alloperands to the Polish string, and allother symbols to a delimeter list, except")". When this is encountered, a symbolis pulled back from the delimeters and isadded to the Polish string, unless it is "(".

The method can be understood in detailby running it with the registers pointing toparts of the screen. One use that springs tomind is a pre-processor for M5 onNascom, although a little modificationwould be necessary.

Register usage is: BC, entry, startaddress of algebraic string; exit, onebeyond end of algebraic string. HL, entry,start address of Polish string; (exit) onebeyond end of Polish string.

HL and BC may point to the sameplaces. DE, entry and exit, address of thestart of a temporary area. The size of thisarea cannot be predicted accurately, but itwill not exceed the number of operatorsand `(' symbols plus one.

CVTRPN LD A '(

LD (DE) AINC DE

MAIN LD A (BC)

INC BCCP 40H

JR C NOTOPR

CP 5BHJR NC NOTOPR

PUT LD (HL) A

INC HLJR MAIN

NOTOPR CP'(JR Z LPARENCP')JR NZ NOTPAR

DEC DE

LD A (DE)CP'(

JR Z MAINDEC DEJR PUT

LPAREN LD (DE) A

INC DEJR MAIN

NOTPAR DEC DE

CP '.

JR Z ENDITPUSH AF

LD A (DE)

CP'(JR NZ NOTPA2INC DE

POP AFJR LPAREN

NOTPA2 LD (HI-) A

;enter dummy 3E 28end delimeter

;pick-up nextsymbol

1213

OA

03;check for range FE 40A to Z;otherwise it 38 08is not;an operand FE 58

30 04;add a symbol 77to the Polish

23;more 18 F2;not an operand FE 28

28 ODFE 2920 OD;must be an

operator;pull back last 1Bsymbol from;delimeters IA;add to Polish FE 28unless parenthesis

28 E41B18 EB

;add left-paren- 12

thesis todelimeters

;point to lastdelimeter;full stop means FE 2Eend

28 11F5;save current

symbol;see what last I Adelimeter was

FE 2820 0413

13

18 EF1B

Fl18 ED

;previous de- 77limeter to Polishstring

;if '(', appendnew symbol;to delimeters

PRACTICAL COMPUTING May 1981

INC HLPOP AFLD (DE) A

INC DEJR MAIN

ENDIT LD A (DE)CP '(RET ZID (HL) AINC HLDEC DEJR ENDIT

23Fl

;new symbol to 12delimeters

13

18 C7;final tidying -up IA

FE 28C877231B18 F7

Binary/decimal/hexTHIS IS a program for binary to decimal toHex conversion for machine -code buffs,writes N R W Sargent of London, E7. Ihave formatted the printing specially forresolving bit patterns especially usefulwith Z-80, and straight conversioncoding. The listing is in Sord EBasic.

10 / REXCON/ FOR PRINTING ONLY

30 / RE -WRITTEN FROM ORIGINAL SORCERER VERSION OF 1978 *NRWS

40 / 24-01-198150 OPEN "SOUTA" FOR OUTPUT AS FILE 160 VTCLEAR70 DIM A$(16)80 LET A$ "0123456789ABCDEF"90 LET US "#88"100 LET D2 0

:LET J - 1

:LET K 1

:LET X U110 GOSUB 360

:PRINT 91:PRINT #1

120 FOR B 1 TO 2: FUR C 1 TO 2

FOR

FOR E - 1 TO'2130 FOR F - 1 TO 2

FOR G I TO 2FOR H I TO 2

FOR I 1 TO 2140 LET BO - MID(A$,B,1)150 LET C1$ - MID(A$,C,1)160 LET D1$ - MID(A$,D,1)17U LET EIS MID(A$,E,1)180 LET F15 MID(A$ ,F,1)190 LET G1$ - MID( A$ ,G,1)200 LET R1$ - MID( A$ 04,1)210 LET 11$ - MID(A$,I,1)220 LET KI5 - MID(A$,K,1)230 LET J1$ - MID(A$,J,1)240 LET A1$ Bl$+Cl$+Dl$+El$+Fl$1-G1$+Hl$+11$+"250 PRINT #1 , TAB(T) ; A1$ ;

260 PRINT #1 USING U$ D2 ;

PRINT 81 , " "+K1S+J1$+"270 LET T T+25

IF T > 75 THENLET T 0PRINT #1

280 IF D2 <> 127 THENGOTO 290

ELSEPRINT #1 , CHR$(12) ;

GOSUB 360290 LET J J+1

IF J > 16 THENPRINT #1PRINT #1LET K K+1LET J 1

300 LET 02 D2+1310 PAGE

320 NEXT INEXT H

NEXT CNEXT F

NEXT E: NEXT D

NEXT C:NEXT B

330 PRINT #1 , CHR$(12)340 CLOSE 1350 END

360 / HEADER ROUTINE370 LET X - 0380 PRINT #1 , TAB(X)390 LET X X+25

:IF X < 76 THEN: GOTO 380:ELSE: PRINT #1

LET X 0400 PRINT #1 , TAB(X)410 LET X X+25

:IF X < 76 THEN: GOTO 400:ELSE: PRINT #1

LET X m. 0RETURN

NO END MARK

BINARY DEC HEX" ;

109

Reverse charactersTHE RECENT purchase of a 16K RAM packfor my ZX-80 has made me go throughmy IK games programs and expandunderstated games responses, such as"Bang, you are dead" into more express-ive, screen -filling white letters on a blackbackground, writes Keith Berry ofNewtown, Birmingham. The problem ofhow to overcome the tedium of having toenter CHR$(128) for every single blacksquare produced the following idea whichworks well in practice.

Select a piece of graph paper and markan area three blocks of 10 wide by twoblocks deep. Put your design into thisarea, blocking in each small square withpencil where black is required in the finaldisplay. Number the three vertical blocksof 10, 1-3, and number each horizontalrow of small squares, 0-9 - and 0-9 againin the second block down.

You now need 2,000 lines of unusedprogram, say, 3,000 and 4,000. Enter:3000 REM BANG YOU ARE DEAD3001 PRINT CHR$(128);CHR$(128); 10 of

them, ending with a semicolon- Newline -

Now Edit, Rubout, 2, Newline, Edit,Rubout, 3, Newline. You now have yourfirst line of black background in lines3001, 3002, 3003. Continue Editing to giveyou your next line numbered 3011, 3012,3013 and then 3021, 3022, 3023, and so onuntil you arrive at 3091, 3092, 3093.

Repeat for 4001 and you have twoblocks of black on which to Edit yourwhite lettering. List 4082, Edit, forexample, gives immediate access to themiddle column of the second, lowerblock, line 8.

Using Shift 8, move along the line andRubout 128 and replace it with 0 wherevera white space should appear. Rememberto eliminate the last semicolon in everyline whose number ends in three.

Any all black rows should be replacedby, e.g.,FOR J =1 TO 30, PRINT CHR$(128); NEXT Jand similarly a row of CHR$(0) should bereplaced by "(Spaces)". It is a good ideato Run 3000 after Editing each line, tocheck how you are doing.

Telephone bookA LIST of names and corresponding tele-phone numbers can be recorded in codeform in two single arrays: X and Y, writesLloyd Tribello of Basingstoke, Hamp-shire. These are dimensioned at the begin-ning of the program. Each separate itemin each array can be located using twoaccess vectors; a position vector whichgives the position of the first code of theitem and a length vector which gives thenumber of elements in the item.

The first part of the program enablesthe data to be loaded into the arrays. M isthe number of items to be recorded. Thearrays P and T store the position vectorsfor the names and telephone numbers res-pectively. The arrays L and D store the

I I 0

length vectors. Subroutine 500 is the LENsubroutine submitted by Eric Deeson,January 1981 ZX-80 Line-up.

After recording the data it is useful tocheck that it has been entered accurately.The Check Program overwrites lines 90 to220. All other lines can be removed exceptfor lines 500 to 540 which house the sub-routine. The Check Program is initiatedby "GOTO 90".

Finally, the Search Program is entered.It will search the X array for an inputname and, if the name is found, willlocate the corresponding telephonenumber in the Y array. Both name andnumber will then be output.

90 PRINT"NAME""TEL.NO"100 FOR N=1 TO M110 FOR I=P(N)TOP(N)+L(N)-1120 PRINT CHR$(X(I));130 NEXT I

140 FOR I=1TO17-L(N)-1150 PRINT"160 NEXT I

170 FOR I=T(N)TO T(N)+D(N)-1180 PRINT CHR$(''(I));190 NEXT I200 PRINT210 NEXT N220 STOP10 PRINT "HOW MANY ITEMS?"20 INFur M30 DIM X(100)40 DIM Y(50)50 DIM P( M:'60 DIM L(M)70 DIM T(M)80 DIM D(M)90 LET I=1100 LET J=1110 FOR N=1 TO N120 PRINT "NAME?"1.30 INPUT A$140 LET B.$=A$151_1 GOSU8 500160 LET L(N)=L170 LET P(N)=I1R0 FOR I=1 TO I+L-1190 LET X(I)=CODE(A$)200 LET A$=TL$(A$)210 NEXT I220 PRINT "TEL.NO."230 INPUT A$240 LET B4:=A$250 GOSUB 500250 LET D(N)=L270 LET T(N)=J2R0 FOR _1= _3 Ti J+L-1?9n LET Y(J)=CODE(A$)300 LET A$=TL$(A$)310 NEXT J7c?ci CLS330 NEXT N340 STOPFIPIA LET L=0510 LET El=TL$(A$)520 LET L=L+1530 IF NOT 8$=""

THEN GOTO 510540 RETURN90 PRINT "NAME SOUGHT?"100 INPUT A$110 LET EI=A$

120 CLS130 GOSUB 500140 FOR N=1 TO N150 IF X(P(N))= CODE(A$)

AND L(N)=L THEN GOTO 190160 NEXT N170 PRINTAWNOT FOUND"180 GOTO 290190 LET B$=A$200 FOR I=P(N)+1TOP(N)+L-1210 LET E4=TL$(8$)220 IF NOT X(1)=CODE(E4)

THEN GOTO 160230 NEXT I240 PRINT A$,250 FOR I=T(N)TOT(N)+D(N)-1260 PRINTCHR$(Y(I));? 7n NEXT I

PRINT290 STOP

Screen pokeNOTICE that in ZX-80 Line-up, many

games which require movement use Printstatements to move a ship, car, etc., writesMark Lancaster of Carlisle, Cumbria. Anexample of this is Pete Rowan's animateddisplay in February 1981 Practical Com-puting.

This can be a problem especially if youwant something to move right to leftacross the screen. Here is how to Poke anycharacter on to the screen. The ZX-80 canonly Poke where something has alreadybeen Printed. So the first thing to do is toPrint all the screen, i.e.,10 FOR A =1 TO 73620 PRINT " ";30 NEXT A

736 is the amount of squares on thescreen, but if you obtain an out of screenerror code 5, just reduce the 736 untilyou no longer obtain the error. You cannow Poke on to the screen. The top left-hand corner of the screen is Poke number16485 and the width of the screen is 32 sothe Pokes are:16485 TO 16517 first line16518 TO 16550 second line

17211 TO 17243 last lineThe second number in a Poke is the

code for a character. Here is a small ex-ample program to make a snail crawlalong from right to left:

10 FOR A = 1 TO 55020 PRINT"_";30 NEXT A40 LET C = 050 LET B =1685660 POKE B,370 POKE B-1,13680 POKE B + (C + 1),090 POKEB + C,3

100 POKE B + 3,0110 IF C = 0 THEN POKE B + 2,0120 LET B =130 INPUT AS140 IF C = 0 THEN GO TO 170150 LET C = 0160 GO TO 60170 LET C = 1180 GO TO 60

Lines 10-30 Print enough space on thescreen for the program. B is the presentposition of the snail and decreases by oneafter every move. Lines 80,100 and 110remove the snail from the previous move.

PRACTICAL COMPUTING May 1981

ZX-80 Line-upThe variable C determines the length ofthe snail's tail while crawling.

The only way to leave the program iswhen after pressing Newline to slide yourfinger on to the break key. To see the nextmove you have to press Newline.

String arraysZX-80 BASIC is not too user-friendly when itcomes to string handling, writes GeorgeGregson of London SE6. Many programsrequire the analysis of a string, extractionof a substring or concatenation of strings,none of which is directly possible in ZX-80. An indirect approach is required ifsuch programs are to be written.

An effective technique, which alsoallows string space to be released frommemory, is to substitute an array of ZX-80 character codes for the string. Such anarray can then be subjected to numerical,arithmetical or logical processing. When-ever needed, the current string can be out-put by a PRINT CHR$(n); loop, n beingread from the array.

It is useful to note that the code for nullis 1 and the code for space is zero.

10 DIM A(50) or any desired length.20 LET A$ = "STRING"....or 20 INPUT AS.30 FOR X = 1 TO 5040 LET A(X) = CODE(AS)50 LET A$ = TLS(AS)60 IF CODE(AS) = 1 THEN GOTO 8070 NEXT X80 LET A$ = " "

At this point, the array A holds theZX-80 character codes for STRING andX = 6. You will appreciate that X =LEN(A$) - a new function in ZX-80.Now suppose we wish to add the wordBAG to STRING to form the concaten-ation STRINGBAG:90 LET A$ = "BAG" (or 90 INPUT A$)

100 FOR X = X + 1 TO 50110 LET A(X) = CODE(A$)120 LET AS = TLS(AS)130 IF CODE(A$) = 1 THEN GOTO 150140 NEXT X150 LET A$ = " "

Now array A holds the codes forSTRINGBAG and X is valued at 9, thenew LEN(A$). In both operations, thestring space has been released - lines 80and 150 ensure this, even if the TL$ func-tion has not already done so. To outputthe result:160 FOR Y = 1 TO X170 PRINT CHR$(A(Y));180 NEXT Y190 PRINT

Note that the loop variable is now Y topreserve X as LEN(A$). This method canbe used to keep track of input charactersin, e.g., Hangman -type games, by addingthe code of the input letter to array A andoutputting the entire array contentsbefore each fresh guess is made.

Two further arrays would be used inHangman; one to store the codes of thekeyword and one of the same length toinitially store a row of dash codes. Eachdash code would be replaced with the codeof a successful guess. I leave it to you tocomplete the program.

PRACTICAL COMPUTING May 1 98 I

Pursuit shipIN THIS program the idea is to shoot downthe randomly moving space ship in frontof you - the inverse space - by lining itup with your rocket sight, writes ChrisCarr of Evesham, Worcestershire.

You have five commands; up, down,left or right - U,D,L or R - for thrustand F to fire. As you are in space, you willmove in the opposite direction to thethrust and will continue to move until you

counter balance the thrust of your ship.The graphics routine in this program

plots the vertical angle against the hori-zontal angle (VA and HA) and so couldprobably be a useful routine for plottinggraphs. It is done totally in Basic, withoutthe use of a "memory mapped screen"and so takes slightly longer but is muchmore reliable. The whole program takesapproximately 480 bytes and so it fitseasily on a 1K machine.

L3 LET A$=" PURSUIT SHIP2t1 PRINT30 FOR J=1 TO 1440 PRINT CHU(CODE(A$)+128);50 LET A$=TL$(A$)60 NEXT J70 LET HA=RND(10)-5SO LET UA=RND(10)-590 LET 0=0100 LET W=011A INPUT 6$12A IF 8$="R" THEN LET 0=0-117:0 IF 6$="L" THEN LET 0=0+1140 IF 6$="U" THEN LET W=W -115A IF 6$="D" THEN LET W=W+1160 IF 6$="X" THEN STOP17A LET HA=HA+0+RND(3)-21RA LET UA=0A+W+RND(3)-219A IF 6$="F" THEN GOSUB 430'7471A CLS

210 FOR L=1-1013IF L=7 -UN THEN GOT0270

27t71 IF L=7THEN GOTO 350240 PRINT

NEXT L*764_1 GOTO 110'7A FOR H=1 TO 20T'RA IF H=10+HA THEN GOTO 41A290 IF UA=0 AND NOT H=10 THEN PRINT "-";:CAA IF 0A=0 AND H=10 THEN PRINT "+";310 IF NOT VA=0 THEN PRINT " ";

320 IF H=20 THEN PRINT77A NEXT H340 GOTO 25075n FOR P1=1 TO 20360 IF P1=10 THEN PRINT77A PRINT "-";'RA IF P1=20 THEN PRINT79A NEXT P14041 GOTO 250410 PRINT CHR$(128);420 GOTO 33047A IF ABS(HA)<2 AND ABSWA)<1 THEN GOTO 45A44A RETURN45A CLS4A4=1 PRINT " HIT"470 PRINT "RERUN? Y/N"4RA INPUT Z$49A IF NOT Z$="Y" THEN STOP54_10 GOTO 70

Re -re -numberI TRIED Michael Whittle's re -numberingprogram for the UK101 given in the 6502Special, September 1980 issue writesGraham Thomas of Hatfield, Hertford-shire, only to find several seriousproblems. The program will re -sequence Gotos,

etc., only if there are no spaces be-tween the Goto and the line number.

Contrary to what is stated in thearticle, the program does not "givethe line number for subsequent re-typing" when it needs to replace a

five by a 10, and so on. In fact, itgoes on to insert the longer linenumber, overwriting the GOTO onthat line.

If the program is used to re -sequencea program with more than 100 lines,it aborts on a "BAD SUBSCRIPTERROR IN LINE 63140", and leavesthe program being re -sequenced inan unrecoverable mess.

Here is a fully -debugged copy of there -numbering program, which overcomesall of the above problems. It will changeGotos, etc., regardless of how manyspaces separate the Goto and the line

6300063005630106302063025630306304063050630516305263053630546306063065630706308063090631006310263104631106311563120631306314063150631516315263160631626316463166631706318063190632006321063212632206323063240

OK

REM CORRECTED RENUMBERING PROGRAMML=100:SP=10:08=0DIMA(ML):AD=771:1=0GOSUB63230:IFLN>62999THEN63060I=I+1:iFI>MLGOTO63051N=I*SP-FOSN11-7-INT(N/256):NL.N-256*NmRTKEADt.NiL:POKEAD-1-1,NH:A(1)=LNAD=NA:GOT063020PRINT"OVER-ML"LINES- RESTORING PROGRAM"AD=771:FORI=1TOML:NH.INT(A(I)/256)NL=A(1)-2564;NH:GUSUB63230:POKEAD,NLPOKEADA-1,NH:AD=NA:NEXTI:ENDAD=771:H=0B=8+1tGOSUB63230IFLN)62999THENPRINT-COMPLETE":ENDFORJ=AD+2TONA-4:C-..PEEK(J)IFC)136ANDC<>140ANDC(>160THEN63220L-.PEEK(J-1-1):IFL>=48ANDL<=57THEN63110IFL=32ANDO<NA-3THiNJ=J11=GOT063100t,OTO 63220Cli="":FORK=J+1T0J48:C=PEEK(K)IFC.32ANOK=J+1THENJ=J+1:GOT063110IFC(480R0>57THEN63140C$-.C$+GHRS(C):NEXTKL=VAL(C$):FORH=1T01;IFA(H)=LTHEN63160NEXTH:PRINT"NON-EXISTANT LINE"L;PRINT"REFERENCED IN LINE"B*SP+OSGOT063210NS=STRS(H*SP+09):R=LEN(NS)IFK-R>=JGOT063170PRINT.CHANGE'L"IN LINE"B*SP+OS"TO"N$GOT063190FORX=2TORPOKEK-FX-R-1tASC(MIDS(N$,X,1)):NEXTXIFK-J-R=OTHEN63210J=J+1:POKEJ,32:GOT063190IFC=44THENJ=K:GOT063110IFC=32THENK=K+1:C=PEEK(K):GOT063210NEXTJ:AD=NA:GOT063065NA=PEEINAD-1)*256+PEEINAD-2)4-2LN=PEEK(AD4.1)*2564PEEK(AD):RETURN

1 1 2

number. If it needs to replace a short linenumber by a longer one, e.g., Goto 5 toGoto 10, it prints:CHANGE 5 IN LINE xxx TO 10

If the program is used to process aprogram with more than 100 lines, itprints an appropriate message andrestores the program to its originalcondition before stopping. The programalso includes a more comprehensible errormessage which is printed when a Goto to anon-existant line number is encountered.

In addition, the program can bemodified easily to deal with longerprograms by changing one of the threevariable values in line 63005. ML is themaximum number of lines the programcan deal with - limited by the amount ofmemory available. SP is the line spacingfor the re -sequenced program, and OS isthe "offset" for the re -sequencedprogram.

For example, SP = 2 and OS = 198would cause the re -sequenced program'slines to be numbered 200, 202, 204, etc.This feature is useful for re -locating aprogram so that it can be placed at aspecific point within another program.

String searcherHERE IS a program written for the AIM65but could be adapted for other 6502 -basedsystems by changing the I/O subroutineswrites Rob Wilson of Cirencester,Gloucestershire. The program is a string,searcher. It will search memory within theentered limits for a given string of up to10bytes. It is particularly useful for tryingto decipher someone else's machine code.

Line traceA FEATURE that the Superboard lacks is aBasic trace command writes Jack Pike ofChawston, Bedfordshire. So, here is amachine -code routine which prints theBasic line number every time it changes. Itis assumed to be located in the unusedRAM starting at $0222, but the code isre -locatable.

The trace routine works by patching itinto the Basic GETCHR routine at$00BE. That means addresses $00BE to$00C1 are changed to 20 22 02 EA Hex, togive a jump to $0222. The trace is turnedon by Poke 550,165 and off by Poke550,96. By holding down the ESC key, thescreen display can be frozen so that youcan inspect the line numbers whilerunning the program.

Replace code overwritten in GETCHR:D002 BNE ; IS C3 = 0?E6CH INC ; Yes, add 1 to CH

Detect line number change:60 87 RTN Replace 60 with AS to

run traceC5 E8 CMP is line number 10 the

same?FO 19 BEQ yes, branch to test high85 E8 STA store new line number lowA5 88 LDA load line number high85 E9 STA store high

Loop when ESC key is held down:

PRACTICAL COMPUTING May 198I

6502 Special

0000:

0000:0002:0004:000E:

000F:

OF40:0E43:OF46:OF49:OF4B:OF4E:OF50:0E52:0E55:OF58:OF5D:OF5D:OF60:

2020AD85AD85A92020AD85AD85

OF62: 20OF65T AOOF67: 20OF6A: AOOF6C:OF6F:OF71:OF73:OF75.OF77:OF79:OF7B:

VF/D:OF80:OF81:OFF13:

OF OS:

OF87:OF89:OF8B:OF BD:

2090C9FOCOFODOFO

24 EA83 E7IC A400ID A40'1

207A E9A7 E71C A402ID A403

2400FO005DOC2016

ODOCE7C3

EA

OF

EA

; *********** STRING SEARCH PROGRAM **************** SEARCHES FOR A GIVEN HEX STRING ************** R.W.J. WILSON 2/10/80

;ASKS FOR START AND END ADDRESS - HIT ESC TO;RETURN TO MONITOR.

;ASKS FOR STRING TO BE FOUND (UP TO 10 BYTES;;ENTER SPACE 10 REUSE LASI STRING.

;IF STRING IS FOUND THE ADDRESS WILL BE DISPLAYED;ENTER SFACE TO CONTINUE OR CR TO RE3TArl..

;IF STRING IS NOT FOUND 'END. IS D1SPLATEG;ENTER SFACE TO RETURN TO MONITOR OR CR 10 RESTART

;PROGRAM IS RELOCATABLE (NO INTERNAL JUMPS)

;MONITOR SUBROUTINES AND ADDRESSESCRCK =$EA24FROM =$E7A3TO =$E7A7OUTPUT=$E97ARD2 =SEAS;WRAX =$EA42MONIT =$E182ADDR .$A41C

*=0;DATASTADENADSTRINGCOUNT

;CLEAR DISPLAY;PRINT 'FROM.FGET ADDRESS;PRINT .1.0.;GET ADDRESS;PRINT ATREAD;SET C IF 5P OR CR UR NON -HEX;PRINT HEX IN A AND M

;MONITOR ENTRY POIN1;LOCATIONS USED BY 'FROM. ANC .10.

RESERVATION*=*+2 ;START ADDRESS*.*+2 ;END ADDRESS8=8+10 ;STRING VALUES*=*+1 ;NUMBER. OF BYTES IN STRING

*=$F40;GET ADDRESSESSTART JSR

JSRLDASTALDASTALDA(SR

JSRLDASTALDASTA

;GET STRINGENTRY JSR

LOYJSRLDY

AGAIN JSRBCCCMPDEOCmFBEGBNE

BRANCH BEG

CRCKFROM ;GET START ADDRESSADDR ;PUT IT INTO STAGSTADADDR+1STAD+11$20 ;PRINT SPACE.OUTPUT

;GET END ADDRESSADDR ;PUT IT INTO ENADENADADDR+1ENAD+1

CRCKtoMSG OF'

*0RD2STOREi$20REUSE**ODENSTRENTRYSTART

99 04 00 STORE STA STRING.YCB INTCO OA CPT *10DO E7 BNE AGAIN84 OL ENSTR STY COUNTCO 00 CPY *0DO 08 BNE SEARCHCO 00 REUSE CPO *0DO F6 BNE ENSTR

;CLEAR

;PRINT 'BYTES,'

TREAD;VALID ENTRY;SPACE?;YES;CHECK IF FIRST ENTRY:cR?;YESREND OF ENTRY;NON -HEX, REDO ENTRY;USED TO AVOID A JUMP FROMNOW2 ROUTINE

;ALLOW 10 BYTES

;END OF ENTR..;NO ENTRIES?

;FIRST ENTRY!;NO

OF8F: A5 OE0E91: FO CF

0F93: AO 00OF95: B1 00OF97: D9 04 00OF9A: DO 1EOF9C: C8OF9Dl C4 OEOF9F: 90 F4

OFAI: 20 24 EAOFA4: A5 01OFA6: A6 00OFA8: 20 42 EA

OFAB: 20 5D EAOFAE : 90 FBOFBO: C9 20OFB2: FO 06OFB4: C9 00OFB6: FO 88OFB8: DO Fl

OFBA: 18OFBB: A5 00OFBD: 69 01OFBF: 90 04OFC1: E6 01OFC31 FO OAOFC5: A5 02OFC7: C5 00OFC9: A5 03OFCB: Et... 01OFCD: BO C4

;SEARCHSEARCHSLOOP

LDA CUUNIBEG ENTRY ;OUST HAVE NON ZERO COUNT

MEMORY FOR THE STRINGLDY *0LDA (STAN.YCMP STRINGrYBNE INCRINTCPT COUNTBCC SLOOP

;FOUND MATCH-SHOWJSR CRCKCIA STAD+1LDX STADJSR WRAX

;GETNOWT

COMMANDJSR RD2BCC NOWTCOP t$20BEG INCECMP 480DBEG STARTBNE NOWT

;GET BYTE FROM MEMORY;COMPARE;TRY NEXT MEMORY BYTE

;FINISHED STRING?

ADDRESS

;CONTINUE

;RESTART;NON -VALID ENTRY

;INCREMENT AND TEST ADDRESSESINCR CLC

LDA STADADC *1BCC CHECKINC STAD+1BEG ENDMES

CHECK LEA ENADCOP STADLDA ENA0+1SIC STAD+1BCS SEARCH

;END MESSAGEOFCF: 20 24 EA ENDMES JSR CRC*OFD2: AO 06 LDY 4M2 -M1OFD4: 20 FO OF JSR MSOCIPOFD7: 20 5D EA NOW2 JSR RD2OFDA: 90 EH BCC NOW2OFDC: C9 OD CMP **ODOFDE: FO 9B BEG BRANCHOFEO: C9 20 CRP *820OFE2: DO F3 BNE NOW2OFE4: 4C 82 El JMP MONIT

OFE7: 42°FEB: 590FE9: 54OFEA: 45O FEB: 53orEc: BFOFED: 45OFEE: 40OFEF: C4

OFFO: B9 E7 OFOFF3; 48OFE4: 29 7FOFF6: 20 7A E9OFFS: C8OFFA: 68OFF;: 10 F3S EED: 60$:

;MESSAGE DATAMI .TEXT 'BYTES'

.BYTE *BF:TEXT 'EN'

.BYTE $C4

:HAVE REACHED $0000;TEST

;HAVE NOT REACHED END

;PRINT 'END.;GET COMMAND

;RESTART VIA BRANCH

;NON -VALID ENTRY;RETURN TO MONITOR

1.?..}t80

1 .D.+$80

;MESSAGE OUTPUT SUBROUTINE;***MSD OF LAST CHARACTER ISMSOOP LOA 111,Y

PHAANDJSRINTPLABPL (IMPRTS

*87FOUTPUT

lit*

A9 DE LDA ; load ESC key codeCD OC DF CMP ; compare to keyboardFO FB BEQ ; try again if ESC

Print line number:A9 4C LDA ; load character "L"20 E5 A8 JSR ; print "L"20 5A B9 JSR ; print line numberA5 OF LDA ; load max line length85 OE STA ; next print on new line

Check line number high, in case:A5 88 LDA ; with line number highC5 E9 CMP ; any change in highDO E5 BNE ; yes, back to store new

high, etc.60 RTN ; and return

Writing a Basic program to input thistrace is an interesting little problem,because of the required modification tothe GETCHR routine while Basic isrunning. There are, however, ways toaccomplish it. Would anyone care tosupply a solution?

Variable inputTHIS SHORT program is written on aSuperboard, though it will probably run

PRACTICAL COMPUTING May 1981

on a Compukit as well, writes JonathanTurpin of Stanford -Le -Hope, Essex. Theprogram is designed to be used when youare in Basic and want to input a variablewithout the problem of hitting Return andjumping out of the program.

The routine also operates on the Basicinput routine and does not allow acarriage return unless the input buffer ispartly full.

Here is the disassembled listing:0222 20 BA FF JSR$FFBA Call keyboard/

cassette inputroutine

0225 C9 ODOCMP £$OD

0227 FO 01

0229 60

022A E0 00

022C FO F4

022E 60

Is the char-acter a carriagereturn?

BEQ $022A If so, see if any-thing in buffer

RTS If not, return withcharacter

CPX £$00 Is the input bufferempty?

BEQ $0222 If it is, recall theinput routine

RTS If not, return withthe character

The basic listing is:10 FOR I = 546T055820 READA:POKEI,A30 NEXTI40 REM Alter Input Vector (HEX 218)50 POKE536,34:POKE537,260 END70 DATA32,186,255,201,13,240,0180 DATA96,224,0,240,244,96

Square puzzleTHIS PROGRAM emulates the simple puzzlewhich has 15 sliding squares mounted in aframe which is so designed to allow onlyone square at a time to be moved writesPJ Cooper of Southminster, Essex. Eachof the 15 squares has a different letter -from A to 0 - printed on its face and theobject of the puzzle is to place the squaresin alphabetical order.

Although it all sounds simple, I canassure you it is not and if you have a dayto spare - one hour to enter the programand the rest to solve the puzzle - then thisis the one for you.

(continued on next page)

1 I 3

6502 Special(continued from previous page)

It has been written for the standardSuperboard II and contains many peeksand pokes which owners of othermachines may find difficult to disen-tangle. Those enterprising UK101 usersUK 101 should not find it too difficult. Asa guide the screen display for the Super -board II more or less starts at 53285, topleft, and finishes at 54140, bottom right,with 32 locations per line.

Incidentally, the program presents adifferent puzzle each time it is run.

Line numbersTHERE ARE thousands of tips and ideasbegging to be explored writes Peter Jonesof Standish, Lancashire.

For instance, it is not difficult to write afile -search program whereby after

inserting the required List Line Number,the computer will search through theincoming tape listing, until the requiredList Line Number appears.

On receiving this List Line Number thecomputer will either: carry -out theinstructions in the List Line or print outthe whole List Line.

Can anyone suggest a program for theSuperboard in which the computer will doall the searching, etc., at the same timeleaving the screen blank?

List route

STEVE PURDY'S solution to the Listproblem on the Superboard in theFebruary 1981 6502 Special may have leftreaders wondering why I wanted theprogram to continue execution afterLIST.

With a routine using the facility, RUN63000 will save your Basic program up toline 62998 on tape, so that on re-loading, the program runs automatically:62999 END63000 SAVE : POKE 4,194: POKE 5,16563100 LIST - 62998 : POKE 4,195: POKE

5,16863200 PRINT : PRINT "0 POKE 515,0 ":

PRINT "RUN63300 POKE 517,0

To save the routine with the program,remove the - 62998 after LIST. TheSuperboard is very reliable on saving andloading but occasionally you obtain aspurious single -digit line number, i.e.,from 0 to 9, from the rubbish on the tapebefore the load starts. This problem canbe overcome by changing line 63200 to63200 PRINT : PRINT " 0 POKE 515,0 :

GOTO first line number " : PRINT" rr,RUN

5 FORZ=07025:PRINT:NEXTZ10 GOSUB45515 Y=16920 FORX=53295705330825 POKEX,Y:POKEX+32,Y:POKEX+704,Y:POKEX+736,Y30 NEXTX35 FORX=53359T053967STEP3240 POKEX,Y:POKEX+13,Y45 NEXTX50 R=5342555 FORR=ATOFi+9STEP357 IFA>53911THEN8560 GOSUB10065 NEXTR70 A=A+14880 GOTOSS85 POKE53914,9690 A=5342595 GOT0130100 POKER-65,189:POKEA-64,135:POKEA-63,190105 POKEA-33,136:POKER-31,143:POKEA-1,136110 POKEA+1,143:POKEA+31,136:POKEA+33,143115 P0KEA+63,190:POKER+64,1281POKEA+65,189120 POKEA,96125 RETURN130 REM*RANDOM LETTERS*135 X=1:Y=1140 A$="ABCDEFGHIJKLMNO"145 B=INT(<1-14)*RND(1)+14>150 8$=RIGHT$(AS,14-13)+MID$CAS,2,8)+LEFT$CA$,1)155 X=X+1:A$=8$:IFX<25THEN145160 REM*PUT IN SQUARES*165 FORA=AT0A+9STEP3170 X$=MIDS(A$,Y,1)175 Y=Y+1:IFY>16THEN200180 Z=ASC(X$>185 POKEA,Z190 NEXTR195 A=A+148:GOT0165200 REM*KEYBOARD*205 POKE11,34:POKE12,2210 DATA32,0,253,141,128,2,96215 FORX=546T0552:READC:POKEX,C:NEXTX220 GOSUB500225 X=USR(>0230 D=PEEK(640):REM*SQUARE*235 IFD>64ANDD<8OTHEN245240 G0T0225245 REM*SEARCH FOR SQUARE*250 A=53425255 FORA=RTOA+9STEP3260 IFPEEK(A)=DTHENPOKEA-32,58:80T0285265 NEXTR270 R=A+148275 IFA>53914THEN250280 G0T0255285 GOSUB560290 X=USR(X)295 D=PEEK(640):REM*DIRECTION*300 IFD>48ANDD<53THEN310305 GOT0290310 REM*VALIDATE MOVE*315 IFD=49ANDPEEK(A-160)=96THEN355

325335345170

355360365370375380385390395400405410415420425430435440445450455460465470475480485490495500505510515520525530560565570575580585590595600605610615620625630635640645650655660K

IFD=50ANDPEEK(A+160)=96THEN380IFD=51ANDPEEKCA-3)=96THEN405IFD=52ANDPEEK(A+3)=96THEN43080SUB595:P0KEA-32,32:8070220

REM*MOVE UP*E=A:F=PEEK(A)IFA=E-160THENPOKEE,96:8070220GOSU8635:A=A-32:GOSUB100POKER,F:FORT=070500:NEXTT:8010365REM*MOVE DOWN*E=A:F=PEEK(A)IFA=E+160THENPOKEE,96:G0T0220GOSUB635:A=A+32:GOSUB100POKER,F:FORT=070500;NEXTT:GOT0390REM*MOVE LEFT*E=A:F=PEEK(A>IFA=E-3THENPOKEE,96:GOT0220GOSUB635:A=A-1:GOSUB100POKEA,F:FORT=0T0500:NEXTT:GOT0415REM*MOVE RIGHT*E=A:F=PEEK(A>IFA=E+3THENPOKEE,96:GOT0220GOSUB635:8=A+1:GOSUB100POKEA,F:FORT=OT0500:NEXTT:GOT0440PRINT" SQUARES"PRINT"PRINT:PRINT:PRINTPRINT" KEY 1="CHR$(16):PRINTPRINT" KEY 2=";CHR$C20):PRINTPRINT" KEY 3=";CHR$C22):PRINTPRINT" KEY 4=";CHR$(18):PRINTFORX=01.010:PRINT:NEXTXRETURNREM*INSTRUCTION*D$="INPUT SQUARE TO MOVE"Y=1FORX=54119T054138Xf.iMIDIA(DS,Y,1)POKEX,ASC(X40:Y=Y+1:NEXTXRETURNREM*INSTRUCTION"Dt="NOW INPUT DIRECTION "Y=1FORX=541191054138X$=MID$CD$,Y,1)POKEX,RSC(X$):Y=Y+1;NEXTXRETURNREM*ERROR*D$="THIS IS NOT POSSIBLE"Y=1FORX=541191054138X$=MID$CD$,Y,1>POKEX,ASC(X$):Y=Y+1:NEXTXFORT=0702000:NEXTTRETURNREM*SQUARE DELETE*POKER-65,32:POKEA-64,32:POKEA-63,32POKER-33,32:POKEA-31,32:POKEA-1,32POKEA+1,321POKEA+31,32:POKEA+33,32POKEA+63,32:POKEA+64,32:POKER+65,32:POKEA,32RETURN

114 PRACTICAL COMPUTING May 1981

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Circle No. 175

THE RICOH 1600SIf it's high performance your're

looking for, the Ricoh 1600S is for you,offering an amazing 60 characters inlust I second. An updated version ofthe tried -and -tested 1600, the new Smodel has been re -designed and fittedwith all sorts of extras. Yet one thinghasn't changed - the price, makingthe 1600S cheaper than any equivalentmodel on the market. This superbperformer incorporates the Z80 micro-processor, auto bidirectional printingand look -ahead logic, increasing speedand efficiency. Other capabilitiesinclude proportional spacing, graphplotting and word processing enhance-ments. The printer includes a standardcentronics interface, and RS232 and1 EEE options are available.

The Ricoh 1600S is available onlyfrom Micropute and their authoriseddealers, all backed up with a nation-wide service network. If you'reinterested in the 16005 either as acustomer or as a dealer, send thecoupon now.

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'RICOH 1600S THE PERFORMANCE HASk'RISEN - THE PRICE HASN'T

,zEATURES COMPETITORS

DIABLO QUME SPIN -630 SPRINT 5 WRITER

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PRINT SPEED(CPS) 40 45/55 55 60 60

PRINT ELEMENT DAISY- DAISY-WHEEL WHEEL

THIMBLE DOUBLE DOUBLEDAISY- DAISY-WHEEL WHEEL

AUTOBIDIRECTIONAL No No Yes No Yes

AUTO LOGICSEEKING Yes No Yes No Yes

PROPORTIONALPRINTCAPABILITY Yes Yes Yes No Yes

EXTENDEDCHARACTER SET No No Yes Yes Yes

LETTER QUALITYPRINT Yes Yes Yes Yes Yes

CUSTOM INTER-FACE OPTION No No No No Yes

PRICE £1675 £1950 £1950 £1450 f1450

The above information was gathered from distributors andabstracted from their current literature. Prices shown are thoseadvertised at the present time. MICROPUTE

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Circle No. 176

The On xC8000 SeriesThe C8000 Series is a

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Based on the Z8000*processor, the C8002 may beconnected to a high speed localnetwork for further expansion.

Industry compatible versionsof COBOL, PASCAL, BASIC,CBASIC2*, FORTRAN and C areavailable on OASIS*, CP/M*, MP/M*and UNIX* operating systems.Also available are packages forcommunications, data basemanagement, word processing andbusiness applications.

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*Z80A and Z8000 are trade marks of Zilog Inc. CP/M and MP/M are trade marks of Digital Research Inc. OASIS is a trade mark of PhaseOne Systems Inc. UNIX is a trade mark of Bell Telephone Laboratories. CBASIC2 is a trade mark of Compiler Systems Inc.

Circle No. 177

If the front panel....

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IIS

Tandy forum

Video Genie ideas

A FEW months ago I bought a Video Geniecomputer, writes Simon Goodwin ofHereford. As many will know, thismachine is based on the Tandy TRS-80level 2 computer, with a few enhance-ments - a second cassette port isstandard, as is a built-in tape recorder onport 1.

The dreaded TRS-80 keyboard bouncehas been largely eliminated. A VideoGenie does not return to a cold -start whenthe re -set key on the back of the box ispressed; it returns to Basic with variablesand program intact. This feature makes aprogram crash less likely than on a Tandymachine. It can, however, be inconvenientif the user wants to change the area ofprotected memory on the computer. Thereason for the potential inconvenience isthat, according to the manual, themachine must be turned -off and turned -on - after a 10 -second wait to allow thepower supply to discharge - to return tothe prompt requesting reserved memorysize.

In fact, it is easy to branch to thisprompt - clearing the current program- from Basic without having to turn themachine on and off. Enter System new -line followed by slash zero new -line toreturn to the system start-up prompt. Youcan now enter the starting address forreserved memory as if you had just turnedthe machine on.

The instruction slash zero tells theVideo Genie monitor to execute theprogram at location zero. This is wherethe Basic ROM starts, and where the Z-80looks for the first instructions when it isturned -on. Obviously, it is much betterfor the system if you can re -start itwithout having to turn it on and off -chips are at their most vulnerable at thesetimes.

There are a few characters whichapparently cannot be obtained directlyfrom the Video Genie keyboard. Under-line, backslash, up arrow, close squarebracket, tabulator and clear screen can beobtained, according to the manual, onlyby using the CHR$() function. In fact, alook at the TRS-80 technical manualshows that it should be possible togenerate all these codes by pressingcombinations of keys.

Try holding down the "Z" and "2"keys with your left hand. With those keysstill down, type two backspaces to removethe last two characters from the display -now tap "3" gently, with "Z" and "2"still depressed. If you were gentle, an opensquare bracket character "[" will haveappeared. If you were too fierce the "["will still have been produced, but it will befollowed by a "3". You can delete the"3" with another backspace, still holding"Z" and "2" down.

So far, that may not seem very useful -you could have produced a "[" just bytyping the ESC key. Still, hold down "Z"and "2" again, type two backspaces,

PRACTICAL COMPUTING May 1981

followed by a light press on "4". Thisshould produce a backslash " " symbol,which used to be unobtainable from yourkeyboard. Keep the first two keys downand tap "5" - you produce theubiquitous close square bracket "I". Try"6" - it produces another untypablecharacter, an up-arrow or 'A'S Finally, stillwith "Z" and "2" down, press "7"briefly to produce an underline "-"symbol. This procedure may soundcomplex, but with practice it is really verysimple - "Z" and "2" are used as a kindof extra "shift" key.

Those functions can be very usefulwhen entering programs - particularlyones that use graphics generated from textsymbols. When using the line editor, adifferent set of shift keys must be used tohave the same effect - in fact, othercombinations of keys can be used toprovide the shift - "Z" and "2" werechosen for their proximity on thekeyboard.

Control codes can also be produced by asimilar technique. Hold down "shift" and"CTRL" together - they should notproduce any characters on their own.Now press "I". This combinationproduces a TAB function and prints avariable number of spaces to take thecursor up to the start of the next eight -character wide tabulator field. This is veryuseful when tidying listings or using theeditor assembler, as it allows you tospread information easily into neatcolumns. If you try to enter a TAB whilein insert mode in the Basic editor, you willproduce a rather less useful reverse line-feed.

Obviously, it is possible to type theentire range of characters available on aVideo Genie by pressing groups of keys.TRS-80 users may also find this useful,though as their keyboard has more keyson it, the advantage will be correspond-ingly less. I am mystified by the way ashifted zero on the Video Genie producesa space, CHR$(32). It must be the most

useless extra way yet invented to type acharacter.

Finally, I would like to recommendfrom personal experience the TRS-80manuals to owners of Video Genies. TheVideo Genie manuals are clear, but theBasic manual is definitely too short tocover all the details. I have found theTRS-80 level 2 Basic manual excellent as asupplement to this - it is comprehensive,properly indexed in its second edition andcontains many useful routines andprograms illustrating functions in Basicand simple machine code.

Faster conversionIT GRIEVED me to see the Decimal -to -Hexconversion program by N Brickellpublished in your January 1981 TandyForum, writes John Leach of Deal, Kent.Apart from writing a very clumsyprogram, Brickell never asked himself:What if? What if a negative number isentered? What if the number is > 65535?

A little thought and ingenuity will soongive a far more flexible subroutine,including the vital error flags, which canbe tested for in the main program onreturn from the subroutine, in a mereeight lines of code.

Practical Computing obviously tries toencourage good programming style, forwhich many thanks. The Hex programfalls down badly; lines 30 to 64 should bein a simple loop - see lines 1110 to 1130in my program - while lines 100 to 150are quite absurd. All that is needed is100 B$ = CHR$ (VAL (A$) + 55): RETURN

I dare say the program works as listed,but no wonder it is so slow. Suppose youwanted to convert 1,000 decimal numbers.Far too many published programs containlong lists of If Then statements, which cannearly always be changed to a short loop,utilising a simple arithmetic conversion asin my example, or by using a look -uptable in DATA. Apart from savingmemory, the program can normally bemade to run much faster.

1000 REM Convert a decimal number to a Hexadecimal string with error flags1010 REM AZ$ . Output string102G REM LZ .= Length of output string (defined in main program)1030 REM EZ = Error flag (EZ . 0 if conversion satisfactory)1040 REM FZ = Negative number flag (FZ = 1 if negative, otherwise = 0)1050 REM NZ . Decimal number to be converted (not changed by the subroutine)1060 AZ$="": EZ=0: IF LZ < 1 THEN EZ.1: RETURN: REM Length not defined1070 QZ=NZ: FZ=U: KZ.16T(LZ-l): IF QZ >=0 GOTO 1100: REM Check sign1080 FZ=1: IF ABS(QZ) > KZ.8 THEN EZ=2: RETURN: REM Negative number out of range1.09G QZ.KZ.16 + QZ: REM Adjust QZ when negative1100 QZ.INT(QZ): 07=48: REM Get ready for conversion loop1110 FOR IZ=1 TO LZ: TZ.INT(QZ/KZ): IF TZ>15 THEN EZ=2: RETURN: REM Out of range1120 AZ$.=AZ$+CHR$(DZ+TZ-7*(TZ>9)): REM Convert Hex value to ASCII1130 QZ=QZ-KZ*TZ: KZ=KZ/16: NEXT IZ: RETURN1140 REM For TRS 80 substitute FIX for INT1150 REM IZ, KZ, TZ and QZ are temporary variables within the subroutine1160 REM Line 1120 uses Microsoft BASIC logical operator (TZ>9)1170 REM If this is not allowed in other versions, change to

1120 JZ.TZ: IF JZ>9 THEN JZ.JZ+71125 AZ$=AZ$+CHRS(DZ+JZ)

1190 REM All variables end in Z to avoid confusion with main program variables1200 REM Sample program

10 INPUT "LENGTH, NUMBER ";LZ,NZ20 GOSUB 100030 IF EZ = 0 THEN PRINT AZ$: GOTO 1040 PRINT "ERROR TYPE ";EZ: GOTO 10

119

Pet cornerPet sort by selectionTHIS PROGRAM uses a sort by selectionprocedure, writes Simon Letts of Run-corn, Cheshire. That is, it searches the un-sorted array for the lowest item - thedata is ASCII coded. When this is found itis swapped with the item at the bottom ofthe array. The base address of the un-sorted array is then incremented.

In this way, a sorted array is built-up atthe bottom of the unsorted one - whichdecreases in size as each item is removedfrom it. The method was chosen for itssimplicity rather than its efficiency andcould be improved in that respect. Forexample,Unsorted 1st pass 2nd pass 3rd passarray1 Peter Andrew Andrew Andrew2 John 1 John Charles Charles3 Andrew 2 Peter 1 Peter John4 Charles 3 Charles 2 John 1 Peter

In fact, the program does not move thedata itself, which could be very lengthy,but when sorting the data, it moves theaddresses of that data. Each one is onlythree bytes long and the Pet holds them alltogether above the Basic program andvariables.

Null stringsThe program is designed to leave null

strings in position in the array and to placea longer string after a shorter one that isthe same for the length of the shorter. Forexample,Unsorted 1st pass 2nd pass 3rd passarraySmith A B Jones P Jones P Jones Pnull null null nullJones P Smith A B Smith A B Smith ASmith A Smith A Smith A Smith A B

The program is stored in the secondcassette buffer but is completely re -locat-able as it uses only relative addressing.The program uses some of the zero -pagememory normally retained for cassettehandling work space. Due to consider-ations of size, speed and simplicity in use,this version of the sort can only handlearrays of up to 256 -0 - 255 - elements.

Call from BasicThe routine must be called by the

following line of Basic:POKE 18 0,C: NM$(0) = NM$(0) : SYS(826)

where C is the length of the array andNM$ is the name of the array which canbe anything.

The POKE puts the length of the arrayinto the zero -page work space and settingthe zero array element equal to itself putsthe address of the array into zero pageaddress 68-69 - Hex 0044-0045 - whichis the current variable address where it canthen be found by the machine -coderoutine. SYS(826) calls this routine.

Program notesFurther notes may be found in the

listing.Workspace use - hex addresses, all in zero

page00B4 Array length, decimal address 180

120

00B5 -B6 Base address of unsorted array00B7 -B8 Address of lowest element so far in

this pass00B9 -BA Address of next element to be

checked0OBB-BD Address of data in lowest element00BE-00 Address of data in next element to

be checked00B1 -B3 Temporary storage for address swap

Notes:Addresses 033A - 033F saves the 6502

registers on the stack.0340 - 0356 loads the address of the

array into the zero page workspace.0357 - 0363 increment the address of the

present array element to form that of theelement next to be compared.

0364 - 0372 loads the addresses of thedata to be compared - the actual strings.

0373 - 037A are either of the stringsnull? If so, do not compare.

037B - 0383 checks if every character ineither string has been compared.

0384 - 0393 compare the next characterof each string. Try next characters if thesetwo are the same. Try next string if lowestvalue is still the lowest. Otherwise, (038C),store address of present element in spacefor lowest element.

0394 - 0396 decrement length of arrayleft to be searched. Try next string if endof array not reached.

0397 - 03A9 swap addresses of lowestelement and element at bottom ofunsorted array. This builds up the sortedarray.

03AA - 03B6 increment base address ofunsorted array by three - this shortensthe unsorted array and lengthens thesorted one.

03B7 - 03BA decrement unsorted arraylength register, continue with sort if endof array not yet reached.

03BB - 03C1 restore 6502 registers fromthe stack and return to Basic.

READY.

Er*

PC0401

IRO SR AC 6R YR SPEE2E 32 04 5E 00 F8

c' 48 8A 48 98 48 88 A50342 44 85 95 A5 45 85 95 AS034A E4 A5 95 .A5 85 E9 A5

035'D 95 85 88 °' BA 18 A5 99085A 5R 03 85 99 A5 9A 69 000352 R"-', BA AO 02 91 97 99 98035A 00 91 99 39 BE 00 82 100372 F3 A5 BE FO 18 A5 BD F0027A 19 C8 C4 BE F0 OC C4 99

7,2 FO 10 91 BC 81 BF F0 Fl

30 08 A5 99 85 97 AS BA85 98 CA DO CO AO 02 91

39A 97 99 91 00 B1 D5 91 9703A2 99 81 00 91 85 88 10 EF03AA 18 AS 95 69 03 85 95 A50392 96 59 00 85 95 C5 B4 DO03PA 8E 58 A8 68 HH 68 28 60

FFADy03A 00D338 48

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07,7B

27r:

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03RA038A

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03A203A503A703A8189903RE03A D

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039903PC031:71

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48384::

A544

054585BEA684ASES

8578599

HSBS85.93=SBA12A5E96,;103

A599A5DA1,;90n

=SBAA002818799990091999,-;TPTin

8810E3A59EFOlDA599F019C8CABEF 000O 499

F0109190D 1DF

FOF19008A59985E7A5DA8598CADOCOA002E1973981009195319799910091952810FF18A59559038585A596590085950594DOCE58A858HH58

ISO

PHPPHATXAPHATYAPHACLD

LDA 44STA 95LDA 45STA 95LDX 94LDA 95STA 97STA B9LDIR

=TASTA

OLCLDAABC8THLTIF1

ADCSTA

D'r'

9588DR

99#0383BA#00BA#02

LDA +:D7) .YSTA 0088 Y

LDA ::8_9).YSTA 009E Y

DEYBPL 0:355LDA BEBE!_! 4_1:7194

LDA DBDEG 0:=19.4

I NY

CPY BEBEIQ 0380CPY BBREID 0334LDA ( BC ) , Y

CMP ( BF ) , Y

EEO 0378BCC 0394LDA D9STA 97LDA BASTA 92

DE`

ENE 0357LDY #02LDA (971:

STA 00E1 YLDA (95 ) YSTA (97 ) Y

LDA 0091 YSTA (95), Y

DEYRpt_

CLCLDA 85ADC #03STA 95LDAADC #00STA BEDEC 94EHE 0349

PLATAYPLATAXPLAPLPRTS

PRACTICAL COMPUTING May 1981

Apple Pie--Miniassembler facilityI WAS very disappointed to discover thatthe 48K Europlus lacked the mini -assembler facility writes David Kyte ofBristol. When flicking through backcopies of Practical. Computing, I noticedletters concerning re -locating the pro-gram.

My first problem was finding a copy ofthe listing, there was no copy in the latestmanuals which accompany the system. Ifound it in the old manual, a copy ofwhich I obtained from my local dealer. Ibelieve there is also a listing in the 2020manual.

A point not mentioned in the letters inPractical Computing is the influence ofDOS. At first I tried to re -locate it at$b000 as the program is only $166 byteslong. The effect of trying to save the pro-gram on disc and watching the systemcrash, coupled with DOS overwriting thecode in memory is crippling. After severalfruitless attempts I offer the followingadvice.

DOS alters high memory thus:System High memory DOS high memory48K $bfff $960036K $8fff $660032K $7fff $560024K $5fff $360020K $4fff $260016K $3fff $1600

The problem is solved if the program islocated from address $0800 to $0966. Thisinvolves changing the following segmentsof codeAddress Old code$f535: 4c 95 f5$f559: 4c 95 f5$f5bd: 20 34 f6

New code- 4c 95 08- 4c 95 08- 20 34 09

$f5d5: 20 34 f6 - 20 34 09$f5e5: 20 34 f6 - 20 34 09$f631: 4c 5c f5 - 4c 5c 08$f666: 4c 92 f5 - 4c 92 08

The rest of the code is identical. Theminiassembler is run by typing $0966g.

Cross-referencingA QUICK glance at E McGeough's Cross -Reference program, Apple Pie, January1981, showed that it did not handle namesmore than 4 characters very well and waslimited to 999 references writes NeilLomas of Crewe. It seemed rather slow,however, even for Basic - a programcontaining 878 references took 37 minutes15 seconds.

The most obvious cause of its slowspeed was that it sat on top of the pro-gram being analysed. Every Goto causedthe whole program to be scanned - andthere are very many Gotos during a sort.Removing of the program once the refer-ences had been assembled seemed toprovide the answer.

Although it may appear a disadvantageto have to preserve the string array on discwhile the program is changed, thisproduced a significant reduction in theoverall time and also opened the way toremoving the 999 limit. Instead ofassembling all the strings and writing themto one file, a new file is written whenever acertain number of references, 512, have

been assembled. The files are sorted inde-pendently and then merged.

Further savings resulted from clearingstring array elements to null as soon asthey were no longer required - reducingthe frequency of garbage collection - andby sorting an array of pointers instead ofthe strings themselves. I was a littlesurprised at this, as I had some vaguenotion that two strings with the samevalue were merely two pointers to thesame string. If there are circumstanceswhere this is true, it does not happen here- otherwise sorting a string array wouldonly amount to swapping pointers.

Finally, the printer had a habit ofstopping for long periods while garbagecollection took place. Assembling eachprint line in memory is a high-speedgarbage generator - unloading theassembly job on to the printer cleared theproblem completely.

Since this process now destroys theprogram being analysed, it is first saved ina file called In case of accidents. After thecross-reference has been produced, Incase of accidents may be loaded if neces-sary, lines 63955 onwards deleted, and theprogram saved under its proper name.

If the program to be analysed has beenrun, Clear the data areas before runningthe cross-reference. If any program hasreduced high memory, re -boot. DOS andre -load the program. Failure to do thiswill greatly slow the process, if it does notstop it altogether. Note that the lastcharacter of a long name is now saved, todistinguished $ and 07o.

The program as listed analysedMcGeough's program in 23 minutes 36seconds, a saving of more than 36 percent.Although the original listed the programas well, the times quoted compare likewith like. To accelerate the initialassembly phase, try removing the progressprint and assembling the arrays directly todisc. This would involve replacing theindividual file sizes and continuationmarkers with a separate index.

A note about the printing: the protocolused is for a parallel printer which adds itsown line feed, actions received LFs, andhas a reverse LF facility. It can be adaptedfor any parallel printer except one whichadds LFs and cannot reverse. In that case,the program must be changed to begin anew print line for each disc file - evenwhere that results in repeating a variablename - or to revert to the originalmethod of assembling print lines inmemory. If you have a serial printer, thismay not apply.10 REM XREF20 REM RUNNING THIS PROGRAM WILL SAVE30 REM THE LINES 1000-63999 IN AN10 REM EXEC FILE 'CROSS -REF' WHICH MAY50 REM BE EXECUTED DIRECTLY ON A PROGRAMHo REM IN MEMORY TO GIVE A CROSS -REF70 REM LIST OF THE PROGRAM'S VARIABLESBO REM EXTENDED py H.LOMAS FROM PROGRAM BY E.MCGEOUGH, P.

C. JAN 8190 REM LINES 63955-63999 ARE LOADED ON TOP100 REM OF THE PROGRAM AND RUN TO. EXTRACT

1gREM

1HOLZEO:EIT40::Mg:CnLV:I.TE THEM130 REM THE PROGRAM IS DELETED AND140 REM REPLACED WITH LINES 1000 - 1720150 REM (WITH STRIPPED) WHICH SORT60 REM AND MERGE THE DISC FILES AND

170 REM PRINT THE CROSS-REFERENCE LIST.180 REM EACH DISC FILE CONTAINS UP TO 512190 REM REFERENCES PRECEDED BY TWO NUMBERS.200 REM THE FIRST NUMBER IS THE NUMBER OF210 REM REFERENCES ON THE FILE.220 REM THE SECOND NUMBER IS NON -ZERO IF230 REM THERE IS ANOTHER FILE TO FOLLOW.210 NES = .CROSS -REF.

250 D. . CARP (4)260 PRINT D$1.0PEN .1HF$270 PRINT 0111.DELETE .:NF$280 PRINT D$T.OPEN 'INFO290 PRINT D$1.WRITE 'INFO300 LIST 63955,310 PRINT .RUN63955.320 PRINT .NEW.330 LIST 1000,1020340 LIST 1060,1070350 LIST 1100,1170360 LIST 1210.1240370 LIST 1270390 LIST 1310,1450400 LIST 1470,1180410 LIST 1510420 LIST 1530.1550440 LIST 1590450 LIST 1640,1660460 LIST 1710,1720470 PRINT "RUN.480 PRINT 050"CLOSE "INFO190 END1000 ON = CARS (4):I$ = CHR$ (9):YA 1:PD$ =

Al DIM T1(513),U$(513),PP(512)1010 OP$ = .OPEN XREF LIST .1RD$ = "RENO XREF LIST "OURS

WRITE XREF LIST ":CL. = "CLOSE XREF LIST .1020 PRINT DCOPSIYAI",01"1030 REM INPUT THE STRING ARRAY AND1040 REM CONSTRUCT A MATCHING ARRAY1050 REM OF POINTERS1060 PRINT DSIRDSIYAI INPUT XI INPUT YO: FOR C = I TO XI INPUT

TII(C):Pp(C) = CI NEXT1070 T.IX I, = CARS (255): PRINT Of;CLMA1080 REM PERFORM A SHELL SORT1090 REM OF THE ARRAY OF POINTERS1100 T = XIM6 = I: PRINT "SORTING --- WAIT"1110 M6 = INT (M6 / 2): IF M6 = 0 THEN 12101120 X6 = Y - M61J6 . 1

1130 16 - J61140 L6 = 16 M6: IF T4(PP(I6)1 C = TS(PPILE.)) THEN 11601150 PP PPIL6):FT(L6) = Pp(I6):PP(I6) PP:I6 = 16 - M6: IF

16 S = 1 THEN 11901160 J6 = J6 * 1: IF J6 - K6 THEN 11101170 GOTO 11301180 REM END OF SORT1190 REM WRITE THE SORTED FILE BACK1200 REM TO THE DISC1210 PRINT 011;01.$;YA: PRINT 111;WRS;YA1220 PRINT X: PRINT YB: FOR C = I TO X: PRINT TS(pP(C1): NEXT

1230 FOR C = I TO XITN(C) -, NEXT1240 PRINT DPICL.IYA: IF TB < 0 THEN VA = IA COTO 1

0201250 REM IF THERE IS ONLY ONE FILE1260 REM CO DIRECTLY TO PRINT1270 IF YA = I THEN 14701280 REM READ THE FILES IN PAIRS1290 REM AND MERGE THEM BACK1300 REM ON TO THE DISC1310 FOR YC = 1 TO YA - 1: FOR ID = YC 1 TO YA: PRINT "ME

RCINC FILES .ITC:. AND .:YO:1320 PRINT DS:OP$1YC: PRINT WIRD11:YC1330 INPUT XA: INPUT YB: FOR C = I TO XA: INPUT TII(C): NEXT

ITCXA * 1) - CHR$ (255)1340 PRINT 1.1CLS:YC1350 PRINT 0$10P$M1 PRINT 0$11,06:Y01360 INPUT 081 INPUT YE: FOR C = 1 TO 081 INPUT UCC): NEXT

:114((8 * 1) . CARS (255)1370 PRINT 0111CL41YD: PRINT 06;01.61YC: PRINT 0$1141MYC: PRINT

XA: PRINT YB1380 XT = 110U . 1: FOR XE = 1 TO XA1390 IF Tt(XT) V U11(XU) THEN PRINT 116(XU)1U$(XU) ..:XU

XU 11 GOTO 14101400 PRINT T4(XT)1T11(XT) = ":XT = XT * 1

1410 NEXT PRINT 06:CL$M1 PRINT D$10P11;YD: PRINT 06:WRII:TO PRINT 08: PRINT YE

1420 FOR C = I TO XS1930 /F TS(XT) S 0510U) THEN PRINT US(XU)1US(XU) ..:XU

XU 1: GOTO 14501140 PRINT TSMO:T11(XT) '.":XT = XT 1

1150 NEXT 1 PRINT 06;CL$1YD: NEXT 1 NEXT1160 REM READ A FILE1470 TOOT) = PO4: FOR YC = 1 TO TA: PRINT 011:0PWC1 PRINT D

$01304:YE1480 INPUT X: INPUT YO: FOR C = 1 TO X: INPUT MC); NEXT1490 REM PRINT THE FILE AND RETURN1500 REM FOR THE NEXT1510 GUS. 1590: PRINT 0.;CL.I1C: NEXT1520 REM DELETE ALL WORK FILES AND END1530 FOR IC . 1 TO YA: PRINT DWOELITE XREF LIST "'.RC: NEXT

1540 END1550 PRINT DIII.F1/11": FRONT IWK";: PRINT I.;w80N.;: RETURN

1560 REM PRINT FILE1570 REM OPEN PRINTER AND SPACE ALONG1500 REM LINE IF NOT FIRST FILE1590 GOSUB 1550: IF MN < > 0 THEN PRINT SPC( NW);1600 REM IF THE NEXT VARIABLE DIFFERS FROM THE LAST1610 REM START A NEW LINE.1620 REM IF NOT APPEND LINE NUMBER1630 REM UNLESS PRINT LINE IS FULL.1640 FOR C 1 TO X: IF LEFTS (TUC - 11,4) 5 LEFT. IT

t(C),4) THEN PRINT .": PRINT Tf(C);:WW 10: GOTO 1710

1650 IF WA > = W THEN PRINT ww: PRINT PD$I:184 5 4

1660 PRINT RIGHT. (111(C),6);:WW = NN 61670 REM AT END OF FILE SET T$(0) TO1680 REM THE LAST REFERENCE PRINTED1690 REM TO COMPARE WITH 1ST REF ON NEXT FILE.1700 REM EXECUTE REVERSE LF AND TERMINATE LINE1710 NEXT :TAGS) = Tf(X): PRINT CHRIF (27) CH. (10)1720 PRINT °4:"M..: RETURN63955 TEXT : HOME63956 PRINT "VARIABLE LISTER"63957 0$ . CARS (4)63958 PRINT DIFI.SAVE IN. CAPE OF ACCIDENTS,31"63959 0 . 0:1 = 1:LL = 639531 REM HIGHEST LINE63960 PON =63961 DIM T50512)63962 REM FIND FIRST LINE63963 NL . 201963964 F 204963965 REM RETURN HERE FOR NEXT LINE63966 NL = PEEK (P) PEEK (P 1) 25663967 /F NL = 0 THEN 6399763968 F = P 2

63969 LN = PEEK (P) o PEEK (P + 1) 256:P = p 1

63970 IF LA S LL THEN 6399763971 LABS = ww63972 GOSUB 63980: REM GET NEXT ALPHA63973 LABS . LABS * CHITS (CH)63974 OMB 63988: REM GET NEXT CHAR63975 IF CH 5 61 AND CH < 91 THEN 6397363976 IF CH - 47 AND CH 5 58 THEN 6397363977 IF CH = 36 OR CH . 37 THEN 6397363978 GOSUB 6399363979 GOTO 6397163980 GOSUB 63540063981 IF CH - 34 THEN GOSUB 63984: GOTO 6398063982 IF CH 5, 65 OR CH 90 THEN 6398063983 RETURN63984 GOSUB 6398863985 IF CH 5 > 34 THEN 6398463986 RETURN63987 REM GET NEXT CHAR63980 P =63989 IF P = NL THEN POP ; POP,: GOTO 6396563990 CH = PEEK (P): IF CH = 178 THEN P NL: POP : POP: COTO

6396563991 RETURN63992 REM STORE LABEL63993 PRINT LSI" wILAS.63991 IF X 512 THEN IA 1: GOSUB 6399863995 IF LEN (LAB.) 4 THEN LABS m LEFTS (LABS,3) * RIGHT.

(LABS,.63996 X = X . 1:LN. = STR. (LN)ITS(X: . LEFTS (LAB* PDS,

5) RIGHTS (PD. 1,1.5)I RETURN63997 16 = 0: GOSUB 639911: END63998 PRINT Dt;"OPEN XREF LIST .;Y:",01.1 PRINT DIII.WRITE X

REF LIST .1Y63999 PRINT X: PRINT TA: FOR C 1 TO X: PRINT TS(C):T.(C)

..: NEXT : PRINT D.I.CLOSE XREF LIST ";Y:1 Y 1IX =0: RETURN

PRACTICAL COMPUTING May 1981 121

MicromouseIF YOU have followed my advice from theprevious micromouse pages and now havea movable chassis, you are about to dis-cover the two basic laws of dynamics: When a moving object meets an im-

movable object, the immovable objectis knocked out of the way.

Every static object exerts an equal butnot opposite attraction to any nearbymoving object.The underlying principle of the first law

is that a robot must detect an objectsufficiently far away from it to be able tostop. One mouse, based on ordinarymotors, had the problem that - althoughit could detect objects at a distance -when the wheels were stopped the mousekept on sliding until it hit a wall. On onememorable occasion it burst out of theside of the maze and leapt into space - itwas caught just in time.

Remember, the base of the maze ischipboard painted in a smooth, matt -black paint. I believe slightly spongywheels - such as the model aircraftwheels I used - are essential.

It is also worth noting that the walls ofthe maze are designed only to withstand aforce of one Newton - the weight of amedium-sized apple, I am told. Anothermouse, based on stepper motors, hadtrouble with deceleration. Stepper motors

by Nick Smith

need to be accelerated if high speed is tobe achieved but this means, of course,they need to be decelerated to stop. It canmean that sensors need to be able to detecta wall in front from a considerabledistance.

The mouse from Finland took about ametre to stop from its top speed. Itssensors could detect a wall at a distance ofabout 4in. Before you fall out of yourchair in hysterical laughter, I would like topoint out just how clever their softwarewas. Like all good mice it built-up a bitmap of the maze. Unlike any othermouse, however, it had three possiblestates for each wall: wall present, wall notpresent, not known.

When running in a straight line, thesoftware checked ahead to find thenearest known wall or unknown position.It then continuously calculated its speedon the basis that it must be able to stop ifthere was a wall at that point. The firsttime it went along a passage it went rela-tively slowly, accelerating anddecelerating in little bursts from square tosquare.

The second time along a passage, itaccelerated smoothly to a much higherspeed until, half way along, and then itdecelerated smoothly to the end. When itbecame confused, however, it managed todemolish several walls before it stopped.

The underlying principle of the secondlaw is that however hard you try, yourmouse will not travel in a straight line. It ismuch better to accept this and startplanning on what your mouse is going to

122

Dynamics laws createcontrol 'nightmare'do as it is magically attracted towards aside wall, rather than to try harder andharder to build a mouse that will gostraight. A mouse could travel several100ft. not to mention going round many90° corners during its 15 minutes in themaze.

After the July trial last year, the com-petition organiser John Billingsley was soconcerned about peoples lack of under-standing of control theory that he sent thefollowing advice to all competitors:

The most important thing to bear in mindis that what the controller does not knowabout, it cannot control. When guiding amouse along a straight run, everybody thinksabout the mouse's displacement from thecentre line, but at least as important is theangle at which the mouse is pointing. For avehicle with a steering wheel, running at con-stant speed, the behaviour can be describedby two state equations:1. Rate of change of displacement isproportional to angle - roughly.2. Rate of change of angle is proportional tosteering.

For stability, the feedback signal whichcontrols the steering must contain inform-ation of both displacement and angle. Thesimplest way to achieve this is by mountingthe wall -sensor forward of the unsteered axle- the further forward, the more the signalwill depend on the angle: Since, in mostsystems, this signal will be on -off, its use tocontrol steering angle would result in thefront wheel(s) snapping to-and-fro. If insteadit is used to control the rate -of -turn of thesteering wheel, there is a third state equation:3. Rate of change of steering is proportionalto input.

Thus the feedback signal must also reflectthe steering angle. This can be achieved bymounting the sensor on a forward boomwhich rotates with the steering - not an easything to fit within the confines of a maze,however.

The mice which entered the Portsmouthheat were not based on a car, but on a wheel-chair. The two main wheels, one each side,are driven independently. To preventtoppling, other wheels are fitted but thesemerely act as castors. For steering, one wheelis driven forwards while the other is drivenbackwards - or less strongly, or not at all.This scheme is mechanically much simpler,but it can become a controller's nightmare.The state equations now become:1. Rate of change of displacement is propor-tional to angle - rather more roughly.2. Rate of change of angle is proportional toleft -motor -speed minus right -motor -speed.3. Rate of change of left -motor -speed is pro-portional to applied left drive minus motordamping effect times left speed.4. Rate of change of right motor speed is pro-portional to applied right drive minus motordamping times right speed.

Having built what John Billingsley des-cribes as a controller's nightmare, I wasnot entranced by the idea of writing thesoftware to solve four simultaneous diff-erential equations. How I eventuallysolved the steering problem will be thesubject of a future article.

It does not matter how good your logicand software are if your sensors are not

gathering the necessary information andtransmitting it correctly to the controller.My own mouse was based entirely onmechanical sensors because I did not havethe electronic knowledge to do anythingelse. For the benefit of the more advancedconstructor, I have obtained informationand suggested circuits for using UltraSonics which should be ideal for long-range sensing.

I have, however, failed to glean anyinformation about using infra -red devicesfor sensors. The Plessey team - whosemouse used infra -red rays - are nottalking. Anyway, I understand their cir-cuit included purpose-built chips notavailable to the general public. If anyonecan supply me with details of using infra-red devices, especially for measuring dis-tance, please write.

The code to generate the sequence of bitpatterns for my stepper motors was in-correct. The third and fourth lines wereinterchanged. If, when you do a shift, a 1drops off one end, you add a 1 to theother end to maintain the bit pattern. So,if a zero is shifted out, you skip theaddition.

Summer heatsFOR THOSE trying to plan your summerholidays you could go to:Paris May 4-9 for Micro -Expo 81, heatHolland June, heatLondon July 29-31 for the Online Exhib-

ition, heatParis September 7-10 for the Euro-

micro Symposium, finalsThe Paris heat and finals are at the

Palais De La Decouverte. There will alsobe a number of weekend trials held thereduring the summer.

Entry formsFOR DETAILED information about the com-petition and entry forms please contact DrJohn Billingsley, Portsmouth Poly-technic, Department of Electrical andElectronic Engineering, Anglesea Build-ing, Anglesea Road, Portsmouth, P013DJ.

John Billingsley is about to reduce hisregular mailing list to those people whohave sent in completed entry forms. So, ifyou have obtained details and have not yetsent in your entry form, do it now.

There have been enquiries from justabout every European country you canthink of and an entry from Japan. Therehave even been two enquiries fromRussia. I would guess the most commonlanguage between the contestants is likelyto be Z-80 machine code despite the factthat the RCA 1802 is a much more usefulmicro chip. [7.]

PRACTICAL COMPUTING May 1981

User groups

User Groups is a region -by -region list of micro clubs in Britain. If a new clubhas been formed, send us the details and we will include them in the nextavailable issue.

AVON CLEVELAND M Pullin 13 Ladywood RoadBAUD, Bristol Apple Users Cleveland Microcomputer Club 45 Merestones Drive Cuxton, Rochesterand Dabblers J H Telford The Park Kent.Geoff Smythe 13 Weston Crescent Cheltenham GL50 2SU. Tel: 0634 78517.Datalink Microcomputer Norton, Cleveland. Tel: 0242 25617. North Kent AmateurSystems Ltd Tel: 0642 550061. 990 User Group Computer Club10 Waring House Chris Cadogan B J BiddiesRedcliffe Hill DEVON 21 Thistle Downs 3 Acer RoadBristol BSI 6TB. Acorn Atom User Group Northway Farm, Tewkesbury. Biggin HillTel: 0272 213427. T G Merdeith Tel: 0684 293821, Ext. 310. Kent TN16 3SP.

Bristol Computing Club Sheerwater Tel: 29 71742.

Leo Wallis Yealm View Road HAMPSHIRE6 Kilbernie Road Newton Ferrers Independent Pet Users' Group LANCASHIREBridge Farm Estate South Devon. G A Parkin Amateur Computer ClubBristol BS14 OHY. Exeter and District Amateur Robert May's School 2650 LibraryTel: 0272 832453. Computer Club West Street, Odiham. Roger A MuntBrunel Computer Club Doug Bates Tel: 025 671 2700. 51 Beechwood DriveS W Rabone 2 Station Road Southampton Amateur Feniscowles, Blackburn18 Castle Road Pinhoe Computer Club Lancashire.Worle Exeter. P G Dorey Tel: 0254 22341.Weston-Super-Mare Tel: 0392 69844. Dept. of Physiology Chorley Computer ClubAvon BS22 GJW Plymouth and District Amateur The University Chris HicksTel: 0934 513068 Computer Club Southampton S09 3TU 131 Market Street

Keith E Gould or Andy Low. ChorleyBEDFORDSHIRE Willoby House Tel: 107031 555605, Ext. 34. Lancashire.U.K. Intel M DS Users' Group Meavy Lane UCSD Pascal User Group Tel: Chorley 78376 or 71875.Lewis Hand Yelverton John Ash North Lancashire User Group29 Chaucer Road Devon PL20 6AL. Dicoll Data Systems Ltd Denise GreenBedford. Tel: 082285 2575. Bond Close 550 Midgeland RoadTel: 0234 41685. Kingsland Estate, Basingstoke. Blackpool.6502 Users' Club DORSET Hampshire RG24 OQB. Tel: 0253 692261.Joe Manifold Tangerine Users' Group North-west Group Amateur16 Bun Yam Close International HERTFORDSHIRE Computer ClubPirton, near Hitchin Microtan 65 Users' Apple/ITT 2020 Users' Group Ken HortonHertfordshire. R B Green John A Sharp 50 Lymfield Drive

'Tel: 0462 18522. 16 Iddesleigh Road 20 The Glebe Worsley.Charminster Garston Tel: 061 228 6333, Ext. 372.

BERKSHIRE Bournemouth Watford TRS-80 Users' GroupCommodore Pet User Club Dorset BH3 7JR. Hertfordshire WD2 6LR. Melvyn D F FranklinM Gulliford Tel: Garston 75093. 40 Cowlees818 Leigh Road DURHAM The Harrow Computer Group Westhoughton, BoltonSlough Industrial Estate North-east Pet Users' Group N P Butcher Lancashire.Slough Jim Cocallis 16 St Peter's Close Tel: 0942 812843.Berkshire. 20 Worcester Road Bushey Heath West Lancashire Pet Tel: 0753 74111. Newton Hall Estate Watford. Users' Club

Durham. Hertfordshire WD2 3LG. D W JowettBUCKINGHAMSHIREApple Users' GroupS F ProffittThe GranaryHill Farm RoadMarlow Bottom

Tel: 0385 67045.

EAST ANGLIAAnglia Computer User GroupJan Rejzl128 Templemere

Tel: 950 7068.Harpenden MicrocomputerGroupDavid M James5 Ox LaneHarpenden

197 Victoria Road EastThorntonBlackpool FY5 3ST.Tel: 0253 869108.

LEICESTERSHIREBuckinghamshire.Tel: Marlow 73074

Sprowston RoadNorwich N R3 4EQ.

Hertfordshire.Tel: 05827 5366, evenings.

Leicestershire PersonalComputer Club

01-7507298, day. Jill Olorenshaw

National TRS-80 Users' GroupBrian Pain40a High StreetStony StratfordMilton KeynesBuckinghamshire.Tel: 0908 566660.International NascomMicrocomputer ClubThe Secretaryc/o Oakfield CornerSycamore RoadAmershamBuckinghamshire.HP6 6SU.

ESSEXLondon and South-east SharpMZ-80K User GroupJoe Seet16 Elmhurst DriveHornchurchEssex RM11 I PE.Tel: 04024 42905.TRS-80 User GroupMichael Dean22 RoughtonsGalleywoodChelmsfordTel: 0245 76127.UK101 User GroupAdrian Waters, 117 Haynes Rd

INTERNATIONALInternational Association ofCromemco UsersPO Box 17658Irvine, California 92713 U.S.A.Tel: 714 955 0432.

ISLE OF WIGHTTRS-80 Users' ClubMike Collins3 Altofts GardensVentnorIsle of Wight.

KENTIndependent Pet Users' Group

c/o Arden Data ProcessingMunicipal BuildingsCharles StreetLeicester.Tel: 0533 22255.

LINCOLNSHIRELincolnshire MicroprocessorSocietyEric BoothBishop Grossetest CollegeNewport, Lincoln.Tel: 0522 27347.

LONDONComp80 - Scientific

Hornchurch South-east Region Computer Users' GroupCAMBRIDGESHIRE Essex. 164 Chesterfield Drive P L RobertsPeterborough Computer Club Tel: 494 0490. Sevenoaks 50 Cromwell RoadTrevor Marchant. Springfield Computer Club Kent TN13 2EH. WimbledonTel: 0733 76681. Steve Cousins Tel: Sevenoaks (0732) 53530. London SW19 8LZ.

1 Aldeburgh Way Gillingham User Group Tel: 01-540 3713.CHESHIRE Springfield, Chelmsford A Aylward ComputerclubNorth-west Computer Club Essex CM1 5PB. 194 Balmoral Road Roger R FramptonJohn Lightfoot Tel: 0245 50155. Gillingham. 42 Great Windmill Street135 Ashton Drive Tel: 0634 56830. London W1V 7PAFrodsham, Warrington GLOUCESTERSHIRE Medway Amateur Computer CPIM Users' Group U.K.Cheshire WA6 7PU. Cheltenham Amateur and Robotics Organisation D Powys-LybbeTel: 0928 31519. Computer Club Mrs C Webster (continued on next page)

PRACTICAL COMPUTING May I 98 I 123

User groups(continued from previous page)11 Sun StreetLondon EC2M 2PS.Tel: 01-247 0691.Medical Micro Users' GroupPatrick Dixonc/o Medicom14 BroadwayLondon W13.Tel: 01-579 5845.National TRS-80 Users' GroupJ S Wellsman292 Caledonian RoadLondon N1.Tel: 01-607 0157National ZX-80 Users' ClubTim Hartnell44-46 Earls Court RoadLondon W8 6EJNorth London HobbyComputer ClubRobin BradbeerDept. of Electronic andCommunications EngineeringPolytechnic of North LondonHolloway RoadLondon N7.Tel: 01-607 2789.Southgate Computer ClubPanos Koumi33 Chandos AvenueLondon N14or Alan Tootill on01-360 7014 (home) or01-882 6111 Ext 2281 (work)South-east LondonMicrocomputer ClubPeter Phillips61 Craigerne RoadLondon SE3.Tel: 01-853 5829.MK -14 User ClubGeoff Phillips8 Poolsford RoadNW9 6HP.Tel: 01-200 6209or 01-207 2000, Ext. 233.OSI U.K. User GroupRichard Elen12 Bennerley RoadLondon SW11 6DS.Pet Users' ClubCommodore Systems Division360 Euston RoadNW1 3BL.Tel: 01-388 5702.Pet Users' Education GroupDr Chris SmithDept. PhysiologyQueen Elizabeth CollegeCampden Hill RoadW8 7AH.Tel: 01-937 5411, Ext. 429.

MANCHESTERManchester Atom Users' GroupClement M Rutter3 Leopold AvenueWithingtonManchesterM20 8JG.Tel: 061 434 3092Manchester Computer ClubDavid Wade28 Hazel RoadAltrinchamCheshireWA14 15L.Tel: 061 941 2486.

MERSEYSIDELevel 1 User GroupN Rushton123 Roughwood DriveNorthwood, KirkbyMerseyside L33 9UG.U.K. Pilot User GroupAlec WoodWirral Grammar SchoolCross Lane

BebingtonWirralL63 3AQ.

MIDDLESEXIndependent Pet Users' GroupGeoff Squibb108 Teddington Park RoadTeddingtonMiddlesex.Tel: 01-977 2346.Richmond Computer ClubR A Forster18a The BaronsSt Margaret'sTwickenhamMiddlesex.Tel: 01-892 1873.West London PersonalComputer ClubG J Brain81 Rydal CrescentPerivaleMiddlesex.Tel: 01-997 8986.

NORFOLKEast Anglia ComputerUser GroupUnder East Anglia

NORTHAMPTONPersonal Computer Users' ClubJ R JacksonMereway Upper SchoolMerewayNorthampton NN4 9BU.Tel: 0604 63616.

NOTTINGHAMSHIREIndependent TRS-80 User GroupMike Costello17 Langbank AvenueRise ParkNottingham NG5 5BU.NottinghamMicrocomputer ClubP McQuoney28 Seaford AvenueWollatonNottingham.Tel: 0602 751742.UK Apple Users' Group5b The PoultryNottingham NG1 2HWTel: 0602 583254

OXFORDSHIREOxford UniversityMicrocomputer SocietyPhillip TaylorSt John's CollegeOxford.Tel: 0865 47671.Oxfordshire MicrocomputerClubS C Bird139 The MoorsKidlingtonOxford 0X5 2AF.Tel: 08675 6703.Research MachinesUsers' GroupTony Crowle134 Howard StreetOxford.

SCOTLANDCentral Scotland Computer ClubJames G Lyon78 Slamannan RoadFalkirk FK1 4NF.Tel: Falkirk (0324) 22430.The Grampian AmateurComputer SocietyM BasilOrton CottageBurnsideLumphananKincardineshireGrampian Region.

Tel: 033 983 284.Scottish AmateurComputer SocietyAlistair Macpherson6 CurriehillCastle DriveEdinburgh 14.Tel: 031 449 6658.Ithaca Audio S-100 User GroupStrathclyde Computer ClubDave Weaver 16 Etive PlaceCondorratCumberlandNear Glasgow G67 4J F.Tel: 023 67 36570 or1 Barracloughc/o S T V CowcaddensGlasgow.SOMERSETOhio Scientific U.K.User GroupTom Graves19a West EndStreetSomerset BA16 OLQ.Tel: 0458 45359.

STAFFORDSHIREIndependent Pet Users'Group IPUG57 Clough Hall RoadKidsgroveStoke-on-TrentStaffordshire.The Amateur Computer Clubof North Staffordshire1 Roll 16 Hill StreetHednesfordStaffs WS12 5DJ.Tel: 05438 4363or 0785 3251 Ext. 441 work.

SURREYForth Interest Group U.K.H Dobsonc/o 38 Worsley RoadFrimley, CamberleySurrey GU16 5AU.Tel: Deepcut 1025161 6254.ZX-80 Users' ClubDavid BlagdenPO Box 159Kingston -Upon -ThamesSurrey KT2 5YQ.

SUSSEXCrawley Computer ClubJohn Fieldhouse18 Seaford RoadCrawleyWest Sussex.Tel: 0293 543509.Mid -Sussex MicrocomputingClubBernard Langton228 St Leonard's RoadHorshamWest Sussex RH13 6AU.Tel: 0403 61156.Southern Users' of PetAssociation SUPAHoward W Pilgrim42 Compton RoadBrightonSussex BN1 5AN.Tel: 0273 561982.

TYNE AND WEARNewcastle PersonalComputer SocietyJohn Bone 2 Claremont PlaceGateshead, Tyne and WearTel: 770036 home, or0632 781412, Ext. 236 work.

TRS-80 User GroupDr S Tetlow 3 Highbury CloseSpringwell, GatesheadNE9 7PUWashington 462532

WALESGwent Amateur Computer ClubIan Hazell 50 Ringwood HillNewport, Gwent NPT 9EB.Tel: 0633 277711.National TI -58159 ClubR M MurphyDept. of Electrical EngineeringUniversity College SwanseaSwansea, South Wales.

WEST MIDLANDSCentral Program ExchangeMrs J BrownDept. of Computing andMathematical SciencesThe PolytechnicWulfruna StreetWolverhampton WV1 1 LY.Tel: 0902 27371, Ext. 56.Amateur Computer ClubJohn Tracey 100 Booth CloseBrierley HillWest Midlands DY6 8SP.Tel: 0384 70097.Birmingham 7166 User GroupSue DunnNewbear Computing StoreFirst Floor Offices, Tivoli CentreCoventry Road, Birmingham B26.Tel: 021 707 7170.Midland Amateur ComputerClubRoy Diamond27 Loweswater RoadCoventry CV3 2HJTel: 0203 454061.West Midlands RML User GroupPeter Smith BECCCamphill Centre, Stratford RoadBirmingham B11 1AR.

WORCESTERSHIREMinicomputer Users InSecondary Education - MUSER Trigger 48 Chadcote WayCatshill, BromsgroveWorcestershire.Worcester and DistrictComputer ClubD J Stanton 55 Vauxhall StreetRainbow Hill, Worcester WR3 8PA.Tel: 0905 22704.

YORKSHIREWest Yorkshire MicrocomputerGroupP R Clark Suite 204, Crown HouseArmley Road, Leeds LS12 2EJ.Tel: 0532 450667.Leeds and District Branchof the British Computer SocietyDave J Sheppard20 Green Lane Close, OvertonNear Wakefield WF4 4SE.Tel: 0924 270419.Darlington Computing ClubL Boxell 8 Vane TerraceDarlington DL3 7AT.Tel: 0325 67766.Penine and District ComputerClubDouglas R Bryant 26 Mill HeyHaworth, West YorkshireBD22 8NA.Tel: 0535 43007.

South Yorkshire PersonalComputing GroupS P Gray11 The MeadwaySheffield S17 3EB.Tel: 0742 351440.

Sharp PC -1211 Users' ClubJonathan Dakeyne 281 Lidgett LaneLeeds LS17 6PD.

York Computer ClubS Wilson 1 Grange CloseSkelton, York Y03 6YR.Tel: York 470464 after 6pm. UJ

124 PRACTICAL COMPUTING May 198I

Book reviews

Machine -code pro-gramming for theNascom 1 and 2By G R Wilson. Published byInterface Components Limited,Oakfield Corner, SycamoreRoad, Amersham, Bucking-hamshire, HP6 6SU. Tele-phone 02403 22307. 125 A4pages paperback, availablefrom the publisher. Price £4.50plus 50p postage.

THIS BOOK is intended for theNascom programmer with littleor no previous experience ofmachine -code programming. Itcovers the necessary ground tostart the reader programmingconfidently, but lacks the extrafeatures which would make itespecially useful.

Following an introduction tonumber systems and tocomputer concepts, the textdescribes the detailed functionof the most important Z-80 in-structions. They include theregister -register and memory -register -memory moveinstructions, conditional andunconditional branches, arith-metic and logical operationsand shifts, and simple input-output. The instructions areextensively illustrated by

with associated descriptivetext, flowcharts and diagrams.

AppendicesThere are five appendices

which describe the CPUregister sets and memory mapsfor Nascom 1 and Nascom 2,give a routine for displayingCPU registers, explain theattachment of simple I/Odevices; describe the method ofentering and executing a pro-gram under Nas-Sys; and,finally, provide a list ofNasbug routines equivalent tothe Nas-Sys routines used inthe text.

The contents are perfectlyadequate for an introductionto Nascom machine -code pro-gramming, but the provision ofa few extras could have easilylifted the text into a higherclass altogether. A full list ofZ-80 operation codes,mnemonics, timings, and asymbolic description of eachinstruction would only take afew extra pages but wouldmake this a useful referencetext once the reader has gainedproficiency. A simple indexwould help.

Most valuably, the inclusionof 12 or so useful subroutineswould save a great deal ofwasted programming effort asmany readers reinventstandard algorithms.Candidates for inclusion mightbe integer multiplication anddivision - for eight- and 16 -bitvalues - simple floating-point,one or two sorts, a hashingroutine, a search, a randomnumber generator, a simplestorage manager, and routinesto convert printable charactersto binary numbers and viceversa, for integers, decimalsand floating-point. Such sub-routines would serve the addit-ional functions of providingsubstantial examples of goodprogramming techniques.

With the additions men-tioned, this would be an except-ionally good text for readerswho want to teach themselvesmachine -code programmingwith a Nascom. It should bestressed, however, that thereare some disadvantages tolearning programming by start-ing at the machine -code level.

Real dangerThere is a danger that the

detail of registers, bits and in-struction codes will obscure thereal nature of the problembeing solved, and that thenewcomer to programming willdevelop a preoccupation withimplementation details andefficiency which will make itharder to solve the larger -scale,complex, interesting problemsof computing.

There is an increasinglywidespread view among pro-fessional programmers thatassembly or machine -code pro-gramming should be reservedfor the few small sections ofprograms where the access tomachine instructions is essen-tial, and that high-level lang-uages should be used else-where.

The pressures on amateursare, of course, different andthey have different interests,but anyone who plans a careeras a programmer might do wellto remember the professionals'increasing preference forhigher -level languages.

Conclusions A valuable book, providinga clear and accurate introduc-tion to Z-80 machine -codeprogramming and the Nascom. With a few additions this

book could be exceptional;with its present contents it isstill a thoroughly satisfactorybook and good value formoney.

Martyn Thomas

Business informationprocessing with BasicGeorge Struble. Published byAddison Wesley PublishingCompany. 354 pages hardback.ISBN 0 201 07640 3.FIVE TO 10 years ago it seemedas if everyone able to programwas writing books on IBM360/370 assembler. One textstood out as a standard againstwhich all the others were judgedand found wanting; one texthad clearly been written bysomeone who had considerableexperience of teaching the sub-ject successfully.

That book was written byGeorge Struble, and if anyreader is looking for a text-book to serve as a tutorial textand reference book on IBMassembly language, BAL,Struble's book can be thor-oughly recommended.

Nowadays, it seems as ifeveryone who can bothprogram and spell is rushing topublish a book on program-ming in Basic, and once againGeorge Struble has rushed tothe rescue with a thoroughly -professional book - onesurely destined to become aclassic and a standard forjudging future texts.

Struble's book is intendedfor students who wish to learnhow to use a computer to solvebusiness data-processing prob-lems. It is equally suitable foruse in a taught course and as aself -study text. No previousknowledge of computers, dataprocessing or mathematics isrequired.

The book starts with anintroduction to computerapplications in businesses, andto the structure, organisationand use of a computer. Pro-gramming is introduced as alogical activity which shouldlead to a clear and correctstatement of the actions whichhave to be performed.

The ideas of structured pro-gramming are introduced fromthe very beginning and arecarried through the text, so theunstructured nature of theBasic language is not allowedto lead the novice programmerinto bad habits which will haveto be lost when a more power-

ful language such as Pascal islearned.

Struble explains in his pre-face that he prefers Basic toCobol or RPG for an introduc-tory business data processingcourse because it lends itself tothis well -Structured, procedur-al approach to programming.

He certainly carries convic-tion - the example programsare very good examples ofclear, efficient, correctprograms. The examples arenoteworthy for other reasons,too. The use of REM is exem-plary and the listings seem tohave been reproduced fromclear computer output, remov-ing the dangers of errors intro-duced in the typesetting pro-cess.

Each of the chapters of thebook ends with a summary ofthe main ideas and with anumber of "questions forimagination and review". Thequestions are well-chosen and,best of all, the odd -numberedquestions have answers givenat the end of the book. There isa glossary and a good index.

Since it is a book for the realworld of business applications,the whole text has a very prac-tical air. Much emphasis is laidon file processing and a chap-ter is devoted to testing and de-bugging. There is also achapter on systems analysis -the process of studying the waysomething is done in a businessand deciding how it can best beimplemented as a computersystem.

The particular dialect ofBasic used in all the examples isDEC -10 Basic, but not all thefeatures of this are used, and,in any case, the use of pseudo -code as a design tool makes iteasy to translate into the localdialect of Basic the reader hasavailable.

According to the preface tothe book, there are a numberof workbooks available givingthe example programs invarious other dialects, butnone of these were providedfor review.

Conclusions An excellent book, thor-oughly recommended toanyone who is serious aboutlearning to program in Basic,particularly for businessapplications. It is destined to become ayardstick for measuring thecomparative success of otherauthors' work. Martyn Thomas

PRACTICAL COMPUTING May 1981 125

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How to translate6502 to Z-80assembly languageTO KEEP things to a manageable size, theprogram is intended to take a general 6502listing, and translate it to a general Z-80listing. Thus, machine -specific sectionsare only translated as assembly code -they are not altered to suit the architectureof the target computer. For example, aPet program may write directly to thatcomputer's memory -mapped display -the translation would not automatically

by David Peckett

write to, say, the TRS-80 display area.Similarly, you will have to make your owndecision about where to put the stack.

In this first article, I shall describe someof the theory behind the program; in part2, I shall give its listing. The second partwill also go into some of the practicalaspects of using the translation program. Ihave to assume all the way through thatyou are familiar, to some extent, with thetwo micros' assembly languages - if youneed more details, may I refer you to myrecent series on the subject?

First of all, though, what is the use ofsuch a program? If you only use a high-level language such as Basic, it is of novalue at all. However, if you work inmachine code, you will often meet appar-ently useful listings you cannot usebecause you have the wrong micro.

Figure 2. Basic Z-80 architecture.

For instance, you might want to take aprogram for the 6502 in an Apple, andrun it on your Video Genie Z-80. To do it,you would have to understand fully theoriginal listing, and effectively work outits flowchart. You could then re -write it inZ-80 code. A translation program woulddo all this work for you - feed it 6502code and it gives you Z-80 code.

Why 6502 to Z-80 translation? Thereare two main reasons. In the first place, itis easier than the other way, and in thesecond place, I own a Z -80 -basedcomputer.

At this point, it is worth seeing just whyit is easier to go from 6502 to Z-80. Forthose of you who did not see my earlierseries, let us have a quick look at thearchitecture of the two micros.6502 architecture. Figure 1 shows thebasic 6502 configuration. The micro has asingle eight -bit accumulator, in which allthe arithmetic is done, and a status regis-ter, containing flags which show theresults, e.g., carry generated, accumulatorzeroed, etc., of the majority of the oper-ations performed.

There are two eight -bit index registers,X and Y, which are, in many ways, inter-changeable and can be used for temporarydata storage, as loop counters, and asindices for the micro's numerous address-ing modes. I shall return to the subject of

7 0 7 0

A F

B C

D E

H L

7 07 0

15

7

At

0 7 0

Ft

IX

BI CI

DI

H Lt

7 07 0

0

I Y

SP

PC

PRACTICAL COMPUTING May 1981

Figure I. 6502 architecture.

6502 addressing modes in more detaillater.

The 6502 also has an eight -bit stackpointer, SP, which is used to point to astack permanently located on page 1 ofmemory, and a conventional 16 -bit pro-gram counter, PC.Z-80 architecture. The architecture of theZ-80 is shown in figure 2. The micro isobviously much more complex than the6502, and its structure centres around twosets of working registers. It can use eitherset at any given time, but not the twotogether.

Each set has an eight -bit accumulator,A, with its associated flag register, F,and six general-purpose eight -bit registers,B -E, H,L. These six registers may be con-catenated into three 16 -bit registers, BC,DE and HL, in order to perform eitherlimited 16 -bit arithmetic, or to give poin-ters to anywhere in the micro's memoryspace. HL is more useful than either BCor DE.

The Z-80 also has a 16 -bit SP, whichmeans that the stack can be anywhere inmemory, and a 16 -bit PC. It also has two16 -bit index registers, IX and IY. Theaction of these two is very different from

PRACTICAL COMPUTING May 1981

Machine code

that of the 6502 X and Y, and I shall notbe using them. So you can forget aboutthem again.Similarities between the micros. Bothmicros have an eight -bit accumulator, inwhich virtually all arithmetic isperformed, and both offer substantiallythe same operations - the Z-80 actuallydoes a few more than the 6502. The resultsof the operations are reflected in the flags,and both chips have almost equivalentcarry, zero and sign flags. The PC oper-ation is effectively identical in the twomicros, and the 6502 eight -bit SP is asubset of the Z -8016 -bit one.Major differences. The most importantdifference between the two micros lies intheir addressing modes. The 6502' has avery rich choice of indexed, indirect andcompound modes, as well as the moreobvious immediate and absolute modes.

The Z-80, on the other hand, effectivelyhas only immediate and indirect oper-ations; the latter use HL as a pointer. It ispossible to load and store A via absoluteaddressing, but you cannot, say, adddirectly to A in this mode. The micro hasa form of indexing, but as I mentioned, it

(continued on next page)

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(continued from previous page)is totally dissimilar to that of the 6502.

The other major area of difference is inthe way that the two micros use theirflags. For a start, the 6502 sets its flagswhenever it loads or manipulates A, X orY; the Z-80 alters flags only after an arith-metic or logical operation. In subtractionand comparison operations, the 6502 setsits carry flag to show no borrow, while theZ-80 clears it to show the same state.During addition, both micros work in thesame way.

The Z-80 lacks the 6502 break anddecimal flags, and its overflow flag is onlyroughly equivalent to that in the 6502.The Z-80 does not have an interrupt flageither, but it can obtain the same effectanother way. On the other hand, the Z-80has two flags which the 6502 lacks.

That sounds like a depressing list ofdifferences, but when you examine them.it is possible to fool the Z-80 intobehaving much like a 6502. There aresome grey areas, like the overflow flag,but in practical terms they are not

ABS,Xgives:

LD HL,ABSCALL 1XIX

!XIX EX AF,AF'ADD HL,BCEX AF,AF'RET

;SAVE FLAGS;INDEX;RESTORE

Figure 3. ABS,X mode.

important. In fact, there are only four6502 instructions which cannot be trans-lated to a Z-80 format. They are SED, SEtDecimal, CLD, CLear Decimal, BRK,BReaK, and BIT, Blt Test. Otherwise,translation is possible.

The basic translation approach is to usethe registers of the Z-80 to emulate thoseof the 6502. The two accumulators, flagregisters, SPs and PCs are equivalent andso present no problems. C is used to repre-sent X, and E models the Y register. Bykeeping B and D at zero, we can then, asyou will see, work through HL to obtainthe same effects as the 6502 addressingmodes.

You will probably have gathered bynow that the translation program willhandle one 6502 instruction at a time -not an ideal approach. It was constrained,however, by a need to fit the program into16K. With more RAM, it would not betoo difficult to generate a rather more in-telligent program, able to translate thesense of small blocks of 6502 code intoequivalent Z-80 instructions.

Inevitably, this translation approachcauses a growth in code size. A translatedprogram will take up about three times asmuch RAM as the original, and run atabout one-third of the speed. In realterms, I do not consider either of thesepenalties would be significant in the vastmajority of cases. The need to watchevery last byte and microsecond is often ahangover from the very early days of com-puting.

So, we will translate programs by taking

A. Untranslatable:BIT, BRK, CLD, SED

B. Single -line, no operand:CLI, DEX, DEY, INX, INY, NOP,PHA, PHP, RTS, SEC, SEI

C. Single -line with operand:BCC, BCS, BEQ, BMI, BNE, BPL,BVE, BVS, JSR

D. Standard format:ADC, AND, ASL, CMP, DEC, EOR.INC, JMP, LSR, ORA, ROL, ROR,STA, STX, STY

E. Irregular - short:CLC, PLA, PLP, RTI, TAX, TAY,TXA, TYA

F. Irregular - long:CLV, CPX, CPY, LDA, LDX, LDY,SBC, TSX, TXS

Table I. 6502 instruction categories.

a single line of 6502 code, and replacing itwith functionally equivalent Z-80 code.With an operation like ADD, or LDA,this is quite straightforward. Some oper-ations, for example CLV, are much morecomplex.

If you like, the translation program is aspecialised macro -assembler for the Z-80.On the other hand, it is also an off-line6502 emulator; on-line emulators slowexecution time by a factor of 50 or so.

The first problem, then, is how to trans-late the 6302 operations. I have not spaceto list all the details - if you really wantto know, you can winkle them from theprogram listing next month. I will say,however, that the 6502 instructions fallinto six general categories - table 1.

Untranslatable instructions are self-explanatory. The single -line commandsare ones in which, as you might guess, asingle line of Z-80 code can replace asingle 6502 operation. Some of thoseoperations use implied addressing, while

gives:LDCALL

IXFY EXADDEXRET

ABS,Y

HL,ABSIXIYAF,AF'HL,DEAF,AF'

Figure 4. ABS,Y mode.

the second group, all branches and jumps,use a relative or absolute address. To giveexamples, the 6502 instructions:

DEYand:

BNE LOOPcan be translated exactly by:

DEC Eand:

JR NZ,LOOPThe standard multi -line translations

define a group of commands in which thebasic operation can be translated by asingle line, which must then be topped andtailed by other lines to control flags andthe addressing mode.

All the instructions in the standardgroup need identical topping and tailing.For example:

ADC STOREIcan be translated as:

LD HL,STOREIADC A, (HL)

and:

PRACTICAL COMPUTING May 1981

Machine codeFOR TEST

becomes:LD HL,TESTXOR (HL)

In general, all these translations involvesetting HL to the operand address, andthen performing the equivalent Z-80 oper-ation using HL as a pointer.

The first three groups of translatableinstructions obviously lend themselves totranslation by a methodical technique. Wehave only to identify the operation, pro-vide the single equivalent Z-80 opcode,and add the operand, which has a regularformat.

The last two categories, however, donot fall into a regular pattern. The onlyreason that I think of two categories at all

gives:

IXIND

(IND,X)

LD HL,1NDCALL IXINDEX AF,AF'ADD HL,BC ;NEW POINTER

ADDRESSLD A,(HL) ;LOW BYTE...INC HLLD H,(HL) ;HIGH BYTE...LD L,A ;...OF POINTEREX AF,AF'RET

Figure 5. Indexed indirect.

is because of the way in which the trans-lator works. Each 6502 instruction inthese groups must be handled as an indiv-idual. For instance:

TAXbecomes as:LD C,AINC C ;THESE 2 LINESDEC C ;SET THE FLAGSwhile:

CPY SABCDhas to become:LD D,A ;SAVE ALD A,E ;A = YCMP OABCDHCCF ;ADJUST CARRY FLAGLD A,D ;RESTORE ALD D,B ;D=0 AGAIN

We have to adjust the carry flagbecause the two micros affect it in diff-erent ways. In the translated program, theflag is held at its 6502 status. It has,therefore, to be complemented before andafter subtraction, and after compares, tokeep things in order.

In fact, the flags cause a problem all theway through, as the 6502 changes themfar more often than the Z-80. I found thatthe easiest way to set the flags after, say,loading A from memory was to use:

INC ADEC A

The shorter alternative, 'OR A', wouldzero the carry flag, which we do not want.

It is no use being able to translate oper-ations of a 6502 if we cannot also translateall its addressing modes. The absolute andimmediate modes are not too difficult,and neither is the pure indirect mode -but only JMP (x) uses that. It makes nodifference to the translation whether ornot Page zero addressing is in use - theZ-80 always uses 16 -bit addresses.

Somehow, though, we have a deal with

PRACTICAL COMPUTING May 1981

the 6502 indexed, indirect -indexed andindexed -indirect modes. Fortunately, therules for each of these modes are preciselydefined, and, at the expense of a few linesof code, it is possible to emulate them allwith a Z-80.

The basic technique I chose was alwaysto load HL with the central label of theoperand, e.g., 'TOTAL' from 'LDA(TOTAL,X)'. It is followed by a call toone of four possible subroutines, whichmodify HL to point to the actual addressintended. When the whole program istranslated, any of the four subroutinesactually called by the translation is addedto the output. Figures 3-6 show the foursubroutines.

Why subroutines? Mainly to minimisethe size of the translated program. Inlinecode would run a little faster and wouldavoid the slight risk of the subroutine'scorrupting the stack. On the other hand, itwould make the translation much longer.Using macros would, at least, control thesize of the output listing, but would stillgive plenty of object code. Furthermore,not all Z-80 assemblers have a macro facil-ity. I decided, therefore, that the sub-routine approach was the least undesir-able one.

As an example of this technique inaction:

FOR (STORE2),Ytranslates as:

LD HL,STORE2CALL INDIXXOR (HL)

The heart of the translator is its hand-ling of the 6502 operations and addressingmodes. Once that is resolved, the rest ofthe program reduces to little more than

gives:(1ND),Y

HL,INDINDIX

INDIX AF,AF'A,(HL) ;LOW BYTE...HL

LDCALLEXLDINCLDLD

ADD HL,DEEX AF,AF'RET

H,(HL)L,A

;HIGH BYTE...;...HL =POINTER;OFFSET

Figure 6. Indirect indexed.

control structures and facilities for read-ing the source code and outputting thetranslation.

I do not intend to go into the details ofthe actual implementation - I shall coverthat in part 2. It is, however, worth look-ing at just what the program has to do,and how it should go about doing it.

A program of this complexity is diffi-cult to describe with flowcharts. A moreflexible technique is to use a ProgramDefinition Language, PDL, and listing 1

is a specification for the translator,written in a simple PDL.

If you have not seen a PDL before, itdescribes a program in a format inde-pendent of any specific programminglanguage - actually, it looks vaguely like

(continued on next page)

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Price: E30.00 in EPROM.BAS12K - a 12K BASIC interpreter offering 11 digit

precision arithmetic, PRINT USING, IFTHEN . ELSE and other advanced

features.Price: E25.00.NASGEN - a fast 3K assembler generating a full

symbol table and with many assemblerdirectives and commands.Price, E15.00 on tape. 125.00 in EPROM.

NASNEPA - a 2 'hi( disassembles which interfaces toNASMON's front panel to produce singlestep disassembly. Optionally it produceslabels and 0/13 may be directed to a testbuffer suitable for NASGEN.Price, £10.00 on tape, E15.00 in EPROM.

All the above software runs under NASMON exceptNASPAS which can run under NASMON or NAS-SYS.All prices are fully inclusive.FREE a free CHESS program with every order ofNASMON.Full details may be obtained from:

HisoFr 60 Hallam Moor, UDEN, SWINDON, Wiltshire.

Circle No. '191I 29

MAKE THE MOST OFYOUR MICRO

A RANGE OF ONE AND THREEDAY COURSES COVERING THEFOLLOWING:CPM, BASIC, SYSTEMS ANAL-SIS AND DESIGN. BUSINESS.MAN'S OVERVIEW ANDWORDSTAR

CONTACT

THE EDUCATION CENTRE70-72 HONOR OAK PARK SE23

TEL: 01-699 2202

Circle No. 192

MAINTENANCE ORSERVICE CONTRACT FOR

APPLEThroughout North West EnglandSame day serviceVery attractive ratesPlease write for details or phone

NORTHERN COMPUTERS128 Walton Rd., Warrington WA4 6NP.

0925-601683

SUPERB QUALITY

OLIVETTIDAISYWHEEL PRINTERS

f 1 295EVERYTHING FOR APPLEPART EXCHANGE YOUR SINCLAIRZX80 FOR AN APPLE.SECOND HAND SINCLAIRS £59SUBJECT TO STOCK

NORTHERN COMPUTERS128 Walton Rd Warrington WA4 6NP

0925-601683 Circle No. 193

ZX80ACORN ATOM!

The monthly magazine INTERFACEgives at least six complete programsfor each computer, plus hints andtips.

Large s.a.e. for free copy.

INTERFACE 44 EARLS COURTLONDONROAD,WS 6EJ.

130

Circle -No. 194

(continued from previous page)

Pascal. The PDL itself has very few re-served words - BEGIN, END, IF, ENDIF, THEN, ELSE, DO WHILE, etc. Theydefine the program's flow, and are alwayswritten in capitals. The other words incapitals are the names of functionalelements of the program - roughly, theyrepresent subroutines. The lower-case textshows what each part of the program hasto do.

With this approach, you can define aprogram in as much, or as little, depth asyou want before you start coding. Also, asyou can see, it forces you to use a struct-ured approach. It is, therefore, a goodway not only of describing a program, butit is also a good way of planning one.

I hope that the listing is reasonably easyto follow, and shows the logic of theprogram clearly. You have probablynoticed that it is rather short on descrip-tion in some areas, and that it is for one oftwo reasons.

The segment 'TRANSLATE LINE' isalso very brief, and I have only given oneexample of the routines it calls. I have notshown the details of translating specific6502 operations. If you want to know howeach opcode is tackled, you can work itout from next month's listing.

The translation has to do a reasonableamount of syntax checking. However, donot expect it to do a full check of thesource code. It only has to look for errorswhich might confuse it. Examples are: Comments not starting with `;'. Operation field not having three char-

acters. More than six characters in a label. Labels not starting with a letter. Non -label, or non -immediate, operand

fields.Some errors could, therefore, slip

through, but should be caught by the Z-80assembler after the translation.

In next month's article, I shall detailhow to use the translator. It is worthnoting, however, a few of its limitations. Ido not think that any are too serious. Theoperand field can only be a label, or animmediate quantity, in the latter case, itmust start with `#'. In other words, youcannot use: LDS $12137

or similar expressions.The 6502 has a very useful ability to

handle BCD quantities directly. Withmore space, that could have been trans-lated, but I could not fit it into 16K.Because the Z-80 PUSHes and POPsmove two bytes at a time, compared to the6502's one, you can only have a maximumof 128 items on the stack at any one time.That is because the translated program'sstack must be confined to a single page.Also, manipulating data in the stack mayoccasionally cause corruption.

On the other hand, the translator willhandle a more complete and rational setof addressing modes than the 6502provides. As far as the program is con-cerned, every instruction which addressesmemory can use any addressing mode

other than implied. As you know, the6502 imposes an apparently arbitrary setof restrictions on what modes you can usewhen.

This bonus feature of the translatorarose because it was easier to leave in,rather than to try to trap all the exceptions- now you can use `STX (IND,X)' withimpunity.

Listing I.

BEGIN TRANSLATIONINITIALIZE SYSTEMDO WHILE there is a program to be translated

INPUT DATAIF data overflowTHEN

warn operatorENDIFDO WHILE there is data to be translated

PARSE DATA LINETRANSLATE LINESAVE TRANSLATION

ENDOWRAPUP TRANSLATION

ENDOEND TRANSLATION

BEGIN PARSE DATA LINEIF comment lineTHEN

indicate comment lineELSE

read label, operation, operand, comment fieldsENDIFCHECK FOR SYNTAX ERRORSIF no errorsTHEN

BEGINIDENTIFY OPCODEIF opcode OKTHEN

IDENTIFY ADDRESS MODEELSE

set error flag

ENDENDIF

END PARSE DATA LINEBEGIN TRANSLATE LINE

IF errorTHEN

INDICATE ERRORELSE

CASENTRY operation typeCASE untranslatable

INDICATE UNTRANSLATABLECASE single -line and no operand

TRANSLATE ONE LINECASE single -line and operand

TRANSLATE ONE LINE AND OPERANDCASE 'standard' group of operations

STANDARD TRANSLATIONCASE irregular -short

TRANSLATE IRREG-SHORTCASE irregular -long

TRANSLATE IRREG-LONGENDCASE

ENDIFEND TRANSLATE LINE

BEGIN SAVE TRANSLATIONwrite 'output' to VDUIF tape drive switched to 'record'THEN

WRITE OUTPUT TO TAPEENDIF

END SAVE TRANSLATION

BEGIN WRAPUP TRANSLATIONIF 'IXIX' calledTHEN

'output' ' IXIXSAVE TRANSLATION

ENDIFIF 'IXIY' calledTHEN

'output' = IXIYSAVE TRANSLATION

ENDIFIF `IXIND' calledTHEN

`output' = IXINDSAVE TRANSLATION

ENDIFIF 'INDIX' calledTHEN

'output' = INDIXSAVE TRANSLATION

ENDIF'output' ---- 'END'SAVE TRANSLATION

END WRAPUP TRANSLATION

BEGIN CHECK FOR SYNTAX ERRORSIF bad labelTHEN

set error flagELSE

IF operation format wrongTHEN

set error flagELSE

IF comment field format wrongTHEN

set error flagENDIF

ENDIFENDIF

END CHECK FOR SYNTAX ERRORS

BEGIN IDENTIFY OPCODEcheck list of allowable opcodes

PRACTICAL COMPUTING May 1981

Machine code

IF opcode foundTHEN

record opcode numberELSE

set error flagENDIF

END IDENTIFY OPCODE

BEGIN IDENTIFY ADDRESS MODEIF no operandTHEN

impliedELSE

IF operand = 'A'THEN

accumulatorELSE

IF first character a letterTHEN

IF penultimate character aTHEN

IF last character 'X' or 'Y'THEN

INDEXEDELSE

set error flagENDIF

ELSEIF last character alphanumericTHEN

absoluteELSE

set error flagENDIF

ENDIFELSE

IF opening bracketTHEN

IF ',X)' endTHEN

indexed indirectELSE

IF '),Y' endTHEN

indirect indexedIF ')' endTHEN

indirectELS

set error flagEND IF

ENDIFENDIF

ELSEIF openingTHEN

immediateELSE

set error flagENDIF

ENDIFENDIF

ENDIFENDIF

END IDENTIFY ADDRESS MODE

BEGIN INDICATE ERROR`output' = error message + faulty line of source code

END INDICATE ERROR

BEGIN STANDARD TRANSLATIONIF addressing mode unsuited to operationTHEN

INDICATE ERRORELSE

extract translated operationIF immediate or accum. modeTHEN

'output' = label + operation + operand + commentELSE

IF indexedTHEN

select appropriate CALLELSE

`output' = label + `LD HL,' + operand + commentENDIF'output' = 'output' + operation + 'MU

ENDIFENDIF

END STANDARD TRANSLATION

PRACTICAL COMPUTING May 1981

with full Software Support forbusiness and professionaluse, including Invoicing.Ledgers, Stock Control. WordProcessing, Hotel Systems,Petrol Station Management,Data Base. Mailing Listsand many other applications.Dataforce (U.K.) Limited,Bush House, Prince Street,Bristol BSI 4HU.Tel: 279016.

Circle No. 195

UNDECIDEDSTRIKE NOW

OURPET RRP PRICE4008N 8K £450 £4054016 16K £550 £4954032 32K £695 £6268032 32K £895 £806Disk Drive4040 343K £695 £6268050 950K £895 £806Printers4022 8000L £395 £3568024 132COL £1160 £10448026 DAISY £995 £896VAT to be added to the above figures.Carriage 15 per Item.

If you know what you want why wait?These are the prices you need.

ORCHARD COMPUTER SERVICESOrchard House, 21 St Martin's Street,Wallingford, OxonTel. Wallingford 0491-35529OPEN 6 DAYS PER WEEK

Circle No. 196

FULLY ASSEMBLED & TESTED

ProfessionalASCII KeyboardsAll complete with Metal mounting Names

IQ

ken IA ill el

is

0 b61ffiriorigeileffuo-Ardritrii

150 ift of rtOneeri

o MODEL KB 771 B 72 Key £59.50MODEL KB 756 MF 56 Key £39.50

MATER KEYI304 ADSAccessories supplied with Keyboard only:DC to DC Converter DC 512 0.00

(tor operation off single 5v supply)Model 756 ME Only

Edge Connector KR 15 P L1.95Numeric Key Pad KB710 L7.50Plastic Case (Black) KB705 £12.75UK Orders add 15% VAT On order total

Overseas Orders add £2.00 p&p.FULL DATA SHEET ON REQUEST

CITADEL PRODUCTS LIMITEDDepartment PC, 50 High Street Edgware

Middlesex HAS 7EP Telephone: 01-951 1848

Circle No.197131

ADELTA SYSTEMS LTD

Agents for DYNACOMPPET. APPLE II PlusBRIDGE 2.0Hearts 1.5CribbageChessmasterStartrek 3.2Space TiltGames Pack 1Games pack 2GraphixTidyData SmootherFourier AnalyzerTransfer FunctionRegression 1Regression 2Black HoleValdezFlight SimulatorText Editor

SOFTWARETRS 80 (Level Illf7.50£6.25£6.25 (TRS-80 only)£8.30 ITRS-80 only)f4.00f4.50 (Apple only)£4.00£4.00£5.50 (TRS-80 only)£4.50 ITRS-80 only)£6.25E6.25f8.30£8.30£8.30£6.25 (Apple only)£6.25f6.25£6.25

All programs on tape with superb documentation.VAT extra. Postage 20p.Semi for lull detailed list.

32 FINCH ROAD, DOUGLAS, ISLE OF MAN0624 27522

Trade Enquiries Invited

Circle No. 198

Cromemco Users Take Note!

Hard Disk Back UpTape Cartridge Device togetherwith S100 card and special FileSecurity Software for CDOS Et

Cromix.Cromix software provides file and

directory tree back up.

£1950.00(plus VAT)

Now available from:Wheatcroft Hards Ltd.BRACKENHILL, THE COMMON,

BERKHAMSTED, HERTS.Berkhamsted (04427) 3842

Cromemco Software Specialists

Circle No. 199

ITT2020son-wARE APPLE II

DATABASE in sr !

that writes a program. DATABASE cancreate a flexible record -keepingsystem custom designed to YOURspecification.

HUNDREDS MEMBERSHIP DETAILS0 F MEDICAL RECORDS

APPLICATIONS MAILING LISTS, ETCa direct replacement for the CARD INDEX- - - - - - - - - - - - - - - - -Simply draw the format you require onthe screen using the editor. Then letthe computer do the rest! Easy to use.FEATURES: protected screen editingautomatic date and number checkingcomprehensive search & print functions£.120 +VAT. for the complete system!Phone 01-242-7394 or write for details

DISK DEAN LTD23 BEDFORD ROW, LONDON WC1R 4EB

Circle No. 200132

Tracking downthe cause of Pet'sdisc -drive problemsTHE PET dual drive floppy disc unit withits 15 memory chips and two micropro-cessors is a much more intriguing devicethan many conventional disc systems. Myinterest in the operation of the 2040 discunit was aroused when people started tobring their machines to us, I am technicalservices manager at Intelligent ArtefactsLtd, complaining of being unable to loadprograms which had been previouslysaved using the same machine.

After eliminating a variety of problems

by P Krueger

caused by discs being wedged tightly intheir envelopes, or so loose that they didnot settle down on to the conical mandrelcorrectly, and a case of burnt -out inte-grated circuits on the memory board, wewere left with problems which could notbe traced to hardware at all.

The only remaining possibility was thatthe discs were being corrupted in somemysterious way. So a program was writtenwhich would enable a disc to be accessedsector by sector and analysed. Even tobegin to do this, we had to know exactlyhow the disc system operated and howdata was held on disc.

Data is passed between the physical discand the disc unit memory when usercommands 1 or 2 are executed. One blockof data is transferred between a specifiedsector of a track and a buffer in the discunit memory.

Data is transferred between the discunit memory and the Pet memory whenmemory read, M -R, or memory writeFigure I.

commands, M -W, are executed. A bufferpointer command, B -P, is used to indicatewhere in the buffer reading or writing is tostart - see figures 1 and 2.

Track 18 is of special interest whenlooking for any corruption which may becausing loading problems as that is thetrack reserved for disc administration.The first sector on track 18 is the blockavailabilty map indicating how full thedisc is, and also the disc ID - theinformation put in by the user whenNewing the disc.

The rest of the sectors on track 18 areused as a directory of the files stored onthe disc. Each sector of the directory issplit into eight file entries which hold thefollowing information.I. A code to differentiate programs from data

files.2. An address, track and sector, at which the file

starts.3. The name of the file.4. The number of blocks used by the file.

The program was built up to performthe following tasks: Read a block of, or contents of, a sector

from the disc and display it on thePet screen in both Hexadecimal nota-tion and Asci. Hex was used to easescreen formatting.

Each disc sector is displayed on thescreen in two passes; one for bytes1-127 and then after clearing thescreen, bytes 128-255 are displayed.

We decided not to scroll the screenoutput as the information would needto be translated and studied.

There was also another reason why theoutput should be held static on thescreen: the user should be given a

PRACTICAL COMPUTING May 1981

Hardware

The disk itself is structured int the following way

Tracks 1 to 17 split into 21 sectors

18 to 24 " e

25 to 30 " " 18

" 31 to 35 " 17I I

Up to 255 characters may be recorded on eachsector of the disk.

Synch hole for disk sector location

Figure 2.

chance to remove any corruptionsfound on the disc. The edit mode todo this works by the line to bechanged being input by the user,i.e., 1 to 16. The cursor then movesup and deletes the line requested andwaits until the user types the correctdata in decimal notation. The editedsector is then written into the discmemory and then read out again inHex to be checked. Once checked,it can then be written on to thephysical disc itself from the discmemory.

The program was first used on a discwhich would not respond to LOAD "C",8 which should load the first file in thedisc directory, but was instead causingread errors. By running the disc debugprogram, we found the following on track18 sector in the second section of bytes,127-255 - see example 1.

Example I.

The corruption was deleted by re-writing lines 7, 8, 9 and 10 using DiscDebug. The corruption had been causedby the power to the machine being turned -off while the disc was still in the drive.

That has been the most common causeof the disc corruption found so far andillustrates the need to ensure discs areremoved from the drive - even if theyhave write protects - when powering -down. The corruption itself was an errormessage written from channel 15 when thepower was cut. It demonstrates theproblem with two -state systems ofpredicting the result of unexpected powerloss.

Once we had found this method ofediting discs directly, it was tempting toexamine the way programs werestructured on the disc. A program wasassembled which joined two routines

(continued on next page)

nn 00 On 00 On 711:1 Ci

AO 00 on la ci o D F5 D7

00 43 4F 4D 57 4F 52 44

00 52 4F 20 49 49 49 An

00 AA An 4D 41 20 20 1:40

An AO An n0 On 00 On n0

L_10 0000000033312C

00 59 4E 54 41 20 45

00 52 4F 52 20 30 30 20

OA ZA OD 7,n 7,n op 20 20

Circle No. 204133

nn @@@@@@@@

n1 @@@@MoA

50 COMWORDP

AA RO III

MA

:Dalala);ij

=77 @@@@31

YNTW ER

ROR,00,n

00 nmonm

contents ofchannel 15written on to thedisc.

PRACTICAL COMPUTING May 1981

18 to 24 "

25 to 30 "" 31 to 35 "

e" 18

17I I

A Complete New Computer -DrivenHome Study Course in German9 Apple/ ITT Diskettes 6 Audio CassettesTextbook with illustrations 1206 pages)Workbook -- 250 pages Beginners to post 0 -Level.Introductory Offer (till 30 June)£99 excl. VATClassroom version (full sets of textbooks) also avail-able. Try us for single disks of testing routines.Send for Details to..

WIDA Software2 Nicholas Gardens, London W5 5HY

1011-567-6941 or 10621-882-5206

Circle No. 201

MICRO COMPUTER HOBBYISTS

Earn Money Part-timeIf you are a Micro Computerenthusiast or keen to learn andhave two evenings a week freedo not miss this opportunity tocapitalise on your knowledge.For further information write with detailsof your experience to

Box No 100 PRACTICAL COMPUT-ING, QUADRANT HOUSE, THEQUADRANT, SURREY, SM25AS.

Circle No. 202

STOKE on TRENTfor

TUSCANand

TANGERINEand

VIDEO GENIE + SOFTWAREand

BOOKS

MICRO-PRINT Ltd.,59, Church Street, Stoke on Trent.

(0782) 48348. Barclaycard and Access

Circle No. 203

CP/MSOFTWAREFOR MANUFACTURING Et

GENERAL BUSINESS. BILL OF MATERIALS STOCK/WIP CONTROL PIECE -WORK AND PAYROLL ACCOUNTING

ALSO SUPPLIERS OF:-VECTOR GRAPHIC HARDWARETAYLOR MICRO SYSTEMS

HAMSTEAD INDUSTRIAL ESTATEOLD WALSALL ROAD, GREAT BARR,

BIRMINGHAM B42 1DF 021 358 2436

Circle No. 204133

OF:-VECTOR GRAPHIC HARDWARETAYLOR MICRO SYSTEMS

HAMSTEAD INDUSTRIAL ESTATEOLD WALSALL ROAD, GREAT BARR,

BIRMINGHAM B42 1DF 021 358 2436

D BRUCEELECTRONICS

THE BEACON,

BLACKHALL ROCKSCLEVELAND TS27 4BHTel. (0783) 863612

dimensions75 x 50 x 28mm

The KSI is a single connection to theSinclair ZX80. FOR EVERY keyboard entrythe KSI gives you a short Bleep. The KSIis also supplied with the probe and powersupply lead which are already made up,also a diagram is supplied.

A simple connection to the hole alreadyon the Sinclair mainboard takes 5 minutes.

The keyboard sounder adds realism tothe Sinclair ZX80 and also cuts eye fatigue.The total cost including p/p is only £15.

Circle No. 205

SOFTWARETemple of Apshai (L2 16K TRS-80) £16.95Courtball (L2 16K TRS-80) £5.95Martian Invaders (Sorcerer) £11.95Starbase Hyperion (Sorcerer 16K) £13.50Screen Editor (Sorcerer) £8.95Battleship Commander (32K Apple)f11.95Wilderness Campaign 132K Apple) £10.95Dungeon Campaign 148K Apple) £10.95Pascal(16/32K NEW ROM Pet) £29.00The BOOK; Vol. 1 (TRS-801 £8.95Supermap + (TRS-80) £7.95

SPECIAL: f2 for 2 program cassette introducing oursoftware's quality. State which version (Pet, Apple, L2TRS-80, Sorcerer). Cassette is free with any order ofmore than f10 from list above. Many more programsavailable; ask for our catalogue. Written any programs?We pay good royalties. Trade inquiries invited.

Send cheque or P.O. to:C3, Sapphire Software Ltd.

PO Box 244, Milton Keynes

Circle No. 206

APPLE Et ITT2020BUSINESSSOFTWAREProfessionally written packages now availablewith comprehensive manuals, built-in validitychecks, interactive enquiry facilities, useroptions, satisfying accountancy, InlandRevenue and Customs Er Excise requirementsOn diskette under DOS 3.2. in Applesoft withSPACE utility. Not adaptations. Written forApple System. Support all printer interfaces.Sales, Purchases and General Ledgers £295-00each.Manual only £3.Payroll £375. Manual only E4.General Ledger supports Incomplete Records,Job Costing, Branch and ConsolidatedAccounts etc.General Ledger Applications Manual £10.Prices exclusive of V.A.T. From our shop oryour nearest stockist.

COMPIJTECH SYSTEMS168, Flachley Road, London, N.W.3.

Tel: 01-794 0202

Circle No. 207

134

Hardware(continued from previous page)which were originally stored as separateprograms on the disc. The purpose of theprogram was to have one subroutine onthe disc which, although it could not beloaded on its own, was loaded at the endof several other programs.

The program works in the followingway: the user gives the name of the mainroutine, the directory is then read fromthe disc and searched until the program isfound. The program then goes to theroutine of address which is given in thedirectory. The first two bytes found willeither be a 0 followed by a number givingthe number of bytes of program in thatsector or there may be a track and sectornumber indicating that there is more ofthe routine on another sector.

The search continues until the lastsector containing the routine is found.The end of the routine is marked by threebytes, @ @ @ . They are removed and therest of the sector is also cleared of anygarbage left from previous programs -see example 2.

The user is then asked for the subroutine

Example 2.

name. It is found in the same way as theroutine and its header changed from adirect loading routine to a continuationsector. The track and sector of the sub-routine are taken and written into the lasttrack and sector of the main routine. Thatwill cause the subroutine to be pointed toduring the loading of the main routine.The routine can be pointed to by morethan one main routine thus saving discspace. The disc can be edited back tohaving separated programs if requiredusing the Disc Debug program.

Although it is not possible to load thesubroutine, edit it, re -save it and stillensure it is appended to the main routines,it is possible using the disc debug programto edit it directly on the disc. Just as errorscan be overwritten, so minor edits may beperformed using Disc Debug to input thespecial codes used by the Pet disc torepresent Basic commands on the disc.

Disc Debug and Concat are available ona disc, price £14.95. Documentation onlyis £1.98 from the Technical ServicesDepartment of Intelligent ArtefactsLimited.

The following program is shown in its Pet disc form:

10 FOR I = 1 TO 1020 PRINT "EXAMPLE"30 NEXT40 END

Number of bytes in routine

oo 00 2D 01 04 OE

IF 81 20 49 EL 31 A4

1E on ID 04 14 00 99

2[: 58 41 4D 50 4C 45

3C 23 04 1E:300

4B 2:00:000000

5A 2A 2A 2k 2A 2A 2A 2A

k9 2A 2A 2A 2A nn 4F OE

78 07 86 20 CE 28 43 24

87 83 33 32 21_1 A7 20 43

96 82 CA 28 46 53 24

H5 AC C6 28 43 24 29 AA

E4 2C 33 29 =H E

C3 84 03 3E: Ck 28 43

D2 29 E:2 33 34 20 BO 20

El 28 43 24 29 82 79 38

n4

00 7c,

Start of Basic line

01:4 nn

71 70

22 4f

2 ne

29 04

:A 2H

/10t 1 1-1 FOR 1 = I TO 10/120 PRINT"E

;II D 1"11 " XAMPLE'_30_NEXT40 END

#D-all;i1)D

yl

2A icie::+14:+::f :1,, Denotes end ofroutine

H

29 C -<C$

24 -132 ICS

33 -rv.FS$-L

31 11-(C$1 11

OE :/111)H

24

C6 )-T34 r -

20 (1_$)798

HEX ASCI

Garbage fromprevious programs

PRACTICAL COMPUTING May 1981

BUYERS'GUI ESoftwareSoftware packages are listed by application, in alphabeticalorder, with the systems on which each package will run alsolisted alphabetically. The guide is not exclusively for businessapplications : if your company is the source or dealer for apackage with a more unusual application, send us the detailsand we will create a new category.

The usual criteria have been applied. The minimum con-figuration is 32K of RAM, a disc and a printer; the price of thepackage must lie between £50 and £1,000; the companieslisted are the source of the software or the main dealers inthe U.K., and the capacity quoted is per disc or drive.

Machine type by application

Combined-Ledger/Stock/Invoicing

Machine Type Supplier Name Price CapacityApple II Vlasak Electronics Ltd £855Apple II/ITT 2020 Informex London Ltd £298 500 A/CsCommodore 3032 Compfer Ltd £400 variesCommodore 3032 Bristol Software Factory £300 1,000 A/Cs 6,000

transCommodore 3032 G W Computers Ltd £275-- 1,000

£575

PRACTICAL COMPUTING May 1981

LINCOLNSHIRE

APPLEDISTRIBUTORS

Stocks of Apples and most acces-sories Texas, Qume Et Paper TigerPrinters 8" Discs, Corvus Disks forApples.

SOFTWARE

Financial Planning Databases MailingVisicalc Accounts Word Processing.Also the well known "Estate Com-puter Systems" Estate Agents Pack-age in use throughout the U.K.

ESTATE COMPUTER SYSTEMS30 Carre St., Sleaford, Lincs.

Tel: (0529-305637)

Circle No. 208

TANDY TRS 80FULL SALES &

SERVICE IN BRADFORD

PrintersMicroline 80 336.00Microline83 768.00Epson MX80 360.00

ExpansionInterface 32K 283.00Teac Dusk Drive 236.00Twin Teac 440.00

DISKETTES51/4 " High quality diskettes £19.208" High quality diskettes £24.95

EMERGENCY SERVICES AVAILABLEFOR SYSTEM CRASHES

All prices exclusive of VATn rniBRIARWOOD COMPUTER

SERVICES LIMITEDBriarwood House, Preston Street,

Bradford, West Yorkshire, BD7 1NS.Tel: (0274) 306018

Circle No. 209

Software forCP/M Systems* Interpreters and compilers* Programming aids* Database management systems

* Word processingWrite or 'phone for detailed catalogue'

Mike Lewis Consultants Ltd.(ROOM 3148 WILLOUGHBY ROAD,LONDON N.W.3.TEL: 01-794 8838

Circle No. 210

1 3 5

THORNGUARD LTDThe APPLE Agents for

the Wirral and North WalesMemory and Micro Supplies

2114 450nS 2.20 Z80 CPU 6.852708 450nS 4.40 6502 6.95

2716 450nS 5.40 6800 4.50

4116 200nS 1.95 6802 6.80Please add 15% VAT Postage & packing 30p

Barclaycard and Access Welcome

THORNGUARD LTD144 IRBY ROAD, HESWALL, WIRRAL,

MERSEYSIDE L61 6XQ

Tel: 051-648 2162

Circle No. 211

SUPERBRAINSPRINTERS:

MICROLINE 80EPSON MX80NECSPINWRITER

SOFTWARE:M BASICWORD STARUCSD P PASCAL

DISCOUNT PRICESJAGOR TECHNICAL SYSTEMS

81 ATHERLEY ROAD

SOUTHAMPTON 20579

Circle No. 212

DISKWISETHE Apple Agentsin Devon & CornwallPresentQuality Software direct or from yourlocal Apple Dealer.

HOTEL PLAN - Hotel Management systeminc. booking Eti guest billing f475TV RENTAL MANAGEMENT f395

TRADE ENQUIRIES WELCOMEDISKWISE

25 Fore St., Callington, CornwallTel. 05793 3780

-1111193)at5e

compute,, r

Circle No. 213

UK101 SOFTWARE ON TAPEfrom the guy who wrote "La Passe Temps"

GALACTIC HITCHHIKER 18K) An Adventure, all inmachine code. A beauty! 1£7.001SUPERTREK 18K1 Sail boldly through the universe zap-ping moving Klingons in real time. Superb graphics.1E7.00)LUNAR LANDER A real challenge. You won't getdown in less than three hours. 113.001LE -PASS -TEMPS This is what a computer gameSHOULD be like 113.001HANGMAN Excellent graphics . P.E. said so! 1£3.001STARTREK 18K) The old favourite, beautifullypresented. Not real time but great graphics nonetheless116.00) * NEW *MAD MONK 18K) An original graphics Adventure.Something completely different for all the Hitchhikerfans. 117.001Others available include a BASIC TUTOR 18 x 4KPrograms) £12.00 and lots more games.Each program comes on its own cassette by return 1stClass Mail. Available for 16 x 48 or 32 x 48 display andcompatible all monitor ROMs. All inclusive from:

A. KNIGHT (DEPT PC)28 SIMONSIDE WALK, ORMESBY. CLEVELAND

Tel: (0642) 321266

Circle No. 214

136

Commodore 3032 Analog Electronics £550Commodore 3032 Stage One Computers £600 variesCommodore 3032 Logma Systems Design £600 1-6 shopsCommodore 3032 Commodore B M (U.K.) Ltd £650 650 A/Cs/ledgerCommodore 3032 Compfer Ltd £600 500 A/Cs 1,000 itemsCP/M Minicomputer CS Ltd £650 variesCP/M Computastore Ltd £1,000CP/M Minicomputer CS Ltd £850 variesCP/M North Star Benchmark CS Ltd £950 200 A/Cs 500 trans

300 itemsCP/M North Star Profcomp Ltd P.O.A.CP/M North Star Intelligent Artefacts £510 1,500 A/Cs 5,000

transCP/M North Star Instar Business Systems £999 600-2,900Metrotech System Metrotech £500--

£1,000Ohio Scientific Microcomputer B M £656Tandy TRS-80 Microcomputer Applications £90 eachTandy TRS-80 T & V Johnson Ltd £110 750 trans/discTandy TRS-80 Microcomputers Applications £350TECS Jar Software Systems £650 500 A/Cs 300 nom

A/CsZ-80/8080 Graffcom Systems Ltd £995Z-80/8080 Great Northern C S Ltd £995 varies

General Ledger

Machine Type Supplier Name Price Capacity

Apple II Vlasak Electronics Ltd £225 200 A/Cs 1,000 transApple II Computech Systems £295 500 A/Cs 1,700 transApple II/ITT 2020 Systematics International Ltd P.O.A.Commodore 3032 Analog Electronics £450Commodore 3032 HB Computers Ltd £200 Linked to S/L & P/LCommodore 3032 Bhstol Software Factory £300 1,000 A/Cs 6,000

transCP/M Haywood Associates Ltd £500CP/M Median-Tec Ltd £500 500 A/Cs 600 transCP/M Computastore Ltd £ 500 999 A/Cs 99 centres

nine companiesCP/M Ludhouse Ltd £500 200 A/Cs 5,000 transCP/M Comput-A-Crop £400CP/M Benchmark CS Ltd £250 500 A/Cs 5,700 transSDI 00/200 Barcellos Ltd £250Tandy TRS-80 Tridata Micros Ltd £225-- 500 A/Cs 1,000 trans

£375Z-80/8080 Great Northern C S Ltd £275 variesZ-80/8080 Graffcom Systems Ltd £390

Incomplete Records

Machine Type Supplier Name Price Capacity

Apple II Personal Computers Ltd £250 1,000 trans 2,600A/Cs

Apple II/FIT 2020 Padmede Computer Services £450 900 A/Cs 2,000'trans/disc

Commodore 3032., Stage One Computers £750 500 centres 2,300A/Cs

Commodore 3032 Micro Computation £555 120 A/Cs 5,000 transCP/M Profcomp Ltd P.O.A. 2,000 entriesDurango F85 Kesho Systems £1,000Exidy Sorcerer Basic Computing £350 incl. see also Micropute

PRACTICAL COMPUTING May 1981

Buyers' Guide

Job Costing/BillingMachine TypeApple II/ITT 2020Apple II/ITT 2020Commodore 3032Commodore 3032CP/MZ-80/8080

Supplier NamePadrnede Computer ServicesPadmede Computer ServicesStage One ComputersCSM LtdGraf fcom Systems Ltd.Great Northern C S Ltd

Mailing Systems

Machine TypeApple IIApple II/ITT 2020Apple 11/ITT 2020Apple II/ITT 2020Commodore 3032Commodore 3032CP/MCP/MCP/MCP/M HorizonCP/M North StarTandy TRS-80Tandy TRS-80Tandy TRS-80Z-80/8080Z-80/8080

PayrollMachine TypeApple II/ITT 2020Apple II/ITT 2020Apple II/ITT 2020Apple II/ITT 2020Apple lI/ITT 2020Apple II/ITT 2020Apple II/ITT 2020CommodoreCommodore 3032Commodore 3032Commodore 3032Commodore 3032Commodore 3032Commodore 3032Commodore 3032

CP/MCP/MCP/MCP/MCP/MCP/MCP/MCP/M HorizonCP/M North StarDurango F-85Sharp MZ-80KTandy TRS-80Tandy TRS80

Tandy TRS-80TECS

Supplier NameKeen Computers LtdSystematics International LtdGuestel LtdThe Software HouseStage One ComputersMMS Computer SystemsGraffcom Systems LtdMedian-Tec LtdStructured Systems GroupMicrotek Computer ServicesMicromedia SystemsComput-A-CropCleartone ADPT & V Johnson LtdMicro FocusIntereurope S D Ltd

Supplier NameT W Computers LtdIntormex London LtdInformex London LtdAlgobel Computers LtdVlasak Electronics LtdMinster Micro SystemComputech SystemsPetsoft LtdLandsler SoftwareCommodore B M (U.K.) LtdAnalOg ElectronicsACT (Petsoft) LtdL & J ComputersIntex Datalog LtdComputastore Ltd

Haywood Associates LtdMedian-Tec LtdSelven LtdGraftcom Systems LtdPCL Software LtdLudhouse LtdComput-A-CropMicrotek Computer ServicesMicromedia SystemsKesho SystemsTridata Micros LtdA 1 Harding (Molimerx)Tridata Micros Ltd

3 -Line ComputingJar Software Systems

PRACTICAL COMPUTING May 1981

Price£300£300£100£600P.O.A.£300

Price£300£300£190£57£100£250£250£500£50£500£195£78£50P.O.A.£90£500

Capacity1,000 A/Cs 99 centres150 A/Cs300 appointments1,000 jobs 100 people100 activity codesvaries

Capacity500 addresses500 addresses400 addresses750 names & adds350 records3,000 recordsvanes

variesvaries

varies660 entries3,000 names/addressesvaries3,000 entries

Price Capacity£145£50£198 200 employees£295 500 employees£360£199 100 month 50 weekly1379 300 employees£50 - 200 employees£95 incl. 200 employees1150 200 employees£90£195 600 employees£220£195 200 employees£200 &£350 275 & 500 employees£350£500P.O.A.£500 250 employees£600 800 employees/MBYTE£450 300 employees£450Lease varies£495 350 employees£500£250 400 employees£95-£200£218--£375 400 employees£140£250 300 employees

Limited OfferCOMPLETE

FUNCTIONALBUSINESS SYSTEM

£2775.00+ VAT No Extras

INCLUDES FULLY INTEGRATED Very Comprehen-sive Business Software. INTEGRATION Includes:Automatic Update of STOCK, INVOICE, V.A.T,DEBTORS, CREDITORS, BANK, ADDRESSES,STATEMENTS, MAILING LIST etc, etc. FULLReporting Facilities e.g. Up to 30 on Sales Ledger.Any record retrieved within a second User AlterableVocabulary. The Programme is stored in memoryReleasing Both Disks for Data Storage. Power failureonly means loss of actual entry you are working on. TheSystem does not require pre-printed stationery.ALSO INCLUDES THE FOLLOWINGThe INTERTEC SUPERBRAIN 64K. Twin Z80's. 320KDisks. Housed in one Desktop unit. Leader in Perform-ance -Price Field.THE OKI MICROLINE 80 Printer. Quiet and Depend-able. INTERFACE For The Oki.Set Of Manuals.DON'T FORGET. THIS SYSTEM IS COMPLETE FtREQUIRES NO EXTRAS OR SOFTWARE.

Finance Available.Also available our unique Functional BusinessSoftware for

TRS 80 16K LIIwith fast data transfer on cassette, some examplesBANK A/C PROGRAMME22 Column analysis, self totalling on all columns. Keepsfull alpha & numeric records. At command shows 17monthly 8 yearly Totals to date, including Partnersdrawings, Total 0' heads etc. £21.95SALES LEDGERFull record up to 17 headings for each invoice. Totals 8columns, searches 8 totals individual accounts at will,also weeks sales, months individual heading totals,agents sales 8 displays entire records page by page.£21.95MAILING LISTSearches by Name, Town, County & code no. whichcan be used to create your own reference system.Search by name Does Not Require Exact Spelling ToFind. £9.95 All programs are menu driven needing nooperator expertise. Most responses require only singlekeystrokes. Operator errors are correctable. CustomSoftware.TYPER III "Mini Wordprocessor" 112.95Use your Tandy as a Typewriter but have some of thefacilities of a Wordprocessor. No need for a carriagereturn, Automatic Paragraphs, Right Justification.Screen Display 8 Correction During Typing. Choice ofthree Print Sizes etc. Manual Incl. Runs on OKI. Easilyadaptable for other printers.OKI Micro Line 80 £315.00.NEW! New range of Terrific Games. Written to a HighStandard from 15-17.50. All Original. P&P plus .75pence.Quality Plain LISTING PAPER 9%" 11"2000 Sheets 114.00 + £2.55 p&pQuality 4 PART FORMS 81/2"x 11"500 SETS £17.28 + £2.55 pEtp

ACCESS COMPUTERS2 Rose Yard, Maidstone, Kent. ME15 1HN.

Tel: Maid. 106221 58356

Circle No. 215

THE ATOM MAGIC BOOK£5.50

A wealth of games nad other programs plusmuch useful software and hardware informa-tion. A 'must' for every Acorn Atom user.

THE ZX80 MAGIC BOOK£4.75

Games programs, hardware and softwareinformation, and circuits for static and dynamicRAM and I/O extensions.

MAKING THE MOSTOF YOUR ZX80

£5.95Tim Hartnell's superb book on writing gamesprograms for the ZX80, with many manyexamples.

1KZXBO Moving Display Programs on Cassette!!!No flicker, no fuss. S.a.e. for details.

TIMEDATA Ltd. 57 Swallowdale, Basildon, Essex

Circle No. 216137

APPLE DEALERFOR

PETERSFIELD Et PORTSMOUTH

WILL DEMONSTRATECOLOUR GRAPHICS

DATA BASE/MAILING LISTTABS ACCOUNTING SYSTEM

FOR SALES & SERVICE,

ACCESS CONTROL SYSTEMS LTD.72 WINCHESTER ROAD,

PETERSFIELD, HANTS GU32 3PWTel: Petersfield (0730) 5274

dapple Circle No. 217

Business SystemsSystems Development

Programs designedand written for North Star

and CP/M computer systems

Consultancy Feasibility studies Independent advice Project management Single source supply of

complete systems.We specialise in accounting,order processing, invoicingand stock control systems.

McMillan Computing Services3 Tithebarn GroveCalcot, ReadingTel: 0734 414751

Circle No. 218

TRS 80LIGHT PEN

The most versatile and inexpensive peripheral for yourTRS-80 or Video Genie.The Photopen package includes:

A fully assembled Photopen" A cassette of four programs" Four pages of instructions" A 9v battery

The Photopen connects to your system via thecassette recorder and requires no modifications toyour system. Full details of programming in Level2 Basic are given using a simple subroutine in yourown programs. Video Genie users require secondcassette recorder. The Photopen will work withany TV or monitor.Price only £14.99 + 50p p&p.

Business software for minimal 16K Level 2 TRS 80CSL Database Manager E9.50CSL Inventory Manager E13.50CSL Videopad Suite E15.50

CSL MICRODATA4 GREENBARN WAY, BLACKROD, LANCASHIRE

BL6 5TATel. 0204 694265

138

Circle No. 219

Z-8018080 Graffcom Systems Ltd £490 250 employeesZ-80/8080 Liveport Data Products £250 500 employees

Property Management

Machine Type Supplier Name Price CapacityApple II/ITT 2020 Cyderpress Ltd £650 500 properties; 420

applicantsApple II/ITT 2020 Informex London Ltd £298 300 entriesApple II/ITT 2020 Algobel Computers Ltd £650 400 buildings 250

Own 2,000 transCP/M Algobel Computers Ltd £650 2,000 transZ-80/8080 Graham Dorian Software £325 varies

Purchase Ledger

Machine Type Supplier Name Price CapacityApple II Vlasak Electronics Ltd £315 200 A/Cs 1,000 transApple II Computech Systems £295 500 A/Cs 1,600 transApple II/III 2020 Padmede Computer Services £ 300 900 A/Cs 4,500

trans/discApple II/III 2020 Systematics International Ltd P.O.A.Commodore 3032 Microact Ltd £350 2,000 A/Cs 7,000

transCommodore 3032 HB Computers Ltd £350 800 A/Cs, 4,000 transCommodore 3032 Compfer Ltd £300 1,000 A/Cs 7,000

entriesCommodore 3032 ACT (Petsoft) Ltd £120 200 A/Cs 700 transCP/M Haywood Associates Ltd £350CP/M Median-Tec Ltd £500 500 A/Cs 600

trans/ACsCP/M Structured Systems Group £460 variesCP/M Ludhguse Ltd £500 500 A/Cs 5,000 transCP/M Comput-A-Crop £400 500 A/CsCP/M Computastore Ltd £400 500 A/Cs 3,100 transCP/M North Star Benchmark CS Ltd £250 500 A/Cs 2,000 transDurango F-85 Kesho Systems £500Exidy Sorcerer Basic Computing £125 Ind See also MicroputeSD -100/200 Barcellos Ltd £250Tandy TRS-80 Al Harding (Molimerx) £225 1,100 entriesTandy TRS-80 Tridata Micros Ltd £225-

£375 125 A/Cs 1,000 transZ-80/8080 Great Northern CS Ltd £275 variesZ-80/8080 Graffcom Systems Ltd £440

Records Management

Machine Type Supplier Name Price CapacityApple II Courtman Micro Systems £106 100K CharactersApple II/ITT 2020 Diskdean Ltd £120 variesApple II/ITT 2020 Systematics International Ltd £125 1,000 referencesApple II/ITT 2020 Informex London Ltd £198 500-1,200 recordsApple II/ITT 2020 T & V Johnson Ltd £95 112K per driveApple II/ITT 2020 Systematics Intl Ltd £72 &

£175Apple/ITT 2020 The Software House £140 900 recordsCommodore 3032 CPS (Data Systems) Ltd £200 variesCommodore 3032 Amplicon MS Ltd £140 1,500 recordsCommodore 3032 Compsoft Ltd £95-£170 600-5,000 recordsCommodore 3032 Microact Ltd P.O.A. 400K -800KCommodore 3032 Commodore BM (U.K.) Ltd £150 650Commodore Pet Stage One Computers £130-

£250 165K

PRACTICAL COMPUTING May 1981

Buyers' Guide-CP/MCP/MCP/M SWTPC

Clenlo Computing ServicesMedian-Tec LtdVerwood Systems

£90-£325 varies£500

Metrotech System Metrotech £200-£1,000

Ohio Challenger U -Microcomputers Ltd £175+Ohio Scientific Microcomputer BM £175SD -100/200 Barcellos Ltd £500-

£1,000Tandy TRS-80 T & V Johnson Ltd £200Z-80/8080 Structured Systems Group £135 variesZ-80/Cromenco Xitan Systems Ltd £850 4,000 records/disc

Sales Ledger

Machine TypeApple IIApple IIApple II/ITT 2020

Supplier NameVlasak Electronics LtdComputech SystemsPadmede Computer Services

Price£315£295£300

Capacity200 A/Cs 1,000 trans500 A/Cs 1,600 trans900 A/Cs 4,500trans/disc

Apple II/ITT 2020 Systematics International Ltd P.O.A.Commodore 3032 Microact Ltd £350 2,000 A/Cs 7,000

transCommodore 3032 Anagram Systems £320 500 A/CsCommodore 3032 ACT (Petsoft) Ltd £120 200 A/Cs 700 transCommodore 3032 HB Computers Ltd £350. 800 A/Cs 600

trans/ACsCP/M Median-Tec Ltd £500 500 A/Cs 600

trans/ACsCP/M PCL Software Ltd £500 1,000 A/Cs/MByteCP/M Ludhouse Ltd £500 1,000 A/Cs 5,000

transCP/M Ludhouse Ltd £1,000CP/M Computastore Ltd £400 500 A/Cs 3,500 transCP/M Haywood Associates Ltd £350CP/M North Star Benchmark CS Ltd £250 500 A/Cs 2,000 transDurango F-85 Kesho Systems £500Exidy Sorcerer Basic Computing £125 incl See also MicroputeSD -100/200 Barcellos Ltd £250Tandy TRS-80 Tridata Micros Ltd £225-

£325 175 A/Cs 1,350 transTandy TRS-80 Al Harding (Molimerx) £225 1,350 entriesTECS Jar Software Systems Ltd £550 500 A/CsZ-80/8080 Graffcom Systems Ltd £440Z-80/8080 Great Northern CS Ltd £275 varies

Stock Systems

Machine Type Supplier Name Price CapacityApple II/1TT 2020 Microdigital Ltd £225 625 itemsApple II/ITT 2020 Systematics Intl Ltd £500 200-2,500 itemsApple II/ITT 2020 Vlasak Electronics Ltd £285Apple/ITT 2020 The Software House £80 800 itemsCommodore 3032 SMG Microcomputers £395-

£495 2,450-7,000 itemsCommodore 3032 Logma Systems Design £600 1-6 shopsCommodore 3032 L & J Computers £230Commodore 3032 ACT (Petsoft) Ltd £75 2,400 items 1,000

A/CsCommodore 3032 Compfer Ltd £350 200 lines 20 barsCommodore 3032 Microact Ltd £350 2,500 items, 1,000

A/CsCommodore 3032 Bristol Software Factory £300-

£360 2,300

PRACTICAL COMPUTING May 1981

for SHARP

Lots of ill t- MEI( s andPC1211s for IMMEDIATEdelivery. We try to matchbest prices anywhere!!!

King PinComputersPO BOX 40 - STEVENAGEHERTS SG1 2NATEL: STEVENAGE (0438159677

Circle No. 220

AT LAST!A book thatdoesn't pretend

to teach youabout theaBo. Justpage afterpage of great

INVADERS£6.95 *

new games,

plus some

excitingadaptations of

a few oldfavourites.

GALAXY WARS£6.95 *

Both of these incredible games are written by John Edmonds, and containhis Genuine Moving, Completely Flicker -tree Graphics Display! Bothcasseoes are supplied to tit 4K machines. Documentation enclosed. NOWIN STOCK. 1K SUPAPACKS ALPHA, BETA; GAMMA Et DELTA atf4.95* each.

4K WUNDAPACK ONE at CB.95' AND NOW, 4K WUNDAPACKTWO. contains.- ZXW YAHTZEE: LEAGUE CHAMPIONSHIP, BLPCK-JACK (Full graphics) + HEADS WILL ROLL (Cricket with a difference)only f5.95

Incl. VAT Et P+ P Send large S.A.E. for catalogue.Make Cheques/ P.O. payable to: -

SYNTAX SOFTWAREDEPT PC496 COLLINWOOD GARDENS,GANTS HILL, ILFORD ESSEX.

Circle No. 221

SPECIAL CARDS FOR

APPLESDo you want to connect an

APPLE to the OUTSIDE WORLD?We can make this possibleby designing and building

BOARDS CARDS SYSTEMSto suit your needs

Contact:MR P. HERBERT

DAWSON SHANAHAN LIMITED

01-440 9372131415

Circle No. 222

139

1

?MICRO PROBLEMS? Time ledger package - for

time, expenses and salesrecording by project

Fully integrated salespurchase and nominalledger packages

Customised Software Consultancy and Training APPLE II and most micros

covered

DELTIC COMPUTINGMAY PLACE HOUSE, MAY PLACE,BASINGSTOKE, HANTS. RG21 1NX

10256) 59715 Telex: 858151

Circle No. 223

EXCEPTIONAL OPPORTUNITY

Basic ProgrammerREQUIRED

To run his own Micro SoftwareHouse on our premises. Weprovide a telephone, office, aSuperbrain Micro and masses ofwork.

CONTACT

ATLANTIC MICRO SYSTEMS70-72 HONOR OAK PARK SE23

TEL: 01-699 2202

Circle No. 224

FALCON SOFTWARE89 ALLERTON GRANGE WAY LEEDS LS17 6LR

PC -1211 HYPERPACK 1 £8 CESIL INTERPRETER SUBHUNT DALLAS CAPACITOR COLOUR CODES MATHS QUIZ BATTER THE BURTLE SAILING.

PC -1211 HYPERPACK 2 VI MORSE CODE MASS CONVERSION MODULOMATHS PARACHUTING MASTERMIND EMPIRICAL FORMULAE BATTLESHIPS. BOTHPACKS ORDERED TOGETHER - £72.

TRS-80 LEVEL II 16K £8 PROJECTILES WAVES. More under development.S.A.E. for details on ZX-80/ 2X-81 software. 7K and16K.WE GUARANTEE NO LOADING/SAVING PROBLEMSPC -1211 PACKS HAVE FREE LEAFLET ON HOW TOINCREASE TO 7936 STEPS!!! CHEQUES/ P.O.'sPAYABLE TO PC/1211 USERS' CLUB.

ALLOW 21 DAYS FOR DELIVERY

Circle No. 225

Apple -II in ScotlandCore Data Systems Ltd

Suppliers of APPLE hardware andsoftware.We offer advice on the use of micro-computer systems, and undertakethe design of systems to client'sspecifications.Specialists in UCSD Pascal.Now in new premises at:

101 COLINTON ROADEDINBURGH EH14 1AL

Phone 031-443 8710Authorised APPLE Service Centre

Circle No. 226

140

Commodore 3032Commodore 3032

Commodore B M (U.K:) LtdAnagram Systems

£150£395

650500-600 items 255A/Cs

Commodore 3032 SA Systems £650 300 records/discCommodore 3032 Petsoft Ltd £50 2,500 itemsCommodore 3032 L & J Computers £60 500 itemsCommodore 3032 Rockliff Brothers Ltd £120 3,900 itemsCommodore 3032 Stage One Computers £100 650 itemsCP/M Haywood Associates Ltd £350CP/M Median-Tec Ltd £500-

£800CP/M Graffcom Systems Ltd £350 520-6,000 itemsCP/M Cromemco Micromedia Systems £1,000CPM/Horizon Microtek Computer Services £1,000 variesCP/M North Star Benchmark CS Ltd £450 1,000 items 750 transExidy Sorcerer Basic Computing £125 Incl See also MicroputeTandy TRS-80 Microgems Software £150 " 1,000-2,000 itemsTandy TRS-80 A I Harding (Molimerx) £225 630 itemsTandy TRS-80 Cleartone ADP P.O.A.Tandy TRS-80 S A Systems £650 300 stock recordsTandy TRS-80 T & V Johnson Ltd £115 1,000 itemsTandy TRS-80 T & V Johnson Ltd £145 1,000 items/invoicesTandy TRS-80 Tridata Micros Ltd £200-

£375 630 items/discTECS Jar Software Systems £800 10,000 items 5,000

ordersTECS Jar Software Systems £850 1,000 items 300 A/CsZ-80/8080 Graham Dorian Software £325 variesZ-80/8080 Rogis Systems Ltd £500 900-3,500 itemsZ-80/8080 Great Northern C.S. Ltd £275 varies s

Z-80/8080 Graffcom Systems Ltd £340Z-80/8080 Graffcom Systems Ltd £580Z-80/MCZ Software Architects Ltd £600 varies

Word Processing

Machine Type Supplier Name Price CapacityApple II Personal Computers Ltd £150 17 A4 pagesApple II/ITT 2020 Vlasak Electronics Ltd £120Apple 'urn- 2020 Systematics International Ltd £75Apple II/ITT 2020 Guestel Ltd £190 100K charactersApple II/ITT 2020 Algobel Computers Ltd £75 800 linesCommodore 3032 Act (Petsoft) Ltd £325 12,000 bytesCommodore 3032 Act (Petsoft) Ltd £325 12K bytesCommodore 3032 Dataview Ltd £159Commodore 3032 HB Computers Ltd £70 39 A4 pagesCommodore 3032 Commodore BM (U.K.) Ltd £75 &

£150 170 pagesCommodore 3032 Stage One Computers £100 130 pagesCP/M Median-Tec Ltd £300CP/M Computastore Ltd £400CP/M Southdata Ltd £350 160,000 wordsCP/M North Star Micromedia Systems £495Ohio Scientific Microcomputer B M £116Tandy TRS-80 T & V Johnson Ltd £109 10,000 wordsZ-80/8080 Structured Systems Group £120 variesZ-80/8080 Intereurope S D Ltd £500 varies

There is an increasing number of packages which donot fit into any of the standard categories we havecreated and so we have consequently listed themunder the title Miscellaneous. They appear inalphabetical order by machine type. The names of

PRACTICAL COMPUTING May 1981

Buyers' Guide-similar packages can be very different so users of theguide should check every entry under their machinetype. The full address of the supplier can be found atthe end of the guide.

Miscellaneous applications for all machine types

Machine Type Application and Price CapacitySupplier Name

Apple II/ITT 2020 Auction system £650 400 entriesCyderpress Ltd

Apple II Cashflow/Bank forecast £80Vlasak Electronics Ltd

Apple II Credit control £130Microdigital Ltd

Apple II/ITT 2020 Employment Agents' system £298 600 entriesInformex London Ltd

Apple II/ITT 2020 Estate Agents' system £650 280 propertiesCyderpress Ltd 360 applicants

Apple II/ITT 2020 Estate Agents' system £850Systematics International Ltd

Apple II Estate Agents' register £120Vlasak Electronics Ltd

Apple II/ITT 2020 Financial planning £295Systematics International Ltd

Apple II 3D graphics package £150Fylde MicrocomputerServices

Apple II/ITT 2020 Hospital administration £198 300-600 recordsInformex London Ltd

Apple II/ITT 2020 Insurance records £198 600 recordsInformex London Ltd

Apple II Letter writer £80Vlasak Electronics Ltd

Apple II/ITT 2020 Medical records £198 300-600 recordsInformex London Ltd

Apple II/ITT 2020 Modelling, VisiCalc £95 VariableMicrosense Computers Ltd

Apple II/ITT 2020 Pipeline engineering £175Aerco-Gemsoft

Apple II/ITT 2020 Property/Estate system £650 500 propertiesCyderpress Ltd 420 applicants

Apple II/ITT 2020 Property/Estate Agents' £298 300 entriesInformex London Ltd

Apple II/TIT 2020 Property valuation £650Cyderpress Ltd

Apple II Sales analysis £200 500 A/CsMicrodigital Ltd

Apple II Structural engineering design £200James C Steadman

Apple II/ITT 2020 Time recording-solicitors' £198 300 clientsInformex London Ltd

Apple II/ITT 2020 TV rental management system £395Diskwise Ltd

Commodore 3032 Appointments planner £50 200 entriesCommodore BM (U.K.) Ltd

Commodore 3032 Bank account reconciliation £100Stage One Computers

Commodore 3032 Building conversion £300- 320 clausesMicro Computation £400

Commodore 3032 Cash book £90L & J Computers

Commodore 3032 Estate Agents' package £250 325 propertiesStage One Computers

PRACTICAL COMPUTING May 1981

SCHOOL OF

Cranfield ELECTRONIC

SYSTEM DESIGN

MODERN TECHNIQUES INELECTRONIC SIGNAL PROCESSING

An introductory course coveringDIGITAL FILTERS, FFTsMICROCOMPUTERS

CCD AND SAW DEVICES11-15 MAY

ELECTRONICS FORMECHANICAL ENGINEERS

27 APRIL -3 JULYMay be taken in modules

SOFTWARE ENGINEERING ANDDESIGN MANAGEMENT

15-19 JUNE NEW 81Closed courses can be arrangedfor a Company at Cranfield or

elsewhere.Further details from:Short Course Office,

Cranfield Institute of TechnologyBedford MK43 OAL,

Bedford (02341 750111. Exct 284

Circle No. 227

The better CPIM Word Processing system -

MAGIC WANDWe now have in stock the latest version 11.11,

with many new features. MAGIC WAND is easy

and quick to learn, and includes facilities to

merge data from external files. We can tailor the

system to use the function keys on your VDU.Available in 8" or North Star formats. Please

specify VDU and printer types when ordering.

£190.00 plus VAT

Roundhill Computer Systems LtdPO BOX 14MARLBOROUGH, WILTS. SN1 1LGTELEPHONE 0672 54459

BARCLAYCARD

ttty

Circle No. 228

Sii lairMOMProgrammingcur SE Second editionThere are now many books concerning the ZX80 around,and you are probably wondering which to buy.. Thisbook is not just a book of programs - it sets out toimprove YOUR programming skills with minimum efforton your part. It does not leave you with the task oftyping in all the programs yourself; many are on theaccompanying cassette - simply LOAD them and RUN.This gives you more time to learn about them. Thebook is easy to read and deals with arrays, PEEK,POKE, USA and machine code, flowcharts etc.etc. Thecomplete course consisting of book & cassette, costsjust £8.95 inclusive, and when you order it, youwill receive:-

/

FREE

FREE

complete catalogue of ZX80software.

program listing for noughts& crosses - fits in 1K.

FREE voucher giving you 5% offyour next order of ZX80

software.

251 HENLEY ROAD COVENTRU

Circle No. 229

141

ALGOL -60Z80-CPIM, PDP11 PDP8

A family of high level languagesfrom RHA larlinisystems) Ltd.

ALGOL -60, the language from which PASCAL isderived. A mature implementation withcomprehensive operating system and machinecode interfaces.

SYSTEJ-ALGOL, the subset of Algol -60 in whichall the compilers are written. Compiled code isshorter, execution faster.

Z80 based CPIM systems including TRS80RML Algol -60, includes the option of 32 bit integersinstead of floating point. About 7 times faster thanTRS80 level II BASIC, speed comparable withMicrosoft Fortran. Document £10, system £99 + VAT.System -Algol £50+ VAT, free leaflet.

PDP11 WITH RT-11, RSTS, RSX or IAS and PDP8with OS/8 or stand alone

Complete package including both compilers inmachine readable source form ... £250+ VATconsultant.

83, Gidley Way, Horspath, Oxford 0X9 1TQ 1086771 3625

Circle No. 230

LOOKThe latest version of the famous

EPSON TX -80The TOPPER with GRAFTRAX

1131111111.=111This unique option from DATAPLUS gives theTX -80 a FULL HI-DEF GRAPHICS capability.When the bit plot mode is invoked, each bitarriving via the parallel interface individuallycontrols one of the 7 print head needles.Additional facilities include software control ofline feeds in .007" increments, and many others.You have NEVER been offered a better dealthan this.TX -80 with parallel interface £355 + VATGRAFTRAX option £4.50 + VATApple, PET, Sharp, TandyRS.232 Interfaces £ 40 + VATCash or Credit Cards accepted.

DATAPLUS LTD.39-49 Roman Road, Cheltenham.

0242-30030 or 37373.

Circle No. 231

SORT OUT YOUR CATAPPLE AND ITT SOFTWARE

CATSORT' Sorts Disk Catalogue into Alpha Order.Apple/Palsoft and Machine Code. Req 32K £10

CATINDEX Auto. Index of Disks keeps Alpha Order listFull Search edit Fac. Apple/ Palsoft and MachineCode Reqs 24K £12

CUSDOS* Customise your Dos commands. Change'Catalog' to 'Cat' etc.Apple/ Palsoft and Machine Code E10

MORTGAGE AND INVESTMENT ANALYSIS - Severalfeatures incl. mortgage Repayment table. Apple/Palsoft Reqs 16K E20

SHAPER Plot Hires Shapes in Hires and save shapetable on disk or cassette. Apple/ Palsoft. Reqs 16K.

E7.50TELNOS' Personal file of name, address, post code,

tel no and exchange Search any field. Apple/Palsoft. Reqs 24K £ 8

FINDER* Your own personal library index. Facilities tofind mag. articles in seconds. Reqs 24K E10

PLOT -A -SKETCH Hires drawing like you know what.Uses paddles or keys - state option. Apple/Palsoft. Reqs 16K E6.50

CLOCK 12 hr digital clock in machine code 5MORSE Morse Code send and rec. Interface details

supplied. Apple/ Palsoft and Machine Code. Reqs 8K.£25

'Supplied on Disk and reqs Disk Drive.Others supplied on Cassette - Disk £5 extra.

G.A. HUNTINGTON,176 STRINES ROAD, STRINES, STOCKPORT.

CHESHIRE. SK12 3AA.

142

Circle No. 232

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

Commodore 3032

CP/M

CP/M

CP/M

CP/M

CP/M

CP/M various

CP/M North Star

CP/M

CP/M

CP/M

CP/M North Star

Tandy TRS-80

Tandy TRS-80

Tecs

Durango F-85

Z-80/8080

Z-80/8080

Z-80/8080

Z-80/8080

Z-80/8080

Financial planningACT (Petsoft) Ltd

Hotel room systemLandsler Software

Hotel system and billingLandsler SoftwareInsurance Brokers' system £100Stage One ComputersInvoicing/Costing-jewellers' £575CPS (Data Systems) LtdJob/Appointments planner £100Stage One ComputersMachine hire £420L & I ComputersOrder control £250MMS Computer SystemsPrinters' job control £450Stage One ComputersPrinters' quote system £175MicrolandSales analysis £600Logma Systems DesignService company packageStage One ComputersStock/farming livestock £650S.A. SystemsWindow replacement £500CSM LtdWork measurement £150The Alphabet CompanyCashflow forecasting £250Ludhouse LtdFinancial analysis £500Median-Tec LtdHire purchase systemGraffcom Systems LtdInvoice discount/factoringMicromedia SystemsOrder entry & invoicing £350Graffcom Systems LtdP & L budgeting system £495Micromedia SystemsPersonnel records £595Micromedia SystemsPurchasing system £450Graffcom Systems LtdStatistical analysisResearch Resources LtdTime recording £500Haywood Associates LtdVehicle maintenance £195Micromedia SystemsFinancial analysis £55A J Harding (Molimerx)InvoicingTridata Micros LtdProduction analysis £600Jar Software SystemsTime recording/ledgerKesho SystemsAppointments systemGreat Northern CS LtdCivil/structural engineeringdesignEquinox Computer SystemsConference organiser £500Intereurope SD LtdFinancial modelling £500Intereurope SD LtdPersonnel records £500Intereurope S D Ltd

£1,000

P.O.A.

£1,000

£240 pa

£75-150

£1,000

£150 Varies

£430 200 rooms

£295 280 rooms

300 appointments

3,600 orders

130 jobs/disc

1-6 shops

300 records/disc

Depends on system

500-5,000 orders

540-7,000invoices

Linked to stock andsales1,000 products2,500 items

£220-275 Depends on system

£500 varies

30,000 entries

1,000 items100 reports200-300 items

PRACTICAL COMPUTING May 1981

Buyers' Guide --Z-80/8080 Sales analysis retail

Graham Dorian Software£325 Depends on system

Alphabetical list of suppliers

Supplier

3 -Line Computing0482-445496Minster Micro Systems04254-4751ACT (Petsoft) Ltd021-454-5341

Aerco-Gemsoft04862-22881A I Harding (Molimerx)0424-22039Algobel Computers Ltd021-233-2407Amplicon M S Ltd0273-562163Anagram Systems0403-68601Analog Electronics0203-417761Barcellos LtdLeicester 26584/5Basic Computing0535-65094Benchmark CS Ltd0726-61000

Bristol Software Factory0272-314278Cleartone ADP0495-244555Clenlo Computing Services01-653-6028

Commodore B M (U.K.) Ltd0753-74111Compfer Ltd0772-57684

Compsoft Ltd0483-39665Comput-A-Crop01-771-0867Computastore Ltd061-832 4761Computech Systems01-794-0202Courtman Micro Systems0222-495257CPS (Data Systems) Ltd021-707-3866

CSM Ltd021-382-4171

Cyderpress Ltd0491-37769

Address

36 Clough RoadHull HU5 1QL88 Christchurch RoadRingwood, Hampshire, BH24 1DRRadclyffe House66-68 Hagley Road, EdgbastonBirmingham27 Chobham RoadWoking, Surrey GU21 1JD28 Collington AvenueBexhill -on -Sea, East Sussex33 Cornwall BuildingsNewhall Street, Birmingham B3 3QR143A Ditchling RoadBrighton, Sussex BN1 6JA9 Michell CloseHorsham, West Sussex RH12 lIT47 Ridgeway AvenueCoventryKimberley HouseVaughan Way, LeicesterOakworth RoadKeighley, West Yorkshire BD22 7LATremena ManorTremena Road, St Austell CornwallPL25 5QGMicro HouseSt. Michael's Hill, Bristol BS2 8BSPrince of Wales Industrial Estate,Abercarn, Gwent NP1 5RJ15 South View CourtThe Woodlands, Beulah Hill, LondonSE19818 Leigh RoadTrading Estate, Slough, BerkshirePreston Computer Centre6 Victoria Buildings, Fishergate,Preston, LancashireOld Manor LaneChilworth, Guildford, Surrey32 Whitworth RoadLondon SE25 6XH16 John Dalton StreetManchester168 Finchley RoadLondon NW348 Melrose AvenuePenylan, CardiffArden House1102 Warwick Road, Acocks Green,Birmingham B276BHRefuge Assurance HouseSutton New Road, Erdington,Birmingham B23 6QX2 Church LaneWallingford, Oxfordshire

PRACTICAL COMPUTING May 1981

Salescontact

Tim Hill

R Kilpatrick

M Wauchope

Nigel Tylor

John Harding

Steven Linden

Jim Hicks

Ion Quigly

K Tapp

Mike Collier

S Willmott

W J Kyle -Price

E Balding

T Froud

Nick Green

D Steele

Nick Horgan

Jenny Wilson

David Nicholson

Laurence Payne

G Stuckey

N Ashbourne

Peter Mart

C Murphy

COMPUTER MAINTENANCEWe have highly trained engineers oncall throughout East Anglia and theWest Midlands.If you need help, we're only a phonecall away.

To find out more, ring

Attleborough 454342and as for

Martin AvonsCinsal Computer Systems Limited

London Road, Attleborough, Norfolk, NR17 2BX.

CINSAL Circle No. 233

APPLE

WITH 41°Sales TABSand Servicefor Business Systemsin Hampshire Et Sussex

ACCESS CONTROL SYSTEMS LTD72 WINCHESTER ROAD PETERSFIELD, HANTS.TEL: 0730 5274

Circle No. 234

BOOK-KEEPING forACCOUNTANTS Et TRADERSPurchases Day Book, Sales Er VAT to runon a 32K PET.Neat, Clear and Comprehensive Printouts.Error -proof, Fast Er Easy to operate.Computes all NINE Retailer Special VATSchemes.Box 11 Er 12 amounts and End of Yearadjustments, etc.100 Expense analysis + Goods at Zero andStd. Rates.100 Supplier analysis.Approved by Customs and Excise.

Only £250Far further details and sample printout

E. Stanton MBIM, 86 Bracken Drive, CHIGWELL,Essex 1G7 5RD

Tel. 01-600 4318 or 01-505 7830

Circle No. 235

32K VIDEO GENIEUpgrade Kit (20 mins to fit) 49.95Upgrade Kit (factory fitted) 74.95

(inc. Securicor return carr.)

UHF TIIIIIDU (switchable) 74.95inc. Free Sound MOD for V. Genie

Sound through TV Speaker

Sound Kit separately (\LG. oai9y95

Prompt repair service for superboardsand V. Genie

ARC ElectronicsSANDAL, WAKEFIELD, W. YORKS.

WAKEFIELD 253145

Circle No. 236

143

ZX80NEWSFLASH

Campbell Systems announces a flicker -free dynamicINVASION game to fit STANDARD 1K ZX80. Thisamazing program features fired/missed; hit/damagecounts updated in real time, and missiles launched froma moving gun at a moving alien target instantly on thetouch of the trigger key. And, incredibly, an accuratestopwatch clocking in 50ths of a second. All in 1K, andin perfect TV sync. Send f7 for cassette, fullinstructions, and we'll also explain how everything isdone. Also we offer 2K INVASION for £7, or both forES.Also available on cassette for 3K ZX80, we offer theunique DISSASSEMBLER program, which unravelsyour monitor etc in Z80 assembler format.

Campbell Systems (Dept PCI15 Rous Road. Buckhurst Hill, Essex IG9 6BL.

Circle No. 237

GERMAN WHISTThis popular 2 play adaptation of perhaps the most widelyplayed of all card games is now available on cassette ina compulsive computerised version using the high resol-

ution graphics of the

APPLE 11(32K)Each card is pictorially displayed and player control is

maintained solely by means of the games paddles. A singlegame lasts between 5 and 15 minutes but the cumulativescore could take a determined player well into the nightin his attempt to beat the machine. This and other games

are also under development for the

EXIDY SORCEROR andSINCLAIR ZX80 (1K + 16K Version)

For the Apple German Whist cassette and instructionssend a cheque or P.O. for D3.50 (incl. of postage and

packing) to

13 HAWTHORN GROVE, WILMSLOW,

OCCAM SOFTWARE CHESHIRE S69 50E WILMSLOW 524228

Circle No. 238

23807 BYTES FREE That's the memory size returned when youexpand your 8K UK101 or SUPERBOARD withour new:

16K DYNAMIC RAM BOARDFor just £95.00 Fully built and tested Onboard power supply and transformer Socket for further expansion 40 Pin DIL jumper includedSend toBaringwood Ltd., Apt 6,56 Cameron Rd., Seven Kings, Ilford, Essex 153 8LFAdd VAT at current rate Ft. 50 p p

Circle No. 239

Algor

ZX-80 ProgramsFour programs on cassette

MAZE BATTLE: A game of skill for two.MISSILE LAUNCH: Blast the invaders!SKETCHER: A useful drawing programMAZER: A random -maze generator andgraphics analysis program, very flexible.

ALL FOR 1K BYTES

A FULLY EXPLANATORY BOOKLET IS PROVIDEDWITH THE CASSETTE INCLUDING FURTHERUSEFUL SUBROUTINES.

SEND CHEQUE/P.O. TO:ALGORDOVER COURT. ST. JAMES RD.,

NORTHAMPTON. TEL NH 586462

144

Circle No. 24.0

Diskdean Ltd01-242-7394Diskwise Ltd05793-3780Equinox Computer Systems01-739-2387/9

Fylde Microcomputer Services0253 692954G W Computers Ltd01-636-8210Graffcom Systems Ltd

01-734-8862Graham Dorian Software01-379-7931Great Northern C S Ltd0532-589980Guestel Ltd0225-65379Haywood Associates Ltd01-428-9831HB Computers Ltd0536-83922 & 520910Informex London Ltd01-318-4213/7Instar Business Systems01-680-5330Intelligent Artefacts022020-689Intereurope SD Ltd0734-789183Intex Datalog Ltd0642-781193James C Steadman0903-814923

Jar Software SystemsBolton 26644Keen Computers Ltd0602-583254Kesho Systems041-226-4236L & I Computers01-204-7525Landsler Software01-399-2476/7Liveport Data Products0736-798157Logma Systems DesignBolton 389854Ludhouse Ltd01-679-4321Median-Tec Ltd0734-596842Metrotech0895-58111Micro Computation01-882-5104Micro Focus01-379-7931Microact Ltd021-455-8585

Microcomputer Applications0734-470425Microcomputer BM01-981-3993Microdigital Ltd051-227-2535Microgems Software0602-275559

23 Bedford RowLondon WC IR 4EB25 Fore StreetCallington, CornwallKleeman House16 Anning Street, New Inn Yard,London EC248 Lomond Avenue, Blackpool,Lancashire89 Bedford Court MansionsBedford Avenue London WC152 Shaftesbury Avenue

London W I V 7DEdo Lifeboat Associates32 Neal Street, London WC2H 9PS116 Low Lane, Horsforth,Leeds LS18 8PXRefuge House2-4 Henry Street, Bath BA I 11

11 Station ApproachNorthwood, Middlesex22 Newland StreetKettering, Northamptonshire8-12 Lee High RoadLondon SE13 5L061 High StreetCroydon,SurreyCambridge RoadOrwell, Hertfordshire19-21 Denmark StreetWokingham, Berkshire RG11 2QXEaglescliffe Industrial EstateEaglescliffe, Cleveland TS16 OPN18 Manor RoadUpper Beeding, Steyning, SussexBN4 3T1124 Newport StreetBolton, Lancashire5B The PoultryNottingham72 Waterloo StreetGlasgow G23 Crundale AvenueKingsbury, London NW9 9P129A Tolworth Park RoadSurbiton, Suriey KT6 7RLThe Ivory WorksSt Ives, Cornwall TR26 2HF2-10 BradshawgateBolton, Lancashire2-6 Marian RoadLondon SW16 5HR120 Oxford RoadReading, Berkshire RG1 7NLWaterloo RoadUxbridge, Middlesex UB8 2YW8 Station ParadeSouthgate, London N14do Lifeboat Associates32 Neal Street, London WC2H 9PSRadclyffe House66-68 Hagley ROad, Edgbaston,Birmingham B16 8PF11 Riverside CourtCaversham, Reading RG4 8AL4 Morgan StreetLondon E3 5AB25 Brusnwick StreetLiverpool L2 OBJ32 Buckingham AvenueHucknall, Nottinghamshire

R Cornforth

M Kusmirak

B Seedle

T Winter

BarbaraCastledine

1 Clifford

P Clark

Allen Timpany

I Clarke

Stuart Whittaker

K Tayfoor

S Kent

D Sands

E Stoneham

T Ingle

James Steadman

Blackburn

Bob Ellis

Angus Nial

Jack Goodman

E Landsler

G Wilkinson

R Odell

M Ward

W Stevenson

C Ogilvy

Graham Dicker

C Barnes

John Farthing

W Jupp

Graham Jones

Mrs J Wyatt

PRACTICAL COMPUTING May 1981

Buyers' GuideMicroland0723-70715Micromedia SystemsNewport 59276/7

Micropute0625-612818

Microsense Computers Ltd0442-41191/48151Microtek Computer Services0689-26803Minicomputer CS Ltd0494-448686

MMS Computer Systems0234-40601Padmede Computer Services025-671-2434PCL Software Ltd021-544-5071Personal Computers Ltd01-626-8121/2/3Petsoft Ltd021-455-8585

Profcomp Ltd01-989-8177Research Resources Ltd07073-26633Rockliff Brothers Ltd051-521-5830Rogis Systems Ltd0580-80310SA SystemsNewbury 45813Selven Ltd0376-42900SMG MicrocomputersGravesend 55813Software Architects Ltd01-734-9402Southdata Ltd01-602-4604Stage One Computers0202-23570

Structured Systems Group01-379-7931Systematics International Ltd0268-284601T & V Johnson Ltd0276-62506T W Computers Ltd061-456-8187The Alphabet Company03046 7209The Software House01-637-2108/1587Tridata Micros Ltd021-622-6085U -Microcomputers LtdWarrington 54117Verwood Systems0788-87629

Vlasak Electronics Ltd06284-74789

Xitan Systems Ltd0703-38740

17 Victoria RoadScarborough, North Yorks Y011 1SBSeymour House14-16 Chepstow Road, Newport,GwentCommunique Place9 Prestbury Place, Macclesfield,CheshireFinway Road, Hemel Hempstead,Hertfordshire HP2 7PS50 Chislehurst RoadOrpington, Kent BR5 ODJPilot Trading Estate163 West Wycombe Road, HighWycombe, Buckinghamshire26 Mill StreetBedford112/116 High StreetOdiham Basingstoke, Hampshire146-150 Birchfield LaneOldbury Warley, West Midlands194-200 BishopsgateLondon EC4M 4NRRadclyffe House66-68 Hagley Road, EdgbastonBirmingham B16 8PF107 George LaneSouth Woodford London El8 IAN40 StonehillsWelwyn Garden City, Hertfordshire2 Rumford StreetLiverpool L2Keeper's LodgeFrittenden, Cranbrook, KentAllington Lodge, Round End,Newbury, Berkshire RG14 6PLNewhaven-Ludham HallBlack Notley Braintree, Essex39 Windmill StreetGravesend, Kent34/35 Dean Street,London W1V SAP2/4 Avon Trading EstateLondon W146 Criterion ArcadeOld Christchurch Road,Bournemouthdo Lifeboat Associates32 Neal Street, London WC2H 9PSEssex HouseCherrydown Basildon Essex165 London RoadCamberley, Surrey GU15 3JS293 London RoadHazel Grove, Stockport, Cheshire2 Whitefriars WaySandwich Kent CT13 9AD146 Oxford StreetLondon W1Smithfield HouseDigbeth, Birmingham B5 6BSWinstanly Industrial EstateLong Lane, WarringtonVerwood HouseHigh Street, West Haddon,NorthamptonshireThameS BuildingDedmere Road, Marlow,Buckinghamshire SL7 1PB23 Cumberland PlaceSouthampton

R Howard

H Harrison -Allen

Don Cooper

D Page

J Rothwell

B Conlon

D Nicholls

John Packwood

P Hemmings

Steve Derrick

Mr Whitcombe

M Taylor

W Everard

R Crowther

Tom Wood

G Matheson

Tony Macilwaine

N Hewitt

J Clifford

R Young

T Johnson

G Thompson

A L Minter

Keith Jones

A Plackowski

Dr W Unsworth

N Howard

Paul Vlasak

G Lynch

MICRO ADSare accepted from private readers only, pre -paid and inwriting, 20p per word, minimum charge £2.

Please make cheques payable to Practical Computingand send to Room L311, Quadrant House, The Quadrant,Sutton, Surrey SM2 54S.

PET PROGRAMS: Games/Business Software/Utilities for Sale (changing system) Tel. 0427788443.

UK101/SUPERBOARD INTERFACE Upto 32Input/Output, 8 AtoD, 2 DtoA. P.C.B.assembled/tested with I.C. sockets. Add yourown I.C.s and connectors. £29 or SAE fordetails. Mr. D. Butler, 82 Banks Lane, Riddles -den, Keighley, West Yorks.PLAN AND IMPROVE YOUR LIFE with a Bio-rhythm and Compatability program for theSharp MZ-80K. State memory size whenordering, minimum 18K. Cassette £4.95.J. Tyler, 2 Chester Ave., Cranham, Upminster,Essex.

TELETYPE 43 PRINTER (with keyboard) forsale. £550 or offer. Telephone Storrington 2663.

ZX80 SOFTWARE - Four listings for 1K. ZX80.Moonlander (graphics), Pontoon, Calendar,Mathstest. Send £2. to: P. Pickering, 56 LennoxRoad, Todmorden, Lancs. OL14 8QD.

CBM 2001/32K PET, Large keyboard, cassette,toolkit, cover etc. £595. Phone Rossendale26313 Evenings.

DARTS, game of skill and dexterity for Nas-corn 2 with 8K, send £3.50 to P.E. Firmin,63 Lady Lane, Chelmsford, Essex, CM2 OTQ.FOR SALE Teletype 33 KSR excellent mech-anical condition, complete with stand. £170.Sorcerer Development Pac £50. 029 83 4426(Darley Dale)

APPLE II PLUS 48K. Disk with and withoutcontroller (DOS 3.3). 12 inch monitor. Silentypegraphics printer. Applewriter and databasesoftware. (Value £2500). Sell for £1950 o.n.o.Tel. 01-876 4613 Evenings.

UK101 PROGRAMMERS AID. Features Find,Trace, Delete Renumber, Variables List andmore. Super Board compatable (2K machinecode) 021-308-7012 (Richard.16K SORCERER plus dev. Pak, blank EPROMpaks, full range of manuals, software, seldomused, £595 o.n.o. 01-226 1612 (after 7pm).FOR SALE: Tandy Quick Printer II for TRS80,no interface required. £100 o.n.o. Telephone01-543 0360, evenings or week -end.

IBM SELECTRIC GOLFBALL computer term-inal. (Reconditioned) £200 Paper feed byadjustable width tractors or pressure. Ideal forhigh quality output. Non-standard keyboard.Composite computer grade power supply: -+ 5V 5A, -5v 0.5A, + 15v 2A, + 24v 2.5A.Current and voltage protected. £10 - Isolationtransformers, 250v/250v 200W. £5 - ASR33Teletype £200 - High speed cassette unit(RS232) £70. - Suffolk Telephone 0787 76785.LOWER CASE AND TEXT on Hi -Res Screenfor Apple. Software, Demonstration Programsetc. All supplied on cassette. State size ofmachine. £5. V.J.M. Harris, 25 Thirlmere Ave,Nuneaton, Warks.

ZX80 PRINTER Hardware/Software detailsto interface unexpanded 1K ZX80 to Teleprinter.SAE for leaflet or £1.50 to R.T. Barton, 157Duncombe Street, Sheffield S6 3RL.TRS-80 L2 16K, 6 months old, with leads,c/recorder, books, magazines, software. £330.Tel. 01-435 0882, Alan (evenings).

APPLE 32K, Disc Drive and Controller B/W.Modulator. Brand new in makers boxes £1100o.n.o. May split. Westerham (0959) 64393.SUPERBRAIN 64K, 320K disk plus softwareand diskettes. As new. £1,450 (cost new withVAT £1,830). N.E.C. Spinwriter with severalthimbles and ribbons. As new. £1,350 (costnew with VAT £1,550). Tel: 01-599 3943.

PRACTICAL COMPUTING May 1481 145

Peruse ac choose

Epson printers may share asuper, slim, stylish exterior but underneath

are the differences which makes them really special.The MX -80 range has a worldwide

reputation for reliability, superior print quality and price.Now there's a choice to suit your precise needs and pocket.

Take these two for instance.MX -80 F/T offers the usual Epson features - bi-directional,80 cps, 9 x 9 matrix, standard parallel interface, cartridge

ribbon, PLUS the option of friction or tractor feed.MX -80 Plotter/Printer not only gives you an international

character set (USA, UK, Germany & France) in 40, 65, 80 and132 column widths and high general mechanism setting of

96, 115 and 159 column widths, but also boasts high resolutiongraphics. So now you can print illustrations, charts, graphs,

block lettering etc.

We makemore printer mechanisms than anyoneelse in the world - it makes a big differenceFind out more - contact Epson today!

EPSONEpson (UK) LtdSherwood House, 176 Northolt Road,South Harrow, Middlesex HAZ OED Tel: 01 422 5612/4Telex: 8814169

Circle No. 258

Applesoftware from Leicester Computer Centretriecorresp nuent

by R. Wagner* Now with mathematics routine *

THE CORRESPONDENT is sure to be one of themost versatile programs in your library! It can beused as:A Text Processor: Upper/lower case, 1-80 cols.(4 -way scrolling). Text move/copy/insert/delete,tabbing, justify text, auto -centering and more!A Database (with or without printer!) Extremelyfast find routine and easy editing make it a naturalfor free -form data files. Create and fill out forms,access phone lists or index your magazines.A Programming Utility: (printer or not).Examine, edit, transfer random or sequential textfiles. Create versatile exec. files. Even put bi-directional scrolling in your own programs!Use the Correspondent to print-out your Visicalcformula. Apple disk £29.95 + VATSUPER DISK COPY III48K Et DISK II required, APPLE II or APPLE II PLUSSDC is a menu -driven programme that allows manipulation of alltypes of files under DOS 3.1, 3.2 and 3.3. SDC is the only diskutility available for the APPLE that combines these features:COPY single files (Integer, Applesoft, Binary, or Text), COPYDOS, COPY entire disk, UNDELETE deleted files, LOCK orUNLOCK files, PLOT of disk usage, and optional rearrangementof files so that they occupy contiguous sectors for improvedaccess times, SDC supports the wildcard character " = " in filespecifications. SDC makes the conversion to DOS 3.3 less painful(than MUFFIN) and also allows files to be transferred back to DOS3.2 since both 13 and 16 sectored disks can be accessed at thesame time. £24.95 + VAT

Apple -DocBy Roger WagnerAn Aid to the Development and

'Documentation of Applesoft ProgramsThis 3 program set is a must to anyone writing or using programs in Applesoft! It not onlyprovides valuable info. on each of your programs, but allows you to change any elementthroughout the listing almost as easily as you would change a single line!!

With Apple -Doc you can produce a list of every variable in your program and the lineseach is used on, each line called by a GOTO, GOSUB, etc., in fact, every occurance ofalmost anything! You can rename variables, change constants and referenced line numbersor do local or global replacement editing on your listing.

Apple -Doc is a must for the serious Applesoft programmer.Diskette complete with full documentation £24.95 + VAT

©,,, , nPeAwSaCddAitLio-n ro0yRouTrRpAasNcalCliObraMryPATenAabBleLsEyoAuntoexccrietiantge

411 ee 3D graphics, viewable from any angle and distance. As easyto use as Turtlegraphics. Procedures include Ortho,

Perspec, Rotate, View, Move to -3, View -from. Complete with comprehensive instructions£49.95 + VAT

Apple World is here. The fast 3D graphics package thatruns on your Apple II plus. Zoom, pan, tilt and scale your own designson the Apple screen, at only £24.95 + VATPlus a complete range of "off the shelf" programs for finance, commercial, scientificand education. Keep yourself up to date, send for our "Fact Sheets" givingfull program details.Now available Apple FORTRAN, Dos 3.3, Apple Plot

74'; = Ejler,computer centre limited67 Regent Road, Leicester LEI 6YF. Tel: 0533 556268

rand Service Apple III! Send for details now

Circle No. 259146 PRACTICAL COMPUTING May 1981

End of file

Son of Hexadecimal KidSamson Synapse has become a secret computer freak. He has also discovered that he caninfluence living things, causing plants to grow into computer peripherals. Yet when he takes afancy to drinking his new-born sister's blood, things have clearly gone too far.

The cry of Samson's baby sister split thenight. Cleo sat up in bed. "Samson, is

that you? What are you doing"?Samson ran upstairs to his room and bolted

the door. He was shaking. Shame andrevulsion at what he had done swept overhim. Quickly he pulled on his shoes. Down-stairs there was quite a commotion. The babywas still crying, and Cleo was trying tosoothe it. He could hear McNull's raisedvoice and Cleo telling him to be quiet.Presently, there came the sound of foot-steps on the stairs. There was a knock.

"Samson, come out". The door handlerattled. Samson backed towards the window.

The door would not budge. There wasa pause. Then he heard his aunt's voice

giving a command to Piltdown 2 in Esperanto.The wooden latch began to bend and crack.

Samson did not wait for it to break.Clutching his precious potted plant he leaptout of the window and plummeted into thesand beneath. He picked himself up, shookoff the dust, and tore off into the hills. Heran until he could no longer hear theconfusion of shouts behind him.

Next morning he took stock. He wastoo proud to go home, and would not

be welcome there in any case. To visit aNullard Village, even where he was notknown, would be to court death. Yet he hadno idea how to survive on his own in thewild. He was a dab hand with a soldering ironand a wizard at machine code but what heneeded now was food and drink. He wasalready feeling thirsty.

The more he thought about it, the moredepressing it seemed. There was only onething to do. He switched -on the MoonshineMicro, sat down at its keyboard and slotted apair of his home-grown floppies into the discdrives. The drives hummed and the screenfilled up with a cloud of menacing crater -pitted asteroids rushing towards him atalarming speed, cleverly projected to give anillusion of depth. It was his favourite -Astro-Pinball.

Soon he was lost among the meteorites,oblivious to the cares of the world. The

counter at the top corner of the screenclicked up and up as he manoeuvred his waythrough the meteor swarm. He was at thehelm of a great spacecraft which leaped andturned in response to fingertip pressure,weaving past the onrushing planets andzapping any alien ships foolish enough tocross his path.

Higher and higher climbed the score. Hewas intoxicated. Now he was destroyingeverything in his path - comets, moons,planets even stars with the touch of a buttonas he raced to the ends of the galaxy.

PRACTICAL COMPUTING May 1981

Suddenly a cracking twig brought him downto earth again. The sound, though quiet,stood out from the shrill electronic bleeps ofhis video game. He looked around. His eyesprobed the chinks in the foliage. Was it just arustle of leaves in the wind?

That moment of inattention had costhim the game. His starship had ploughed

straight into a neutron start. Now the screenwas a field of little dots of light, twinklingserenely. On the bottom line was an invitationfor him to record his name for posterity.Desite his lapse of concentration he hadbeaten the previous top score by a substantialmargin.

As he tapped in his initials he heard anothertwig snap. This time he was sure: he couldfeel someone's eyes on his back. He sprangup and pushed aside the overhangingbranches. For an uncomfortable second hewas eyeball -to -eyeball with a coarse face.The brow was furrowed in a leering frownand the eyes filled with distrust. Then it fled.

e watched the figure, clad in raggedfurs, loping down away from him. It

was one of the village lads from HappyValley.

"But what the Hell was he doing up here"?Samson asked the heavens out loud. Perhapsthe intruder had been out fur -trapping andhad overheard the Astro-Pinball soundeffects. Perhaps he had been minding sheepand one of them had strayed. The answer didnot matter. What was certain was that hewould head back to his folks and tell themwhat he had seen. A Nullard search partywould be on its way before nightfall.

Meanwhile, far out in the frigid vacuumbeyond the orbit of Pluto, the space

freighter Green Tangerine drifted help-lessly out of control. Her metal sides glinteddully in the faint light from the distantpinprick of fire that was our sun as she rolledponderously end over end.

On the foredeck, Prestel, the ship's parrotand commanding officer, had called the twomost senior of the mutant cybernoids whocrewed the ship to him for an explanation.He directed his questioning at the first mate,an experienced veteran of the space lanes.

"Rom, what's the meaning of this"?"Navigational computer sir. That cosmic

ray storm put the refresh circuits out ofaction".

"Well, can't you fix them? What aboutthe back-up modules"?

"Same problem, sir, we've tried. We'llhave to take her to Arcturus under manualcontrol".

Prestel gnashed his beak in frustration.He thought of the long haul to the repair

depot at Arcturus, limping along undermanual guidance. It would take an eternity.

"Do you realise what we're carrying onthis trip"?

Rom had no idea. He had been surprisedand annoyed by the obsessive precautionsduring loading on Zargon 7. A security guardhad machine -handled him off his own shipwhen he came aboard early unannounced.

"Well I'll tell you. There's no point insecrecy any more. We have a cargo of half-baked ideas to replenish the dwindling supplyat Omega Solaris. It is vital we get themthrough before they go stale".

Rom drew in a long breath. So that wasit. Now he understood the reason for

all the cloak-and-dagger stuff in port. If thesupply of half-baked ideas to the Think Tankin Omega Solaris dried-up, it would throwthe whole galaxy into chaos.

There was silence. Prestel shifted fromclaw to claw on his perch.

"Well"? asked Prestel."Permission to make a suggestion sir''?

chimed in Ram, the other cybernoid, whohad held his peace so far.

Prestel leaned forward. "Yes"?"I was checking the instruments after the

radiation storm to inspect for damage when Inoticed something interesting".

"Go on"."The sensors detected evidence of

intelligent life on the third planet of the localstellar system."

" ntelligent life on Terra Firma? It mustI be an instrument failure"."With the greatest respect sir, there's

only one configuration of signals whichindicates a score of more than 10 billion onAstro-Pinball. I'd know that patternanywhere".

"Astro-Pinball", murmured Prestel as hechewed over this nugget of information.Even their shipboard computer had an Astro-Pinball rating of less than 5 billion. As forRom, he wasn't in the same league. A pilot ofthat calibre, if one truly existed, could notmerely get them to their destination on timebut ahead of schedule. He, Prestel, would beshowered in glory.

He spoke to Rom and Ram. "You twoare going on a little recruiting drive".

"Understand sir", they replied in unison,and started heading towards the exit hatchesat the stern of the ship.

"Oh, and Ram -"."Yes sir", said Ram, pausing at the door."You'd better be right"."I am sir"."Good. Because if you're not back with

your Pinball Wizard within four temporalunits we'll blast off without you". FII

147

Askfor detailsabout AllnaTC

hard DiscSystems

Almarc

VectorGraphicThe complete partnership

in Microcomputing

DATA SYSTEMS148

System VIP* Vector 3 terminal with 6 -slot 5100

bus.* Fast (4 MHz) CPU using the powerful

Z80.* 56K of user RAM.* Serial RS232 port (110-9600 baud

selectable), 3 8 -bit parallel ports.

* 80 x 24 display using 8 x 10 matrix.* Full QWERTY keyboard plus

separate numeric keypad andcapacitance keys.

* UNISTOR disc drive giving 315Kbytes of storage.

PLUS CP/M 2, Microsoft BASIC 80,SCOPE (text editor) and RAID(simulator debugger).

System B* Vector mindless terminal.* Z80 CPU with fast 4 MHz clock.* 64K bank -selectable RAM (56K user

RAM).* 4 serial ports (all switch -selectable

110-9600 baud), 5 parallel ports.* Flashwriter II video board (80 x 24).

* Interrupt handling on I/O board.* Twin disc drives - 630K capacity.* CP/M 2.2 operating system.PLUSMicrosoft BASIC 80, SCOPE (screen -oriented program editor), RAID (fullscreen dynamic simulating debugger),ZSM Z80 Assembler.

System 2800* Vector 3 console chassis with 12 inch

CRT and capacitance keyboard.* Z80 based single board computer

with serial port, 3 8 -bit parallel ports,3 PROM slots and IK RAM.

* 64K dynamic memory board and disccontroller.

* Flashwriter II video board (80 x 24).* 6 slot SI00 motherboard* Switch -selectable asynchronous baud

rates (110-9600 bits/sec).* IBM-compatible DUALSTOR twin

8 inch double density disc drives,giving 2M bytes capacity.

At ALMARC DataSystems, you can be sure ofour experience of hundredsof Vector Graphic systemsinstalled throughout the U.K.- all with 12 -monthwarranty and the back-up offull service facilities carriedout by experienced staff.

ALMARC are thespecialists in Vector Graphicequipment with applicationsin word processing, business

systems, laboratories,research, schools, colleges,universities and industry. Plusan ever-growing list ofcompatible software -Pascal, Fortran, Cobol, APL,Algol, BasicCompilerandothers.

We will be pleased todemonstrate how ALMARC+ VECTOR GRAPHICSystems equals TheComplete Partnership inmicrocomputing.

906 Woodborough Road, Nottingham NG5 SQS.Telephone: (0602) 625035. Circle No. 260

PRACTICAL COMPUTING May 1981

AINIIM1111111111111111111.11111111.1111r

Ri I L2 new low costprinters.

MPI 88G

Full dot addressable graphicsO IK buffer standard, 2K optional Tractor, Paper roll or single sheet feed Bidirectional 100 cps. impact printingO ASCII, 20m/A loop, RS232, IEEEO 80, 96 and 132 ch per lineEl 96 ch ASCII. Upper, lower case +NLQ 11x7.

40 and 80 column impact matrix printers withsensible price tags- just right for the personaland professional user.

EATONLRC 7000+

PRINTERS

/1111111111111011111W

Rugged low cost design matrix impact printer 40 columns, 1.25 lines per sec.O Interface cables for PET, TRS80, ATARI, APPLE

etc. 100 million character head life.

Russet Instruments LtdUnit 1 Nimrod Way, Nimrod Industrial Estate,Reading, Berkshire RG2 OEB, U.K.Telephone 0734 868147 Telex 849721

Circle No. 261

NICE AND EASY DOES ITPanasonic Hardware

+CPS SoftwareThe quality and reliability of Panasonicmicrocomputers is complimented bytwo new CPS programs speciallydeveloped to work with Panasonichardware-OASIS and COMTEXT

v,\DI'' CPS are Panasonic Distributorsye- Would you like to sell Panasonic

micros, OASIS and COMTEXT

CPS (DATA SYSTEMS) LTDThird Floor, Arden House,

Ci__))C 1diOrm2 iWngahrwamickBlrRoad, Green,

Tel: 021-707 3866

-CI IABSmagCONItextims Wordprocessing and

Communications SystemAn interlinked suite of programs forming anadvanced wordprocessing and communica-tions system which facilitates the creation,manipulation and distribution of textsimultaneously around an organisation withoffices in different locations

If you want to know more about OASIS,COMTEXT and Panasonic microcomputers, talkto CPS on 021-7073866 or complete the coupon

MIMI INN INE

B usi ness systemFully integrated

Easy to useLinked Functions

SALESLEDGER

SALESANALYSIS

ORDER ENTRY

- INVOICING MIN CONTROL

PURCHASELEDGER

CPS (Data Systems) Limited, FREEPOST, Birmingham B27 6BR

Please send me details of Panasonic micros,I OASIS and COMTEXT

NameII Position

ICompany Name and Address

A member of the CPS Group Telephone

mom=mmmill CPS where performance and good value matter immimmimm pc.," Circle No. 262

PRACTICAL COMPUTING May 1981 149

SuperFile Ends file -handlingSUPERFILE gives the programmer a:

CONTENT ADDRESSABLE DISC

*COMPLETELY FLEXIBLE - add newinformation and new KINDS of informationwhenever you like. Start with a list of names,addresses and telephone numbers. Then addinvoices, employee details, a stock list. Youdon't have to guess today what sort ofinformation you'll want to store tomorrow.

*WORD PROCESSOR with on-line spellingcorrection coming soon: store all your documentsin the database - indexed by dates, names,subjects.

*THINKS LIKE PEOPLE - is it: Thomson,Thompson, Tomson, Tomassen, Tomassin,Thomasson? No problem: SUPERFILE has afuzzy matching mode which will bring backanyone whose name sounds like Thomson.

*VERY FAST - a//data Items are indexed.Access any Record in an 8MB file (CP/M 2.2'slimit) in 1/5th of a second.

*MOVE UP direct to hard discs and networkingunder CP/NET. SUPERFILE is designed withthem in mind. No changes necessary to programsor files.

*COMPACT - 10K of relocating code thatextends CP/M at the top of memory.

*RUNS WITH MBASIC - you don't have to learna new, complicated database language. Loadand run MBASIC (and FORTRAN or machinecode) just as you would under CP/M. We giveyou a skeleton program in MBASIC - writeyour own code in the middle.

*INTERACTIVE ENQUIRY facility supplied asstandard. Have a quick look at the database anytime you want without writing a program.

*GOING TO MISS FILEHANDLING? Going tomiss paying to have filehandlers written? Tough.

SUPERFILE is written in Z80 machine coderunning under CP/M. It is supplied on 8" SSSD.Dealer enquiries invited.

Prices: £650 (UK and Europe); £50 for demodisk with Enquiry Facility and manual; £10 formanual.

CORRECTOR spelling correction package: £150,Manual £5.

SOUTH DATA LTD221 PORTOBELLO RD, LONDON W11.

Circle No. 263

KRAM ELECTRONICSRUTHLESSLY SLASHESTHE COST OF PRINTING I

Centronics 730 100cps printer £345 Centronics 737 Proportionally spaced word processing quality £395 Case for UK101/ Superboard £24 Pet -Centronics Decoded Interface £50 4K Ram for UK101 £30 Additional Educational Discounts Pet -RS232 Interface £80 Channel Synthesiser for Pet (IEEE Compatible) £50 Numeric Pad for UK101/Superboard £12

KRAM ELECTRONICS30 HAZLEHEAD ROADANSTEY LEICESTER

053-721-3575ALL PRICES SUBJECT TO 15% VAT

ISO

Circle No. 264

PRACTICAL COMPUTING May 1981

SIRTON COMPUTERS

(sc)#(\#

eri4

76 Godstone Road, Kenley (Nr Croydon) Surrey CR2 5AATel: 01-668 0761/2

MIDAS 1: From £750MIDAS 2: From £1580MIDAS 3: From £2150MIDAS 4: From £5900ITHACA-DPS 1: From £1075

MIDAS S.100 SYSTEMS

Our versatile Z80 Microcomputers are available as standard units or custom configured to your exactspecification from a comprehensive range of stocked S100 boards.

Disc storage capacity of the MIDAS 3 can be 2M Bytes, expandable to over 20M Bytes with aWinchester Hard Disc Unit in our MIDAS 4 range.

MIDAS runs CP/ M and MP/ M is also available. Other Software includes M -BASIC, C -BASIC,FORTRAN, COBOL, CIS -COBOL, PASCAL and Word Processing.

A MIDAS 3, with 64K RAM and 2M Bytes storage on two 8" drives with two Serial I/O Portsand CPIM 2 only £2835.

Multi -User System (four users) - MIDAS 3 with four 48K blocks of RAM, 1 MByte disc storage on two8" drives and four Serial I/O Ports, and CP/M 2 + MP / M - £3850.Printers, VDUs and other peripherals stocked to give complete package systems at keen prices.

Business Packages include Accounts, Stock Control, Purchase Ledger etc etc.

Boards stocked from Ithaca, Godbout, SSM, S D Systems, Vector, Micromation, Mullen, Mountain Hardware, Hi -Tech, VideoVector, Pickles Er Trout, Central Data, Cromemco, Thinker Toys - Send for full Price List (many available in kit form).

Processor RAMZ80 Starter Kit £188 Dynamic RAM 16K -64K from £205SBC100 £208 Static RAM 8K -64K from £958085/88 CPU £237 Memory Manager £52Z80 CPU 4 MHz from £130 110

2S/4P prov 4K RAM/4K ROM £169EPROM 2S/2P or 2S/4P or 3P/1S or 4S/2P from £1352708 EPROM (16K) £60 Analogue 8 or 12 bit from £2872708/2716 Programmer from £134 Optically isolated I/O £114

IEEE 488 Interface £350Video Miscellaneous16 lines, 32/64 ch from £104 Real Time Clock £18024 lines, 84 ch from £265 High Dens Graph/8K RAM £333

Hi -Tech Colour £295Disc ControllersVersafloppy S/ DDoubler D/ DMainframesWe are the sole UK Distributor for Integra nd Mainframes and Disc Enclosures, available in nine models including Desk Top and RackMounting, with or without provision for Disc Drives. All units totally enclosed, painted on all external surfaces and complete withpower supply etc.

SoftwareCP/ M 1 5- 2, MP/ M, PL/1, C -BASIC 2, M -BASIC V5, XYBASIC, FORTRAN 80, COBOL 80, CIS -COBOL, PASCAL /Z, PASCAL(UCSD), PASCAL M/T, Forth, MAC, ZSID, Disassembler, Wordstar, Datastar, Magic Wand, Wordmaster, Supersort etc etc.

WRITE OR PHONE FOR CATALOGUEPRICES EXCLUSIVE OF VAT

£198£280

Motherboards - various fromExtender Board/logic probeMaths Board AMD 9511

£34f39

£330

PRACTICAL COMPUTING May 1981

Circle No. 265

151

Your search for the rightprice stops here.

MEPPet

Well known for making shortwork of accounting, word processing,mailing lists. A great buy from NSC.

AppleYou know what the Apple system

will do but you don't know the dealwe're offering. Come and see foryourself.

RairThe exciting new 3/30 system

offering 5 mb of fixed disc storage onbrand new 51/4" Winchester drives.64K Machine £4,313 incl. VAT.Full range of black box systemsavailable. Rental terms available.

152

CromemcoWe can now supply the Cromix

operating system for single and multiuser working. The first big systemoperating system to be offered on asmall system-the only system whichoffers up to 63K memory spaceper user.

Acorn AtomNow available ex -stock. Special

offer to ZX80 owners: We will takeyour ZX80 in part exchange for anAtom.

Used Bargain: Second handZX80's from £50.

North Star HorizonA complete word processing

system extendible from 32K -56KRAM, with up to four mini disc drives,4MHz Z80A processor, serial andparallel I/O ports and extended BASIC.Full range of accounting packagesavailable. You can lease this verypopular system for as little as £25per week.

Bargain Offers

South West Technical Products56K 6809 based system, with twin

8" disc drives and Centronics 779printer. From £3,163 incl. VAT., whilestocks last. Keenest prices around onindividual boards and peripherals.

48K Apple for £695Buy a 16K Apple from NSC

Computer Shops now and get 32KFREE.

After Sales ServiceWhen you buy from NSC Computer

Shops you have the opportunity to takeadvantage of a special service contracton favourable terms.

Order by post with confidenceInstead of calling personally at NSC

Computer Shops you can send cash withorder. Orders are despatched by carrier,please telephone for details of deliverycharges.

BOOKS: Send s.a.e. for our full price list,or call in at our shop to see our wide range ofpublications.

Most of our prices are heavily discountedand therefore payment must accompanythe order. Credit card payments will beaccepted. Please quote credit card numberand type of card.

WE WILL NOT BEKNOWINGLY UNDERSOLD.

N #%

. COMPUTERSHOPS

Computing to suit your size.NSC Computer Shops, 29 Hanging Ditch, Manchester M4 3ES. Ring 061-832 2269 for further information. Circle No. 266

PRACTICAL COMPUTING May 1981

60 CHARACTERS PER SECONDTHE FASTEST DAISY WHEELPRINTER.FAST, heavy duty commercial DAISYWHEEL printer, with high qualityprintout, coupled with low noisenecessary for office environment. 124char: upper/lower case. 10/ 12 chars:per inch giving 126 or 163 columns. 15 inch wide friction platen. BOLDING, underline, and host of otherfeatures. Centronics type parallelinterface as standard options: serialinterface f60 PET interface £65APPLE interface £75.

Made by Ricoh in JapanDEALER ENQUIRIES INVITED

NEW MAXI ANADEX WITHGRAPHICS £895

Takes upto 13.6 inch widepaper Upper/lower case withdescenders f sign 132 or175 chrs/line with double widthprinting* Fast 150 CPS bi-directional logic seeking printing

Heavy duty print head giving650 million chrs print life serial, Parallel and Current LoopInterfaces built in Host of otherfeatures found on printers costingtwice as much.Also AvailableDP8000 £425 (Not Illus)DP 9501 £995 (Same as 9500 Illus)

LONDON COMPUTER CENTRENew! - Improved! NEW LOW PRICE £1095

Additional Facilities -+ Built in proportional spacing+ Look -ahead logic + On -off switchNEW LOW PRICE £1095 TRS 80 Model I Et II

SUPERBRAINAPPLEPET

HORIZON EtcTRACTOR FEED 0/E £175SHEET FEEDER OPTIONAL EXTRA £550

NEW! Revolutionary! Epson MX8OFIT £399the PRINTER with FRICTION Et

ADJUSTABLE Removeable TRACTOR FEEDDual print modes letter quality standard dot matrix

ULTRA QUIET.LOWER CASE DECENDERSBI DIRECTIONAL, LOGIC SEEKINGPRINT HEAD40, 80, 66, 132 Columns per lineUNIQUE BOLD FACE to DOUBLE STRIKE(BUILT IN FEATURE)64 Graphic Characters (TRS80 & Prestel)9 x 9 PRINT MATRIX. f signForms Handling; Top of FormHorizontal and Vertical Tabs.

Centronics parallel interface standard.Optional extra Serial, PET & APPLE interfaces.Easily replaceable head.

characters the head canbe replaced without technical knowledge or assistance for £15.00'Approx. 38,000 copies of A4 letters.

TRS-80MODEL II

State the art second generation computer. Over10,000 already sold in USA; 8 slot bus ensuresexpansion of hard discs & other peripherals., 76Key professional keyboard, self test on power up,TRSDOS & Level Ill basic standard. CPIM availableas option, making a wide range of accounting,educational, scientific & word processing packagesinstantly usable.Nationwide service through 180 Tandy stores Etcomputer centres.NOW WITH CPIM 2.24 £1999

CPM SOFTWAREWord Star f250Word Star Mail/Merge f315Magic Wand E185Magic Wand with dedicated keys £235Data Star £195T/Maker £155Report Writer f90Accounts Packages from £295Payroll from 0295Various other packages available - ask for details

SOFTWARE FOR TRS-80Electric Pencil (disc)Electric Pencil (cassette) £35Scripsit (disc)Scripsit Icassettel £60Mail -Merge for Pencil / Scripsit £45

SUPERBRAIN

111111111111M11111111111111111111111Ir

350K £1595700K £1995 64K RAM Standard

1600K £2595 on all models

NOW with MULTICOLOURED DEDICATEDKEYS for MAGIC WAND, the ULTIMATE

WORD PROCESSOR

VAT Ali Programme (45.00Visicalc f52

MISCELLANEOUSFloppy discs (Box 0110) including library case.

XLtron Silver 5" S/Sided D Densitytor TRS-80, PET; Apple to Superbrain . £25.00XLtron Gold 5" D/Sided I)/ Densityfor Superbrain 130.00XLtron Silver 8" S/Sided S/Oensity 120.00Memorex 8" S /Sided D/Density for TRS.80Model II £35.00Gorse Daisywheels MOORP -1600 Daisywheels £15.002000 Sheets 11" 9.5" Fanfold Paper £15.002000 Sheets 11" x 14" Fanfold Paper 120.00Ribbons, Paper Rolls etc. POA

DEALER ENQUIRIES INVITED ON ALL PRODUCTS

OKI MICROLINE 801132. THE QUIETPRINTER YOU CAN LIVE WITH

NOWWITH SIGN

NOW

The quietiest Dot Matrix available. 40, 80or 132 cols per line excellent printquality 3 way paper handling: letterheads,fanfold, or paper rolls graphics Idealfor software written for large 132 colprinters continuous rating printing day inand day out centronics parallel standard.Options: R5-232, PET, Apple.Dealer enquiries invited.

NEW LOW PRICE £350

TRS-80 MODEL I FROM £312

NEW LOW PRICES48K system with Dual Disk Drives £1095With Epson Printer £1350New green screen VDU with rock steady display.Redesigned 32K expansion interface with trouble freeoperation and two 40 track disc drives.16K Keyboard with Modulator £31216K System: Keyboard, Green Screen to

Cassette f414Dual 40 Track Disc Drives to Cables £42032K Expansion Interface £299

VISICALC for TRS-80 MODEL I £52

LOW COST WORD PROCESSOR IBased on TRS-80 level 216K cassette recorder,electric pencil software, upper/lower case mod,printer interface and OKI Dot Matrix printer.Complete ready to go £895 free mailing list program.WORD PROCESSOR IISame as above but with 48K, 2 disc drivesand ricoh daisy wheel printer £2275WORD PROCESSOR IIIBased on Superbrain Computer shown above.With Ricoh printer to "Magic Wand" the ultimatein word processing. Letters automatically formattedwith addresses fetched from separate file.Complete system £2950. Invoicing, stockcontrol,sales ledger, purchase ledger, payroll available forabove computers from £250 per package.

43 GRAFfON WAY, (OPPOSITE MAPLES), LONDON W1TEL: 01-388 69911 2 OPENING HRS: 11-7 MON-FRI, 12-4 SATS. 24 HOUR ANSAPHONE 01-388 5721

PRACTICAL COMPUTING May 1981

Circle No. 267

I 53

Microtrend software andthe Adler Alphatronic

now YOU'RE TALKInG BUN nEssMicrotrend Ltd., has software now for the microcomputer with a future.This wide range of well -specified, user- friendly and professionally -packaged products includes five accounting systems, two word

processors (plus an inter -micro communications system for electronicmail and other data transfer operations).

Adler Business Systems provide Microtrend's Trendisk/1Data Management System free of charge with each Alphatronic.

Combine our excellent software with the superb Alphatronicand you are really talking business. Microtrend products

are available off the shelf from your local dealer or distributor.Call 0423-711878 or write toMicrotrend Ltd.,P.O. Box 51,Pateley Bridge,Harrogate, HG3 SDP.,for more details.

ArItirlifillltfirroZ41

ImilrtetrOWNIP0dra,h,

microtrend

?IS*,SS

000.0 **+4

Professional Software'f crocomputors

154

Circle No. 268

PRACTICAL COMPUTING May 1981

TRIPS TO THE

HANOVERFAIR

APRIL 1-81981

IPC Electrical -Electronic Press Ltd., the world's largestpublishers of computer, electrical and electronic journals, inassociation with COMMERCIAL TRADE TRAVEL LTD.,have arranged special visits to the Hanover Fair.All accommodation has been reserved at the Hotel Konigshof,DBAD OEYNHAUSEN. However space is limited on alldepartures, so in order to avoid disappointment, earlyreservations should be made.

FROM LONDON (Heathrow)

TOUR A -4 days (3 nights)Tuesday, March 31 Dep. Heathrow BA776 17.15

Arr. Hanover 19.40Friday, April 3 Dep. Hanover BA775 18.20

Arr. Heathrow 18.50

TOUR B -4 days 13 nights)Friday, April 3 Dep. Heathrow BA774 15.15

Arr. Hanover 17.40Monday, April 6 Dep. Hanover BA775 18.20

Arr. Heathrow 18.50

INCLUSIVE PRICES (Single room with facilities)Tours A Et B £260.00

More information: Commercial Trade Travel LtdCarlisle House, 8 Southampton Row, London WC1

PRACTICAL COMPUTINGBACK NUMBERS &BINDERS

BINDERSUK -- £4.60 including packing, postage and VATOverseas - £5.75 including packing and postagePlease make all cheques payable to Practical Computing and sent tothe General Sales Dept.

BACK NUMBERSFill in the coupon in every issue and return it with your remittanceto Practical Computing, General Sales Dept. Room 205,Quadrant House, The Quadrant, Sutton, Surrey SM2 5AS.

IBM SELECTRIC GOLFGALL PRINTERS

INPUT, OUTPUT 735 TYPEWRITERSPRINTERS FROM735 TYPEWRITERS FROMWIRING AND COMMISSION TO SUITACULAB INTERFACEACULAB INTERFACES EX STOCK

ALSO AVAILABLE IBM 71, 72, 82 typewritersFull workshop facilities for rebuilds and servicing.Keyboard ASCID-ASCII, 10-12 pitch, languageconversions undertaken.11", 13", 15" platen lengths, split platens pin feedplatens. Operational keylever repeats fitted on request.Full IBM range of 10-12*pitch heads including language,symbol and metric.Language keybuttons blue or grey.

WE BUY SELL OR EXCHANGE ALL IBM SELECTRIC TYPEWRITER MODELS

£195.00£245.00

£ 48.00£155.00

FOR FURTHER DETAILS PHONE STUART KIRBY OR LOUIS BAKERPRICES EXCL VAT @ 15%

KEYTIRONICS SAUL LODGETSEALU0L45G2L704U0C61E2STER GL2,7JE EtRCARRIAGE £tPACKINGONY

LEASE

PRACTICAL COMPUTING May 1981

Circle No. 269

155

:EITS!:IPCOMPUTER PRODUCTS LTD

4 Westgate, Wetherby, West Yorks, LS22 4LLTelephone (0937) 63744/63774

THE NORTH'S LEADING NASCOM SPECIALIST

PROGRAMMABLE CHARACTER GENERATOR FOR NASCOM 28192 Programmable dots Memory mapped with demo software and free game E60.00

NEW PRODUCTS FOR NASCOM:DISCS:Single driveDouble drive with CPM & EBASICAsk for detailsProfessional designed for your NASCOM

KENILWORTH CASEA high quality case made from stelvetite coated steel and solid mahogany E49.50Mounting Kit for two cards £350Mounting Kit for five cards £19.00

SARGON CHESS PACKThis pack includes the book and a tape with Sargon prepared to run underNAS-SYS. Also included in a special graphics rom and a PCB giving your NASCOMthe ability to switch between two graphics ROMs, your original and the chess ROM.All the above for only £35.00

EPROM PROGRAMMERThis unit allows the NASCOM user to programme both 2708 2716 EPROMS completewith operating software £25.95

£380.00£640.00

EPROM ERASERErasers 28 rows in 20 minutes E34.00

INTERFACE EPROM BOARDProvides sockets for both 2708 and 2716 EPROMs (up to 16 EPROMs) and alsoprovides a fully decoded socket for the NASCOM 8K BASIC ROM. This boardis produced to full NASBUS specification and can be used in "page mode"together with the new NASCOM RAM B. Wait states may be generated on board toallow a NASCOM 1 to run at 4MHz in BASIC. The complete Kit at only E55.00

CASTLE INTERFACEGives the following features: - Auto tape drive Auto cassette muting Auto serialprinter muting 2400/1200/300 BAUD cassette. This interface built and testedcomplete with documentation at only £17.50

ASTEC 10" B/W MONITORA Professional Cased 10 inch Monitor giving superb resolution, only £80

ANALOGUE TO DIGITAL CONVERTERThis unit gives 4 Channels with an Input Range of 0 to 120mV up to 0 to 24V.Conversion time (average) 0.5mSec. Supplied built and tested at only E49.50

DUAL MONITORThis Kit allows switching between two monitors on a NASCOM 1e.g. T4 and NAS-SYS E6.50

PORT PROBEA very useful device for testing and evaluating ports and peripheral softwarewith improved documentation £17.50

HEX AND CONTROL KEY PADSOur popular range of add on key boards for the NASCOM microsHEX for NASCOM 2 £34.00HEX & CONTROL KEYS for NASCOM 1 E40.50

PROGRAMMERS AIDIn 2 2708 EPROM gives the NASCOM ROM BASIC many extra commands: AUTO,RENU, DELE, DUMP, FIND HEX, APND, HELP . . etc. £28.00

BITS & PC.s GAMES TAPE 1Good value - ten excellent games E8.00

BOOKSFull range including INMC mags

Epsom MX80Eikosho GP80Software interface details supplied for Nascom usersPRINTERSSHARPMZ-80K 48K RAMPC12 Pocket ComputerPC12 11 Cassette InterfacePC12 11 Printer

TEXAS T19914 SPECIAL OFFER 3 onlyComplete with accessories normal price £950.00including B & W Monitor OUR PRICE £480.00

BUILT SYSTEMS REPAIRS MAIL ORDER and ADVICEare our SPECIALITY

FULL RANGE OF NASCOM PRODUCTSSAE FOR DETAILS. PRICES EXCLUDE VAT AND

POSTAGE/PACKAGEAccess Er Barclaycard Welcome

£360.00£250.00

£450.00£82.00E13.00£85.00

Circle No. 270

156

Why Software Housesshould talk to us fast!

The best in microcomputers from Extel: We are aDivision of the Group bearing one of Britain's foremostnames in communications-and a City institution in itsown right for over a century.

We are able to offer from our associated company,Digital Microsystems Inc of California, the range of'DSC' microcomputers based on the Z80A processor.These are available in single -user and multi-userconfigurations, operating under CP/M or MicroCobol. The 'Hi Net'® multi -tasking and network microsare also being delivered now.

We have a range of printers and VDU's to enableyou to offer a turnkey system without hardware worries.

We want to talk to Software Houses like yours onmatters of mutual interest and the benefits we canpass on are impressive. Run your eyes down the list!

* We operate a nationwide maintenance service withover 100 field engineers.

* We will provide you with inquiries from our NationalAdvertising Campaigns.* We will assist you in running Seminars.

* We have literature and promotional material available.

* We have software and hardware support teams to giveyou assistance.

* Our demonstration facilities are available in Londonand Manchester.* We will help sell your software through our Salesforce.*We believe in a close working relationship to achieveour mutual aims.

Don't wait to discover what co-operation with Extelcould mean to your organisation. Do something aboutit now! Telephone, telex or write to John Brooks(Principals only please).

The Exchange Telegraph Company Limited,73-75 Scrutton Street,London EC2A 4TA.Telephone: 01-739 2041.Telex: 27595.

Circle No. 271

PRACTICAL COMPUTING May 1981

commodore

NorltiStar cuppI® I C ARnadex Ltd.

APPROVEDfor

CommodoreApple II

North Star HorizonIndustrial Micro Systems 5000

& 8000

INDUSTRIALMICROSYSTEMS

clume

APPROVED APPROVEDby

Local GovernmentCentral Government

National LaboratoriesMaritime Research

UniversitiesSchools

byAccountants

Importers/ExportersRetailers

ManufacturersPrinters

Surveyors

WE WILL GET YOUR APPROVALWhy? Because Micro -Facilities know that whether you are alarge establishment or a small business you are going to needhelp and good service. We believe, and our hundreds ofsatisfied customers seem to agree, that the service we give issecond to none.Our service starts right from your initial contact. We will meetwith you to discuss your requirements and your business,without blinding you with computer jargon. We will arrange foryou to have a demonstration of one or more computers fromour range together with programs to suit your particular needs.If a ready-made program is not suitable then we can analyse,design and program your particular procedures (we havenearly twenty years experience of doing this).As a further service we are able to arrange both leasing andfinancing of your computer equipment.

Micro -Facilities Ltd. 129 High Street,

Hampton Hill, Middlesex TW12 1NJ

PRACTICAL COMPUTING May 1981

Our service does not stop when you have purchased yoursystem; to ensure the smooth transfer of your work we trainyou and your staff to use the computer and its programs inyour own environment. As additional security we offer fullmaintenance contracts. Above all we will be available togive you genuine after sales service. Not for just one weekor one month but everytime it is wanted.

Please contact us to discuss your problems and requirements,we offer you a lot more, but only charge the same. Our abilitywill give you peace of mind and confidence that,the job will bedone properly.Central Computer & Telecommunications Agency ApprovedTenders from Local Authorities, Education and GovernmentDepartments welcomed.

_MICRO01-9411197 and 01-979 4546 FACILITIES

Circle No. 272

I 57

Master YourMicro fASI) with...Little Genius floppy diskettebased courses will teach you,how to use your system and howto realise the full potential of the"Mighty Micro". These fullyinteractive computer lessons willguide you quickly to a high levelof understanding and confidencein your ability to make the most ofyour microcomputer system.Courses now available.- Applesoft BASIC - Palsoft BASIC- Advanced - Advanced Palsoft

Applesoft BASIC BASIC- Using your Apple - Using your 2020

- PET BASIC - 380Z BASIC- Advanced PET - Advanced 380Z BASIC

BASIC - Using your 380Z

Little GeniusEach course, comprising a floppy diskette, and starting

instructions, costs only £40.00 plus VAT.SPECIAL"3 in one" OFFER for 3 courses covering the same

system only £99.00 plus VAT.Little Genius courses are available from most computer retail

outlets, or direct mail order rom:LITTLE GENIUS

Suite 504, Albany House, 324 Regent Street, London W1R 5AA.Telephone: 01-580 6361

Circle No. 273

AtomExplosion

inCambridge!

See the sensational Acorn Atom ondemonstration at Cambridge Computer

Store. Also the Acorn kit systems and theUK101: all available off -the -shelf or on

short delivery.

We have low -power 2114 RAM atcompetitive prices and the stock in ourElectronics Department includes a huge

range of IC's and components.

Cambridge Computer Store1 Emmanuel Street

Cambridge CB1 1N EPhone (0223) 65334/5

Circle No. 274

SUPERBRAIN

350K Superbrains* atcompetitive prices. Exstock.700K Et 1.54 Megabytemodels available.

Hard disk - 10 MegabyteWinchester drives.

Super video board - addstrue lower descenders,reverse video Et flashingunderline cursor to yourSuperbrain.

SOFTWARESUPERBIOS has arrived!£100. It enhances yourSuperbrain, supports 5'/4 Er8" drives, has repeat keyfunction, type aheadfacility, speedier diskaccessing and real timeclock.

LANGUAGES - BASIC, COBOL,FORTRAN, PASCAL, APL etc.

Word Processing Database Integrated Accounts Incomplete Records Solicitors' Accounts

Etc.

Tailor made software tosuit your particular needs.

DAY 1 MAINTENANCE AVAILABLE - FULL TRAINING ft SUPPORT

WE SERVICE ALL OF THE ABOVE EQUIPMENT(Maintenance contracts available) VAT at 15% should be added to all prices.

*Trade mark of Intertec Data Systems

PRINTERSIBM GOLFBALL PRINTERS

From £395 + VAT

Reconditioned printers withkeyboard and RS232 serialor parallel interface.

Tec DAISYWHEEL printerwith DIABLO mechanismwhich produces qualityprint at a dot matrixprice. From £1085.

Oki range of reliable, quietdot matrix printers.80, 82 Et 83 Ex stockfrom f349

E.I.S.Electronic Information SystemsFrampton CotterellBRISTOLTel: Winterbourne104541774564 or 775150

158

Circle No. 275

PRACTICAL COMPUTING May 1981

4'sY Daisy..Tt

114

%

The ultimate answer to your printer needs

NEXOSTomorrow's Office Systems -Today.

PRACTICAL COMPUTING May 1981

The Nexos Ricoh RP1600 Daisywheel Printerwith the unique Double Daisy. She's tough-and fast. 1Vvo characters per petal, plusrugged dual -plastic construction add upto double your printer - 60cps with theexcellent print quality you need -for lessthan you need to pay.

Now available ex -stock from our new dealer network.Micropute Microcomputer SystemsMacclesfield (0625)612759 /612818

Camden Electronics LimitedBirmingham (021) 773 8240/ 772 5718

Betel Comco Southampton (0703139890Macron Computer Services Limited

Bourne End (06285) 27510HB Computers Kettering (05361520910Sumlock Bondain London 1011250 0505

Softech Ltd Dublin 2 (00011784739Software Development Services Ltd Dublin 4

(0001)685755Irish Micro Computers Ltd Dublin 2

(0001)763201

Circle No. 276

159

CPS Data Systemsis not just a hardware shop.

Our name means what it saysWhilst we have a fine reputation for a wide range of

computer hardware WE ALSO OFFER ALL THESERVICES you would expect from one of the longestestablished companies in the microcomputer industry.

Systems AnalysisProgramming

Personnel TrainingInstallation and Commissioning

Total Engineering back-upRing us to find out more about any of these

essential services.

Our hardwaredeals are: -

Commodore microsat competitive prices e.g. 8032-for £820.00 + VAT

32K 4000 series CPU £555 + VAT

Qume Daisy Wheel PrintersFor volume output of letter quality from £1,550 + VAT

New Olympia ScriptaDaisy Wheel Printer from £806 +- VAT

Sanders Media 12/7The unbelievable letter quality printer that can change type size

and style as it prints-has to be seen to be believed.From £2,390 + VAT

Ask about our special deals on demonstration equipment-at well below list prices.

* Before you buy! ring us and if we can't match or better the price youalready have we will send you free a 5/" mini floppy discette

with our compliments* *Free with all orders over £2,000.00

CPS (DATA SYSTEMS) LTDThird Floor, Arden House,1102 Warwick Road, Acocks Green,Birmingham B27 6BHTel: 021-707 3866

A member of the CPS Group

Circle No. 277

160

£250.00Winter Stock Clearance Sale

(LIMITED OFFER)

80 COLUMN DOT MATRIX PRINTERS

SPECIFICATION

Please

Matrix 7 x 5150 c.p.s.70 lines/min.Uni-directional220/240 v 50 H z.Mains supplyInterfacesavailableat extra cost

send cheque/postal order for

£299.00(includes VAT and packing and carriage)

TO:

INTEGRATED SUPPLIESUnit C, Britannie Trading Estate, Hayes, Middx.

Circle No. 278

CROYDON COMPUTERCENTRE

Part of the Zero One Electronics Gp.

YOUR BEST BUY FOR PRINTERS!Just look at these prices:

OKI MICROLINE 80Pin feed only, centronics interface completewith paper rack.

SEIKOSHA GP80The cheapest on the market, centronicsinterface pin feed.

Z 800Rugged and reliable. Friction and tractor feedcomplete with RS232, Centronics and IEEEinterface.

ANACOM 150High speed (150cps) 9 x 9 dot matrix withcentronics interface. 3-15" tractor feed.All printers serviced on our premises.Many more Spring offers, eg Video Genie £299. We will behappy to quote for all your computing requirements,machines printers paper etc. Please send SAE for detailsor call in.

All prices exclude VAT and carriage.

CROYDON COMPUTER CENTRE29A BRIGSTOCK RD, THORNTON HEATH, SURREY CR4 7JJ

01-689 1280Unsure of what to buy?Why not hire and try?

£299

£199

£319

£695

Circle No. 279

PRACTICAL COMPUTING May 1981

MICROS

Micros, memory and supportMC1489 96 74S287 2.60MC1488 IN 745288 2.60MC14411 11.96 745471 4.96MC14412 11.95 74S472 11.951702 6.16 74S474 11.962101 2.98 8726 1.602102 90 8728 1.502111 2.32 8795 1.802112 2.32 8797 1.802114 3.45 BT98 1.902114L 3.75 SC/MP2 9.962142 10.40 8080 5.492376 11.60 8085 11 962513 6.50 8086 89.00251615v) 13.95 8154 11.602532 29.00 8155 12.602708 0.50 81LS95 1.304027 2.96 81LS96 1.304116 4.95 81LS97 1.304118 14.95 81LS98 1.305204 7.95 8212 2.4657109 12.43 8216 2.5057161 9.96 8224 2.606011 4.95 8228 4.206402 4.16 8251 4156502 716 8253 10.966520 4.50 8255 4.95

16522 7.96 8257 10.9616532 8.50 8259 11.966545 17.50 8678 12.966576 14.96 8602 2.206800 7.95 96364 10.966802 12.49 Z80-2mHz 7.506809 19.116 Z80 -P10 8.966810 3.96 Z80 CTC 5.966821 4.60 Z80-4mHz 4.966845 1910 280-PIO 7.506850 3.16 Z80-CTC 7.606852 5.96 Z8003 120.0074500 N ADC0817 14.4774504 66 DG300 3.5074S201 3.96 F8 9.95745188 2.50 F8SMI 9.9674S262 9.95

SOFTWARECP/PA'

DISKWITH /MAN

MANUALAvailable on

8" IBM format &5% for TUSCAN

& TRITON

TCL SOFTWARETCL Disc Basic E55/19TCL Pascal E120/19MICROSOFTBasic -80 1155/115Basic Compiler C195/E15Fortran -80 f205/E15Cobol -80 025/115Edit 80 £45/£10Macro 80 £75/110MICROPROWord Star 055/115Word-Star/Mail-Merge £315/115Data Star E195/£25Word -Master 175/E15DIGITAL RESEARCHCP/M 1.4 [75/118CP/M 2.2 £95/118MAC 05/£10SID 145/110OTHERSKISS C190/115SUPER SORT I - [125/115C BASIC 2 175/110ZEIODev Pack [50/112ZSID 160/17POSTMASTER 05/110MEDIA5% S/Sided D/D 0.50" per 10 £29.50

S/Sided D/D £4.50" per 10 05.00

C12 Data Cassettes 50p

9

MAIL ORDERTEL &MAIL ORDERS ACCEPTED

LSOOLS01LSO2LSO3LSO4LSO5LSOBLSO91510LS11LS12LS13LS14LS15LS20LS21LS22L526LS27LS28LS30LS32LS33LS37LS38LS40LS42LS47LS48LS49LS51LS54LS55LS63LS73LS74LS75LS76LS78LS83LS85LS86LS90LS91LS93LS95LS96LS107LS109LS112LS113LS114LS122LS123LS124LS125LS126LS132LS133LS136LS138LS139LS145LS148LS151LS153LS155LS156LS157LS158LS160LST61LS162LS163LS164LS165LS166LS168LS169LS170LS173LS174LS175LS181LS190LS191LS192LS193LS194LS195LS196LS202LS22115240LS241LS242LS243LS244LS245LS247LS248LS249LS251LS253LS257LS258

LS259S261

LS2273LS66

LS275LS279LS280LS283IiS290LS293LS296LS298

LS3224LS99

LS325

LS3327LS26

LS352LS353LS355

74LS0013 L5366 8613 LS367 6516 LS368 8616 L5373 16020 LS374 16023 L S375 16023 LS377 199M LS378 1

20 l S379 21855

M .S386 8532 LS390 14040 1. S393 14076 LS395 21040 LS396 1111

24 LS398 27532 LS399 no40 LS445 14049 LS447 11646 LS490 16046 LS668 10524 LS669 10630 LS670 210

CMOS39 4000 16

2040014002 24so

N 4006 12120 4007 22

4008 Q12079

40400940

10 4630 24O 24150

40124013 46

40 4014 160

414015 96

4645

1051064650

125

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96497096

180

soso30so70go

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N1101001151661762102102881%147110ns120120125125in125120346120225225232232225360135136135130130115120110460

751110

320

no190130130216215 74XX4202003203303151115166

4016 424017 824018 IS4019 484020 664021 1054022 95'4023 M4024 754025 264026 1804027 454028 112

4029 1%4030 504033 1754034 2104035 1254040 1054041 SO4042 so4043 so4044 164046 13040474049 464050 414051 504052 804053 804054 1304055 1354068 254069 294070 304071 254072 754073 254075 2640754078 3040131 284093 es4502 1254507 504503 3264510 994511 1504512 654514 1954515 2964516 1204518 1054519 704520 1154521 2504522 1604526 1604527 1804528 120

REGST03 + ye7805 1467812 1467815 1457818 146-ye7905 22o7912 22010220 pleat7805 407812 90

78187815 SO

so7824 so7905 8579127915 857918

74CXXL1NEARSMany other AVAILABLEtypes Instock. Tel Catalogue wdellable Send Wiltfor details & S.A.E.(A4 size).

WE HAVE MOVEDTO OUR NEW CENTRAL. LONDON SHOWROOM

59/61 THEORALDS RD, WC1 TUBE HOLBORN.

FLOPPY DISK DRIVES

Single 61/4 DriveSingle 8" SA800Dual 51/4 PSUDual 8' PSUDual Cabinet Er PSU 1xErDual 8" Drive UnitDual 5'4 Drive Unit

We sell all youneed cased or un-cased. Cables Ei

connectors. Brandnew fully guaranteed.

PriceE195£395

£59E76

£5651945£440

TUSCAN 5100A Z80 based 5100 Computer

Single board will Sold up to 814 RAM, 8KROM, Video interface Z80 processor -I/0 and cassette interface. 5 spare S100expansion sockets for memory/disc expassion System monitor. residentBASIC or CP/M system option. All corn-ppnents available separately or ready builtNEW LOW PRICESTUSCAN MAIN BOARD KIT ONLY £235

VAT SAE FOR DETAILS

VIDEO TERMINAL24x80 display

Pentland VideoTerm:nal f 611

featuresprofessional

terminal. Full details on requestPrice f5g6

S100 CARDS;IV NEWLOW

III PRICES

16K STATIC KIT ASSMwith no RAMI2114 £ 62 f 82

" 8K RAM " 1109 £130" 16K RAM " E157 £178

8K static 116x2114 chips) £ 4844K DYNAMIC 141161with 16K RAM 1149 1165with 32K RAM £189 £205with 48K RAM £229 E245with 64K RAM £269 £28516rupgrade 8x4116 E 40

16/32K EPROM CARDWithout EPROMs2708/2516 163 £ 89

FOC DOUBLE DENSITYDouble Density for 54.or 8" Drives £ -- E1.9.

TRITON8090 BASED SINGLE BOARDsystem with EU ROCARDEXPANSIONComplete Kit PSU/Case/KeybdExpansion Motherboard Kit8K 121141 RAM Card Kit8K 127081 ROM Card KitExpandable up to CP/MDisc System. SAE fordetails.

E286150£ 97f 97

SINGLE BOARDPERSONALCOMPUTER

TCL PASCALFOR PET Et CP/M systemsPut Pascal on your PET nowPascal conversion ROM E 20Pascal manual E 9Complete package includingcompiler E120

VATAUGURPRICESEXCLUDEVAT Er Pic.

CENTRONICS 737 PRINTERLETTERQUALITYFOR

476

Uses any paper roll, fanfold,single sheets, 96 characterASCII, 7 x 7 dot matrix, 50CPS. RS232 or parallel I/O

OK TOOLSFull range of wire wrapping accessones Et boards Et dipJumpers etc. Visit our showroomor send for our catalogue.VEROS100 prototyping boards and fufrange of accessories.BOOKSComplete range of microcom-puter books and magazines onsale in our showroom.

Edge £4.00ConnectorsS 100

DIP Switches4 way 11.207 way E1.758 way 1'1 BO

DIP Plugs14 DIL E 6524 DIL E2 2040 DIL E3.60 EdgeOIL SOCKETS Connectors(TEXAS) 1 156

Low Wire 2x 6 way - 1.75Prof Wrap 2x12 way - 3.00

8pin,10p 25p 2x10 way -- 2.0014pin 12p 36p 2x 15way - 3.2016pin 13p 42p 2x18 way - 3.5018pin 16p 60p 2x22 way 3.203.6520pin 22p 90p 2x25 way 3.60 -22pin 25p 2x30 way 4.15 -24pin 30p 66p 2x36 way 4.753.9028pin 36p 90p 2x40 vvay 5.00 -40p,n 40p 1.10p 2x43 way 5.504 60

Insulation/PiercingRibbon/Cables

1/OHEADER PLUG10 way £220 10 way £1 6020 way C3 40 20 way £2.3026 way E4 00 26 way £2.7034 way £4.80 34 way 0.3040 way £5 40 40 way £3.7550 way £6.00 50 way 14.60

Zero Insertion 60 way £6 50 60 way E6.00Force Sockets Insulation Piercing

16 way £4.95 Edge Connectors24 way £6.00 20 way £3 60 40 way £5.3040 way [9.50 26 way £4.00 50 way £6.00

D -Types 34 way E4.6025W Male £2.80 Insulation Piercing25W Female 0.80 DIP Plugs25W Cover (1.80 14 way DIP Plug £1.30

16 way DIP Plug £1.5024 way DIP Plug 12.80

flibbon CablePRICE/M

Grey Coloured10 65 1014 9016 1.2020 14026 1.6034 24040 2.80503.3060 400

14

16202634405060

1 20

1.401.602402.803304005.50

CATALOGUE

CRYSTALS FOR MICROS32.768KHz 3.00 4.00MHz 2.70 10.00MHz 2.70100KHz 3.00 4.43MHz 1.00 10.7MHz 2.70200K Hz 3.70 5.0MHz 2.70 16.00MHz 2.901.0MHz 3.60 6.0MHz 2.70 18.03MHz 2.901.008MHz 3.50 6 144MHz 2.70 18.432 2.901.8432MHz 3.00 7.0MHz 2.70 36MHz 2.902.00MHz 1.50 7.168MHz 2.50 48.0MHz 2.702 45760MHz 3.05 8.03MHz 2 70 100MHz 2.903.276MHz 2.70

TEAINAM 59 / 61 THEOBALDS RDLONDON WC1

TEL: 405 5240/2113TELEX 444198. TRAINAM

PRACTICAL COMPUTING May 198!

Circle No. 280

161

COMPUTERS

Decisions! Decisions!Who do you turn to?

Up to now there hasn't been anybody willingenough to give you impartial advice, on whichtype of microcomputer and/ or wordprocessingsystem is right for your business. We at Petalecthave made it our business to give you that help. Astudy of the market has meant that we can offeryou a wide selection of systems to meet mostapplications, at a cost that is not going to burn ahole in your pocket.

They range between £1,000 - £15,000 andinclude the best known names - Commodore,Sharp, ACT, Hewlett-Packard and Apple. Allbacked by our reliable after -sales service. Sobefore you make a decision, chat with us first.

Make theright choice,right from the start.

COMPUTERS

32, (Pt, Chertsey Road, Woking, Surrey GU21 5JE Tel: Woking 69032/21776

Circle No. 281

CRYSTAL ELECTRONICSCC ELECTRONICS

THE SKY'S THE LIMITFOR YOUR SHARP MZ8OK with

SHARP CP/M 2.21 (XTAL)CP M s, the trade mark of Digital Research

This sophisticated interactive programdevelopment system will give your home computer

BUSINESS/INDUSTRIAL potential.Basic CP/M facilities include:

Dynamic file management Fast assembler General purpose editor Advanced debugging utility

YOUR SHARP CP/M 2.21 (XTAL) PACKAGE INCLUDES Hardware modification (if fitted by a SHARP dealer does

NOT break the guarantee) SHARP CP/M 2.21 (latest version) on disc XTAL Monitor and Operating system

7 Digital Research manuals CP/M Handbook (by RODNAY ZAKS)

12 months guarantee and up -datesIF YOU ARE A SHARP MZ8OK OWNER, CP/M 2.21 (XTAL)

IS A MUST FROM £200.00Ask your SHARP dealer for further details or contact

CRYSTAL ELECTRONICSCP/M SOFTWARE HOUSES-XTAL CAN HELP YOU

ESTABLISH YOUR SOFTWARE ON THE SHARPMembers of Computer Retailers Association & Apple Dealers Association

Shop open 0930-1730 except Saturday & Sunday40 Magdalene Road, Torquay, Devon, England, Tel: 0803 22699Telex 42507 XTALG

`Access and Barclaycard 19,14COMPUTERS

ANDCOMPONENTS

Circle No. 282

BASIC INTEGER COMPILERFOR COMMODORE SYSTEMS50-150 times speed of Commodore Basic.

Any length variable names.Single dimension string and integer arrays.Full Integer arithmetic & logical (1 byte variables)for extra speed.Code & Data can be set to reside anywhere inmemory.Many facilities for interface with CommodoreBasic programmes.

New commands can be added to CommodoreBasic automatically using WEDGE statement.

Several extra low-level commands for precisionI/O programming, eg DELAY, SETBIT, MOVE,etc.

Automatic insertion of code into interruptroutine.Variables can be individually set to reside at anylocation allowing direct access to page zero I/Oports, etc.Full logical file handling.Compiling speed of 3 lines per minute.

Suite includes resident compiler, disk compiler, editor, loader and debugger. Editing environment and languagesimilar to Commodore Basic. Produces ready -to -run 6502 Machine Code.

Detailed Manual £7.50 inc. VAT Compiler: 3000 series £150.00 inc. VAT8000 series £150.00 inc. VAT

CIfforFV-) 'orm_punqQ{F oqamo5 Oxford Street Woodstock Oxford 0X7 1TQ Telephone: Woodstock (0993) 812838

62

Circle No. 283

PRACTICAL COMPUTING May 1981

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Microeneral

MATRIX PRINTERS_ FROM £295Choose from our selection of Matrix Printers for all your low cost printer requirements. There is amodel to suit your budget. Printer prices include FREE DELIVERY to U.K. Mainland plus 90 dayparts and labour warranty.

MICROLINE PRINTERSMICROLINE 80 - 80 cps uni-directional printing with

Parallel Centronics Interface- Serial RS 232 Interface and Tractor £295

Feed Options available. plus VATMICROLINE 82 Er 83

* Head life of 200,000,000 charactersBi-directional printing with short line seeking

* Centronics Parallel and RS 232 Serial Interface96 ASCII characters and 64 block graphic shapes

Programmable selection of 4 character sizes Programmable vertical forms and tab control

Self test Optional High Speed Serial Interfaces with various

communications protocols and buffer sizes

80 cps. Pin andMICROLINE 82

£510MICROLINE 83120 cps. Tractor and

Friction Feed plus VAT Friction Feed. Takesup to 16 inch paper.

EPSON MATRIX PRINTERMX 80 PRINTER - 80 cps bi-directional printing

-4 print sizes, bold and emphasised- Upper and Lower case with true _

decenders- Vertical and horizontal tabulation- Interface boards for PET/APPLE/ TRS

80 and RS 232 available.

APPLE Et ITT 2020 SALES AND SERVICEExtra 32K RAM supplied free with everysystem purchased.

£799plus VAT

£345plus VAT

PRINTER PAPER11 v 9 Y2 Plain with side £18perf. 2000 sheets plus VAT

INTERFACE CABLES Serial: £17.00 Parallel: £27.00 + VATEducational discounts on request.Remittance plus VAT please to: --

MICRO GENERAL, 6 The Birchwoods, Tilehurst, Reading, Berks RG3 5UH.Tel: 0734 25226

Circle No. 285

6809Gimix'UNIX on a MICRO* The new standard DEC/ PDP operating system is now

available on 6809 micros.* UNIFLEX is a MULTI-USER/MULTI-TASKING system

for up to 12 users.* RRL provide the complete system with from 128k to

768k RAM.* 2.5 Megabyte floppy disk drives and 16 Megabyte fixed

disks.* Full range of VDU's, terminals, printers, interfaces etc.

MOTOROLA 6809 COMPUTERS* RRL specialises in the EDUCATIONAL and SCIENTIFIC

applications.* Small systems from 32k with 5" disk drives upwards.* PASCAL, FORTRAN, PILOT, BASIC Compiler, LAB -

BASIC, Statistical Analysis etc.* D -A, A -D converters and special interfaces to solve your

problem.

PET Et CPIM STATISTICS SOFTWARE

RESEARCH RESOURCES LTD, P.O. Box 160Welwyn Garden City, Herts. EnglandTel: 107073) 26633

Circle No. 286

odrAlligrfe149.",

APPLETEXASMICROPOLISDIABLOMICROLINE

CENTRALEX-LONDON LTD8-12 Lee High Rd, London SE13

centralem Tel: 01-318 4213/4/5/6/79.30 am -5 pm Mon to Fri -Evenings and weekends byappointment

A comprehensive range of Microcomputers Equipment, Peripherals, Software andServices for those who value Professional Standards, Guidance and ContinuingSupport for Hardware and Software.PET ITT 2020 EXIDY HORIZONOHIO SCIENTIFIC CROMEMCO MICROSTAR SHUGARTCENTRONICS ANADEX INTEGRAL TELETYPEOUME DEC DATA GENERAL EPSONHITACHI LEXICON ETC. ETC.

INFORMEX-80 Printer

£399+VAT

Special offer -fora limited period

For PET, APPLE, EXIDY, TRS80, ETCA high quality, high speed printer(125 cps) Upper and lower case lettersplus graphics as standardInterface and cable for TRS80, PET,APPLE or RS 232 £69 + VATTractor feed option only £39

ALSO Training, Consultancy, Systems Design,Programming and Software

PAYROLL - INVOICING - STOCK CONTROL -SALES/PURCHASE LEDGER - VAT- MEDICALRECORDS - EDUCATIONAL & ENGINEERINGPROGRAMMES - HOTEL RESERVATION - ESTATEAGENTS - BUILDING MAINTENANCE - COBOL -FORTRAN - ETC.

Maintenance Contracts including stand-by equipment during repairperiods- Free Delivery Nationwide -Terms arranged -Credit Cards andofficial orders accepted.

164

Circle No. 287

PRACTICAL COMPUTING May 1981

THE ONE STOPCOMPUTER SHOP

BUSS ISTOP

We Supply Systems for Business, Education and Industry -And We Support Them With Service and Software!Commodore2001-8 £379.00 8032 £895.00 KIM1 £93.003008 £398.00 8050 £895.00 KIM3B £96.953016 £495.00 8024 £1160.00 KIM4 £65.003032 £625.00 8010 £220.00 Toolkit, SuperChip,3022 £383.00 Pet Lead p18.75 Soundbox, Parallel3023 (337.00 IEEE Lead £23.44 and Serial Interfuses3340 £625.00 C2N Cass £49.50 All Ex -Stock.Now on demonstration - The NEW PET MODEM, with SupportingSoftware.

VIDEO GENIE - EG3003 16K RAM, 12K LEVEL II BASIC IN ROM.TRS80 Compatible 32K VERSION £280.00

£37.00NASCOM - Phone for latest Details/Prices.Dolphin Printers - The Superb BD8OP now 80/132, chrs/line.Down to £450.00 While Stocks Last.The New BD136, The Ultimate Intelligent Matrix Printer - Printsat 240 Chrs/ Sec. £1200.00

RICOH, QUME, NEC Spinwriter etc, Also Available, Please phonefor Prices.

CONSUMABLES C15's Only £4.00 for 10. 10 Verbatim 51/4" Disks-- 35 Track £19.95 - for CBM 3040. 10 Verbatim 53/4" Disks -

77 Track £36.50 - for CBM 8050.Wide range of Continuous Stationary in stock - Paper, Labels etc.

SOFTWARE - We Sell Only The Best - Wordpro, Wordcraft,OZZ, Communicator, Medicom - and much more! Plus -A WideRange of Books and Manuals for all Machines.

Please phone for carriage charges, all prices + VATPhoto Acoustics Ltd, BUSS STOP Computer Division

255a St. Albans Road, Watford, Herts. (entrance in Judge Street)Phone: Watford 40698

58 High Street, Newport Pagnell, BucksPhone: Newport Pagnell 610625

Circle No. 288

New release from SD systems

The MS -20The ideal Low Cost entry into theworld of Micro computing for theserious small business person. For£3200 the MS -20 offers 2 MB floppydisk storage, 4 Mhtz. Clock,optional CRT terminal 64K RAMand full compatability withthe SD range ofequipment.

0.E. M.enquirieswelcome.

We also supply TexasInstruments OMNI 810printers with lower casefor £1097.00 ex stock.

BARCELLOS Ltd.Kimberley House, Vaughan Way, Leicester.Telephone: 0533 26584

Circle No. 289

Computer Systems

Fully integrated and balancing ledger system

Sales and Purchases Ledgers Nominal and VAT Ledgers

announces -ACCOUNTING BREAKTHROUGH ONCOMMODORE 3000 Et 8000 RANGE

Open Item Large Capacities Multi Ledgers Multi Companies

SEND COUPON TODAYOR TELEPHONE

JOHN PERCIVAL0234-40601

One set of Disks Simple to Operate Powerful Period End Audit Reports

To MMS Ltd.26 Mill St., Bedford MK40 3HAPlease send details of MI CROFACTS to:

Name

Company

Address

PCS 81

PRACTICAL COMPUTING May 1981

Circle No. 290

165

LOCAL DEALERS

LONDONBelmartin Services Lion House (Retail) Limited194 Union Street 227 Tottenham Court RoadLondon SE1 OLD London W1P 04XTel: 01-928 5322 Tel: 01-637 1601

Eurocalc Limited Personal Computers Limited128/132 Curtain Road 194-200 BishopsgateLondon EC2 London EC2M 4NRTel: 01-739 6484 Tel: 01-626 8121

PROVINCESAvonDecimal Business MachinesLimitedDecimal HouseThomas LaneBristol BS1 6JHTel: 0272 214093

Noteset Limited34 Tindalls Park RoadCliftonBristol BS8 1PRTel: 0272 34058

BerkshireThe Computershop Group7-9 Gosbrook RoadCavershamReading RG4 8BDTel: 0734 481008

BuckinghamshireChiltern MicrocomputersLimited7 Amersham HillHigh Wycombe HP13 6NQTel: 0494 20416

CheshireMcNab and Company27 SunfieldRomiley SK6 4PJTel: 061 494 9410

CornwallDiskwise Limited25 Fore StreetCallington PL1 7ADTel: 05793 3780

Exleigh Business MachinesLimited11 Market PlacePenzance TR18 2JBTel: 0736 66577

HertfordshireCCS Microsales Limited7 The ArcadeLetchworth SG6 3ETTel: 04626 73301

Greater ManchesterExecutive Reprographics &Business Consultants Limited2/4 Oxford RoadManchester M1 5QATel: 061 228 163 7

MerseysideCurrie (Business Equipment)Limited8 Upton RoadClaughtonBirkenhead L41 ODFTel: 051 658 5111

NorfolkAnglia Computer Centre88 St. Benedicts StreetNorwich NR2 4ABTel: 0603 29652

166

OxfordshireAlphascan LimitedLittle Bourton HouseSoutham RoadBanbury OX16 7SRTel: 029 575 8202

Hyford Business MachinesLimited120 Botley RoadOxford OX2 OHHTel: 0865 723511

South GlamorganDavid Potter Office EquipmentLimited164 Richmond RoadCardiff CF2 3BXTel: 0222 496510

StrathclydeTurnkey Computer TechnologyLimited23 Calderglen RoadSt. LeonardsEast Kilbride G74 2L0Tel: 03552 39466

SurreyT & V Johnson(Microcomputers Etc.)Johnson House75-79 Park StreetCamberley GU15 3XETel: 0276 20446

WarwickshireBusiness and Leisure MicroComputers16 The SquareKenilworth CV8 1EBTel: 0926 512127

Gelid Limited1 Bilton RoadRugby CV22 7AATel 0788 74442/3

West MidlandsCamden Electronics426 Coventry RoadSmall HeathBirmingham B10 0U6Tel: 021 773 8240

West GlamorganCroeso Computer Services516 Mumbles RoadMumblesSwansea SA3 4BVTel: 0792 60624

WorcestershireArrow Business ComputersLimitedRoyal House11 Market PlaceRedditch B98 8AATel: 0527 62733

YorkshireSaville Audio Visual LimitedSalisbury RoadYork Y02 4YWTel: 0904 52011

1))EliM £998(RO Version £836 + VAT)

Manufactured in W. Germany by OLYMPIA INTERNATIONALSOLE UK DISTRIBUTOR: DATAPLUS LTD.,

* Does the work of both a dataterminal and an electronictypewriter.

* Saves you hundreds of poundsin machine costs.

* Full word processingcapability.

* Library of easily -changeddaisy typewheels.

* Optional tractor unit allowscontinuous feeding of single ormulti -part forms.

* 'Lift-off' and 'Cover-up'correction facilities available.

RO version available withoutkeyboard.

* Contact your nearest dealer orthe address below for moredetailed information.

pLi IDATAPLUS LTD.,39-49 Roman Road, Cheltenham GL51 8QQ.Telephone 0242 30030 or 37373. Telex: 43594 Circle No. 291

PRACTICAL COMPUTING May 1981

Doyou havefinancial control

of your company?

'When did you last have an up-to-date financial statement?Do you have effective cash flow management?Do you get your statements out on time?

The Financial Controller is the solution to theseproblems, and is the first of a series of modular programs thatform the basis of an integrated business system for theApple II/Apple III/ITT 2020. All programs in the series will runon 5t/a" disk drives, 8" drives and the 10 megabyte fixed disk.From a starting price of around £3500 inclusive of the microcomputer system, the Financial Controller offers you Cashflow/budget planning. Balance sheet. Profit and loss statements.Invoicing. Sales ledger. Purchase ledger. General ledger. Payroll.For up to 1000 accounts. All fully integrated.Available soon: Credit control, costing, stock, order processing,works scheduling, parts explosion, word processing, addressingand mailing, time recording, databased. All fully integrated.

London Dalmington WI 01-580 6702 K.A. I. NW4 01-328 3968 The Xerox StoreWC1 01-409 0694 The Xerox Store W101-629 0694 Bedfordshire ComputopiaLeighton Buzzard 0525 376600 Berkshire Lynx Computers Windsor 56322Cambs Q.I.S. Peterborough 47191 Cheshire Systems Integration Altringham9285784 U Microcomputers Warrington 54117 Cornwall Diskwise Callington 3780Cumbria Furness Computer Services Barrow in Furness 24621 Essex CompuskillRomford 751906 Computerist Southend 335298 DDP Basildon 728484 DairElectronics Halstead 472533 Hunt Smee Basildon 21244 Kimfield Chelmsford 64230Gloucs William -John & Co Stroud 70109 Herts Local Business TechnologyHoddesdon 66157 Leics Leicester Computer Services Leicester 708483 MiddlesexLeeway Data Products 01-8984761 Norfolk Anglia Computer Centre Norwich 29652Nottinghamshire Keen Computers Nottingham 583254 Oxon Micromark Henleyon Thames 77926 Rocon Abingdon 24206 Surrey Ferguson West Byfleet 45330Surrey Micros Godalming 22318 Sussex Datatech Eastbourne 36268 Oval ComputersWorthing 44831 Tyne & Wear P.I.P S. Computer Services Newcastle Upon Tyne614939 West Midlands Abovo Systems Ltd Coventry 414258 MicroLogicBirmingham 021 550 8036 Worcs Celtip Star Kidderminster 66201 Scotland PeterMcNaughton & Assoc East Kilbride 33562 Wales Cardiff Micros Computers Cardiff64171 David Potter Office Equipment Cardiff 496785 Swansea 462502Irish Republic CDS Computing Cork 23922 DB Micros Limerick 42733 TomorrowsWorld Ltd Dublin 776861 South Africa Spartan Microware Johannesburg 47-1883

For the solution to your business problems and Systematicsa demonstration of the Financial Controller, contactyour nearest distributor.

PRACTICAL COMPUTING May 1981

International

41. ilkmm iii gh =iiiI. wyrIIP

Systematics International Essex House Cherrydown Basildon EssexTel: (0268) 284601

Circle No. 292

167

Special features include

FULL SIZEDKEYBOARDASSEMBLERAND BASICTOP QUALITYMOULDED CASE

NEW!Colour Encoderfor full colour

graphics

£21.50The Acorn Atom is a definitive personalcomputer. Simple to build, simple to operate.A powerful, full facility computer with all thefeatures you would expect.Just connect the assembled computer to anydomestic TV and power source and you areready to begin. (Power requirement: 8V at800mA). There is an ATOM power unit available- see the coupon below

FREE MANUAL

Unique in concept the home computer that grows as you do!

The Acorn Atom£120

P u VA and OP

11111111`

Also availableready -built

£150plus VATand p&p

The picture shows mixedgraphics and charactersin three colours

Free with every ATOM, kit or built, is a computermanual. The first section explains and teachesyou BASIC, the language that most personalcomputers and the ATOM operate in. Theinstructions are simple and learning quicklybecomes a pleasure. You'll soon be writing yourown programs. The second section is a reference

manual giving a full description of the ATOM'sfacilities and how to use them. Both sections arefully illustrated with example programs.The standard ATOM includes:HARDWARE

Full-sized QWERTY keyboard 6502Microprocessor Rugged injection -mouldedcase 2K RAM 8K HYPER -ROM 23 integrated circuits and sockets Audiocassette interface UHF TV output Fullassembly instructionsSOFTWARE

32 -bit arithmetic (±2,000,000,000)0 Highspeed execution 43 standard/extendedBASIC commands Variable length strings(up to 256 characters) String manipulationfunctions 27 x 32 bit integer variables 27 additional arrays Random numberfunction PUT and GET byte WAITcommand for timing DO -UNTIL construction Logical operators (AND, OR, EX -OR) Link tomachine - code routines PLOT commandsDRAW and MOVE

The ATOM modular conceptThe ATOM has been designed to grow with you.As you build confidence and knowledge you canadd more components. For instance the nextstage might be to increase the ROM and RAM onthe basic ATOM from 8K + 2K to 12K +12Krespectively. This will give you a direct printerdrive, floating point mathematics, scientific andtrigonometric functions, high resolution graphics

From there you can expand indefinitely. Acornhave produced an enormous range ofcompatible PCB's which can be added to youroriginal computer. For instance:

A module to give red, green and blue coloursignals Teletext VDU card (for Prestel andCeefax information) An in -board connectorfor a communications loop interface - anynumber of ATOMs may be linked to each other -or to a master system with mass storage/hard

copy facility Floppy disk controllercard. For details of these and otheradditions write to the address below

ACORN4a Market Hill,

CO PUTER CAMBRIDGE CB2 3NJYour ACORN ATOM may qualify as a business expense. To order complete the coupon below and post to Acorn Computer for delivery within 28 days.

Return as received within 14 days for full money refund if not completely satisfied. All components are guaranteed with full service/repair facility available.

I

I

I

I

I

Quantity ItemItem price inc.

VAT+ p&pTOTALS

ATOM KIT -8K ROM+2K RAM (MIN) 0 £140.00ATOM ASSEMBLED -8K ROM+2K RAM (MIN) 0 £174.50ATOM KIT -12K ROM+12K RAM (MAX) 0 £255.00ATOM ASSEMBLED -12K ROM+12K RAM (MAX) 0 £289.501K RAM SETS 0 £11224K FLOATING POINT ROM (inc. in 12K Version) 0 £23.30PRINTER DRIVE 6522 VIA 0 £10.35(inc. in12K version) LS244 Buffer 0 £3.17

COLOUR ENCODER @ £21.50MAINS POWER SUPPLY (1.3 amps) 0 £1020

TOTAL

To: Acorn Computer Ltd., 4a Market Hill, CAMBRIDGE CB2 3NJ

I enclose cheque/postal order for £

Please debit my Access/Barclaycard No.

Signature

Name please print)

Address

Telephone No.Registered No:1403810. VAT No: 215 400 220 PC5/81

NOMIMP

1

Circle No. 293

Circle No. 294

communitycomputers

Turn your appic® into an Orchard!Community Computers have pleasure in announcing the demise of the Floppy Disc

Using a Cameo DC 500 Controller and an Ampex DM 44010 Megabyte Hard Disc Drive, the Apple 11 grows to give theequivalent storage of 52 Mini Floppies!

With a Cameo Multiplexer, 2-16 Apples can access a single ormultiple Ampex Disc Drives

No Software changes required to operate existingprograms developed for floppy disc

The Videx Videoterm Board will convert a standard moniter to80 Character width -without any floppy disc softwareA further Videx innovation is the Keyboard enhancer whichallows the exsisting Apple Keyboard to be converted to UPPERand lower caseThe NEC 12- phosphor green screen enhances the appearanceof the Apple and gives really clear definition using theVidex Videoterm

PRICE LISTComplete System comprising48k Apple 11 Ampex DM440 10Mb Disc DriveCameo DC500 Controller Centronics 737 PrinterNEC green screen Monitor with Videx Videoterm80 Character Board Videx Keyboard enhancerand Magpie Computer desk £5950

DRE 8840 240 cps printer as illustratedavailable at extra cost

`Workpac' SoftwareFully integrated with Job Costing suitable for anyindustry such as Construction Engineering etc.available to operate on the above system

For adding to Apple 11Ampex DM440 (5+5) 10Mb Drivecomplete with Cameo Controller £3345

Cameo multiplexer for 2 Apples £300for operating on additional Applesprice on application

NEC 12 green screen Monitor £150

Videx Videoterm 80 char. board £169

Videx Keyboard Enhancer £75

magpie Computer desk I 275(also available for floppy disc drives)

Prices Exclude VAT Carriage ExtraPrices subject to changeFurther information from

communitycomputers 169

PO Box No3 Petersfield Hampshire GU32 2ERTelephone East Meon (073 087) 567

Amazing Value-compatible with TRS-80 16K level II

VIDEOGENIE

Fully Supported HardwareMicrodigital are the hardware experts - here's why you should buy your Genie from us.

* Low Pace of £280 + VAT. * Each computer tested by our engineers before despatch. * 12 monthparts and labour guarantee * Free delivery within mainland U.K. * Bona fide official orderswelcome * Latest version of Genie.

The Video Genie is a complete computer system, requiring only connection to a domestic 625 line TVset to be fully operational; or if required a video monitor con be connected to provide the best qualitydisplay.

The system case contains the Central Processor Unit (CPU), 16,000 bytes RAM memory, the cassettesystem, a 12,000 byte operating system and BASIC interpreter in ROM, and a full size keyboard, in astylish case, at a pace that makes the Video Genie better value than some "kit" computers.Applkations

The Video Genie System has many uses in all spheres of life, the easy to use BASIC language meansthat programs are easily written for specific applications, and pre-recorded program tapes areavailable in great variety.

The system has great scope in the home, sophisticated games programs can introduce the computerage to all the family, who can then progress to writing their own programs in BASIC or even machinecode. Software is continuously being developed to aid home budgeting and education.

In a school or college the machine can be used with o large screen TV to allow a whole class to befought at once.

The powerful Extended BASIC interpreter makes the solution of complex scientific problems simple,and the graphics allow pictorial displays of results.

Prices Nett Vot Total

Video Genie Computer 280.00 42 00 322.00EG3013 Expander with RS232 215 00 32 25 247.25EG3013 Expander without RS232 185.00 27 75 212.7532K Memory Board 5100 130.00 19 50 149 5016K Memory Board S100 95 00 1425 109.25Dual Disk Drive (40 track) 410.00 6130 471 502Drive Cable 17.00 255 19.554 Drive Cable 32 00 480 36 80Printer Cable 17.00 2.55 19 55Centronics Parallel Interface

for unexpanded Genie 33.00 495 37.95Sound kit 10.00 1.50 11.50

fitting above 500 75 5.75Lower case kit 35.00 5.25 4025

fitting above 5.00 75 375

CRA

BARCIArC ARC

VISA

164101:AIIPA

Mail Orders to:MICRODIGITAL LIMITEDFREEPOST (No Stamp required)LIVERPOOL L2 2AB

24 Hr Telephone CreditCard Orders 051-236 0707

STEREOCLUB AIM [ItEXPRESS

1111111.71000..

Retail Premises at.25 BRUNSWICK STREETLIVERPOOL L2 OPJTel: 051 -227 2535/6/7

MICRODIGITALI 70

Now

SheffieldICRODIGITAat LlA53 Leopold

anFirStrPhone:

0742et

She750971

Fully Supported Software

V Business V Programming Aids

Personal CustomGames Utilities

7 Years Microprocessor Experience!Send large SAE (44p) for our current Catalogue

of TRS-80/Video Genie software.

A J. HARDING (MOLIMERX)28 COLLINGTON AVE,BEXHILL, E. SUSSEX.

Tel: (0424) 220391Telex: 86736 SOTEX G Ali

es

MOLIMERX LTD Circle No. 295

PRACTICAL COMPUTING May 1981

THE EAST MIDLANDS

SUPERBRAINCENTRE

£1450+VAT FOR

SUPERBRAIN'SD'

(320k bytes)

£1800+ VAT FOR

SUPERBRAIN'QD'

(700k bytes)

THE 'TERMINAL' WITH A DIFFERENCEA CP/M COMPUTER IDEAL FOR REMOTE DATA PROCESSING

CONNECTION TO DEC COMPUTERS WITH SPECIAL COMMS SOFTWARE NOW AVAILABLE

DUAL 4 MHZ Z80 CPUs FULL ASCII KEYBOARD 64K RAM 12" CRT S 100 BUS CAPABILITY DUAL DD/DS FLOPPY DISKS DUAL SYNCHRONOUS/ASYNC 25 LINES X 80 COLS SCREEN RS232 PORTS

SIZE TABLE TOPMOST CPM LANGUAGES, UTILITIES, AND APPLICATION PACKAGES AVAILABLE

including "SUPERACCOUNTS" "SUPERPAY" "SUPERWORD"

SPECIAL YES NO

DO YOU believe in INCREMENTAL BUSINESS? Ei CI Well, does your micro support CP/M? CI Cl Does it have a Serial RS232 printer port? CI and, do you use 'WORDSTAR'? Does your CUSTOMER have a telex machine? CI CI... IF the answer to all of the above questions is YES, then why notcall OCT now and order a 'TELEX -MATE'. TELEX -MATE is adevice designed to produce edited telex -tapes 'off-line' from the

`GPO telex machine. (Ask for the Special Micro -dealer Offer)

1111111111111111=111111111111111

Additional Packages

`WORDSTAR'Fully featured

word-processingpackage

£250.00`DATASTAR'

File creationFile retrieval& File updates

£195.00`MAIL MERGE'

For merging names &addresses with letters.Personalised letters are

produced without individuallytyping each one.

£75.00

Office ComputerTechniques Ltd.

Call or write for further details.Kimberley House, Vaughan Way,Leicester LE1 4SG.Telephone Leicester (0533) 28631

PRACTICAL COMPUTING May 1981

Circle No. 296

171

PUBLIC COMPANY

requires

PROGRAMMERAND

SERVICE ENGINEERwith experience of

EXIDY SORCERERbased in West London with some travel tobranches in the South and Midlands.

GOOD SALARYAND

COMPANY CARAPPLY WITH FULL DETAILS OF RELEVANT EXPERIENCE TO:

Hamilton Nathan Limited2 Fitzhardinge Street

London W1H 9PN

Circle No. 297

tapes programmersHELP HAS ARRIVED

AOPT: Applesoft Program Optimizer is a 2.2Kmachine language utility that will substantiallyreduce the size of the program without affect-ing the operation of the program. £19.95APLUS: Applesoft-Plus Structured Basic is a4K machine language utility that adds struc-tured programming commands to Applesoftbasic. For example 'DO CURVE -FIT'. £19.95

CRAE: A co -resident Applesoft Editor. Globalchanges Et finds. Quote (copy) a range oflines. Append, Renumber, Modify. 15 com-mands in all. £14.95CRAE ft MCAT: Editor a Binary utilitycreating a sorted master catalog. £19.95APPLE PROTECTOR 111: Protect your pro-grams against pirating. The protected diskscan not be copied by presently availble com-mercial copy programs. £60DOS 3.3: Upgrade to 16 sector diskettes,much improved capacity. £33

Add 15% V.A.T. Postage Et Packing FreeWrite or phone for full catalogue of available software

Contact:

S.B.D. SOFTWARE15 JOCELYN ROAD, RICHMOND TW9 2TJ

Tel: 01-948 0461 Telex: 22861

Circle No. 298

An easy to use digitizer thatmakes any form of graphics entrysimple. It can be used as a menudevice or data entry or even forgames.

172

Bit Pad will interface with almost anymicro -computer.

Bit Pad is a 15 sqin digitizer tablet (anIlsqin active area) and a stylus.

The Bit Pad price includes an RS232interface (or IEEE 488 or parallel).

Bit Pad only costs £399 (excluding VAT)Power Supply Optional.

FREESTYLUS rworth145.00 '

Give your computer the flexibility you need,fill in the coupon for more information, ormake the coupon into an order, attach acheque for 1459 (including VAT)- it's time you had a Bit Pad!

trummagiaphici

Bit PadGRAPHICS

Otillechnologv-yourSmcess.

For immediate details- mm

tdsrI GRAPHICS

LSend to: TDS Ltd, Philips Road, Whitebirk Estate, Blackburn, Lancs. BB1 5TH.

Circle No. 299

£399(excluding VAT)

ring our Action Desk on 0254 676921mm mitim mom mem mm moo mm mom

Please send me more details/ Bit Pads@ £459 (including VAT)"

Name

Address

Please delete as applicable PC 5B

PRACTICAL COMPUTING May 1981

FLOPPY DM DRIVESFOR TRS 80

AND V1DEO GENIEDUAL DISK UNITS2 x 40 TRACK DRIVES £4402 x 80 TRACK DRIVES £595

SINGLE DISK UNITS1 x 40 TRACK DRIVE £236

x 80 TRACK DRIVE £315

DISK DRIVE CABLES£19£30

2 DRIVE CABLE

4 DHIVE CABLE

PERCOM DATA SEPARATORS £20

Plugs into the TRS 80 expansion interface and corrects 'READ/VERIFY'and 'CRC ERROR! TRACK LOCKED OUT!' problems on the inside tracks of any

floppy disk system. Comes with full installation instructions -NO SOLDERING, NO CUTTING, JUST PLUGS INTO THE EXPANSION INTERFACE.

Call your nearest dealer for a demonstration:RADIO SHACK LTD.,188, Broadhurst Gardens,London NW6Tel: 01-624-7174

COMPSHOP LTD., 14, StationRoad, New Barnet, Herts.Tel: 01-441-2922

COMPSHOP LTD.,311, Edgware Road,London W2. Tel 01.262-0387

MICRO -CONTROL LTD.,224, Edgware Road,London W2. Tel: 01-402-8842

LONDON COMPUTERCENTRE, 43 Grafton Way,London W1. Tel: 01-388-5721

TRANSAM COMPONENTSLTD., 5981, Theobolds Road,London WC1.Tel : 01-405-5240

N.I.C. 61, Broad Lane,Tottenham, London N15Tel: 01 -8088377

ZERO ONE ELECTRONICS,36, Oaklands Avenue,THORNTON HEATH,SurreyTel. 01.689-7924

P & J EQUIPMENT LTD.,3 Bridge Street,GUILDFORDTel: 0483804801SEVET TRADING, 14, St.Paul's Street, Bristol 2Tel: 0272897757

PARWEST LTD., 58, MarketPlace, Chippenham.Tel: 0249-2131

COMPUTERAMA LTD.,5, Cleveland Place East,London Road, Bath.Tel: 0225-333232

ENSIGN, 13-19, MilfordStreet, Swindon, Wilts.Tel: 0793-42615

H.C. COMPUTERS LTD.,541, Durham Road,Low Fell, Gateshead.Tel: 0632-821924

CAMBRIDGE COMPUTERSTORE, 1, Emmanuel Street,Cambridge. Tel: 022385334

PORTABLE MICRO-SYSTEMS, 18, Market Place,Brackley, NorthantsTel: 0280-702017

I .C. ELECTRONICS,Flagstones, Stede Quarter,Biddenden, Kent.Tel: 0580-291816

MICRO CHIP SHOP,190, Lord Street, Fleetwood,Lancs. Tel: 03917-79511

MICRO CHIP SHOP,197, Waterloo Road, Blackpool.Tel: 0253-403122

MICRO CHIP SHOP,93, Friargate, Preston, Lancs.Tel: 0772-22669

HARDEN MICROSYSTEMS,28-30, Back Lord Street,Blackpool. Tel: 0253-27590

NORTH WEST COMPUTERCONSULTANTS LTD.,241, Market Street, HYDE,CheshireTel: 061-366-8624

HEWART MICRO-ELECTRONICS, 95, BlakelowRoad, Macclesfield.Tel: 0625.22030

KARADAWN LTD.,2 Forrest Way, WarringtonTel: 0925-572668

PHOTO ELECTRICS,459, London Road,SheffieldTel: 0742-63865

GNOMIC LTD.,46, Middle Street,Blackhall, HartlepoolTel: 0783-863871

EWL COMPUTERS LTD.,8, Royal Crescent, Glasgow.Tel: 041-332-7642

CUMANA LTD 35 Walnut Tree Close, Guildford, Surrey, GU1 4UN.Telephone: (0483) 503121.

Please add VAT to all prices.

Delivery at cost will be advisedat time of order.

PRACTICAL COMPUTING May 1981

Circle No. 300

173

1110EPE11001-1 COMPUTER ETETEERITIO LTO

!CROMEMCO SYSTEMS Et SOFTWARE

CP/M 2.2 FOR CROMEMCO - £95MP/M 1.1 for Cromemco - £350Cromemco System Zero - £575S100 Peripherals:

Dump your hard disk to 'reel'tape in 10 minutes -Y2" 9 -track 1600 BPI IBM/ANSIcompatible tape drive+ controller + software - £2500

Hard Disk Systems - from £2500Cartridge Disk - from £3950

CALIFORNIA COMPUTER SYSTEMS

S100 Boards and Systems64K Dynamic RAM (bank select) - £350

ALL PRICES EXCLUDE VAT

Further details, please contact:ICE Independent Computer Engineering16/18 Littleton Road, Ashford,Middlesex TW15 1UCI

TELEPHONE: ASHFORD (STD 07842) 47171TELEX: 8952042 (DPCUST G)

EPSON MX80 SERIES DOT MATRIX PRINTERS* 9 x 9 matrix (true descenders lower case)* 80cps bidirectional printing, with logical

seeking print head* 96 ASCII character set, plus 64 graphics

incorporating 4 switch selectable Europeanlanguage options

* Programmable forms handling* 12 different print modes, up to 132

characters per line* Operator controls Er indicators, self test* Options - high resolution graphics, dual

friction/tractor feed unit* £395 with standard parallel interface

(interface options = RS232, Pet, TRS80,MZ80, Apple)

COMPUTER SOLUTIONS TO BUSINESS PROBLEMS - SOFTWARE PACKAGES / HARDWAREMAINTENANCE I HARDWARE CONFIGURATION Et DESIGN

Circle No. 301

TECPACSThe reliable technical programs fordesktop computers

Professional designers,engineers and scientists mustcarry out a variety of routinecalculations in the course of theirwork. Today, these routinecalculations can be automated tosave time and cut costs. But forreal economic savings, reliabletechnical software is necessary.

TECPACS are high -quality,technical software packages,written and tested by professionalsfor professionals. They can beused in your office, no largecentralised computing facilities

For further details.and up-to-the-minute lists

of TECPACS available contact the:Technical Software Centre

BHRA Fluid EngineeringCranfield. Bedford MK43 OAJ

Englandor telephone Dr Eugene Sweeney on

0234 750 102

are needed, and computingexperience is unnecessary.With TECPACS, designers andengineers can explore the designalternatives with ease andconfidence. Modifications can bemade as the program runs, savingfurther time.

TECPACS are produced by theTechnical Software Centre, set upby BHRA Fluid Engineering andNRDC.TECPACS offer such features asLI Built-in high technical standardLI Easy to use, friendly style

tTechnical Software Centre

epae

EJ Data checking facilitiesLi Trend facilitiesCI Choice of units17, High -quality presentation of

resultsTECPACS add another

professional to your team.In your office, or in the designoffice, just switch on, select yourTECPAC program disk, and inminutes you have the answers youneed.

Circle No. 302

174 PRACTICAL COMPUTING May 1981

Computer HardwareatCash &CarryPrices.SHARPEQUIPMENTModel User Ram

Sharp MZ8OK 20K RAM

Sharp MZ8OK 36K RAM

Sharp MZ80K 48K RAM

Sharp MZ8OFD Floppy Disk

Sharp MZ8OP Printer

Sharp MZ801/0 Input/OutputUnit

exc.VAT

375420460576372

87

inc.VAT

431.25483.00529.00662.40427.80

100.05

FREE LEDGER & STOCK CONTROLPROGRAMME WITH EVERYCOMPLETE SHARP SYSTEM, i.e. 48KSharp, Twin Floppy Disk, Printer andI/O Unit

COMMODORE EQUIPMENTModel

3008 (4008)

3016 (4016)

3032 (4032)

8032

3040 (4040)

8050

4022

8024

C2N

User Ram exc.VAT40 Col. PET8K Mem.

40 Col. PET16K Mem.

40 Col. PET32K Mem.

80 Col. PET32K Mem. 755347K Disk 5851M Byte Disk 755Printer 357Printer 975Cassette 47

inc.VAT

378 434.70

462 531.30

585 672.75

868.25672.75868.25410.55

1121.2554.05

VIC and ATARI equipment - availableMid -May - ring or write for full details.Every machine sold by ComputerSupermarket is fully tested before despatchand is absolutely complete with instructionmanual and tape, including free 13 amp plugfitted on mains lead.All goods sold with full manufacturer'swarranty and subject to conditions of sale.Copy available on request. All machines soldare full U.K. Standard.All prices exclude VAT. FREE deliveryanywhere in U.K.

PRACTICAL COMPUTING May 1981

Gccommacharat sailAwrIes

' "

COMPUTERSUPERMARKET3rd FloorDouglas HouseQueens SquareCorby NorthamptonshireTelephone (05366) 62571Telex COMPSU 341543/4

VISA

*4)S.

4)*So*** OS

0411

.411411: to

e*

e **

** SS

9 Circle No. 303

175

MAXIMUM VALUE . . . MINIMAL COSTThe Houston Instrument HI -PLOT range of digital plotters:

Well designed and ruggedly constructed Easy to interface via RS232C port Easy to use - software listings are

available free of chargeWide choice of models Highly reliable Good quality 0. Imm step size

SINTROM GROUP

Sintrom ElectronicsComplete mini/microsystem capability

DMP-2 The standard A4 sized£695 HI -PLOT

DMP-3 A4 sized but intelligent£800 with remote controlsDMP-4 Intelligent like the DMP-3£887 with the same features but

with pushbutton controlsDMP-5 The A3 sized standardL1080 HI -PLOT with the same

features as the originalDMP-2, but with vacuumpaper hold

DMP-6 A3 sized but intelligent£1185 with remote controlsDMP-7 Like the DMP-6 but with£1271 pushbutton controlsSo now you have SIX good reasonsfor adding a new dimension toYOUR micro!

Sintrom Electronics LtdArkwright Road, Reading,Berks RG2 OLSTel: Reading (0734) 85464Telex: 847395

Circle No. 304

SPECIALFROM C.T.S. THE UK's TOP OHIO DEALER

THE NEW SUPERBOARD IIIThe best value for Money Home Computer available, with the following features:FULL ASCII KEYBOARD 4K RAM EXPANDALE TO 8K ON BOARD 161 GRAPHICS CHARACTERS RS232 PORT INAND OUT (PRINTER INTERFACE) CASSETTE INTERFACE MODULATOR FOR INPUT TO T.V. SPECIAL MODULEGIVING THE MOST STABLE T.V. PICTURE IN THE UK EXPANDABLE TO 32K AND DUAL MINI FLOPPIESSPECIAL FEATURE:24 characters on 28 lines or 48 characters on 14 lines - Software switchable with our NEW INTAMON MONITOR (Note theOHIO Swap tape in not needed)THE NEW MONITOR ALSO OFFERS THE FOLLOWING EXTENDED BASIC:

Trace ON Machine Code SAVETrace OFF Machine Code LOADInkey Clear ScreenGET Clear windowEXIT Home CursorSYS TEXTRUB OUT GRAPH Format Switch

This new ROM is suitable for old and new Superboards and can be customised to other screen formats. It is also compatible with all currentlyavailable monitors.

PRICES: NEW SUPERBOARD III WITH MODULATORNEW INTAMON ROM

£164.95 VAT

£27.50, VATONLY FROM:C.T.S., 31/33 CHURCH STREET, LITTLEBOROUGH, LANCS. Tel: (0706) 79332 or 74342 any time

SCHOOL SPECIALUp to 16 CIPs (Superboard III in a case) tied into a C8P Host System enabling CIPs to access the Host System'sDual 8" Floppies and Printer. The 32K Host System is a full Business System capable of handling School Records,Accounts etc. Double -sided 8" Floppies are optionally extra, giving over 1MByte on line storage.OTHER OHIO SYSTEMSC8P - C3 - C3OEM - C3B and C (Hard Disk Systems up to 74 MegaByte) - networking systems.PRINTERS - ANACOM - MICROLINE - GP80 - CENTRONICS EPSOM - QUME - OLIVETTI ETC.VDUs - TVI - VOLKER CRAIG - LEAR SIEGLER - CIPHER ETC.

RING C.T.S. AND DISCUSS YOUR REQUIREMENTS ON:LITTLEBOROUGH (0706) 79332 or 74342

BUSINESS SYSTEMS

176

Circle No. 305

PRACTICAL COMPUTING May 1981

Ohioare now in Britainwiththeir small business computers.

Youwerewise to wait.Ohio Scientific - one of the leading suppliers of micro-computers in the U.S. - have supplied moreWinchester -based small-business general-purposemicro -computer systems than anyone else in theindustry.Now OS (UK) is here in Britain. Set up in Slough with afull service base, all the equipment you could ask for,more expertise than you'll ever need, and an eagernessto do for small/medium businesses here what they'vedone for small/medium businesses in America.

Ohio Scientific's 02 -OEM is designed to be the costeffective solution to business and industrial applicationswhich can effectively utilize typical micro -computerexecution speed. The 02 -OEM benefits from OhioScientific's years of volume microcomputer productionexperience yielding an extremely competively pricedmedium performance microcomputer. The 02 -OEMutilizes the popular 6502 microprocessors operated at1 Mhz clock speed in conjunction with 48K of 450 NSDynamic RAM memory.

The C3 -D mates the electronics of the popularChallenger III triple processor microcomputer system withthe cost effective 8" Winchester disk. The C3 -D features

t American Data Harm & 1HtiRx Gotrtptitet

PRACTICAL COMPUTING May 1 98 I

the three most popular microprocessors - the 6502A,68600 and the Z80A. When operated in the 6502processor mode, the machine executes instructionsapproximately twice as fast as competitive microcomputersystems. The C3 -D incorporates 52K high speed staticRAM, serial I/O port, bootstrap and diagnostic firmware, 8"floppy disk for transport and backup as well as an 8"Winchester. The C3 -D comes complete with OS -65U diskoperating system which is optimized for use with theWinchester hard disk and includes a fast 9 -digit BASIC byMicrosoft.

The C3C is the most economically priced 36 megabytehard disc systems available in the UK. C3C qualitiesinclude three processors, 6502, 6800, and Z80 withsoftware control and full multi user and multi taskingfacilities, with floppy disk or Alloy Engineering tape drives.C3C is 'state of the art' in microcomputing.

All systems come with fully operational software andlanguages include BASIC, FORTRAN, AND PASCAL withCP/M (R) on C3 series machines. Complete applicationsoftware also available.

If you want the biggest backing a small business couldask for, call Alan Davies on (0753) 75915.

OHIO SCIENTIFIC(UK) Ltd*

Middlegreen Estate,Middlegreen Road,Langley, Berkshire.Telephone: Slough

(0753) 75915

Circle No. 306

177

smallsystems

fAengineeringlimited

2 4 Canfield Place London NVV6 3BT Telephone 01 328 7145 6

IEEE -488 PET INTERFACESB200 Bi-directional RS232C serial £186Type C Uni-directional RS232C serial £120AP Addressable parallel for Centronics

or Anadex printers £106GPI AP Micro based bi-directional serial

interface with buffering £249Custom GPI software developmentfor special interfacing requirements

All serial interfaces incorporate: Software or switched Baud rate selection

with 16 different rates selectable Crystal controlled Baud rate Full RS232C handshake 20 mA current loop 1.0. option.All the above interfaces have two modesof code conversion to match print out tothe PET screen for either display mode.Non Addressable parallel £45TVNideo interface £35We also stock a range of PET connectors

r PET SOFTWAREIntercomm . . .

General-purpose Asynchronouscommunications package ... Emulates a wide range of terminals Sends and receives program & data files Permits communication with mainframes,

networks, other micros, other PETs £350Wordcraft 80 £375Basic Compiler £200TCL Pascal £120

S100 HARDWARE and SOFTWAREP&T S100 IEEE controller board withCP/M, North Star or Custom Software £350Measurement Systems high qualitydynamic memory boards.

Low cost Micro -processordevelopment aids8048 programming card £395Prom simulator development board £249A range of cross assemblers for mostpopular micros £85

PRINTERS...PRINTERS...PRINTERSRP 1600 Daisy Wheel Printer60 CPS PET, centronics, RS232 interfaces

New ... RP 1600 with intelligent interfaceBi-directional printing with large buffer

Centronics 73780 CPS proportionally spaced completewith non -addressable interface for PET £395or addressable interface £445

4

r Full range of Hewlett Packard HP -85--

and CBM PET SystemsLAs IEEE -488 interfacing specialists wecan provide full technical support and adviceon scientific, industrial and wordprocessing application.

Circle No. 307

178

\s\.....

VIDEO DISPLAY UNITTEX VT64 - £299

*UNIVERSAL KEYBOARD

TEX KB62 - £99

*VT64 + KB62 - £389

\.. i 16 x 64 FULL SCREEN REWRITE IN 0.5 SECONDS. 128 CHARACTER U/L SET -,- FULL CURSOR/SCREEN CONTROLS. FOUR -TONE 'BEL'. V24/20mA. 50-19200 BAUD. KEYBOARD INPUT PORT ACCEPTS & POWERS MOST TYPES. KB62 HAS 464 x 8 -BIT KEYCODES IN EPROM. 62 KEYS WITH DEDICATED CURSOR & USER FUNCTIONS. QUALITY 'FEEL'. ALPHA -LOCK. AUTO -REPEAT. QUAD -MODE ENCODING. 2/N -KEY ROLLOVER/LOCKOUT. LATCHED DATA. ± STROBE. CONTACTS OF USER KEY.

r TEX EPROMPT ERASER - £39 inclusive

SIMPLE 32 -CHIP 'A HOUR PROCESS ON 200-250V A.C. TUBE RUNS COOL AT EXACT WAVELENGTH FOR EPROMS.* 'EPROMPT GT' MODEL WITH SAFETY INTERLOCK SWITCH ETC. £49 INCL.* 'TEXTIME' SOLID-STATE 30 -MINUTE ERASE TIMER £19 INCL.

* SPECIAL OFFER: 'EPROMPT GT' + 'TEXTIME' £66 INCLUSIVE.

r"We are the manufacturers and you can buy direct from us. VT64/KB62 pricesexclude shipping and value-added tax. Terms C.W.O. or C.O.D. (add £1) or tradereferences please. Educational & Public Authorities obtain immediate credit.

All orders and enquiries post-free to:

MICROSYSTEMS LTD. FREEPOSTST. ALBANS, HERTS. ALI 113R ST. ALBANS 648771TRING 4797 ANYTIME .i

..."

Circle No. 30E

1.4q$11"THIS BOOK IS EXCELLENT!''

- Clive Sinclair

'30 PROGRAMS FOR THE SINCLAIR ZX-80:1K' is a unique112 page book which contains 30 programs all designed to fitinto your basic 1K version of the Sinclair ZX-80. IN programswhich go far beyond anything that has been published theauthors show the unique capabilities of the Sinclair ZX-80. TheZX-80 is more powerful than you ever thought!BLACKJACK - actually contains a full pack of cards,shuffles them, keeps track of the dealer and player card totals,and the money bet, all within 1K.MEMORY LEFT - an incredible routine, especially useful as itenables you to know exactly how much memory is left, evenduring the running of a program. This also illustrates USRroutines.DR. ZX-80 - a conversational program with the computer asanalysist which uses an ingenious method of storage.GOMUKU - the computer challenges you to this complexJapanese game. Incredibly this program including display ofthe 7 x 7 board, fits into 1K; it only does so because it uses thedisplay as memory!Other programs included are HORSE RACE, LUNARLANDER, (with moving spaceship), NOUGHTS &CROSSES, NIM, SIMPLE SIMON, HANGMAN, LIFE,MASTERMIND, PINCH and 17 others.As well as the programs, the book illustrates programmingtechniques you can use in your own programs - spacecompression, PEEKs and POKEs, USRs and soon.

AVAILABLE BY MAIL ORDER ONLY £6.95 plus 50p p&p

MELBOURNE HOUSE PUBLISHERSOrders to: 131 Trafalgar Road, London SE10.Correspondence: Glebe Cottage, Glebe House, Station Road, Cheddington,Leighton Buzzard, Bedfordshire LU7.

I enclose f7.45 for each . . . . copies of '30 programs for the Sinclair 2X-80: 1K'book. (Orders outside the UK - £7.951.

NAME

ADDRESS

Postcode

Circle No. 309

PRACTICAL COMPUTING May 1981

S100 COLOUR VIEWDATA DISPLAY CARD - UHF £295

S100 COLOUR VIEWDATA DISPLAY CARD - RGB £244

S100 PRESTEL AUTODIAL MODEM (2 CARDS) £300

14" COLOUR VIEWDATA MONITOR (RGB) £325

NORTH STAR VIEWDATA SYSTEM (ILLUSTRATED) £2605

PRICES DO NOT INCLUDE VAT

FULL RANGE OF VIEWDATA ITEMS SUPPLIEDCALL FOR DETAILS

HI.TECH ELECTRONICS54 HIGH ROAD SWAYTHLING SOUTHAMPTON S02 2JF

TEL 0703 581555 TELEX NO 47388 HTEL

Circle No. 310

PRACTICAL COMPUTING May 1981 179

ADVANCED COMPUTER EQUIPMENT (LEEDS) LTD95 MEADOW LANE LEEDS 11 TEL 0532 446960

NEW MICROCOMPUTER STORENOW OPEN

PRICES SHATTEREDCOMMODORE PET

ALL WITH 12 MONTHS WARRANTY

32K PROFESSIONAL KEYBOARD £575DUAL DISK DRIVE 347K £625CASSETTE DECK C2N £ 50PRINTER 3022 MATRIX TRACTOR £375

SHARP Z-80ALL WITH 12 MONTHS WARRANTY

48K WITH 34K USER RAM £47436K WITH 22K USER RAM £42220K WITH 6K USER RAM £380DISK DRIVES, PRINTERS ETC.

PRINTERSBD80/132 BI DIRECTIONAL MATRIX £425IEEE PARALLEL OR RS232 INTERFACERICHO-RP1600 DAISYWHEEL

SPECIAL PRICE £1,150

APPLE II PLUS 12 MONTHSWARRANTY

48K AUTO START £695DISK WITH CONTROLLER £345DISK WITHOUT CONTROLLER £2959" MONITOR B/W £ 80

SUPERBRAIN64K WITH SINGLE DENSITY 320K DISK .... £1,55064K WITH DOUBLE DENSITY 700K DISK ... £2,150FULLY INTEGRATED ACCOUNTS PACKAGE . £950

OPERATING SYSTEM " MBASICCOBOL*FORTRAN

SUNDRIESDATA TAPES SUPER QUALITY (101 £ 4.355'/4" CERTIFIED VERBATIM (10) £27.00PLAIN LISTING PAPER 2000 SHEETS £12.50

BOOKS * GAMES * PROGRAMS * GALOREVISICALC * DESKTOP PLANNER

SPECIAL OFFER

PLEASE ADD VAT TO ALL GOODS EXCEPT BOOKS - CASH AND CARRY OR 24HR DELIVERY - YOUR CHOICEALL EQUIPMENT IS FACTORY FRESH AND FULLY TESTED IN OUR OWN WORKSHOPS

STANDARD CONDITIONS OF SALE APPLIES TO ALL PRODUCTS Circle No. 311

BATE MICROSYSTEMS LIMITEDMICROCOMPUTER SALES + SUPPORT

NOW IN DUNDEE + GLASGOW

Announce: - THEMICROSOFT

Z80 SO FTCAR DFOR YOUR

APPLE II PLUSZ80 Softcard is a circuit board with a Microprocessor and I/OCircuitry which plugs into any slot (except 0 in your APPLE.

* Z80 Softcard allows you to run CP/ M, CP/ M basedlanguages and CP/M application programs on your APPLE.

j&e,. 4ittcs4VP -4'4?

44.4e44P4 `SISetP.0 '14 'veto '44.40t

Z.- 46t 110'14;9 /41.,

1111/1\1\

* Z80 Softcard enables you to switch your APPLE back andforth from 6502 processing to Z80 processing via a singleinstruction.

" Z80 Softcard gives you Microsoft Basic 5.0 on your APPLE.

PRICE £200.00 EX VAT

GATE MICROSYSTEMS LTDTHE NETHERGATE CENTRE66, NETHERGATE, DUNDEE DD1 4ER 10382) 28194

GATE MICROSYSTEMS LTDABBEY HOUSE; 10 BOTHWELL STREETGLASGOW G2 6NU 041-221-9372

Circle No. 312

180 PRACTICAL COMPUTING May I981

After the best selling'Pet Revealed' and

'Library of Pet Subroutines'comes another book from

Nick Hampshire ,, kPET GRAPHICS VI

The way information is displayed on the screen can make or ruin any programwhatever the application. This book shows how you can fully exploit the graphicspossibilities of the PET, essential reading for anyone wishing to write good usefulprograms. The book contains dozens of example programs including a compre-hensive graphics package written in machine code (resides in the top 2K of memory).The contents of 'PET Graphics' include: How the PET display works - designinga display format - cursor control in PRINT - using POKE - an introduction to themachine code graphics package (you don't need a knowledge of machine code touse this package, but the full source code listings are given for those interested),among the packages over 30 routines are those to draw - bars, borders, characterblocks, reverse field blocks, double density point and line plot, fine density bar plot,block scrolling, scrolled multiple page screen, repeat key and protected screenareas, multiple page displays, macro character generator, etc. - Other sections ofthe book cover - interactive graphics, with full circuit designs and comprehensivesupport software for adding a light pen to the PET - simple switch and joystickinput devices - a review of add on hardware to give the PET high resolutiongraphics capability.

Price £10.00

All the programs in 'PET Graphics' are available on CBM format disk price £10.00

Cheques payable to Computabits Ltd.

COMPUTABITS LTD et_P.O. BOX 13, YEOVIL; SOMERSET.

PRACTICAL COMPUTING May 1981

Circle No. 313

181

1 YEAR GUARANTEE

THE BLACKAPPLE

FROM £549

4016 - 16K - £475 + VAT4032 - 32K - £575 + VAT4040 DISK UNIT - £575 + VAT8032 - 32K - £825 + VAT Mara \8050 - "1MB" DISK - £825 + VAT (_ - -

Latest PETS Large Keyboard and greenscreen 8K microsoft basic in ROM.Popular easy to use Microcomputer.

MX8OB tractor £359 + VATMOUT Friction

+ Tractor £399 + VATOKI Microline 82 £375 + VAT

Epson printers, quiet, bi-directional logicseeking. 9 x 9 Matrix £ sign Pet + Appleinterface, lower case descenders.64K+320K - £1449 + VAT64K+688K OD - £1799 + VATDIABLO 630 Daisywheel

- £1199 + VATWORDSTARIMAILMERGE

- £379 + VATSUPER BRAIN popular professionalmicrocomputer can be used as a standalone system or as an intelligent terminal.First class word processor terminal. Fullsystem with printer for £2954 + VAT

Extras

TOOLKIT

%art i CASSETTE

182

SPEECH OUTPUT

PET

PET DISK DEBUG £18

£24£49

FORTH ON DISK £49

£199 + VAT

+ VAT+ VAT+ VAT+ VAT

Pet speech output with infinite vocabu-lary Disk debug a popular aid to diskprogramming. _ -Please send me

Name

Address

I enclose cheque/P.O. for £(add (15 for P&P for each item of hardware).

INTELLIGENT ARTEFACTS LTD.Cambridge Road, Orwell, ROYSTON, Herts.

Tel: 022-020 689 j Circle No. 314

NEWDOS80 - APPARAT'S DOS FOR THE 80's* Up to 4095 bytes per record on disc files* Variable - length records* 5 or 8 inch disc drives of 35, 40, 80 tracks may

be mixed* DOS and BASIC command chaning

Print Spooler provided for concurrent printingand other processing

* NEWDOS and TRSDOS compatible

* PLUS MUCH MORE ! ! !

£65 including detailed manualBUSINESS SOFTWAREContact us to discuss your application

UDMS INFORMATION MANAGEMENT FORTHE NON-PROGRAMMER* Powerful, easy -to -use facilities for data storage,

update, and reporting

* Ideal for business applications

* Extremely felxible* Save M.'s on software costs!* Versions for TRS80 I and 11

* Comprehensive users manual

Basic Version £75 Full Version £150 Manualonly £6.00

MICROLINE-80 PRINTERPhone for lowest pricePrices exclude V.A.T. and Postage.

CLEARTONE COMPUTER CONSULTANTS LTD.PRINCE OF WALES INDUSTRIAL ESTATE

ABERCARN, GWENT NP1 5R1 Tel: (0495) 244555

CLEARMNEd Circle No. 315

COFT1PUTER EEPT PIEMICROCOMPUTERS FOR BUSINESS,

EDUCATION AND HOME

FOR ALL YOUR BUSINESS, EDUCATIONEt LEISURE COMPUTER REQUIREMENTS!!!

ACORN ATOMAPPLE !ITRS-80SHARPNORTH STARHORIZONTANGERINEU.K. 101NASCOMVIDEO GENIE

+ PRINTERS &OTHER PERIPHERALS.BOOKS**SOFTWARE*MAGAZINES**STATIONERY***BUSINESS &INDUSTRIALCONTROL

King's Lynn

Dereham

Thetford

Bury St.Edmunds

WE ARE HERE!!!88 St. Benedict's Street

NORWICH NR2 4ABTel. (0603) 29652

24hr. Answering Service.

Cromer

Great Yarmouth

NORWICH

Lowestoft

Diss

Circle No. 316

PRACTICAL COMPUTING May 1981

1111r a a r tersfir-

MICROLINE 80 MICROLINE 83 MICROLINE 82

UP TO 9.5 INCH PAPER UPI

TO 15l INCHI I

PAPER UP TO 9.5 INCH PAPER

80 cps UNIDIRECTIONAL (1) 120 cps BI-DIRECTIONAL 80 cps BI-DIRECTIONAL

LOGIC1 1

SEEKING1

LOGIC1 1

SEEKING1 1

6 & 81p. 5, 10, 16.5 cpi 6 & 8 1pi 5, 8, 10, 16.5 cpi 6 &'t

8 1pi 5, 8, 10, 16.5 cpi

BLOCKt

GRAPHICS BLOCK1 1 1

GRAPHICSI 0 BLOCK

1 1

GRAPHICSI

1

UKl

or US CHARACTER ET 8 C-IAIZAClIER ISETS 8 CHARACTER1 1 1 1

SETS

CENTRONICS1 t

INTEkFACE CENTRONI1 f

S INTERFACEI

CENTRONICS1

INTERFACEI

OPTIONAL1 1

SER AL INTERFACEI

SERIIALI 1

TO 12001

BAUD SERIAL1 I

TOI

1200I

BAUDI

TO 9600 13AUD.1

011

IONAL IN)1

ERFACE OPTIONALlit

INTERFACEI

OPTIONAL ITRACTOR TO1

960(II WIII H 2K1

131JF FLK TOi

9600I

I3AUD1 I

WITH 2 K BUFFER&xION fi

xo1FFI

& XION/IXOFl'h6399 IEEEI 1 t

VERSIONS AVAILABLE OPTIONALI I I

1 RACTOR

TRIt_ iC1UK STANDARD

6550I 1 I

1 1 1

6799i , I

EXTREMELY QUIET & RELIABLE TRADE--1-ENQUIRIES

& EDUCATIONALWELCOME---- HEAD

200 MILLIONWARRANTY

CHARACTERS111: i

I

...._

MICROLINE 82,...-..1.- MICROLINE 80 NM -

tv ki I i _

. Ie1

.

MICROLINE 83. - I I I

L

QUMEALSO AVAILABLE

/ TALLY / DEC / CIFER

RohanPrice k)r i -ICom-Specialimmlirin itedpericLlonly

1 1

putin41 1 1 1

52 COVENTRY STREET, SOUTHAM,1111111 t

WARWICKSHIRE CV33 OEP. TelephoneIIIIII1 I

SOUTHAM (092681) 4045 Telex 311640

Circle No. 317

PRACTICAL COMPUTING May 1981 183

...fir ITT 2020 and Apple Computers

* YOUR CHOICE OF 2,3 OR 4 DRIVES PER PACK.CAPACITY OF 280K, 560K, 840K & 1120K BYTES.

* MAINS POWER.

* INTERFACE CABLE AND BOARD INCLUDED.* INTERFACE BOARD ALLOWS UP TO 4 DRIVES.

* SWITCHABLE SINGLE/DOUBLE DENSITY IBM3470 FORMAT.

* 2 & 3 PACK HAVE LOCKABLE POWER SUPPLYFOR SECURITY WITH LED POWERINDICA TORS.

p DISTRIBUTED DATA PROCESSING LTD.,36 Nobel Sq., Basildon, Essex. SS13 1LT.Tel. Basildon (0268) 728484

Circle No. 318

r[aculab]

Connects directly to TRS-80 Level 2 Keyboard. Operating andfile handling software in ROM. 8 commands add 12 powerfulfunctions to Level 2 BASIC. No buttons, switches or volumecontrols. Full control of all functions from Keyboard orprogram. Daisy chain multiple drives. Certified digital tape inendless loop cartridges. Reads and writes in FM format at 9000Baud. Soft sectored with parity and checksum error detectionfor highly reliable operation-just like discs. Maintainsdirectory with up to 32 files on each tape, tapes may be write -protected. Supports Basic and machine -language program files,memory image and random access data files. 12 characterfilespecs-: "FILENAME/EXT:d" (d is drive no. 0-7).Automatic keyboard debounce. Full manual with programmingexamples and useful file -handling routines.

COMMANDS (usually followed with a filespec and possibleparameter list).@SAVE, @LOAD, @RUN -for BASIC programs, machinelanguage programs and memory image files. @GET, @PUT-moves a 256 -byte record between a random access file andBASIC's data buffer. @KILL -removes a file from thedirectory and releases tape sectors for immediate re -use. @LIST -displays file directory along with sectorallocation and free sectors. @NEW -formats tape and creates a blank directory.

floppy tape,The tape that behaves like a disc,For TRS-80 LEVEL II and Video Genie.

Master drive with PSU, Manual and a selection of tapes.ror TRS-80 £169 -00, for Video Genie £174 - 00.Slave drives £125-00. (add £2-00 p.p. + vat).

(Export orders pp charged at cost)

For furtherinformation,Telephone0525 371393

aculab Ltd.24 Heath Road,Leighton Buzzard,Beds. LU7 8AB A

184

Circle No. 319

PRACTICAL COMPUTING May I 98 I

Takea step up to your next Computer!THE CONCEPT

How many ways are there to build an 5100 system? Notmany, and all expensive. TUSCAN changes all that.

Five S100 boards on one single board -just forstarters. Plus five extra slots for future expansion.

What a combination! Z80 and S100 with theTRANSAM total package of system and applicationssoftware.

THE PRICE RANGEFrom £235 for complete main board kit to£1481 for 48K assembled with 2 X 51/4 drives.

THE HARDWAREThe first Z80 single board computer with integral S100expansion. British designed to the new IEEE (8 BIT)S100 specification, the TUSCAN offers total systemflexibility. A flexibility available now.

The board holds the equivalent of a Z80 cpu card,8k ram, 8k rom video and I/O cards with 5 spareS100 expansion slots and offers a price/performanceratio which is hard to beat.

Just compare our price with a commercial S100 tenslot motherboard with this specification.

compatible and fully supported with applicationssoftware. Both 514" and 8" drives are supported indouble density.

THE PACKAGETUSCAN is available in kit form or assembled. Withseveral hardware and software options to suit yourrequirements and budget. Attractive desk top case alsoavailable holds 2 x 51/4" Drives.

TRAIIelAMNOBODY DOES IT BETTER!

Send to Transam Components Ltd.. 59/61 Theobald's Road. London WCI.

lam interested in the TUSCAN Z80 based single board computerNEW LOW PRICES, send S.A.E. for further details.

Name

Address

THE SOFTWARETUSCAN offers the user the choice of system monitor,editor, resident 8k basic, resident Pascal compiler or full Telephone

CP/M disk operating system. All options are upwards LTRANSAM COMPONENTS LTD., 59/61 THEOBALD'S ROAD, LONDON WCI. TEL: 01-405 5240/2113

Circle No. 320

PC5/8

PRACTICAL COMPUTING May I 98 I 185

PAXTONBUSINESS

DESKBREAKS

NEWGROUND1.

2.

3.

4.

IT'S COMPREHENSIVEBusiness Desk is a softwarepackage providing fully integratedadministration facilities includingInvoicing, Stock Control, Sales,Purchase and Nominal Ledgers.

IT'S TRANSPORTABLEWritten in C1S:COBOL BusinessDesk is designed for ease ofimplementation on a widest rangeof computer and peripheralcombinations.

IT'S SUPPORTEDBusiness Desk comes completewith comprehensive userdocumentation, demo packages,sales support and proven referals.

IT'S AVAILABLE NOW!New Dealers required in North,Midlands and West.

THE DEFINITIVE SOFTWARE FORMICROCOMPUTER APPLICATION

Paxton Computers Ltd26 New Street St NeotsCambs PE19 1AJTel: (0480) 213785

Circle No. 321

new practicalcomputing books

samsbooks

Walter H. Buchsbaum

Personal ComputersHandbook

Practical, up-to-dateinformation on buying andusing personal ormicrocomputers is given,including technical features.price considerations, locatingdefective components, andtroubleshooting hardware andsoftware.

£7.75 pb 288 pages_J 672 21724 4

Andrew Staugaard, Jr.

6801, 68701 and6803 MicrocomputerProgramming andInterfacing

£9.05 pb 352 pagesI 672-21726-0

Jonathan A. Titus, ChristopherA. Titus and David G. Larsen

8085A Cookbook

£9.05 pb 352 pages672-21697-3

Jonathan A. Titus, ChristoperA. Titus and David G. Larsen

TRS-80 Interfacing.Book 2

[--1 £7.10 Pb 256 pagesH.. _I 672-21739-2

Jonathan A Titus

TRS-80 Interfacing -

Book 1

£5.80 pb 192 pages672-21633-7

Published in 1979

PC5/8 I

prentice-hallbooks

Mark A. Spikell andStephen Snover

Brain TicklersPuzzles and Pastimes forProgrammable Calculators andPersonal Computers

L_i I! 0581h0b181650

pages

£3.85 pb13-081000-2

David L. Heiserman

Programming inBASIC for PersonalComputers

El 1 65 hb 333 pages13-730747-0

I I £5.15 PbI 13-730739-X

Don Inman and Kurt Inman

Apple MachineLanguage

Machine language programmingfor the Apple computer istaught in BASIC in this new book.

£9.70 hb 254 pages8359-0231-5

£6.45 pb8359-0230-7

T.G. Lewis

Pascal Programmingfor the Apple

£9.70 hb 224 pages8359-5455-2

£6.45 pb8359-5454-4

Prentice -HallInternational

Prices are correct at the time of going to press

but may be subject to change.

book ordersThese books can be ordered from your bookseller or in case ofdifficulty from Department 30. Prentice -Hall International,66 Wood Lane End, Hemel Hempstead, Herffordshire, HP2 4RG, England.

Please mark the number of books you wish to order in the boxes beside eachtitle and return the advertisement to the address above with your payment.

Name

Address

I enclose a cheque/P.O. for £

Please add 55p per book for postage and packing. Payment should be madeout to International Book Distributors Please allow 28 days for delivery

Circle No. 322

PRACTICAL COMPUTING May 1981186

Slawla® ] [PLUS48K RAMApple is a trade mark of Apple Computer Inc., Cupertino, CA. USA.

£595Send cheque or money order for

(subject to availability)

£692 (including VAT & Delivery in the UK) to:

Trade EnquiriesWelcome

at our new address:

LIMITED

15 Grand Parade, Brighton, Sussex, BN2 2QB.Telephone: 0273-695264

Circle No. 323

PRACTICAL COMPUTING May 1981 187

'

we can supply printed continuous forms with your company nameand logo plus ex -stock single part listing paper in the following sizes: -

depth x width

11 x 91/411 x 91/211 x 103/811 x97/811 x 81/211 x 12

(in inches) depth x width

NEW

13 x 91/481/2 x 111/2

12 x 91/4 60 gsm12 x 91/4 70 gsm12 x 91/4 85 gsm

multiples in OTC or NCR are available for prices and details telephone:-

Circle No. 324

TRS-80 OR VIDEO GENIE?

THEN MICRO -80 IS FOR YOUA monthly magazine full of articles and programs just for the TRS-80. Written byenthusiasts for enthusiasts MICRO -80 is now available in this country. Fill in thecoupon and send £1 .50 for your sample copy.

To: MICRO -80 (U.K. SUBSCRIPTION DEPT.) 24 WOODHILL PARK, PEMBURY,TUNBRIDGE WELLS, KENT TN2 4NW

PLEASE SEND MY COPY OF MICRO -80 - I ENCLOSE MY CHEQUE/POSTAL ORDER FOR £1.50(SINGLE COPY RATE)

NAME

ADDRESS

PC518 I

I 88

Circle No. 325PRACTICAL COMPUTING May 1 98 1

May the Force be with you Businessmen and professional people alike can ridthemselves of day-to-day problems and increasedworkload with a microcomputer.

Accountants Estate Agents

RetailersInsurance Brokers

DoctorsDentistsSolicitorsArchitectsEngineersChemists

FarmersBankers

Teachersto name but a few

,111111111111

VW \

Just a few tasks a microcomputer could beorganising for your company, division or

department: -

Integrated AccountsSales Ledger

Purchase LedgerNominal Ledger

Sales ForecastingStock Control

job CostingEstimating

PayrollWord Processing

(automatic compilation,editing and production of

repetitive letters anddocuments).

SYSTEM A3asic.ncluding s

computerscreen &

Keyboard

PET

£399

APPLE II

£775

SHARP

£450

SUPERBRAIN RAIR

SYSTEM BAs A', plus floppy diskdrive(s) and matrixprinter for smallbusiness user.

£1700 £1655 £1750 £2200 £2480

SYSTEM Cs '13', but quality printer

or word processingnstead.

£2700 £2050 £2250 £2600 £2850

SYSTEM DAs 'C', plus hard disk folup to 1 0,000,000 bytes online.

...., £5550 £5350

Prices exclude V.A.T Rental, Leasing, and/or Maintenance Contracts plus System Software Consultancy available.

Johnsonmicrocomputers

III

ae111111

A member of the T. V. Johnson Group

Johnson House, 75-79 Park Street,Camberley Surrey. Telephone 0276 20446

48 Gloucester Road, Bristol. Telephone 0272 422061148 Cowley Road, Oxford. Telephone 0865 721461

Circle No. 326

PRACTICAL COMPUTING May 1981 189

1 week courses in Computing forJunior and Senior Management

(or anyone who is interested)The courses, which can be resident ornon-resident, cover all elements of com-puter appreciation, an introduction tomicro computer and mini computersystems and applications packages plusa course in BASIC programming.(There is a micro each so plenty of handson experience).Fees for the course:Non -Resident £165Resident (Includes B&B only)The lectures and practical sessions willlast for eight hours each weekday and4 hours on Saturday.Courses each week throughout thesummer commencing Sunday June 14th.Also we can arrange courses to take placeat a venue of your choice locally.

For further details ring

HURRICANE COMPUTERSon Worksop (0909) 84047

or send cheque together with details of thenumber of places required and the Sunday onwhich the week of your first preference coursecommences.

Circle No. 327

NORTH STAR UsersTAKE THE TEDIUM OUT OF PROGRAMMING WITH THE

QDOS NorthStar Utilities Package(QBS.NSUT)

- Improves Screen Handling- Simplifies Keyboard Input- Ensures robust a- 'friendly' programsBuilt around NS BASIC (re1.5.2), this group of 14sophisticated functions, simply incorporated at thebeginning of your programs, provides:

Controlled Et Checked Numeric, String a Date Input Error Handling Real Tilme Clock functions Processor Pause Cursor Set/Screen Clear functions FULLY controlled Disk Copying Program from Basic Extra String Processing functions With User -Specified VDU Characteristics E17.00

QDOS NorthStar Programmer Aids(CIBS.NSPA)

KREF - (Command) Lists Line Nos. which containspecified BASIC Keywords

XREF - (Command) Full cross-reference listing ofline no. accessed

QLIST - Prints paged and formattedProgram and/or Variable Listings

QPACK - Compresses BASIC programs for fasterexecution/smaller memory usage

QZAP - provides Screen Editting of any Disk -held data

QCOMP - compares two Programs for differences£20.00 (Both packages £34.00)

Fully supported and provided with full documentation on a qualityDiskette.

BUSINESSSOFTWARE 9 Tintern Close Streetly Sutton Colctfield B74 2EL

Circle No. 328

APPLE COMPATIBLEvia DIRECT MAIL KEATINGFROM

Model Description

BOARDS ANDCOMPUTER

Price If) Model

SOFTWARE

Description Price ID

7500A Wire Wrap Board, up to 25 sixteen -pin or 6 forty -pin 12.00 7710A Asynchronous Serial Board, for Paper -Tape Reader, 95.00sockets. Keyboard, VDU, Printer etc. Baud rates selectable

7520A Extender Board, with top connector. 15.00 from 50 to 19.2K baud.7712A Synchronous Serial Board, for high-speed interface 105.00

7114A 12K ROM/PROM Board, 6 sockets for combination 65.00 communications.of 2316 ROMs, 2716 EPROMs. 7720A Parallel Board, for Paper -Tape, Printer etc. control 95.00

7424A Calendar/Clock Board, 12 or 24 hour formats, 149.00adjusts Feb. to 29 days for leap years.

on/off devices such as low current relays, sprinklersetc.

7440A Programmable Timer Board, 3 independent 75.00 7728A Centronics Printer Interface Board, for Centronics- 119.00

software -controllable 16 -bit timers. type parallel printers.7379A Cable for all Centronics, Okidata Mikcroline 80 or 17.00

7470A Analog -to -Digital Converter Board, converts analog 75.00 Microtek MT -88T printers - specify which desired.voltages to BCD numbers then to ASCII charactersfor VDU. Use for monitoring thermostats, fluid levelin tank, Apple power supply etc.

7388A Cable for MPI 88T printer. 17.0078116 Arithmetic Processor Board, floating-pont hardware 249.00

to increase execution speeds and math functions by7490A IEEE488 Interfact Board, up to 15 interconnected 195.00 order of magnitude. Includes interpreter software on

controllers, talkers and/or listners for Counters, diskette for disk drive users.Signal Generators, Digital Multimeters, Colour 7811C Arithmetic Processor Board, same as item 7811B 249.00Graphics Output Devices etc. except interpreter software on ROM.

Prices INCLUDE all VAT, Post & Package charges. You pay only actual net Big savings on other new products including battery operated hand-held PROMfor only £895 complete - ideal for field applications, pocket-sizeProgrammerprices as quoted. Complete the oupon-order, enclose your cheque/postal order

made payable to: Keating Computer.DVM's, Calculators, Interface Cables, Barrier Boxes, VDU's and many more -all at direct -mail prices which save you money. Send £1 for our new catalogueand we'll credit you £5 on your first order. Don't delay - Send Today.

Please ship me:

QUNTY. MODEL PRICE PAYMENT ENCL.

Allow 30 days for delivery. Documentation includes installation guide, operating instructions, schematics Er logicdiagrams plus software listings where applicable.All products warranted for 6 months and backed by full money back guarantee if not satisfied.

K i TING COMPUTER WATCH US GROW 42 KNOLL BECK AVENUE, BRAMPTON,NR. BARNSLEY, SOUTH YORKSHIRE

Gircie No.190 PRACTICAL COMPUTING May I 98 I

KGB MICROS LIMITEDTHE PROFESSIONAL ORGANISATION OFFERING

HARDWARE AND SOFTWARE PLUS FULL CLIENT SUPPORTWHO WISH TO MAKE YOUR BUSINESS OUR BUSINESS

SUPERBRAINI

MICROLINE 80

INDIVIDUAL PRICE £450.00

DIABLO 630

INDIVIDUAL PRICE £1675.00

SOFTWARE SUPPORT

THE MICRO COMPUTER THAT HASTHE BEST PRICE/PERFORMANCERATIO.

£1695 (64K RAM)

THE EFFICIENT BUSINESS SYSTEMSUPERBRAIN

MICROLINE 80 PRINTER

£1995

THE COMPLETE WORD PROCESSINGSYSTEM

SUPERBRAIN

DIABOLO 630 PRINTER

THE PROVEN 'WORD STAR' PACKAGEMAIL MERGE

£3495INCLUSIVE OF INSTALLATION AND TRAINING

* KGB offer a wide range of standard software -- FORTRAN, COBOL, BASIC, PASCAL.* KGB will customise our software packages to meet your unique requirements - Invoicing £95,

Sales Ledger £235, Purchase Ledger £235, Nominal Ledger £235, Payroll £335.* KGB will design and implement software to suit your business needs.

KGB Micros Ltd., 88 High Street, Slough, Berkshire.Tel: Slough 38581/38319

Superbrain is the registered trademark of Intertec Data Systems. Prices exc. VAT.

Circle No. 330

PRACTICAL COMPUTING May 1981 191

Ali_, ..i

ICFPaniadService°computer

48K Apple][EuroplusPrice £695 t VAT

Supplied with free TV Modulator and of courseApple 1 -year warranty.

Disc drive with controller D.Q.S.33Price £383, VAT

All other Apple parts and software available.

Integrated Circuits MemoriesZ80 ACPU 7.95 4116 2.25Z80 APIO 5.95 2114L 1.95Z80 ACTC 5.95 2708 3.50Z80 S10/1 25.00 2716 4.756802 8.95Please add VAT to all prices.

Please send for price list of CMOS Et- TTL I.C.'s.

CONTACTROL LTDFree Delivery

Mail Order Dept.9 High Street, LenhamMaidstone, Kent ME17 2QDTel. (0622) 858753

Circle No. 331

BUTEL-COMC0'4\RP1600 Daisywheel Printer

60cps!

List Price:£1450(excluding VAT)

Price includes an interface Interfaces available are

Serial V24/IEEE/Centronics/Qume/Hytype Trade/OEM discounts available

Write or call for further information

Butel-Comco LimitedGarrick Industrial Centre

Garrick Road HendonLondon England NW9 6AQ

Telephone 01-202 0262Telex 47523

Technology for business L

I am interested in purchasing the RP1600

for connection to

Name

Company

Address

TelephonePC5/8 I

Circle No. 332

NASCOM 216K RAMB BOARDV Et T ASSEMBLER

V. &KT. ELECTRONICSBUILT

330

Z80A 81C BASIC RAM DOWN!2K EASY385 CHEAPMONITORTO EXPAND 1 x 4116< £2

* BRITISH * SEE BELOW

FLOPPY DISK CONTROLLER CARDNASBUS COMPATABLE HANDLES

8" x 51/4" FLOPPIES, SINGLEOR DOUBLE DENSITY WITH

ONBOARD FACILITIES FOR DMAAND 32K DYNAMIC RAM

ALL ON ONE 8" x 8" CARDREADY BUILT AND TESTED

DISC CONTROLLER £160

AS ABOVE WITH DMA £190AS ABOVE WITH 32K RAM £210

V Et T ASSEMBLER:FULLY RELOCATABLE ON TAPE.STATS MONITOR. £12.50PIO Option £12 Zeap Eprom £50VART Option £16 Tape £30C TC Option £14 Nas Dis £37.50NAS SYS 3 £40 Naspen £30

MEMORY8 x 4116 200 ns DRAMTRS80 U/GRADE KIT1 x 2114 300 ns SRAM1 x 4118 250 ns SRAM 1K1 x 2708 x 1K x 8 EPROM1 x 2716 5V 2K x 8 EPROM1 x 2532 5V 4K x 8 EPROM

PLEASE ADD V.A.T. AT 15%

82 CHESTER RD LONDON N19 5BZ TEL (01) 263 2643

£16.00£17.00

£1.75£8

£3.25£5

£12

Circle No. 333

192 PRACTICAL COMPUTING May 1981

SYSTEM 4000EPROM EMULATORIPROGRAMMERS

P4000 PRODUCTION EPROMPROGRAMMERThis unit provides 'simple, reli-able' programming of up to 8EPROMs. It has been designedfor ease of operator use - a single'program' key starts the blankcheck - program - verify seq-uence. Independent blank checkand verify controls are providedalong with mode, pass/fail indic-ators for each copy socket and asounder to signal a correct keycommand and the end of a pro-gramming run. Any of the 2704/2708/2716 (3 rail) and 2508/2758/2516/2716/2532/2732 EPROMsmay be selected without hardwareor personality card changes.2 year warranty. Price £545+ VAT:

VM10 VIDEO MONITORThis compact, lightweight VideoMonitor gives a clean crisp pictureon its 10" screen. Suitable foruse with the EP4000, SOFTY andother systems. 12 month warranty.Price £88 + VAT, carriage paid.

MODEL 14 EPROMERASERS

MODEL UV140 EPROMERASERSimilar to model UV141 but with-out timer. Low price at £61.50+VAT, postage paid.

EP4000 EPROM EMULATOR/PROGRAMMERThe microprocessor based EP4000has been designed as a flexible,low cost, high quality unit foremulating and programming allthe popular NMOS EPROMswithout the need for personalitycards, modules or hardwarechanges. Its software intensivedesign permits selection of the2704/2708/2716 triple railEPROMs and the 2508/2758/2516/2716/2532/2732 single railEPROMs for both the program-ming and emulating modes.The video output (T.V. or monitor)for memory map display in add-ition to the built-in Hex LED dis-play, for stand alone use, is uniquein this type of system. This, withthe doublefunction 28 key key-pad, powerful editing features,powered down programmingsocket, buffered tri-state simul-ator cable and 4k x 8 data RAMgives you the' most comprehen-sive, flexible and compact systemsavailable today.2 year warranty. Price £545+ VAT:

MODEL UV141 EPROM (j.ERASER 4> 14 EPROM capacity Off, Fast erase time

Built-in 5 -50 -minute timer Safety interlocked to prevent

eye and skin damage Convenient slide -tray loading

of devices Avalable Ex -Stock at £78+ VAT

Postage Paid Add £6 to order total for next

day delivery by DATA POST.

PLEASE NOTE OUR NEW ADDRESS/TELEPHONE NUMBER

GP INDUSTRIAL ELECTRONICS LTD,UNIT 6, BURKE ROAD, TOTNES INDUSTRIAL ESTATE,TOTNES, DEVON.TELEPHONE: TOTNES (0803) 863360 (Sales) / 863380 (Technical Service)DISTRIBUTORS REQUIRED - EXPORT ENQUIRIES WELCOME

SOFTlfSYSTEM Poet

Low cost card 2704/2708emulator/programmer features:

Direct output to T.V. Highspeed cassette interface Oncard EPROM programmerMultifunction Keyppad 1Kmonitor in 2708 1K RAM 128byte scratchpad RAM 22 in/outports Access at card edge to allbuses 1K EPROM EMULATION Direct memory access for fastdata transfers Editing facilities,including - data entry/deletion,block shift, block store, matchbyte, displacement calculation Supplied with Zif socket,simulator cable andcomprehensive manualSOFTY Kit of parts £100 +VATSOFTY Built Et tested £120+VATSOFTY Built power supply

£20 + VATP&P IS INCLUDED IN ALL PRICESAdd £6 to order total for next daydelivery by DATAPOST.

SOFTYCONVERSIONCARDEnables SOFTY to program thesingle rail EPROMs, 2508/2758/2516/2532. Selection of devicetype and 1K block are by pcbslide switches. Programmingsocket is zero insertion force. Easyconnection to SOFTY with theDEP Jumper supplied. Built andtested: £40 + VAT, postage paid.SOFTY PRINTER

40 column electrosensitiveprinter 5 x 7 dot matrix printsizes Push button hex print-outof SOFTYs RAM, EPROM orinter -cursor contents On cardPSU Selection of bytes per line.Built and tested £145 +VAT,postage paid.EX -STOCK EPROMS

1-9 10-24 25 up2716 6-95 6-50 5-95(singlerail)2708 4-00 3-80 3-602532 23-402732 21-00ADD VAT AT 15% - POSTAGE PAIDWRITE OR TELEPHONE FOR DETAILSON ANY OF OUR PRODUCTS

PRACTICAL COMPUTING May 1981

Circle No. 334

193

lirbrand new,KmCompare ourrinp9es beforeutyohu buyl elsewhere!sIAll devicesri areS"bfrfactory prime, full spec. and fully guaranteed!

si I " Introducing the incredible

+44t fill oi 4

Single Board

BIG BOARD Computer-% 64K RAM! Ze80 CPU! FLOPPY

DISK CONTROLLER! 24x soviDu!PFM 3.3 2K SYSTEM MONITOR!

LLTHIS ONONE BOARD COMPLETELYASSEMBLED AND TESTED AND JUST

NEW6809 S.100 SINGLE BOARD COMPUTER Meets IEEE S-100 Standard! RS - 232 Handshake! Uses Motorola's Powerful a Selectable BAUD Rates!

MC6809 CPU! Manual includes: 11" x 7" 4K, 8K, 113K ROM! Schematic, Parts List. User Notes. 2K RAM! Software Listings and MORE. ACIA, PIA, 8080 Simlulated 1/0IBareboard only C49! (plus El p&p), CPU (6809) £19.001 AMMON; Monitor(2716) £25! COMPLETE BOARD ASSEMBLED AND TESTED, ONLY £250!(plus C2 p&p).

NEW EXCITING, ENTERTAINING SOFTWARE FOR THE APPLE IIand APPLE II i PLUS!! ASTEROIDS IN SPACE!!!

If you liked Invaders you'll love ASTEROIDS IN SPACE by Bruce Wallace!Your spaceship Is travelling in the middle of a shower of asteroids. Blastthe asteroids with lasers, but beware - BIG ASTEROIDS FRAGMENT INTOSMALL ASTEROIDS! The apple game paddles allow you to rotate yourspaceship, fire Its laser gun, and give it thrust to propel it through endlessspace. From time to time, too, you'll encounter an alien spaceship whosemission is to DESTROY YOU, so you'd better destroy it first! Highresolution graphics and sound effects add to the arcade -like excitementthis program generates. RUNS ON ANY APPLE!! WITH AT LEAST 32KAND ONE DISK DRIVE!

ON DISKETTE ONLY £14.95

THE NEW GICOMPUTER SOUNDCHIPThe amazing AY.3.8910 is afantastically powerful sound andmusic generator, perfect for use withany 8 -bit micro processor. Contains3 tone channels, noise generator 3channels of amplitude controls 16bit envelope period control 2 parallel110. 3DIA converters plus much more.All in 40 pin DIP Super easy tointerface to the S 100 or otherBusses.

ONLY t 8.50 + VAT, including FREEreprint of BYTE 79 article! Also, add£2.25 for 60 page data manual."Perhaps the next famous composerwill not direct a 150 piece orchestrabut rather a trio of microcomputerscontrolling a bank of AY38910s.BYTE July '79.

NEW! SPECIAL OFFER! 4K CMOS RAM (1K x 4) 450 NS ONLY £5.50.The TIC 5514P from Toshiba, CMOS equivalent of the 2114!

* Lower Power Dissipation.10pW/BIT (TYP.) at 3.0V (STANDBY).10uW/BIT (TYP.) at 5.0V (OPERATING)

* Data Retention Voltage 2V to 5.5V* Single 5V Power Supply* 18 PIN Plastic Package* Full Static Operation* Three State Output* Input/Output TTL Compatibleo Fast Access Time 450NS

Toshiba's TC5514P (industry type 6514) is a lull static read write memoryorganised as 1024 words by 4 bits using CMOS technology. Ultra lowpower dissipation means it can be used as battery -operated portablememory system and also as a non-volatile memory with battery backup.Operates from a single 5V power supply with static operation, hence norefresh periods and a much simplified power supply circuit design. Threestate outputs simplify memory expansion for minimum date retentionvoltage is 2V, the battery backup system needs only simple circuit.Toshiba's original C2MOS technology also means wide operating andnoise margins. The TC 5514P is moulded in a dual.in-line 18 pin plasticpackage 0.3 inch in width.

i4.50.1pptipstsndBAREBOARD & ROM SETS only £150! (plus£3 p&p)64K RAM (32 x 4116 200NS) only £64!(plus £1 p&p)

Three years' development went intoBigBoard. designedifrom scratch to run thelatest version of CP/M, so just imaginewhat software you could run WITHNO MODS! Add a couple of 8"Disk Drives, a Video Monitor andKeyboard. an enclosure and the PowerSupply option - and! you've got a completebusiness system for about ONE THIRDthe COST!

That's what BigBoard can offer -flexibility. power, and incredible economy'.Send for your BigBoard TODAY!

Size 91/2 x 13% inches.Requires + SV @ 3 Amps+/- 12V 0.5 Amps.

PLUS THESE OPTIONSON THE BOARD AS WELL

Serial I/O S till 2 channels using .e Z40 S 10 a. Me SMC8 116 Baud.. Generator. You get FULL RS232'For synchronous or asynchronous communication.and docks can be transmitted or received by 3modem in she former Bosh channels can be sec upfor etcher data communication or data terminalsSupoorfs mode 2 Int PRICE JUST CM MK. pip)

Two Port Uses Z-80 P 10 co give full 16 Ms. fully buffered seaPerellel brairemone User selectable leNtseuka polarity.I/O ONLY LIS line. P&M

Peel Time Uses 280 C TC and can be configured as a counter onClock Real ,r33 Clio. ONLY £22 lino p&p)

CP/M 2.2 The popular CP. 0 0.5.asmedried by KovacsS3333313 re run on the BigBoard n net et (Impale).

Power Supply Complete monkled and cased LIAM pap)

Floppy disk Siemens FDD 100-8 L315 (PLUS VAT)Drives

Microchips at micro prices!

NEW, LOW, LOW PRICES ON MEMORIES!!!Compare our prices before you buy elsewhere! All devices are brand new,factory prime, full spec. and fully guaranteed!All prices exclude p&p and VAT. Please refer to Ordering Information before ordering.DON'T DELAY - BUY TODAY - SUCH LOW PRICES DON'T LAST FOR EVER!!

STATIC RAMS 1-24 25-99 100+2114L450 Ns 195p 175p 150p2114L 300 NS 225p 195p 175p2114L 200 NS 250p 225p 195p4118 250 NS 8KNEW!! 895p 795p 695pHM61 16 16K (2K x 8)150 NS 24 -pin NEW!! £19.95 £17.95 £15.95

DYNAMIC RAMS4116 200 NS Ceramic 195p 175p 150p4116 150 NS 375p 350p 325pHM4864 64K(65K x 1) 200 NSSingle + 5V supply16-pinNEW!! £29.95 £24.95 £19.95

CMOS RAMS5101 1K (256 x 4)450 NS 350p 325p 295p

4315 4K (4K x 1) 450 NS 995pTC5514P 4K (1K x 4) 495p 450p 395p450 NSHM6116 16K (2K x 8)150 NS 24 -pin NEW!! £19.95 £17.95 £15.95

EPROMS2708 450 NS 350p 325p 295p2716 Single 5V 450 NS 475p 450p 395p2532 Single 5V 450 NS £14.95 £12.95 £11.952732 Intel -type 450 NS £14.95 £12.95 £11.952564 64K (8K x 8) 450NS 28 -pin £99 £95 £90

NEW SUPER MUSICMACHINE KIT!AT LAST - en al fordable kit thatcan be PROGRAMMED TO PLAYANY SONG OR GROUP OF SONGS!Instead of a nightmare of numerousICs and special expensive BipolarROPAs the SUPER MUSIC MACHINEuses a SPECIAL MASKPROGRAMMED COMPUTER CHIPone CMOS gate and the mostpopular erasable EPROM, the2706/2715 caries. BASIC KIT Includesdrilled,plated and screened PC boardand ALL components except theEPROM and 12V transformer. Thebasic kit will play short renditions of25 tunes through Its 7 WATTAMPLIFIER SECTION. Add anoptional ROM and any tune

programmed will be played. If youhave the equipment to program 2708EPROMs, we supply lull informationon programming your own music!FEATURES* Basic kit contains 25 short tunes

in the main ICI.a Will address external ROM for up

to 1,000 MORE NOTES per ROM(ROM Is not Included).

* Operates on 12V AC or 12V DC at.500mA. (Using unit on 12V DC andwith optional ROM requires 9Vbias battery, not Included).

* 7 watts of audio power will drive8 or 18 ohm speakers or hornspeakers (not included).

a DIP switches not included.a 'NEXT TUNE' provision steps

sequentially through all tunes.* Tune address can be wire jumper

selected or board Is designed totake DIP switches.

* PITCH VOLUME and TEMPO areall adjustable.

* SPECIAL 'CHIME' SEQUENCEScan be activated regardless oftune address to provide formultiple doorbell applications.

* All tunes consist of electronicmusical notes played one al atime. There are no chords orharmony sound to the music.

e STEP-BY-STEP ASSEMBLYINSTRUCTIONS provided.

o Large number ofPREPROGRAMMED ROMS withpopular and classical tunesreadily available. Send SAE for listend prices.

ONLY 319.75 for bask, kit (plusp&p 80p).

INTERFACELINEARMC1488MC1489DM812375150751547518275322753247532575361753857545175491128T26872881958T97

90p90p

125p123p125e195p250p325p325p350p295p

50p75p

175p175p175p

75p

KEYBOARDENCODERAY'5.2378 795p

CHARACTERGENERATORR0.3-2513 UC 450p

DEVELOPMENTMODULE28000 DM £1099

DISPLAYSFND500FND5IOFND567DL704DL707MV57164

80p80p25p85p85p

225p

SUPPORTDEVICES6520652265326551681068206821685068528212821482168224

3 2 5p6 2 5p8 2 5p8 2 5p350p4 2 5p4 2 5p42504 2 5p3 9 5p450p3 9 5p395p

8228 395p8251 4 9 5p8253 01 1.2 58255 4 9 Sp8257 £10.508259 01 3.2 5MC 144 12VL 797p280P10 595p280 CTC 595p280A P10 695pZ80ACTC 6 9 5pZ80 DMA 0l9.95Z80A DMA C24.95Z805100 C 2 9.9 6Z804 S100 £34.95Z805101 C29.93ZEIOA SIO 1 034.95Z80 StO 2 C29.95ZEIOA S102 £34.98

UARTSAY.5.1013A 3259AY.3.1015D 398pI M6402 IN_ 3 2 5p

CPU'S6502 62506504 795p6505 795p6800 8 9 5p6802 9 9 5p6809 C198080A 52508085A C1 0.9 5

Z80Z80AZ8001X8002W 090008

EPROMs2708 450 NS 375p2716 5V 450 NS 495p2532 32K 450 NS 018.952732 intel.type 450 NS C18.952564 64K (8K x 8)

450 NS 28.pin NEW! £99

BIPOLAR PROMS93448 518 x 840 NS934531k x 440 NS93451 tk x 845 NS93511 2k x 850 NS.

795p995p0125095

0199

P 0.8 p o a.

p

FLOPPY DISK CONTROLLERSFD1771 B-01 SID Inverted Bus 029.95FD1791 B.01 DID Inverted Bus 039.95F5179213.01 515 Inverted Bus £34.95FD1793 9.01 DID True Bus C54.95FD179413.01S/DTrua Bus £34.95FD1795 B DID Inverted Bus,

Side Select £59.95FCTI 797 B DID True Bus,

Side Select C 5 9.95

Ordering Information. Unlessotherwise stated, for underC50 add 50p pap. Add 15% VAT tototal we VAT on books). All devicesare brand new, factory prime and lullspec. and subject to prior sales and

Prices subject to changewithout notice. Minimum telephonerorder using ACCESS Is C10. If orderingby post with ACCESS, Includename, add and card no.

written clearly. Please allow 416weeks delivery on books.

MIcrobite,Dept. PCB Unit 9110,let Floor, E Block,

ICRO 38 Mount Pleasant,WC1 X OAP,

Telephone( 01.278 7369Teter 895 30114

Circle No. 335

194 PRACTICAL COMPUTING May 1981

ComputerWeekly brings you

COMPECNUIT111961

Belle Vue,ManchesterJune 23-25, 1981

-for the first time, an extensionof the UK's largest computershow, COMPEC, comes to theheart of industrial Britain.Computers, peripherals,terminals, software, mini- andmicro -computers and services -the most comprehensivecomputer exhibition ever stagedin the North of England.Admission is by businessregistration and £2.00 at thedoor. Save time and money byplanning your visit now - send inadvance for half-price tickets at£1.00 each and mark the dates inyour diary -

Tuesday, June 23: 10.00-18.00Wednesday, June 24:10.00-18.00Thursday, June 25: 10.00-16.30

r CUMPECNUE11-111Sponsored by Computer WeeklyData Processing, Systems International& Practical Computing,Organised by IPC Exhibitions Ltd.

Please send tickets, I enclose remittance of £Compec North '81 Tickets, IPC Exhibitions LtdSurrey House,1Throwley Way,Sutton, Surrey SM1 4QQ(cheques payable to IPC Business Press Ltd .)

Name

Company

Address

PC5/81

(Applications not accepted after June 8. No school parties, no children under 16)

Circle No. 336

PRACTICAL COMPUTING May 1981 195

HellfireWarrior

16k LII cassette £15.95

32k TRSDOS Disk £17.95The basic DUNJONQUEST system presented in The

Temple of Apshai has been expanded with more commandoptions, more potions, (there are now 13!), more magicalitems (including the long-awaited, often requested magicarmour), and more special effects, The result is HellfireWarrior.

In addition to an innkeeper, Hellfire Warrior has anarmorer, an apothecary and a magic shop. There are fournew levels of sixty rooms each. In general, the treasures arericher, the magic more potent, the monsters more dangerousand the levels more challenging.

Level 5: "The Lower Reaches of Apshai" - The first levelof Hellfire Warrior is a sequel to The Temple of Apshai; itis populated by the same sort of giant insects and othernasties that inhabit the upper levels. There are magicalrooms that let an adventurer in but not out, various trickytraps and other surprises, but it is probably a bit lesshazardous than the 4th level of the Temple.

A Puzzle to SolveLevel 6: "The Labyrinth" - This is a classical maze

inhabited by minotaurs and the like. It is as much a puzzle tosolve as a dunjon to explore, because the only exit is hiddedsomewhere in the labyrinth, and hordes of man-eatingmonsters can thwart the most logical search. The graphicpresentation is marvelously realistic: the adventurer's visionis limited to his immediate surroundings; paths go everywhich way and there are no room numbers to help him findthe way.

Tough To SurviveLevel 7: "The Vault of the Dead" - This is a more

conventional level, with rooms, doors, secret passages andso on. Its uniqueness lies in its inhabitants, most of whomrank among the so-called undead: skeletons, ghouls,mummies, spectres - even invisible ghosts. What makesmany of them so terrifying is that they can reduce theadventurer's characteristics permanently; even if he survives,he may be no more than a pale shadow of the hero he usedto be.

Quest Leads To HellLevel 8: "The Plains of Hell" - The culmination of the

adventure lies in an Underworld haunted by lost souls andshades of the dead, guarded by dragons and fiery houndsand riddled with bottomless pits and blasts of hellfire. Theentering adventurer soon faces a choice of three bridges,each guarded by a different fearsome beast. On the far sideis a vast plain cloaked in darkness - a maze devoid of wallsor room numbers. Finding a way back is not too difficult(not as difficult as getting back), but the quest leadsonward, over a hidden bridge on a perilous trail to a slab ofblack stone on which, in enchanted sleep, lies the warriormaid Brynhild, circled by a wall of everlsting fire. To bringher back to sun and air and break the spell that binds her,the adventurer must overcome the legions of the lost, slaythe nine -headed pyrohydra and the great bat -winged demonthat rules the Underworld, cross the bridges of flame,endure a cold that numbs the soul and face Death itself.And live.Morloc's Tower (R.T.G.) £10.95 Rescue at Rigel £10.95

Datestones of Rvn (R.T.G.) £10.95 Starfleet Orion £12.95Temple of Apshai (R.T.G.) £14.95 Invasion Orion £13.95

All prices include p QC p and V.A.T.

ALGRAYALGRAY House, 33 Bradbury Street, Barnsley.South Yorkshire Tel: Barnsley (0226) 83199

00000000000000000000000 0000 0000000000010000000000 000 00000000

Circle No. 337

2YSTEMS2UPERBRAIN 2HARP MZ-80K 2UNDRIES2HARP PC -3201 2ERVICE 2UPPORT

2OFTWARE3D COMPUTERS are suppliers of COMPLETE SYSTEMS based on SHARPand Intertec SUPER BRAIN microcomputers and are now appointeddistributors for MICROEASE software products for SUPER BRAIN andSHARP PC -3201.

EASYFILLER TMComplete information storage and retrieval system. User defined fileformats, report formats and record selection criteria. Records can beaccessed by key or searched for by selection by multiple conditions onmultiple fields. Reports are output on printer or screen with totalling andbreakpoints. Files of extracted records may be produced for input toWordstar/ Mailmerge.Applications: Library, Cataloguing, Indexing Systems; Market research andanalysis; Selective mailshots; Personnel records; Employment and EstateAgency; Laboratory records etc. f275.00EASYPLANNER TMComprehensive resource scheduler. Jobs partitioned into discrete activitiesor processes are allocated over resources such as equipment and aworkforce with variable skills levels. Schedules produced to obtain optimumutilisation of resources. Immediate rescheduling possible if equipment failsor workforce reduced. Capacity and resource planning.Applications: Shop floor control; Service management; Project planning;Timetables; Staff allocation etc. £400.00EASYTIMERTMTime recording and monitoring system. Assignments or jobs can be brokendown into sub -jobs and activities. Charge rates may be set by activity andemployee. Budgets may be allocated. Selective reporting on time spent andbudget status produced on demand. Totals by Account, Job and Employee.Overspends on budget highlighted.Applications: Engineering, Advertising, Management Consultancies; Projectmanagement; Accountants; Solicitors; Architects etc. £400.00Callers welcome at our COMPUTER SHOP on the A3. Kingston By -Pass.Open Saturdays. Dealer enquiries welcome

230 TOLWORTH RISE SOUTH, TOLWORTH, SURBITON, SURREY KT5 9NBTel: 01-337 4317 Telex: 945966 AIRCLA G

Circle No. 338

TAKE CONTROL

II

APPLE 3C

PIP SeriesInterfaces

Or10 BIT

ADC

I ,,oltor

10volt,AmilIMIONMk

.1-- go.,

Step Motor;7a Controller+ Datalogger

Motor drives available for both low and highpower applications.

Cost Effective Control from

J S SYSTEMS Ltd 18 PORTMAN Rd READING 599615

Circle No. 339

1 9 6 PRACTICAL COMPUTING May 1981

r

LOWER & UPPER CASE CHARACTER GENERATOR

COMPUTECH for dappleCOMPUTECH for ITT

PAYROLL

SALES LEDGER

PURCHASES LEDGERGENERAL (OR NOMINAL)LEDGER

UTILITIES DISK 1

APPLEWRITER

VISICALC

CAI

Well proven software for business applications on theITT 2020 and Apple microcomputers.

Prices excluding V. A.T. for cash with order, F.O.B. London NW3

(300+ Employees, 100 Departments, £375hourly, weekly, monthly. Very powerfulbut easy to use).(500+ Accounts, 100 Departments). £295(500+ Accounts, 100 Departments). £295(1000 Accounts, 100 Analyses, multi- £295purpose package). Job costing etc.(Diskette patch, slot to slot copy, £20zap etc).(Word Processing, see below for U/L £42case).(Financial Modelling, Costing, Analysis).

(Converts Apple pictures for ITT display).

Over 500 packages in use, fully supported by us.

£95£10

AND NOW HARDWARE!£50

Replaces character generator to display upper and lower case characters on screen, includespatches to work with Applewriter, supplies the missing link! Specify Apple or ITT.

COMPUTECH DIPLOMAT H/S SERIAL INTERFACE £80This card has been designed and built to the same professional standards that have resultedin the success of our software. The DIPLOMAT observes the proper "handshaking" protocol sothat you can drive fast printers and send and receive date from other peripherals at high speedswithout loss of data. Switch (& software) selectable baud rates to 19200 and many other options.Plug compatible with 'terminal' or 'modem' wired peripherals. Guaranteed.

MICROLINE M80 PRINTER £425This neat, reliable machine prints at 10 characters per inch, 80 characters on an 8 inch line, or 40expanded characters, or 132 very readable characters, upper and lower case and graphics, 9 x 7dot matrix, 6 or 8 lines per inch. Parallel interface is standard, serial optional. Both friction andsprocket feed are standard, tractor optional. We can also supply the parallel interface card forApple System computers for £80 and a driver to enable both text and graphics to be used.Optional custom colour matching for Apple or ITT. Optional character sets. Trade supplied atvery generous discounts for modest quantities.

THE FABULOUS MICROMUX 8000 from £800This is a brand new product, an asynchronous serial multiplexor with up to 16 ports, any one ofwhich may communicate with any other independently, like a 'telephone exchange' for data!Built in test function. Firmware may be customised for special applications. Available in multiplesof 4 ports up to 16.

COMPUTECH SYSTEMS'168, Finchley Road, London NW3 BHP. Tel: 01-794 0202

AGENTS THROUGHOUT THE UK AND OVERSEA5

PRACTICAL COMPUTING May 1 981

Circle No. 340

197

You lucky Apple II owners-by adding applakal you

can have the onlyPO approved

computer connectionWith Appletel you can link your present Apple II

computer direct to Prestel for just £595 plus VAT -which is a major cost saving for a start. Add in theseother major advantages and you'll really appreciatewhat the complete Owl Computer package can dofor you!

* Save on telephone bills by storing pages fromPrestel on a floppy disc - screen them up onApple II when you're ready.

* Programme the unit to automatically call up asequence of pages, and store them for laterexamination.

* Write your own BASIC programs to processPrestel data as well as send commands toPrestel.

* The full keyboard means you can use Prestelto maximum advantage for sending messages.

* Appletel is now available in colour

For full details onwhat Appletel cando for you, andthe name of yournearest dealer.please phoneor write.

Owl Computers18 Hadham Road, Bishop's StortfordHerts CM23 2QRTel: Bishop's Stortford (0279) 52682

Circle No. 341

198

PRICE BEATERS!READY TO USE SYSTEMS

Business System £2295Accountants System £2295 Finance House System £2500*Word Processing System £3000Hotel System £2500Payroll System £2295

+ VATSystems include:

SUPERBRAIN, PRINTER, INTEGRATEDSOFTWARE, FULL DOCUMENTATION.+ MULTI-USER SYSTEMSAVAILABLE.

WE ARE THE EXPERTS!

Contact: 0924 82636

ANPAC SYSTEMSMARTIN HOUSEMARTIN STREET

BRIGHOUSE

92 CANAL LANELOFTHOUSE GATE

WAKEFIELD

Circle No. 342

MMicrocomputers

mownmZ80 48K

OUR PRICE £460.00No gimmicks, No give-aways. Just goodvalue for money

THIS MONTH'S STAR BARGAINSharp PC -1211 Pocket Computer£82.00

TRS-800 Expansion Interface Units £173.8716K Ram Upgrades (same day service) £30.00Disk, Drives, Singles, Twins 40-80 track

from £236.00For TRS-80 and Video GenieStringy Floppies TRS-80 £169. V/Genie £179Video Genie 16K Level II £299.00CREDIT FACILITIES AVAILABLE ON ALL PURCHASESOVER £150.00 (written quotations on request)We fully support the products we sell.

TOP QUALITY 5 'A " Floppy Disks £156 each.Cassettes, Drivers, Tapes, Books, Paper, Cables,Software for Entertainment, Business andEducational purposes.C. W. O. Please add VAT and carriage. Personal callers welcome

Cass.1 facef15.95

ICRO-CHIP SHOPS91 FRIARGATE, PRESTON, LANCS197 WATERLOO ST., BLACKPOOL190 LORD ST., FLEETWOOD

L. D. MORGAN Et CO. LTDComputer Systems DesignHead Office:Tel. Fleetwood 79511/79480

Circle No. 343

PRACTICAL COMPUTING May I 98 1

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4086 72p4089 1SOp4093 70p4094 250p4095 95p4096 95p4097 340p4098 120p409940100

200p220p

40101 132P40102 1801'40103 180p40104 99p40105 I 20p40106 60p40107 601'40108 470p40109 I 00p.40110 300p40114 250p4502 120p45034507 7°P5Sp4508 290p4510 99p4511 120p4512 801'4514 250p4515 300l4516 110p4518 100p4520 100p4521 250p4526 108p4527 150p4528 I 00p4532 I 40p4534 SSOp4536 37Sp4538 120p4543 1801'4553 3201'4556 72p

4560 200p4569 250P4572 40p4583 110P4584 60p4585 150p

PERIPHERALS3242 800p3245 450o6522 600p6532 800p6820 375p6821 300p

MEMORIESRAMS2 01-4L 400p2 02-2L 120p2 II -4L 300p2 12A 300p2 14-2L 400p

INTERFACE ICsAD561J 1400pAD7524 600pDAC I 408-8 200pDM8 I 31 375pDP8304 450pDS8835 250p

MISCEL-LANEOUS6MHz UHF Mod.

350p8MHz UHF Mod.

450p16 Key Pad 450p

4724 2SOp40097 901)14411 700p14412 805p14433 1100p14599 290p

6850 300p6852 370p8155 I loop8205 320p8212 175p8216 200p8224 275p

2 14-3L 350p2 14-4L 250p4027-3 350p4044-4 600p4116-2 300p4118-4 950p5101 400p

DS8836 150pDS8838 225pMC1488 75PMC1489 75pMC3446 325PMC3480 800pMC3487 300P

5100 Busboard1500p

DIN41612 Plug450p

D1N41612 Socket450p

43 way Edge Con

CPUs1600 17200p

1802C 750p2650A 1600p6502 600p

8226 400p8228 400p8251 475p

8253 550p8255 450p8257 900p

6810 200p6116 2000p6514 500p4164 2000p

MM58 1 74 1200p75107 16op

75110 250p75154 175p.

75182 230p75324 375p

250p31 way Plug 0.1-

120p31 way SKI 0 1-

I 20pLogic Probe LP I

6502A 800p6800 550p6802 750p6809 1600pINS8060 1000p

8259 950p8279 950pZ80-CTC 600pZ80A-CTC 700pZ80 -P10 600p

ROMS745188745189 -,27.1,

"" -"745201 350p

350p

75361 300p7536375365

400,

75451 2200p

72,75491 2 lop

01Logic Probe LP2

El 8Logic Probe LP3

E49

8080A 450p8085A 750p9980 2000pZ80 ' 550p

Z8ODART i 1 2Z8OADART L15Z8OADMA £12280A 700p

745287745387 350p

-74547065nP745471 650p

872687288T95

60p60p60p60p

Zero InsertionForce Socket24 pin L7

DMA 750p-P10

Z80-510- I 2400p 745472 900p745571 900p

879781LS9581L596

20p40p

DIL Switches4 way SPST 90p

CHARACTERKEYBOARD

745573 900p(Many more 8 I LS97

8ILS9820p40p

6 way SPST 105p8 way SPST 120p

GENERATORS3257A 1000p ENCODER

AY 700p

stocked)96019602

10p2201'

CRYSTALSR03-2513 U C.32.768KHz650p

-5-2376EPROM TM599 I 4 £25 250p

100KHz 300p903-2513 L.C.

700p745262 1000p

UARTSAY -5-1013A 400pAY-3-101SD 400p

1702A 700p2708 400p2716( + 5v) 700P2732 1000p2532 L 10

FERRANTIZN425E-8 400pZN427E-8 750p

200KHz 370p1.0MHz 320pI .008MHz 350pI .8432MHz 325p

IM6402 450p 2.00MHz 325p2.45760MHz 325p

CRTCONTROLLERMC6845 1000pMC6847 E 1 1

SFF96364 1100pTMS9918 6000p

FLOPPY DISCCONTROLLERFD1791 £30FD 1771 05MINI DRIVEFD -50A f 1 40

VOLTAGE REGULATORSFixed Plastic TO -2201 A + ve -,e5v 7805 60p 7905 6sp

6v 7806 70p 7906 80p8v 7808 70p 7908 80p12v 7812 60p 7912 65p15v 7815 60p 7915 lop

3.276MHz 300p3.579MHz 175p4 00MHz 290p4. I 94MHz 300p4.43MHz 12Sp5.0MHz 325P6.0MHz 300p6. I 44MHz 300p

LOW PROFILE OIL SOCKETS BYTEXAS8 pin 9p 18 pin 16p 24 pin 22p14 pm 10p 20 in 18p 28 pM 26p16 pin I I p 22 pin 22p 40 pin 30p

WIRE WRAP SOCKETS BY TEXAS8 pin 30p 18 pin 50p 24 pin 70p14 pin 35p 20 pin 60p 28 pin 80p16 pin 40p 22 pin 65p 40 pin 100p

18v 7818 70p 7918 80p24v 7824 70p 7924 gop

100mA + ve TO -92Sc 78L05 30p 79L0S lopI 2v 78LI2 30p 79LI2 7op

I5v78 LI 5 30p 75L15 lop

OTHER REGULATORS1_M 309K 140pLM3177 200p 78MGT2C 140pLM323K 500p 79GUIC 225p

7.0MHz 300p7.I68MHz 300p8.00MHz 300p8.867MHz 300p10.00MHz 310pI 0.7MHz 300p12.0MHz 350p16.00MHz 350p18.00MHz 300p18.432 350pI9.968MHz 390p26.690MHz 350p

SEIKOSHA PRINTERType GP80A £1 99.00

P&P E5.00

LM723 37p 79HGKC 650p78GUIC 200p 78P05 900p78H05 SSOp RC4195NB 150p78HGKC 600p TL497 300p

27.145MHz 32Sp38.6667MHz 350p48 OMHz 300p55.5MHz 400p116.0MHz 350p

SOFTY: Ideal software develop-ment tool. Run, De -bug, verify yourprogrammes using SOFTY to simul-ate ROM, then programme EPROmwith SOFTY. KIT [100 + VATACORN ATOM: Kit suppliedwith 8K ROM, 2K RAM. May be ex-tended to 12K R + onOM 12K RAMboard. Full size qwerty keyboard,6502 Processor, UHF TV output.Free manual.KIT £120 + VAT, BUILT f150 + VAT,PS U £10.20 + VAT.

BOOKS (NO VAT)Understanding Microprocessors £3.50Micros - Interfacing Techniques £9.95Programming the 6502 L7.95Programming the Z-80 £8.95

5sk6 02 Applications Books 0.95- Intro. to Micros (Osborne)Vol. 0 (Beginners Book) 15.95Vol. I (Basic Concepts) E7.95TTL Cookbook 0.15Z-80 Interfacing Vol. I E7.75z-oo Interfacing Vol. 2 (8.506502 Assem Lang. E8.256502 Softwarbly

Proge Design £7.95

(Please add P&P 75p per book)

EXPANSION PCB: will hold upto 8KRAM (16 x 2114) plus 4K, 8K, or 16KEPROM. Can be easily interfaced withmost systems. Fully decoded and bufferedlay -out on board. 07.00+ VAT

41 SPECIAL OFFERS ilkI -24 25-99 100

EPROM ERASER TYPE UVI40: willerase upto 14 EPROMS in approx. 20mins. Slide tray for safety. Mains andErase indicators. C62 + VAT

21 I 4L (45Ons) I .60 I .50 1.402708 3.50 3.25 3.002716 (+ 5V) 3.50 3.00 2.754116 (20Ons) 1.50 I .40 1.25(Offer subject to stocks)

MINI FLOPPY DISCDRIVESFD -50A 40 TRACKS 51/4"£140 + 1.20 PEtP + VAT

We carry large stocks of Memories, Govt., Colleges, etc. TECHNOMATIC LTDTTLs, CMOS; LINEARS, TRANSISTORS AND orders accepted. 17 BURNLEY ROAD,OTHER SEMI -CONDUCTORS and welcome Callers MON-FRI 9.30-5.30inquiries for volume quantities. Welcome SAT 10.30-4.30 LONDON NW10

12 min. DOLL'S HILL Tube Station)VAT: Please add 15% to total order value (Ample Street Perking)

PEtP: Please add 40p NEW RETAIL SHOP Tel: 01-452-1500/01-450-6597

ACCESS Et BARCLAY accepted. 367 Edgware Road, W2 Telex: 922800

PRACTICAL COMPUTING May 1981

Circle No. 344I99

THE PRINTER SCOOP OF THE YEAR -SAVE OVER £1400

THE LOGABAX Z80 MICROPROCESSOR CONTROLLED

D(180L MATRIX PRINTERA massive bulk purchase enablesus to offer you this superb pro-fessional printer at a fraction ofits recent cost of over £2000.Utilising the very latest in micro-processor technology, it featuresa host of facilities with all elec-tronics on one plug in P.C.B.Just study the specification andyou will instantly realise it meetsall the requirements of the mostexacting professional or hobby-ist user.

STANDARD FUNCTIONS Full ASCII character set * Standard inkribbon * RS232/V24 serial interface - 7 xtal controlled baud ratesup to 9600 194 characters per line Parallel interface Handshakeson serial and parallel ports 4 Type fonts, italic script, double width,italic large, standard Internal buffer Internal self test 170 CPS Variable paper tractor up to 17.5" wide Solid steel construction * Allsoftware in 2708 eproms easily reconfigured for custom fonts etc.

All this and more, not refurbished but BRAND NEW At Only

£525 + carriage and ins. £18.00 + VATOPTIONAL EXTRAS Lower case £25.00 16K buffer £30.00 Second tractorfor simultaneous dual forms C85.00 Logabax maintenance P.O.A. All pricessubject to VAT - AVAILABLE ONLY FROM:" . . .. 64-66 Melfort Rd, Thornton Heath.... . Croydon, Surrey. 01-689 7702/6800

ELECTRONICSTelex 27924 Ref Fisher

&COMPUTER 86 High Street, Bletchingley

APPRECIATION 0883Surrey843221

Circle No. 345

,..

%,..._lir

Diskwise25 ForeCornwall,Tel: 05793

Street, CallingtonPL17 7AD.3780

Ltd

Quality Business Software for the AppleComputer

HOTEL PLAN - a hotel management program- including reservations 8- billing.

The ultimate in Apple business Reservation chart displaysSoftware HOTELPLAN caters room status for any periodfor large Er small hotels alike. Produces reservation Er

Capacity 100 Rooms with 2 booking letters. Arrivals Et

disc drives, 200 rooms with 3 departures list 26 creditdisc drives etc. Multi user with agencies guest billing pro -hard discs for larger hotels. vision for extras etc print outEqually suitable for small of all financial reports Lotshotels. Price £695. more .. .

UNIVERSAL RENTAL MANAGEMENTDesigned originally for TV Stores Et prints out allrental management this customer Et equipment detailssophisticated program will Various payment periodswork equally well with long or Manual or Auto print ofmedium term rental of most overdue a/c 8 renewal lettersequipent. Price £495. Customer payment history

Handles maintenance con-tracts Financial Reports etc.

Send for details. Dealer Et overseas enquiries welcome.We are dealers for:

Apple II, Video Genie, Transam Tuscan, Et a fullrange of printers etc.

Circle No. 346

IT'S ACTION! IT'S REAL-TIME! IT'S

FROGS!A brand new game from a brand new writer, Chris Smyth, bringing action and excite-ment never obtained before.You have just 250 seconds to shoot down the Frogs, as they leap around the screes in amost haphazard way, or you are finished!You have the ability to aim, controlling the angle of fire with two keys. The computerkeeps a score of the number of shots, the number of hits and of course the time, whichticks relentlessly away. At the end up comes your score - which, damn the thing,makes it addictive!

AND IT'S THREE IN ONENot only do you get this fast action game, but two logic problems as well, which asFrogmaster you have to solve in as few moves as possible. In one you leap the two typesof Frogs into order and in the other you leap the Frogs in pairs to separate the two types.We guarantee that Frogs will take the computer world by storm for the game itself is awinner, but with the two extra logic problems it really is exceptional value for money.For the Tandy TRS-80 and the Video Genie and available only from Kansas £9.50

tatimaaCINO Kansas City Systems, Unit 3, Sutton Springs Wood, Chesterfield, S44 5XF. Tel. 0246 850357

Circle No. 347

200 PRACTICAL COMPUTING May 1981

All prices are Vat paid and post free. Return first class post service. Barclaycard Visa orders sentsame day if phoned in by 3pm. Answering machine ordering service after 6pm and Sundays toallow use of cheap rate. Catalogue available upon request.

%Alba P101110160

FACTORY FRESH BRAND NAME

51/4"MINI DISKS

DISCOUNT PRICES PER TEN -PACKAll Disks are Factory Fresh, and incorporate latest manufacturers mods.

The Ultimate in Memory Excellence

MEM 1 S/Sided, Soft* Sectored, S/ DensityMEM 1D S/Sided, Soft Sectored, D/ DensityMEM 2D D/ Sided, Soft' Sectored, D/ Density

Verbatim : New Datalife Brand, with hub ring reinforcementminidisks

Verbatim

MD525 S/Sided, Soft* Sectored, 35/40 -TrackMD550 D/Sided, Soft' Sectored, 35/40 -TrackMD577 S/Sided, Soft* Sectored, 77 -Track

BASF : Typical West German Precision

BASF 1 S/ Sided, Soft Sectored, S/ DensityBASF 1D S/Sided, Soft' Sectored, D/ DensityBASF 2D D/Sided, Soft' Sectored, D/ Density

NET VAT TOTAL

£16-48 £2-47 £18-95£20-39 £3-06 £23-45£23-44 £3-52 £26-96

£17-35 £2-60 £19-95£26-04 £3-91 £29-95£27-50 £4-13 £31-63

£19-96 £2-99 £22-95£22-50 £3-38 £25-88£25-61 £3-84 £29-45

* All the above, are available in 10 or 16 Hard Sector at the same price, so please specify clearly when ordering,whether soft, 10 or 16 hard sector, and if in doubt, telephone us or name your computer on your order.

EUROPHOIMDisk Drive Head Cleaning KitDisk DirectoriesDisk DirectoriesDiskWriter 'writes with minimum pressure'DiskWriterPlastic Library BoxesSuperLuxe Disk Library 'holds twenty disks'

£18-00 £2-70 £20-70(Each) -83 -12 -95

(Per dozen; post free) £8-65 £1-30 £9-95(Each) -40 -06 -46

(Per dozen; post free) £4-00 -60 £4-60(Each) £1-70 -25 £1-95(Each) £8-65 f1-30 £9-95

You may damage your disks, if you do not use a DiskWriter or equivalent, when writing on your disk labels.

If Order Form has ben cut, send your cheque, payable to EUROPHOIN FREEPOST, Liphook, Hants,Cash with order only please. GU3 7BR. Tel: 0428 722563.

ORDERING INFORMATION ORDER FORM

Order 2 or more Ten -Packs, and wewill also give you a free EURO-PHONIC Disk Directory and Disk -Writer with every pack, so you neednever wonder what's on your disksagain.

SPECIAL BONUS

FREE Brushed chrome Paper MateBallpoint, with 5 to 9 Ten -Packs.10 or more Ten -Packs, A GOLDPlated Paper Mate Ballpoint.

t

SPECIAL BONUS

iiii41.04111

U.K. DELIVERY, PACKING & INSURANCE (parcel post)INC VAT

Disk Drive Head Cleaning Kits -75pMini -Disks (1-5 Ten -Packs) each Ten -Pack -95pMini -Disks (6 plus Ten -Packs) each Ten -Pack -65pDisk Directories (post free with disks) -25pDiskWriters (post free with disks) -25pPlastic Library Boxes (post free with disks) -45pSuperluxe Disk Library -95p

URGENT DELIVERY, PKG. & INS. (first class post)Mini -Disks first Ten -Pack £1-80Mini -Disks second & subsequent Ten -Packs £1-30Payment by Credit CardWe accept BARCLAYCARD & ACCESS CARD, and make a small surcharge of 6%,on the total order value.If your order is urgent, you may telephone your card number to us, and we can shipfrom stock the same day.Please remember to state clearly, your card number, the holder's name & address,and where you want us to send the goods, & who to invoice.Payment by ChequeURGENT ORDERS: Send your order, with a first class stamp on the envelope, andfor us to return your goods FIRST CLASS, see the First Class postal rates above.Please mark your order URGENT.NORMAL ORDERS: Cheques with order, payable to EUROPHONIC Please. If youare a large establishment, and can not raise cheques without an invoice, please postor telephone us your order, and we will return a pro -forma invoice, for your accountsdepartment to pay against.

To:EUROPHOMPlease send me:

MEM 1 Ten -Pack at £18-95MEM 1D Ten -Pack at £23-45MEM 2D Ten -Pack at £26-96Verb 525 Ten -Pack at £19-95Verb 550 Ten -Pack at £29-95Verb 577 Ten -Pack at £31-63BASF 1 Ten -Pack at f'77-96BASF1D Ten -Pack at £25-88BASF2D Ten -Pack at £29-45Cleaning Kit at £20-70SuperLuxe Library at £9-95Disk Directories at -95DiskWriters at -46

FREEPOST, Liphook, Hants, GU3 7BR.No stamp required.

Qty Total

Please add delivery & insuraceTOTAL Value of Cheque enclosed r

Please make cheques payable to `EUROPHOMName: _

Address: _

What you say about us:"Just received your 1W Verbatim Mini Disks, please send another 100.""Your urgent deliveries to us, have saved us from many problems, please find enclosed a cheque for our third order of

"Another 20 BASF please, and thank you for the sheer speed of service in settling impossible deadlines.""Dear Sir, Please find enclosed cheque for yet another Ten -Pack, and thank you for your most courteous service.""There must be something wrong with your disks, your prices are too low!"

The Co -Operative Society, Nuneaton.100 BASF disks, we are delighted."

Carlton Computers, Great Yarmouth.A. T. Grant, Sevenoaks.

R. Pool, Reading.anonymous & sceptical telephone enquirer.

Circle No. 348PRACTICAL COMPUTING May 1981 201

New from Acorn Computers Ltd

Two ComputerCommunications

SystemsEconet

The lowest cost computer communicationnetwork system available in the world. A tenstation network with 400K byte file station costsaround £3,000 and as little as £50 for eachadditional station.

Cambridge RingA very high-speed (up to 20 million bits per

second) ultra -low error rate, communicationssystem for micro, mini and mainframecomputers and their peripherals.

Now Acorn Computers can offer the very bestin computer communications, covering allconfigurations, all price ranges. No othercompany can offer our experience and range ofservices.

For full details of Econetor Cambridge Ring pleasewrite to: Chris Curry, Acorn ACORNComputers Limited,4a Market

CO-

Hill, Cambridge CB2 3NJ. PUTER Circle No. 349

a

ith

FORTRANCP/M

A powerful operating system forthe engineer & scientist

48K APPLE II FLOPPY DISC DRIVE Z-80 SOFTCARD FORTRAN PACKAGE

£1350+ VAT Er CARRIAGE

01-8431971

ig GRAN AT Amplw COMPUTER SYSTEMS

CENTURY HOUSE, HAVELOCK ROAD

SOUTHALLMIDDX

Circle No. 350

AfIllry 1 EON 111.1 LTD.

MAGTRONICS LTD.3 GOLDHURST TERRACE

LONDON NW6 3HXPHONE 01-624 9847

ELECTRONIC COMPONENTS Et COMPUTER SUPPLIES

DISKETTESUNCONDITIONAL GUARANTEE

5.25" MINI -DISKETTES SINGLE SIDED1 SECTOR PER 10 £16.50(SOFT) PET, TRS80, ETC.

5.25" MINI -DISKETTE SINGLE SIDED10 SECTOR PER 10 £16.50

5.25" MINI -DISKETTE SINGLE SIDED16 SECTOR PER 10 £16.50

5.25" MINI DISKETTE DOUBLE SIDED1 SECTOR PER 10 E24.00

8" SINGLE SIDED SINGLE DENSITY26 SECTOR PER 10 £18.00

8" SINGLE SIDED DOUBLE DENSITY26 SECTOR PER 10£24.00DOUBLE SIDED SINGLE DENSITY26 SECTOR PER 10 £30.00

8" DOUBLE SIDED DOUBLE DENSITY26 SECTOR PER 10 £30.00

E. PROMS1702A 500p

27162708I

+ 5v)

2350p50p700p27324

MEMORIES

2114-2L120p2102-2L400p

2114-4L 250p4116-2L 250p6810 300p

INTERFACEMC1488 80pMC1489 80p75451 75p75452 75p8T28 250p

C.MOSSUPPORT DEVICES

TRANSISTORSDIODES

ALL STOCKEDPHONE

FOR QUOTATION

CPUs6502 750p6800 650p6802 1100p

8080A 450p

8085A 1100p

SOCKETS L.P.SPIN 9p14 PIN 10p

16 PIN 11p

24 PIN 22p

28 PIN 30p

ROMS745188 275p74S189 275p745470 650p74:-:471 650p74S472 900p

DISK ORDERS ADD 90p AND COMPONENTS ADD 50p P&P.ADD 15% VAT TO TOTAL.

MANY OTHER TYPES OF HARD Et SOFT SECTOR DISKETTESAVAILABLE. PHONE FOR QUOTATION.

MAGNETIC CARDS, DATA CARTRIDGES, DIGITALCASSETTES ARE ALSO STOCKED.

OFFICIAL ORDERS FROM SCHOOLS, COLLEGES,UNIVERSITIES AND GOVT. BODIES ACCEPTED.

74LS SERIES 74LS26 22p 74L676 36p 74LS125 50p 74LS163 1.00p 74LS221 1.20p 74LS279 65p 74LS375 1.20p

74LS27 22p 74LS78 45p 74LS126 50p 74LS164 90p 74LS240 1.75p 74LS280 1.75p 74LS377 1.60p

74LS00 14p 74LS28 22p 74LS83A 70p 74LS132 60p 74LS165 1.00p 74LS241 1.75p 74LS283 90p 74LS378 1.30p

74LS01 14p 74LS30 20p 74LS85 80p 74LS133 40p 74LS166 1.70p 74LS242 1.75p 74LS290 95p 74LS379 1.80p

74LS02 15p 74LS32 26p 74LS86 40p 74LS136 50p 74LS168 1.70p 74LS243 1.75p 74LS293 95p 74LS381 3.80p

74LS03 15p 74LS33 28p 74LS90 40p 74LS138 65p 74LS169 1,700 74LS244 1.50p 74LS295 1.45p 74LS386 80p

74LL04 16p 74LS37 28p 74LS91 99p 74LS139 70p 74LS170 1.85p 74LS245 2.50p 74LS298 1.45p 74LS390 1.20p

74LS05 22p 74LS38 28p 74LS92 72p 74LS145 110p 74LS173 1.10p 74LS247 1.40p 74LS324 1.85p 74LS393 1.20p

74LS08 20p 74LS40 22p 74LS93 60p 74LS148 1.70p 74LS174 1.00p 74LS248 1.80p 74LS325 3.00p 74LS395 2.00p

74LS09 22p 74LS42 65p 74LS95 100p 74LS151 80p 74LS175 1.00p 74LS249 1.40p 74LS326 3.000 74LS396 2.00p

74LS10 18p 74LS47 75p 74LS96 110p 74LS153 60p 74LS181 280p 74LS251 1.30p 74LS327 3.00p 74LS398 2.75p

74LS11 22p 74LS48 85p 74LS107 45p 74LS154 1.60p 74LS190 1.00p 74LS253 90p 74LS352 1.80p 74LS399 2.00p

74LS12 25p 74LS49 100p 74LS109 35p 74LS155 65p 74LS191 1.00p 74LS257 90p 74LS353 1.80p 74LS424 4.50p

74LS13 40p 74LS54 25p 74LS112 35p 74LS156 75p 74LS192 1,000 74LS258 1.20p 74LS365 50p 74LS445 1,850

74LS14 50p 74LS55 25p 74LS113 45p 74LS157 60p 74LS193 1.00p 74LS259 1.60p 74LS366 65p 74LS447 1.85p

74LS15 25p 74LS63 1.50p 74LS114 45p 74LS158 60p 74LS194 1.000 74LS260 45p 74LS367 65p 74LS490 1.60p

74LS20 20p 74LS73 45p 74LS122 75p 74LS160 90p 74LS195 1.10p 74LS261 4.25p 74LS368 65p 74LS668 1.05p

74LS21 22p 74LS74 28p 74LS123 75p 74LS161 75p 74LS196 1.20p 74LS266 45p 74LS373 1.55p 74LS669 1.05p

74LS22 22p 74LS75 36p 74LS124 145p 74LS162 1.15p 74LS197 95p 74LS273 1.75p 74LS374 1.80p 74LS670 2.50p

202

Circle No. 351

PRACTICAL COMPUTING May 1981

CASTLE ELECTRONICSMICRO COMPUTER CENTRE

Telephone Hastings (0424)437875

TANGERINE microtan 65Microtan 65 is the most advanced, most powerful,most expandable microcomputer available-it also happens to be the most cost effective.

6502 Microprocessor IK Tanbug I K User RAM Full TV Display £79 (ready -built). 20 -way KEYPAD-£10.TANEX-£43IK 16 parallel 1/0 lines. Cassette Interface -1 serial 1/0 line. 2 x 16 BIT counter timers OPTIONS TKRAM total -32 parallel 1/0 lines. 4 x 16 BIT counter timers-RS232. 20MA current loop.10K MICROSOFT BASIC-£49System Rack-£49 in black/ tangerine in brushed aluminium.

Full Ascii Keyboard with numeric pad-£60.85. Cabinet available-£20. Lower Case option-£9.48.Chunky Graphics Pack-£6.52. Tanram Full Memory Expansion to 40K-£119.00. Mini Motherboard-£10.00.

Cassette with counter-£21.70.

have given TANGERINE five bonus points for getting just about everything right"-E.T.I. Mag.. May 1980.

COMMODORE PET ...Everything has been said about PET-Britain's number one selling microcomputer.A full range of accessories and software, £399(both games and business), is held in stock.

8K Inbuilt Cassette-£399,8K Large Keyboard -£42516K Large Keyboard-£499 ; itExternal Cassette-£55Dual Disc Drive-£695Tractor Printer -£395CASSETTE SOFTWARE: Strathclyde Basic Course, BasicBasic Course, Invaders, Treasure Trove of Games 1 to 10 (10 selections ofgames), Basic Maths, Algebra, Statistical Packs and lots more!

£599ilI

CON. app,-

le.

The Apple II + is more powerful than its predecessorswith built-in sound and high resolution graphics, which

make it ideal for scientific and games applications.16K-£599 Cassette with counter-£21.7032K-£649 Disc drive without controller-£29948K-£659 Disc drive with control ler -£349Epsom Printer -£349 16K add-on-£69

CARDS: Prototype/hobby card-£15, parallel printer interface card-£104,communications card-£130, high speed serial interface card-£113, Pascallanguage system -£299.

SHARP VIDEO GENIE SYSTEM

M280 20K... £449 Easy -to -use BASIC language means that programmes are easily written for36K .. £475 specific applications. Many pre-recorded programme tapes are available.48K "95 TRS80 software compatible. Great scope for the home, introducing the

Printer ... £475 whole family to the computer age.Dual disc drive... ... £715

BUSINESS SOFTWARE SALE BOOKS (No V.A.T.)PETACT Purchase Ledger (Disc.) ... ... ... ... £75.00PETACT Sales Ledger (Disc.) . . ... .. £75.00 Basic Computer Game-£5.50, Instant Basic-£7.20, Pet Revealed-£10.00,Commodore Word Processor III (Disc) £75.00 Library of Pet Subroutines-£10.00, Your First Computer-£5.95, Guide toCommodore Stock Control (Disc) ... . .

£75.00 Basic Programming-£8.85. Basic Basic-£6.50. Advanced Basic-£6.00.Commodore Sales/Purchase/Nominal Ledger... .. ... ... £500 Basic Programming Z80-£8.95, 6520 Applications Book-£7.95 and lotsFurther details of business software available on request more. Send for full list of microcomputer and electronic books.

PET SCIENTIFIC & INDUSTRIAL NASCOMAPPLICATIONS NASCOM 1 £125 (Kit form)

16 -channel A / 0 converter ... ... ... ... ... ... ... ... ... £300 NASCOM 1 £140 (Ready -built)16 -channel Relay Unit .. ... ... £350 NASCOM 2 .. ... £225

8 -channel D/A Converter ... £350 IMP PRINTER ... £325

SINCLAIR ZX80 TAKEN IN PART-EXCHA NGE FOR ALL MICROS ATARI Computer due in May

ALL PRICES-ADD 15% VAT. DELIVERY: POSTAGE/ PACKING WILL BE NOTIFIED BARCLAYCARD AND ACCESS ORDERS TAKEN BY PHONE

CASTLE ELECTRONICS7 CASTLE ST., HASTINGS, EAST SUSSEX TN 34 3 D Y Telephone: Hastings (0424) 437875

Shop hours 09 00 to 17.30 Mondays to Saturdays Personal callers welcome

PRACTICAL COMPUTING May 1981

Circle No. 352

203

CRA g

Send me details of the TridataPURCHASE LEDGERSALES LEDGERPAYROLLNOMINAL LEDGERSALES INVOICINGSTOCK CONTROLName

Business Software Systems. I am interested in,For TANDY TRS 80

TANDY TRS 80 Mk. IISHARP MZ-80K

PET

SUPERPETAPPLE

PC5/81

Company

Address

TRIDATA MICROS LTD., Smithfield House, Digbeth, Birmingham B5 6BSTRIDATA MICROS LTD., Smithfield House, Digbeth, Birmingham

Circle No. 353

ST Sworn. Lid

26 New Snoadway. Ealing.London W5 2X4. England

CASH AND CARRYSUPERDEALSSUPERBRAIN 64K £1650QUAD DENSITYSUPERBRAIN £2250NEC SPINWRITER £1600DIABLO 630 £1600CROMENCO- (All hardware andsoftware in stock for immediate delivery)

MATRIXANADEKOKIDATAEPSON

TRIDATA COMPLETE BUSINESSSOFTWARE PACKAGES* SALES INVOICING* SALES LEDGER* PURCHASE LEDGER* NOMINAL LEDGER* PAYROLL* STOCK CONTROL

for use on* TANDY TRS 80* TANDY TRS 80 Mk. II* SHARP MZ-80K* PET AND SUPERPET* APPLE

Our business packages are supplied with master diskettes,detailed operating manuals and training procedures.For small businesses and traders with up to 700 employees,9,999 customers and 9,999 suppliers, our proven programswritten by experienced DP professionals provide fast,simple control, with built in security routines for preventionof unauthorised use, abuse or mishandling.Over 550 Tridata business systems are now in use.

TRIDATA WARRANTYEvery Tridata program has a written 12 month warranty and can beautomatically updated to conform to any legislation that may alter youraccounting procedures.

SEND THE COUPON TODAY'OR TELEPHONE

021-622 6085

PRINTERSThe quietest, mostreliable printersavailable - 40, 80 or132 characters perline with graphics

Telephone:01-840-19262

I

5 Ttorwrwrwai Sworrw Lid

26 New Br ,.derey Ealing.London W5 2%A E rejland

O

MICROPROWORDSTARThe Ultimate Word ProcessingPackage

DATASTARForms Generation, Data Capture,Validation and Retrieval

£250

£180

MAILMERGEMailing List, Standard Letters, etc. £80

SUPERSORTSearch, Sort and Select £125PASCAL, BASIC FORTRAN,PL/I and other CP/M software

Dealers: Best DiscountsCall for DetailsTelephone: 01-840-1926

204

Circle No. 3b4PRACTICAL COMPUTING May 1981

PRESTEL

NE BIGGEST BREAKTHROUGHIN COMMUNICATION

SINCE THE TELEPHONE ANDTELEVISION.

180,000 Pages of information instantly available0 Ask Prestel a question and up pops the answer

in seconds in full colour on your own T.V. screen

EXPENSIVE?

NOT ANY LONGER WITH

nBY TANGERINE

044 el,o #1/47

PRACTICAL COMPUTING May 1981

Simply plugs into your t.v. aeriel socketTantel requires a jack socket on your telephone line (available from the Post Office)

PC5/81

PLEASE SEND ME TANTEL ADAPTORS

I ENCLOSE CHEQUE / P.O. TO THE VALUE OF

OR DEBIT MY ACCESS/BARCLAYCARD No.

NAME

ADDRESS

PAYABLE TO TANGERINE COMPUTER SYSTEMS LIMITED

FOR FURTHER INFORMATION PLEASE SEND A 12p STAMP TO :-TANDATA MARKETING

FOREHILL WORKS

ELY CAMBS CB7 4AE Circle No. 355

205

CP/M SOFTWAREfrom

WORD PROCESSINGWORD -STAR"' is the most complete integrated wordprocessing software system ever seen on a

microcomputer. In less than six months more than fourthousand people have proudly purchased WORD-STAR.WORD -STAR 2.0 £255/E30WORD -STAR 2.0 with MAILMERGE £315/E40

NEW * Commercial Operating System *NEW

At last a secure commercial environment can be createdunder CP/M. COSY offers a true COBOL compiler,ISAM files, enhanced disk I/O, screen formatting andprinter spooling. Requires Z80 or Z80A processor.COSY - including COBOL compiler £450COSY - run time system £200PSORT - £50

COMMUNICATIONSBISYNC-80/3780 and BISYNC-80/3270 are fullfunction IBM 2780/3780 and 3270 emulators formicrocomputers.BISYNC-80/3780 gives you a Remote Job Entryterminal for the price of a micro!BISYNC-80/3270 combines the local processing powerof a micro with a sophisticated screen capability. Makeyour dumb terminal smart!I/O Master is a superb S100 buffered I/O board whichsupports 3780 and teletype communications, plus serialand parallel peripherals.MET/TTY will connect your micro to a timesharingservice in simple teletype emulation.BISYNC-80/3780 £275/£15BISYNC-80/3270 £275/£15MET/TTY £95/£15I/O Master Board £225/120

utility sortFDUMP - utility file dump £30One manual for all the above £15. DATA MANAGEMENT

SELECTOR III -C2

INTEGRATED BUSINESS SYSTEMSWritten specially for the U.K. market, Version 2.0 ofGRAFFCOM'S Integrated Small Business Software isnow available for both floppy (ISBS-F) and hard (ISBS-W) disk systems. Modules available are: Payroll,Company Sales, Company Purchases, Genera!Accounting, Stock Control, Order Entry and Invoicing,

An easy to use Information Management System;requirSELECT CBASIC II £185/£30SELECTOR IVAn advanced Information Management System;requires CBASIC II £275/£35DATASTARPowerful data entry, retrieval and updatesystem £195/£30

Name and Address, Time Recording, Lease, Rental andHP.Prices are available on request, discounts quoted forbundles of the above systems. Manuals £35 each.

FINANCIAL REPORTINGREPORT WRITERYou input the values - Report Writer will perform yourcalculations and produce a report with your headings,

LANGUAGES/UTILITIESCBASIC IICommercial Disk Extended Basic £75/£20SBASIC

totals and summaries £150/£15GLECTORGeneral ledger option to Selector III; Requires SelectorIII and CBASIC II 7E185/E30

Compiler Structured Basic £175/£30SUPERSORT I £125/£20WORD -MASTER Superior Text Editor £75/E20MET/TWAN Index sequential fileAccess in CBASIC II £55/£15

All software is Ex -stock and available on standard 8"disks or 5" disks for Cromemco Z2H, North Star'Horizon, Vector MZ, Superbrain and Dynabyte.

*Add 15% VAT.* Postage and Packing £2 per order.*

MICRO DATA BASE SYSTEMSMDBS is a database system offering full networkCODASYL-oriented data structrues, variable lengthrecords, read/write protection, one-to-one, one -to-many and many -to -many set relationships. Add onfeatures are: an interactive report -writer and querysystem, a dynamic restructuring system and a recovery-transaction logging system.MDBS prices start from £600-£35Primer manual £5

State which disk type and size.* All orders prepaid.

Telephone orders welcome for Access, Barclaycard,American Express or Diners Club.CALL 0895 58111 Ext. 247 or 269or write to:METROTECH MAIL ORDERWATERLOO ROADUXBRIDGEMIDDLESEX UB8 2YWenclosing cheque, PO's payable to METROTECH

tml WORD -STAR is a trademark of Micropro.Prices are shown as Software with manual/Manual only.

Prices correct at time of going to press.METROMECH are sole U.K. distributors of DYNABYTE microcomputer systems.

Circle No. 356

206 PRACTICAL COMPUTING May 1981

the printer peopleEsher (0372) 62071

Tec DaisywriterThe low-cost daisywheel printer

£1050

Epson MX80

£359Complete range of interfaces* 9x9 dot matrix* Fast bidirectional printing

ASCII and graphics, with £ sign* Bold, expanded, condensed print* Parallel interface standardMX8OFT friction/tractor feed: £399MX70 with 7x5 matrix: £259

TVI 912C terminal£475

Fully, intelligent terminal* 24 x 80 character display* Dual intensity, blinking,

reversed, underline, andprotected fields

* Full upper/lower case ASCII* Separate numeric keypadTVI 920C (illustrated) withextended set of function keys: £550

Centronics 737£349

Letter quality printer* 7x9 and it x9 dot matrix* 3 -way paper handling, up to 81/2"* Proportional characters/spacing* Up to 80 characters/second* Parallel standard; serial option

Anacom 150

The reliable commercial printer* 150 characters per second* 9x9 matrix, upper and lower case* Up to 15" paper width*. Full forms control* Centronics parallel/RS232 serial

* 25 cps letter -quality output* Standard 96 -character daisywheels* 136-column/15" print width* Programmable forms handling* Parallel interface; RS -232 option

OKI Microline 80

The quiet workhorse* ASCII and graphics characters* 9x7 dot matrix* Condensed, double width print* Friction or pin feed Rugged, quiet and reliable* Parallel interface standardMicroline 82 - £399* Fast, bidirectional, logic -seeking* Additional forms controlMicroline 83 - £699* commercial unit* 120 cps, 15" paper width

NEC Spinwriter£1485

The word-processing printer* Letter quality for word-processing* 128 -character easy -change 'thimble'* 55 chars/sec - friction/tractor feed* RS232, parallel interface versions

the best prices for peripheralsAll prices quoted exclude VAT and delivery.

Educational and dealer discounts are available - please phone 0372 62072 for details.North of England end users: contact Northern Micro on Hohnfirth (0484 89) 2062

NORTHAMBER Great Oak House, Albany Close, Esher, SurreyImporters, Distributors and Wholesalers Tele 'hone: Esher (0372) 62071

Circle No. 35720-7

AIM 65 DANCES TO A NEW DISKAIM 65 'CUBIT' piggyback card

adds 4K RAM + 4K ROM

4 ',64 way expansion cable 8K

4

joins AIM 65 via CUBIT staticto Acorn 19" rack RAM

VDU cardIndustrial i/o card

It

40 character x 25 lineTeletext VDU with colourand graphics

Acorn 19" rack

Base 2 Impact Printer

51/4' floppy disk with controller48K/16K ROM/RAM/CMOS cardAnalog carddigital/serial i/o cardEPROM programmer

£600 buys a complete single disk extension to the AIM 65This is the first conveniently packaged AIM 65 disk system to be available, and in the same sensible Eurocard presentationit offers memory expansion, impact printer interface, colour VDU, EPROM programmer, digital and analog i/o, andmore. In addition, the owner of this hardware can run Acorn software, which includes BASIC, disk assembler, wordprocessor and business accounting, and can run a 6809 microprocessor card in the same rack.

CONTROL - ALL ROCKWELL SYSTEMS Control Universal Ltd.UNIVERSAL - ALL ACORN SYSTEMS 11-15 Bush House,LTD SUPPLY - EXTENSIONS TO BOTH Bush Fair, Harlow, Essex

Tel: 0279 31604 Circle No. 358

Xitan:South Coast Leaders inMicrocomputer Support Application

and ServiceXitan in BusinessXitan provide cost effective computersupport for wide ranging businessorganisations; from low entry level, standalone systems for the smaller business, tointegrated multiuser/multitaskingsystems

Xitan in Science and ResearchXitan support scientific and research users inuniversities , colleges, government andindependent research establishments withcomprehensive practical experienceembracing hardware, system, andapplicational software.

NTAN SYSTEM23 Cumberland PlaceSouthampton SO1 2BBTel: 0703 38740

Cromestwo SHARP North Star Horizon comart

208

Circle No. 359PRACTICAL COMPUTING May 1981

The news is travelling fastamongst the professionals that Addaare the Number One people to go tofor Commodore PET microcomputersystems.

Commodore's new generationof desk -top computers and software- including packages for accountants,solicitors and doctors - can be madeto realise their full potential withprofessional advice from Adda. This,together with exceptional standardsof service back-up, will help you stayon top and in complete control of thelatest advances in microcomputing.

WORD PROCESSING FROM ASLITTLE AS £2900

With the WORDCRAFT 80programme, Adda can show you howto make use of a CommodoreBusiness System in the dual role of afully fledged word processor. There'scapacity for 250-300 pages of text,the functions you'll find on very muchmore expensive word processors,and a wide choice of output printersincluding daisy -wheel. Add on theDMS file management programmefor £195 and you can access severalthousand names and addresses forpersonalised mailing. Mu -Pet enablesyou to build up a multi -terminal word

umberonefor PET inLondon.

01-5795845

processing system linking from threeto eight microcomputers to oneCommodore disc drive and printerfor as little as £595.

CALCULATOR, PEN AND PAPER- ALL IN ONE -WITH VISICALC

When you need to work thingsout on paper, using a calculator, theVisiCalc programme can do it somuch easier and quicker on computer- and instantly display the answersyou are looking for. And you can geta hard printout later. The applicationsare numerate and innumerable - getAdda to show you.

MEDICOM PRACTICE MANAGER -JUST WHAT THE

DOCTOR ORDEREDMed icom Practice Manager

provides the information needed

to ease the clerical workload andaid the running of an efficient practice.Designed by doctors in generalpractice, this practical computingsystem controls and prints repeatprescriptions, maintains the age/sexregister and monitors patient care -in a complete package costing lessthan £3000. A pharmacy stockcontrol system can be added for just£400.

Find out more about how thesedevelopments can best be employedin the professions - with professionaladvice from Adda.

Phone 01-579 5845 today.

attd5Adda Computers14 BroadwayWest EalingLondon W13 OSREntrance inKirchen Road01-579 5845

we add up to a great deal. Circle No. 360

PRACTICAL COMPUTING May 1981 209

BARCLAYCARD

MUM. TRS-80 OWNERS! Buy k with Amu

LEVEL IIMODEL I

Mastermind II" £5.50 Finance Pack £7.50Typing Tutor £11.50Ultra Mon" £15.00

CASSETTE Mean Checkers* £11.00Morloc's Tower" £9.50

Flight Simulator" £15.00Forth" (incl. Primer) £37.50

X -Ref" £9.50V -Bar £9.50

GAMES Noughts & Crosses £4.50 GSF* E17.50 76 Basic Programs £23.00Adventures: - Othello III £6.50 General Accounting £8.50 Manual for Above £7.00Special Sampler. E5.50 Pentominoes £6.50 Ham Radio E6.50 Library 100 £40.00AdventurelandPirates Adventure"

£9.50£9.50

Pinball* £9.50Pork Barrel £6.50

Histograph/Scattergram ... E7.50Home Finance DISK

Mission Impossible" £9.50 PR Dogfight £6.50 nfinite Basic" £31.00 Accounts Receivable II . £40.00Vodoo Castle" £9.50 Pre School Games £6.50 nfinite Business" £18.50 Advanced PersonalThe Count" £9.50 Robots E4.50 nstant Calculator £7.50 Finance £15.50Strange Odyssey* £9.50 Round The Horn £6.50 nventory Control £11.00 Amateur Radio System ... £15.50Mystery Fun House E9.50 Safari £6.50 nventory 'S' £16.00 APL 80 £30.00Pyramid of Doom" £9.50 Santa Paravia £6.50 RV" £16.50 Auto Disk Directory £9.50Ghost Town" £9.50 Sargon II" £18.50 Keyboard 80" £7.50 Basic Compiler £110.00Savage Island £9.50 Ship Air Battles £5.00 KVP" £9.50 CCA Data Management . £52.50

Air Raid* £8.50 Slalom £5.00 Level III Basic* £30.00 Comproc £13.50Air Traffic Control" £7.50 Snake Eggs £9.50 Linear Programming £7.50 Data Base II £30.00Amazin' Mazes £5.50 Space Battles £9.50 Magic Paper Calculator . £9.50 DCV-1 E8.50Android NIM £9.50 Starfleet Orion* £12.00 Mathdrill £5.00 Dosort £25.00Backgammon £6.50 Startrek 111.5 E9.50 Maths Library I £8.50 Dynamic Data Base £22.50Balloon Race £6.50 Super Nova* £9.50 Maths Library II £8.50 Electric Pencil £75.00Barricade" £8.50 Taipan £6.50 Memdump" £8.50 File Manager 80 £30.00Baseball £6.50 Time Trek* £12.00 Microtext Editor £6.50 Floppy Disk Diagnostic . £13.50Battleship £7.50 Trek 80 £6.50 Mortgage Calculator £5.00 Forth (inc. Primer) £45.00Bee Wary E9.50 Trolls Gold £4.50 Pascal" E26.00 Inventory 2.3 £40.00Bingo £4.50 Up Periscope £9.50 Periodical X -REF £9.50 Inventory II £50.00Bowling (Ten Pin) £6.50 Warfare 1 £5.50 Personal Finance £6.50 Inventory 'S' £40.00Breakaway £4.50 X -Wing Fighter II £6.50 Pilot 2.2" E9.50 KVP Extender £16.00Bridge PartnerCribbageDeath Dreadnaught"Dogstar

£12.00£6.50£9.50£6.50

EDUCATIONALSpelling Builder £12.00All other PDI Pgms 19.50

Pre -Flight E9.50Remodel & Proload" £23.00Renumber £6.50RPN Calculator £6.50

Mailist IV £45.00Newdos 80 £87.50Newdos + £47.50Newdos £30.00

End Zone II £6.50 BUSINESS & UTILITIES RSM 2 Monitor" £16.00 Pencil PAL £12.00Fastgammon E12.00 Accounts Receivable II £13.50 SCRIPSIT" £39.95 Roots £14.50Galactic Blockade £6.50 Amateur Astronomer Screen Hold £6.00 SCRIPSIT" £65.00Galactic Empire £9.50 APL -80" £9.50 Statistics £6.50 Simplify It £15.00Galactic Revolution £9.50 Basic 1P* £11.50 S.T.A.D.* £16.00 ST80D. £45.00Galactic Trader £9.50 Basic Toolkit £11.50 ST -80" £30.00 ST800111* £85.00Galaxy Invasion £9.50 Biorythms £4.50 Super Simon £6.50 SUPERSCRIPT* f17.50Game of Life" £6.50 Calendar Functions £7.50 Super T -Legs" £6.50 Visicalc" E65.00Gammon Challenger" £9.50 Cash Register £6.50 T -Step" £7.50 Taranto & Associates ConversionGangster £5.50 Copys" £9.50 System Copy" £8.50 of Osbourne & Associates BusinessHangman £4.50 Data Base II £17.50 T -Short" £6.50 ProgrammesI Ching £6.50 Debug" T -Short" £12.50 Accounts Payable £90.00Interlude" £10.50 Editor Assembler Plus" . f 18.50 Tarot Cards £6.50 Cash Journal (for G/L) £40.00Invasion Orion" £12.00 Electric Pencil* £50.00 Teachers Assistant I E9.50 Invoicing £90.00Invaders from Space" £9.50 Electronics Assistant £6.50 Teachers Assistant II £9.50 Accounts Receivable £90.00Kamikaze £6.50 EMU 6502" £16.00 Timser £9.50 General Ledger £90.00Kreigspiel II £9.50 ESP Tester £4.50 Tiny Comp E12.50 Complete Co-ordinated SystemLife Two £9.50 File Handling £7.50 TRS80 Opera" £6.50 with Manuals £350.00Lost Dutchman's GoldLost Ship Adventure"

E9.50£9.50 ALL TANDY HARDWARE AND SOFTWARE AVAILABLE AT CATALOGUE PRICES

MODEL IICPM 2. 2. X ... £165.00CBasic (CPM) £80.00Disk Sort Merge £87.50Development System £70.00G S F £30.00Pascal from £100.00Reference II £30.00RM Cobol from £350.00RSM II Monitor £30.00Supersort III (CPM) £80.00Utility Package £87.50Hard Disk Operating Sys . £250.00

WORD PROCESSORSElectric Pencil II (CP/M) .. £200.00Electric Pencil II TRSDOS £225.00Magic Wand (CP/M) E230.00Wordstar (CP/M) £275.00

BUSINESS SYSTEMSAccounting from £150.00Mailist from £100.00Medical from £100.00Property Analysis £175.00

CP/M USERS GROUP23 Volumes Each £12.00

ALL PRICES INCLUDE VAT AT15%, PACKAGING & RETURNPOSTAGE TO U.K. ADDRESSES.PRICES TO OVERSEASADDRESSES INCLUDE RETURNAIRMAIL. SEND ft .00 FOR NEWDESCRIPTIVE CATALOGUE.

"Denotes Machine LanguageTRS-80 Trademark of Tandy Corp.CP/M Trademark of Digital Res.C -Basic Trademark of CompilerSystems.

MICROCOMPUTERAPPLICATIONS

11 RIVERSIDE COURT,CAVERSHAM,

READING RG4 8AL,ENGLAND.

TEL: (0734) 470425

I ntexCOFT1PUTERS

DATALOG LTD

MICRO PAY -200£195.00 + VAT

Micropay-200 is a complete payroll System designed to run on a COMMODORE32K PET microcomputer, interfaced to dual floppy disk drives and a printer.The System provides:1. Weekly/monthly payslips2. Summary page of all payments and deductions that month3. Summary page of all payments and deductions for the tax year to date4. Weekly/monthly cash analysis slip for all cash payments made5. Monthly summary of all payments and deductions6. Year end summary of all payments and deductions

STOCK CONTROL 3750Stock Control 3750 is a complete stock control system designed and written to meetthe needs of a small business.It will accommodate up to 3747 stock items and runs on a COMMODORE PET micro-computer interfaced to a printer and COMPU/ THINK disk drives.The System incorporates programs to:1. Set up a Supplier file.2. Set up Stock files.3. Copy Data files.4. Insert/delete stock records.5. Insert/delete supplier records.6. Update/display stock file.7. Update/display supplier file.8. Print stock list.9. Print supplier list.10. Print reorder report.11. Print stock movement report.12. Print stock valuation report.

And perform other useful routines.Stock Control 3750 is fully protected from misuse and can easily be used by someonewith no knowledge of computers or their operation.The System costs £195.00 + V.A.T. and this price includes a full back-up and advisoryservice from INTEX DATA LOG.

FOR FULL SPECIFICATION WRITE TO:INTEX DATALOG LTD. DEPT PC1280

EAGLESCLIFFE IND. EST., EAGLESCLIFFECLEVELAND TS16 OPW. TEL: 0642 781193

210

MAIL ORDER SERVICEBARCLAYCARD MAR ORDER - ACCESS

ITEM DUSTCOVERS

TOT. INC.PRICE VAT

PET - ALL MODELS 5.75 6.901,143 PRINTER 5.75 6.90ANADEX DP8000CBM 3040 DISK

3 503.50

4354.35

CBM 3022 PRINTER 3.99 4.80COMPUTHINK DISK 3.00 3.75ACCOUSTIC COVER FORCBM 3022 PRINTER 49.00 62.00 ER D DISKETTES IN FREE CASEBASF 35.00 40.83ACCUTRACKLIBRARY CASE

30.003 50

35.084.60

BLANK CASSETTESC15 IPER 101 4.00 5.75C60 IPER 101 CONNECTORS

6.00 8.05

USER' IEEE PORT 1 30 1.78CASSETTE PORT 99 143USERPORT COVERMALE 'D' PLUGS

2.502.50

3.163.16

FEMALE 'D SOCKETS 3 50 4 31'1)' CONNECTOR COVERS RIBBONS

2.50 3.16

TELETYPE 43ANADEX DP8000

7.722.75

9.173.45

ANADEX DP9990,1CBM 3022

15.002.75

16.40345

OUME IFABRICIOUME (CARBON M

4.254.50

5.185.46

OUME (CARBON S 'SIDAISY WHEELS

5.00 604

OUME SPRINT 5 PROGRAMMERS TOOLKIT

6.50 7.76

SPECIAL OFFEROLD ROMS 8K 65.00 75.90NEW ROMS 8K 65.00 75.90NEW ROMS 8:16 32K 45 00 52 90

PROKIT 1PROKIT 1,- PROGRAMMERS AID.ADDS THAT TOUCH OF PROFESSIONALISM TO EVERY PROGRAM YOU WRITE.NUMERIC INPUT ROUTINES:- AUTOMATICALLY ADD LEADING AND TRAILINGZERO'S AND RESPOND ONLY TO NUMERIC KEYS AND DECIMAL POINT.GENERAL INPUT ROUTINES:- SET THE LENGTH OF FIELD REQUIRED. SPECIFYWHICH CHARACTERS YOU WANT PET TO RESPOND TO AND ALL OTHERSWILL BE IGNORED.DATE INPUT ROUTINE:- THE PROGRAM WILL NOT CONTINUE UNTIL YOUHAVE ENTERED A VALID DATE.STRING SEARCH ROUTINE.- FINDS A MATCHING SUBSTRING WITHIN AA STRING ENABLES YOU TO USE ON GOTO WITH ANY CHARACTERS.NOT JUST NUMBERS.SCREEN ROUTINES:- CAN STORE SCREEN DISPLAYS IN MEMORY ANDRETRIEVE THEM IN A FLASH: - SUPER FOR MENUS AND GAMES.PRONG 1. DEFINITELY THE BEST THING FOR PROGRAMMERS SINCE THATOTHER KIT' AVAILABLE ON DISK OR TAPE, READY TO INCORPORATE IN YOUROWN PROGRAMS.PRICE C40.25 INC. VAT AND POSTAGE

Circle No. 361

PRACTICAL COMPUTING May 1981

SUMLOCK BONDAINMakes the decisions easier

HEWLETT PACKARD SERIES 80 GRAPHICS SYSTEM . . .

. INCLUDES NEW HP -83A PERSONAL COMPUTERFLEXIBLE DISC MEMORY, PRINTER AND GRAPHICS PLOTTER

HEWLETTPACKARD

41CPRICE DROP!

HP41C £129.95CARD READERHP82104A £109.95PRINTERHP82143A £199.95MEMORY MODULEHP82106A £18.00NEW QUAD RAM(4 times capacity ofstandard memorymodule) HP82170A £54.00NEW HP-41CV £169.95MAKE FURTHERSAVINGS!PACKAGE DEALS(including card readerand printers)HP -41C £425.00HP-41CV £460.00All prices include postage,packing and VAT. Barclaycard/Access accepted by phone.Request full competitive pricelists. Above prices refer to UKonly.

DISCOVER THE FULLPROFESSIONAL POWER OFHEWLETT PACKARD'SPERSONAL COMPUTERThe New HP83A personal computer has thesame powerful facilities as the HP85A excludingthe cartridge and internal printer. This allows afull system to be installed at a much lower price.Add the HP2631B high-speed, high qualityprinter, the HP7225 high -resolution graphicsplotter and the HP82900 51/4" flexible disc drivesproviding up to 270K bytes of formatted storage.The NEW HP9111A GRAPHICS TABLET can nowalso be added. Ask for a demonstration.It's your personal computer system. You decidewhich HP peripherals you need.See both the HP85A and HP83A and the newperipherals in action. Getting your hands on somuch professional computing power was neverso easy.

HEWLETT PACKARDS NEW HP-41CV HANDHELD SYSTEM . . .

... featuring memory that can accommodate up to 2,000 lines ofprogram or five times that of the HP -41C. Thanks to the increasedmemory, HP -41 CV owners can use the input/output parts for peripheralsinstead of memory modules. Shown here are the card readers andprinters peripherals.

SUMLOCK BONDAINHead Office: 263-269 CITY ROAD, LONDON EC1V 1JX

and at CANNON STREET STATION, LONDON EC4Tel 01-250 0505 Telex 299844

PRACTICAL COMPUTING May 1981

Circle No. 362

211

TOMORROW TODAYat Birmingham Computer Centre

Commodore official distributors

R711101.1111MIIMMIr

4008/16/32 8032 - 8050NEW DAISYWHEEL PRINTER IN STOCKNEW MATRIX PRINTER NOW IN STOCK

THE RELIABLE VALUE FOR MONEY SYSTEMWITH FULL AFTER SALES SUPPORT.

Apple authorised distributorsThe sophisticated quality system witha reputation for advanced design and

innovation.

SHARPZ8OK

The incredible computer systemnow available ex -stock including the

New Duel Drive Double Sided Floppy Disk.

THE ULTIMATE IN DAISYWHEEL PRINTERSRICOH.RP 1600

THE BEST WORDPROCESSOR.PRINTER.AVAILABLEDEALER ENQUIRIES WELCOME

CAMDEN ELECTRONICS LTDMICROCOMPUTER SYSTEMS

462 COVENTRY ROAD SMALL HEATH BIRMINGHAM B10 DUGTelephone: 021-773 8240 or 021-772 5718 Telex: 335909 (Camden Gl

Circle No. 363

212

SYSTEMS

Norlett HouseDormer Road

ThameOxon OX9 3UC

Telephone (0458)47007 (24 hr)

YOUR COMPLETEOHIO SCIENTIFIC SERVICE

HERE ARE FIVE VERY GOOD REASONS FOR CALLING US -1. O.S.I. SYSTEMS- including the popular SUPER BOARD II and CHALLENGER4P as either cassette or disc based systems.2. O.S.I. SOFTWARE- cassette and disk based software covering a broad spectrumof uses. Some of the cassette based software can also berun on the U.K.101.3. BEAVER SOFTWARE- Business, educational and entertainment software - pro-fessional programs with full listings and documentation. Alsoavailable for other systems - especially the U.K.101.4. BEAVER PROGRAMMING AIDS- including Video Workpads, BASIC workpads, MachineCode Workpads, Cassette Index cards and labels and BlankCassettes, all available for OSI, U.K.101, and TRS-80.5. BEAVER EXPANSION- Economy memory expansion using motherboard and slot -in8K RAM boards, 8K EPROM boards, floppy control board &-shortly, PROM Programmer board. Buy as much as you needwhen you need it.

r! CALL OR WRITE...NOW! =5"

Circle No. 364

Old tricks for new Pets...COMMAND -0 is a FOUR KILOBYTE Rom for the 4000/8000 Basic 4 Petswith all the 'Toolkit' commands RENUMBER (improved). AUTO, DUMP,DELETE, FIND (improved), HELP, TRACE (improved B includes STEP),and OFF - plus PRINT USING - plus four extra disk commandsINITIALIZE, MERGE, EXECUTE, and SEND - plus extra editingcommands SCROLL. MOVE. OUT, BEEP, and KILL - plus SETuser -definable soft key, 190 characters - plus program scroll upand down - plus 8032 control characters on key. Ask for ModelCO -80N for the 8032 or CO -40N for the 4016/4032. /50.00 plus Vat

New tricks for old Pets...DISK -O -PRO is a FOUR KILOBYTE Rom that upgrades 2000/3000 Pets,but lets you keep all your old software - including Toolkit. Aswell as REPEAT KEYS and PRINT USING, you get all the Basic 4

disk commands CONCAT, ()OPEN, OCLOSE, RECORD, HEADER, COLLECT,BACKUP, COPY, APPEND, OSAVE, DLOAD. CATALOG, RENAME, SCRATCH andIRECTORY - plus extra disk commands INITIALIZE, MERGE, EXECUTEand SENO - plus extra editing commands SCROLL, MOVE, OUT, BEEPand KILL - plus SET user definable soft -key. 80 characters -

plus program scroll -up and scroll -down. We recommend the 4040disk or upgraded 3040 for full benefit of disk commands. Ask forModel 00P -16N for new Pets 2001-3032, and 2001-8 with retrofitRoma t TK160P Toolkit. 150.00 plus Vet, other models available.

PRONTO -PET hard/soft reset switch for the 3000/4000 Pets. Wedon't think you'll 'crash' your Pet using our software, but ifyou do the Pronto -Pet will get you outl Also clears the Pet forthe next job, without that nasty off/on power surge. £9.99 Vat

and no tricks missed!KRAM Keyed Random Access Method. Kid your Pet It's an IBMI VSAMdisk handling for 3032/4032/8032 Pets with 3040/4040/8050 disksmeans you retrieve your date FAST, by NAME - no tracks, sectorsor blocks to worry about. Over 2,500 users worldwide have joinedthe 'Klub'l Now you can too, at the 1981 price, £75.00 plus Vat.

SPACEMAKER All our Rom products are compatible with each other,but should you want, say, Wordpro with Kram. or Oisk-o-pro withVisicalc, then SPACEMAKER will allow both Rome to address oneRom socket, with just the flip of a switch, for £22.50 plus Vat.

We are sole la distributors for all these fine products. If yourCAN dealer is out of stock, they are available by mail from us,by cheque/Access/Barclaycard LUX post paid) or send for details.

Cabo SoftwareLakeside House Kingston Hill Surrey KT27QT Tel 01-546-7258

Circle No. 365

PRACTICAL COMPUTING May 1981

STACK'S

APPLESHOP

fast delivery one year warranty full technical support

If you have questionson these or any other

Apple orientatedproduct call

051 933 5511(Carl Phillips or

Fiona McKendrick)

7114 12K ROM/PROM/RAMMODULE

The 7114 Card allows you to modify thefirmware of the Apple -II Computer,

without actually removing the on -boardROMS. The 7114 resides at locations

D000-FFFF, using the INHibit signal todisable the Apple ROMS at these

addresses. The 7114 provides six socketsfor accepting any combination of 2316ROMS, 2716 EPROMS, 4016 RAMS, or

equivalent chips. Thus you can build yourcustom firmware in 2K increments. One,

two or more chips may be employed at the

same time for programs longer than 2K. Areset toggle switch allows you to bring theboard active when the system is turned onor reset. The board resides in any slot 1-6and may be enabled and disabled under

software control. There is no conflictbetween multiple 7114, language, ROM orRAM cards resident within a single Apple.For dedicated applications an assembler

or Applesoft BASIC program'can be storedon ROM and executed automatically on

power -on.

Nett VAT Total£70.00 £10.50 £80.50

ANADEX GRAPHICS CARDOur own printer card designed specifically

for the Anadex DP9500/1 and newDP9000/1 printers. The card behaves as anormal Apple centronics interface but also

includes powerful graphics dumpsoftware on the ROM permitting dot -for -dot reproduction of a hi-res image on theprinter with almost any imaginable format

- either hi-res, page, normal or inverse,expanded in X or Y directions with varyingscale factors, left, right or centre justified

across page.

Nett VAT Total£140.00 £21.00 £161.00

OKI MICROLINE 80

The reliable quiet; portable matrix printerthat has become an industry standard. 40,80 or 132 cols per line at 5, 10 or 16.5 cpi.

Excellent print quality with three waypaper handling - letterheads, fanfold or

paper rolls. Centronics -type parallelinterface (RS232 as an option) 96

character USASCII set with 2 x 3 pixelgraphics.

Nett VAT Total£325.00 £48.75 £373.75

MICROSOFT Z-80 SOFTCARD

Microsofts innovative peripheral cardturns Apple into one of the most flexibleCP/M based systems you can buy. The

Softcard actually contains a Z-80processor and lets you switch between the

Apples' 6502 and Z-80 with simplecommands, so you can use software

written for either processor.The Softcard gives you the two softwarestandards-CP/M 2.2 and Microsoft 5.0

Basic with PRINT... USING, 16 Digitprecision, CALL, CHAIN, COMMON,powerful file handling. Applesofts'

graphics extensions are also supported.Softcard allows you to run almost anyCP/M based language or applications

package.

Nett VAT Total£170.00 £25.50 £195.50

ALL PRODUCTS ONTHIS ADVERT ARE EX -STOCK AT THE TIME OF

GOING TO PRESS!

MOUNTAIN HARDWARECOPYROM

CopyRom extends the power of Apples'disk operating system with residentprograms to provide an improved

'CATALOG' command and copy diskettes.CopyRom allows you to identify diskvolume number, free space on disk,

determine active drive or change activedrive, 'CATALOG' gives filename, lengthin sectors, file type and for binary files

stored load address and length in hex ordecimal. Copy program uses single or

multiple drives, single or dual controller,thirteen or sixteen sector and some non-

VTOC diskettes. CopyRom is a 2K ROMthat installs on the ROMPLUS Card.

Operates under all versions of Apple DOSand either BASIC.

Nett£30.00

VAT£4.50

Total£34.50

SPECIAL!!

OKI Microline 80 with CentronicsAristocard, paper- everything you need

to plug in to your Apple and go!

Nett VAT Total£365.00 £54.75 e419.75

CopyRom with ROM -PLUS Card and I

Keyboard Filter ROM

Nett VAT Total I

£130.00 £19.50 £149.50 I

Please send me:

Cheque/P.O. enclosed for: £

Name

Address

Prices include delivery.

Offical orders welcome.

STACK -APPLE 290-298 Derby Road,Bootle, Liverpool 20.Telephone: 051-933 5511. PC5 8141

PRACTICAL COMPUTING May 1981

Circle No. 366213

SEIKOSHAThe lowest cost,

smallest size,80 column impactdot graphic printer

in the world.

Suitable for home, educational and business use, theSeikosha GP80A features include:- Plain paper. 80 columnwidth. 30 cps. Full ASCII character set. Graphics facility.5 x 7 dot matrix. Double width characters. Pin feed.Centronics interface standard.

Other interface and cables available:-IEEE/488, PET, TANDY, APPLE, RS/232C.

Ring the Master Distributor, DRG BusinessMachines, (Supplies and Peripherals Division).Weston-Super-Mare, (0934) 416392 or your nearest dealer:Chromasonic ElectronicsDatalinkElectronic BrokersMicrodigital Liverpool (051) 227 2535Sigma SystemsWatford ElectronicsWestwood Computers Ltd

London (01) 263 9493Bristol (0272) 213427London (01) 278 3461

Cardiff (0222) 21515

Watford (0923) 40588Birmingham 1021) 632 5842

DRG L\A.,,ninitte 8, Lynx Crescent,

Road, Weston-Super-Mare,

BUSINESSAvon BS24 9DN Tel: (0934) 416392

HE FINESTWORLDWIDEMACHINESS

TUPPORTEDNATIONWIDE

Circle No. 367

214

PLANNEDDATAFURNITURE

Terminalwork stationsstands/wing tables

trolley/tableslarge range availablerobust turntables

Roller bearing actionPull out keyboard shelf

Planned DataFurnitureCo Ltd134 ChestergateStockportCheshire SK3.0ANTelephone: 061-477 4890

:using

11

11

11

11

Circle No. 368

'1** COMPLETE BUSINESS PACKAGES ***WIDELY USED IN UK AND USA

DEMONSTRATED IN THE NORTH BY THE EXCLUSIVE NORTHERN DISTRIBUTOR

Freshfield Computer Services

DEVELOPED BYG.W. COMPUTERS LTD

NOW AVAILABLEFOR

DEMONSTRATIONIN THE NORTH

MAIN MENUDISPLAY

PROGRAMS ARE INTEGRATED ..SELECT FUNCTION BY NUMBER ....

01 = *ENTER NAMES AND ADDRESSES02= `ENTER/PRINT INVOICES03= 'ENTER AT RECEIVABLES04= *ENTER PURCHASES05= 'ENTER AT PAYABLES06 =*ENTER'UPDATE INVENTORY07 =*ENTER'UPDATE ORDERS08 =*ENTER'UPDATE BANKS09 = "REPORT SALES LEDGER10 = 'REPORT PURCHASE LEDGER11 = INCOMPLETE RECORDS12= 'USER DBMS AREA13 = "PRINT CUSTOMERS STATEMENTS14= "PRINT SUPPLIER STATEMENTS15 =PRINT AGENT STATEMENTS16= PRINT TAX STATEMENTS17= LETTER TEXT AREA18= ALTER VOCABULARIES19= PRINT YEAR AUDIT20= PRINT PROFIT LOSS AT21 =OPEN AREA22= PRINT CASHFLOW FORECAST23= ENTER PAYROLL INO RELEASE)24= DISK SWAP'EXIT

FOR FULL DETAILS SEE GW COMPUTERS AD. (PAGE 12 AND 131

SUPERBRAIN + SUPERBRAIN + SUPERBRAIN + SUPERBRAINSUPERBRAIN 320K 1695.00SUPERBRAIN 800K 2195.00PRINTERS + PRINTERS + PRINTERS + PRINTERS + PRINTERSNEC -5530 PRINTER 1595.00MICROLINE 80 120CPS 475.00

SOFTWARE + SOFTWARE + SOFTWARE + SOFTWARE +BUS VER 6.00 - 9.00 £775 - £975BUS VER 7.00 CP/M 875.00BUS VER 8.00 CP/M 975.00BUS VER 9.00 CP/M 1075.00Plus WORDSTAR -MAILMERGE-MBASIC 80- SUPERSORT etc.Plus GRAHAM DORIAN SOFTWARE SYSTEMS-PAYROLL, STOCKCONTROL, LEDGERS, etc. etc.

ALL SOFTWARE PACKAGES DEMONSTRATED BY APPOINTMENT. ACONTACT DAVID MAWDSLEY ON FORMBY 107048179186

RIPLEY HOUSE; 56 FRESHFIELD ROAD, FORMBY, MERSEYSIDE L37 3HW

Circle No. 369

PRACTICAL COMPUTING May 1981

Calling all wriou5appkz®Low)!Announcing Applied Analytics

sassmab. riassiatAdr-71 III

MbsimiNissiMIim,,imenewm,- 111MINIF'

The microspeed language system

Runs six to sixty times faster thanBasic.

Programming capabilities well beyondApplesoft.

Auxiliary Processor (Am 9511) for fastfloating point.

High-speed, extended high resolutiongraphics.

Sole distributors for UK and EuropeRetailer enquiries welcome

INITALIN10, Waring House Redcliffe Hill

BRISTOL BS1 6TB Tel: (0272) 213427

PRACTICAL COMPUTING May 1981

Software development time cut in half.

Exceptionally compact, compiled code. Extensible, structured language to

meet your needs.

Bonus: increased speed Applesoftfunctions.

Requires 48K Apple 11 or 11+, singledisk.

r. INN NM MI =I NM MIMI ME MEI =I INN 11111111111111111

To: Datalink Microcomputer Systems Limited.

II Please send El Complete System £265 + VAT

1 0 Detailed information

IName

IAddress

I Tel No:

Lim INE 111111 MN ME ME Circle No. 370

215

£1150+ VAT

VISUAL100

4n,

The VISUAL 100 is a new microprocessorbased video display terminal that offers totalcompatibility with the DEC 1.a100* from both asoftware and operator point of view.

For the operator, the detached solid-statekeyboard has been customized so that all keypositions and LED indicators are in identical loca-tion to that of the V1100.

For the software, all codes and featureshave been implemented in a manner identical tothe VT100 assuring plug -to -plug compatibility.

The big difference between the VISUAL 100and the DEC VT100 is that the VISUAL 100 offersfeatures not available on the VT100, or availableonly as extra -cost options. These added featuresinclude: ETCHED NON -GLARE FACEPLATE

Your operator will appreciate viewing charac-ters through an etched non -glare faceplate.This feature assures crisp, sharp characterresolution even in the brightest office environ-

ments. Further, the tilt screen feature allows anadjustable viewing angle, 10° to 15°, for optimalviewing comfort.

f ADVANCED VIDEO PACKAGE IS STANDARDBlink, bold, reverse video, and underline videoattributes which can be used alone or in anycombination for enhanced video presentations.

CURRENT LOOP INTERFACE IS STANDARDA 20mA current loop interface as well as an EIARS232C interface.

BUFFERED PRINTER INTERFACE OPTIONThis option allows independent prinVcommun-ication baud rates and independent parity. Theprinter option also allows the VISUAL 100 tofunction as a controller between host andprinter, using "XON XOFF" protocol. Printerbusy can also be monitored using XON XOFF,or control line.

Seeing is believing, so see for yourself. For ademonstration and a pleasant surprise on quan-tity pricing of the VISUAL 100, call or write us today.

Circle No. 371

+ VAT

The VISUAL 200 is a new, low cost, microprocessorbased video display terminal which truly stands abovecompetitive teletype compatible terminals in its pricerange.

In addition to the most popular features available (orpartially available) on competitive terminals, such asnumeric pad, upper/lower case, editing, current loop,cursor addressing, columnar and field tab, etc., standardfeatures which set the VISUAL 200 apart and reach theoptimum in human engineering and operator comfortinclude: Detachable Keyboard Smooth Scroll Tilt Screen CIO° to 15° viewing angle) Large 7 x 9 Dot Matrix Characters

Perhaps the most distinctive feature of the VISUAL200 is the Switchable Emulation capability. A switch onthe rear panel programs the terminal for code -for -codeemulation of a Hazeltine 1500, ADDS 520, Lear SieglerADM -3A or bEC VT -52. To an O.E.M. customer itmeans no change in software to displace the older, lesspowerful terminals in his product line with the new,reliable and low cost VISUAL 200. To a Distributor itmeans offering a single modern terminal which iscompatible with all the software his customers havewritten for the older terminals. And you're not limitedto merely emulating these older terminals; you canoutperform them at the same time by taking advantageof the additional features of the VISUAL 200.

Reliability designed into the VISUAL 200 is evidencedby its solid state keyboard, single P.C. Board and selftest diagnostics on power up.

Seeing is believing, so see for yourself. For ademonstration and a pleasant surprise on quantitypricing of the powerful, easy to use and reliable VISUAL200, call or write us today.

Standard Features 24 x 80 Screen Format 7 x 9 Dot Matrix Upper/ Lower Case Numeric Pad Background/ Foreground Blink Line Insert/ Delete Line & Character Columnar and Field Tab Set/Clear Tab Security Mode Inon-display) Clear End Line, Field & Page Clear Line Clear Screen Line Drawing Current Loop or RS -232 Interface Secondary Channel Composite Video Serial Copy Port Hold Screen Baud Rates to 19,200 Self Test Cursor Addressing Cursor Control Keys Read Cursor Address Typamatic Keys Smooth Scroll Microprocessor Detachable Keyboard Solid State Keyboard Read Terminal Status Tilt Screen Switchable Emulations

THE FIRST MICROCOMPUTERWHOLESALER

MLaK)

We offer products frommany manufacturers including:

AltosCentronicsCentury DataControl DataDatasouthDyna ByteHazeltineImpact Data

SIGMA (U.K.)6, THE JAYS;BURGESS HILL,SUSSEX.

Industrial MicroIntegral DataIntertecKonanM, S, Er C.MalibuMicro PeripheralsN.E.C.

Telephone: 04446-44159

North StarOnyxPerSciQumeSorocTelevideoTexas InstrumentsVisual Technology

CATREI COMPUTERSJohn F. Kennedy Avenue,Dublin 12,Ireland.

Telephone: Dublin 509714

DATASOUTH D5180HIGH SPEED MATRIX PRINTER

£1490+ VAT

The Datasouth DS180 is a dotmatrix serial impact printer designed for high performance at an economicalprice. Application flexibility and a long list of standard features make the DS180 an ideal device for smallbusiness systems, distributed communications networks and intelligent terminals.

HIGH SPEED PRINTINGUtilizing 180 cps optimized bidirectional printing, the DS180offers higher throughput than any printer in its class. Its 9 -wireprinthead produces highly legible 9,7 characters with decendersfor lower case letters and true underlining. All 96 ASCII charac-ters may he printed across a 132 column line at 10 charactersper inch. Expanded characters (5 coil may be selected for high-lighting portions of the led

USER PROGRAMMABLEShe DS180 offers a large number of user programmablefeatures. ye is easy to operate. A unique programming keypadwith a non-volatile memory makes printer set-up quick andsimple Top of form, horizontal and vertical tabs, perforationslop -over and auto hne feed are just a few of the features theuser may select Communications sates may also be pro-grammed and monitored using the indicator panel lights and LEDdisplay

ATTRACTIVE DESIGNCompact, Cask -top packaging allows the DS180 to fit intoalmost any installation Its norse dampening cover makessuitable for use in a quiet office environment. The cartridgeribbon makes routine changes clean. fast and convenient.

MICROPROCESSOR ELECTRONICSThrough the use of state-of.the-art microprocessor electronics,reliability and maintainabrRy have been greatly improved. Thesimple modular dens!, of the 0S180 provides easy access o allmajor components. A single printed circuit board contains both

the power supp6 electronics and digital controller lar the printer.A seif-test feature and diagnostic display panel help the userverify proper operation of the one and isolate problems shouldthey occur.

COMMUNICATIONSInterfaces on the DS180 include RS232 and 20mA current bopserial interlaces, and a Centronics compatible parallel interface.Baud rates horn 110-9600 and parity selection may be keyed inby the user for his specific application.

FORMS HANDLINGAdjustable tractors accomodate forms from 3-15 inches wide. Ahead -to -platen gap adjustment ensures optimum print quality onup to 6 -pad forms. Fanfold paper may be fed from the front 0tbottom of the DS180 A paper out sensor may be programmedto send a stop transmission character and sound an audiblealarm

DUALITY MANUFACTURINGReliable performance is ensured by a stringent quality controlprogram. Datasouth uses pretested, high reliability parts fromleading manufacturers. Multiple tests are performed on sub-assemblies during each stage of production, with each com-pleted unit undergoing a final 24 hour print test and bum -in. TheDS180 carries a 90 day warranty on materials and workman-ship.

Circle No. 372

216

Circle No. 373

PRACTICAL COMPUTING May 1981

SYSTEMIC

m

Alk9M(ren1Putar

3 Hillberry Court, School Lane,Bushey, Hertfordshire WD2 1BS(01) 422 3276 (24 hours)

HI-RES PROBLEM SOLVER £45an all purpose hi-res processor, includes upper/lower case, mixed graphics and text, two waywindow scrolling, user shape definition withrotation, enlargement, slanting, stretching,reflection, inversion and many other hi-resfunctions.

LITERATURE SEARCH £25a suite of four programs forming a complete magazinearticle filing system allowing retrieval of references toitems by keyword(s) within category.

MANY OTHER QUALITY PACKAGES INCLUDEClub membership £95Linear programming £85Time recording £125Mailing list £75

DEALER ENQUIRIES INVITED

Circle No. 374

The SENS4TIONN

CROFTON Offer

9" metal cased monitor atlowest ever price - £48.50plus VAT - £55.77 totalplus carriage.

P31 green tube modelsavailable at £60 + VAT- £69 total + carriage

STOCKISTS IN ALL AREASWANTED.

WRITE FOR DETAILS.

12" Model available at following prices.Standard P4 white £145 + VAT£166 total + carriageStandard P31 green £160 + VAT- £184 + carriage

Ask for Crofton MailAll major credit cards accepted. Order Catalogue.

All items subject to availability. The above prices include VATCarriage will be charged at cost

Phone or write to

CROFTON ELECTRONICS LIMITED35 Grosvenor Road, Twickenham, Middx TW1 4AD.

Tel: 01-891 1923/1513 I Circle No. 375

Advertisement IndexA David Richard 188 LAcorn Computers 168 Davinci 29 Leicester Computer Centre 146 Qudos 190Aculab 184 3D Computers 196 Lifeboat Associates 10,11AJD Direct Supplies 36 3D Digital Design 104 Liveport 90A J Harding 95 DDP 184 L & J Computer Centre 22Alan KiddieAlgrayAlmarcAnadexAnglia Consultancy

69196148

86,87182

DigitusDisplay Electronics

E

ao London Computer Centre35 Lowe Electronics

L.P. Enterprises

24,153 Rair29 Research Resources14,15

RohanRussett

51

164183149

Applied Data EducationA W Hawkins

15839

EMGEncotel

29 M33 Manchester University 34

Epson 98,146 Melbourne House 178 SEquinox 57 Micro 80 188 SBD Consultants 172Europhonics 201 Micro Byte 194 Science of Cambridge 88,89

B Exchange Telegraph 156 Micro Centre 2 Sharp Electronics 21Barcellos 165 Microcosm 26 Shelton 118BHRA Fluid Engineering 174 Micro Data 22 Sigma UK 216Bits & PC's 156 Gate 180 Micro Digital 170 Sintrom Microshop 176Brindywell 158 GP Industrial Electronics 193 Micro Faculties 157 Sirtron Computers 151

Buss Stop 165 Graff cow 37 Micro General 164 Small Systems 178Bute! Comco 192 Graham Dorian 117 Micro Management 70 Southdata 150

Grama Winter 16,17 Micropute 116 Sun Computing Services 115Guestel 187 Microperiphals 27,38 Swan Packaging 43

Micro Solution 25 Swanley Electronics 43cCalistoCambridge Computer StoreCamden ElectronicsChris Pym LtdChromasonicComartCommodore

20158180

3423

58,9

HHal ComputersHanover FairHelistar SystemsHewlett PackardHi -TechHurricane Computers

Microsense

45 Microstyle155 Microtek22 Microtrend31 MMS

179190

N

48 Systematics36 Systemics65

154165

TTabsTelesystems

167217

54163

Community Computer 169 Nascom 30 Terminal Display 172Compshop 218,219 Newbear 24 Tex Micro Systems 178ComputaceComputechComputerbitsComputer CentreComputer For All

108197181

7243

nformex Centralexndependent Computer Engineersmacntegrated Suppliesntelligent Artifacts

Newtronics164 Nexos174 Northern Development Corporation43 Northern Software

16062,182

101 This Could Be (Leisure) Ltd159 Tower Management

19 Transdata152 Transam

T V Johnson

2617280

161,185189

Computer StoreComputer SupermarketCPS (Data Systems)CroftonCrystal

4175

18,149,160217

26,162

nteractive Data Systemsthaca Intersystemsnmac

52 0220 Ohio Scientific

69 Office Computer TechniquesOxford Computer System

177 V171

162ViscontiV&T Electronics

77,98192

CTS 176CumanaCurry's Microcentre

17312,13

JS Systems 196 P

Contactrol 192 Paxton Computers 186 wPersonel Computers 53 Watford 6,7

K Pete & Pam Computers 34 West London Micro Centre 39Kemitron 32 Petalect 162Keytronic 155 Professional Data Systems 28

Dataplus 166 KGB 191 Prentice Hall 186 zDatatech 39 Kram 150 Purley Computing 32 Zero 1 160

PRACTICAL COMPUTING May 198I 217

41 )* 41 I Ji

THE NEW ANADEXDP9500 and DP9501

A PROFESSIONAL PRINTER

Bi-directional printing Up to 220 chars/linewith 4 print densities 500 char buffer

R RS232C and CentronicsParallel interface built in

Full software control of matrixneedles allowing graphics capability

200 chars/sec Adjustable width tractor feed.

DP9500 - ONLY £795 + VATDP9501 - ONLY £845 ± VAT

:THE ATARI VIDEO COMPUTERGAMES SYSTEM 00

Atari's Video Computer System VW.now offers morethan 1300 different game

variations and options in twentyGame ProgramTM cartridges!

Most Cartriages only E13.90, -VATPrices may vary with special

editions Basic Maths, AirseaBattle, Black Jack, Breakout,Surround, Spacewar, Video

Olympics, Outlaw, Basketball,, Hunt Et Score., Space War,

Sky Diver, Air Sea Battle,Codebreaker*, Miniature Golf.

Extra Paddle Controllers 'Keyboard Controllers- £14.90 + VAT - E16.90 + VAT

SPACE INVADERS NOW IN STOCK E25

HITACHIPROFESSIONAL

MONITORS9" - £99.9512" -- £149

Reliability Solid state circuitry using an IC and silicontransistors ensures high reliability. 500 lines horizontalresolution Horizontal resolution in excess of 500 lines isachieved in picture center. Stable picture Even playedback pictures of VTR can be displayed without jittering. Looping video input Video input can be looped throughwith built-in termination switch. External sync opera-tion (available as option for U and C types) Compactconstruction Two monitors are mountable side by side in a

standard 19 -inch rack.

LOW COST TELEPHONEANSWERING MACHINE + VATMicroprocessor controlled answering machine. Plug intoyour phone line. Records any phone call messages. Remotebleeper enables you to listen to your messages fromanywhere in the world. Uses standard cassettes. Comescomplete with mains adaptor, microphone, remote bleeper,base unit, cassette with 30 sample pre-recorded messages.

COMP PRO MIXERProfessionalaudio mixer

that you canbuild yourself

and saveover £100.

Only

£99.90plus VAT forcomplete kit.

Plus FREEpower supply

valued at£25.00

ACCESSIT AUDIO ADD-ONS

218

only£399

ANADEXDP8000

Super Quality - Low cost printer. Tractor Feed with full 96ASCII character set. Accepts RS232C at band rates between

100 and 9600 and Parallel Bit data.Attaches either directly or through interfaces to Pet, Apple,

TRS80, Sorcerer, Nascom, Compukit etc.

WE ARE NOW STOCKING THEAUTOSTART APPLE II AT

REDUCED PRICES16K £54932K £579 g

48K £599Getting Started APPLE II is faster, smaller, and mo epowerful than its predecessors. And it's more fun to use toobecause of built-in features like: BASIC - The Language that Makes Programming Fun. High -Resolution Graphics lin a 54,000 -Point Array) forFinely -Detailed Displays. Sound Capability that BringsPrograms to Life. Hand Controls for Games and OtherHuman -Input Applications. Internal Memory Capacity of48K Bytes of RAM, 12K Bytes of ROM; for Big -System Per-formance in a Small Package. Eight Accessory ExpansionSlots to let the System Grow With Your Needs.

You don't need to be an expert to enjoy APPLE II. It is acomplete, ready -to -run computer. Just connect it to a videodisplay and start using programs (or writing your own) thefirst day. You'll find that its tutorial manuals help you make ityour own personal problem solver.

APPLE DISC II3.3 Dos

Disc withController

£349 + VATAdditional Drives

£299 VAT

Powerful Disk Operating Software Supports up to 6drives Name Access to Files for Ease of Use BASICProgram Chaining to Link Software Together Randomor Sequential File Access to Simplify Programming Dynamic Disk Space Allocation for Efficient Storage Individual File Write -Protection Eliminates AccidentalFile Alterations Loads an 8K Byte Binary Image in 6.Esec. (1.2 sec. in Pascal) Storage Capacity of 116Kilobytes 1143K Bytes with Pascal) on Standard 5 Y."Diskettes Powered Directly From the APPLE (Up to 6Drives) for Convenience and High Reliability Packagedin Heavy -Duty, Colour -Coordinated Steel Cabinet

NECSPIN WRITER

only£1350

+ VAT

NEC's high quality printer uses a print "thimble" that hasless diameter and inertia than a daisy wheel, giving a quieter,faster, more reliable printer that can cope with plotting andprinting (128 ASCII characters) with up to five copies, fric-tion or tractor fed. The ribbon and thimble can be changed inseconds. 55 characters per second bidirectional printing -with red/black, bold, subscript, superscript, proportionalspacing, tabbing, and much, much more.

TEACDISK

DRIVES

TEAC FD -50A has 40 tracks giving 125K Bytesunformatted single density capacity.The FD -50A can be used in double density recordingmode.The FD -50A is Shugart SA400 interface compatible.Directly compatible with Tandy TRS80 expansioninterface.Also interfaces with Video Genie, SWTP, Heathkit,North Star Horizon, Superbrain, Nascom, etc, etc.Address selection for Daisy chaining up to 4 Disks.Disks plus power supply housed in an attractive greycase.

40 TRACKSingleDisk Drive

+ VAT Double £389+ VATDisk Drive

77 TRACKSingle 4g...innDisk Drive -zvo + VAT Double c inn

Disk Drive LtWV* + VAT

THE NEWEt EXCITING

TRS80 MODEL III

16K £559 32K £589 48K £619+ VAT + VAT + VAT

The Radio Shack TRS-80TM Model III is a ROM -basedcomputer system consisting of: A 12 -inch screen to display results and other information A 65 -key console keyboard for inputting programs and datato the Computer A 2-80 Microprocessor, the "brains" ofthe system A Real -Time. Clock Read Only Memory(ROM) containing the Model III BASIC Language (fullycompatible with most Model I BASIC programs) RandomAccess Memory IRAMI for storage of programs and datawhile the Computer is on (amount is expandable from "16K"to "48K", optional extra) A Cassette Interface for long-termstorage of programs and data (requires a separate cassetterecorder, optional/extra) A Printer Interface for hard -copyoutput of programs and data (requires a separate line printer,optional/extra) Expansion area for upgrading to a disk -based system (optional/extra) Expansion area for an RS-232 -C serial communications interface (optional/extra)All these components are contained in a single moulded case,and all are powered via one power cord.

SPECIAL OFFERFOR MODEL III PURCHASERS

We will take keyboards only for TRS80 Model I and LevelII in part exchange.

There will be refurbished Model I and Level II keyboardsavailable later in the year - Phone for availability and

price.

only £295*

VAT TRW)32K.Expand your TRS80 by.ANL EXPANSION

32K Memory on board...).' INTERFACECentronics parallel portDisk controller card. Reatime clock, Requires LevelIt Basic. Interface for 2cassette decks, complete

with power supply

We give a full one year's guaranteeon all our products, which

normally only carry 3 months guarantee.We have one of the largest colleCtions of Computer Booksunder one roof, along with racks of software for the PET

and TRS80. Come and see for yourself.

THE VIDEO GENIE SYSTEMIdeal for small businesses, schools, colleges, homes, etc.

uitable for the experienced, inexperienced, hobbyist,teacher, etc.

16K

EG3000Series

WITHNEW

EXTRAKEYSI

16K user RAM£279 plus extended 12K Microsoft

VAT BASIC in ROM Fully TRS-80 Level IIsoftware compatible Huge

range of software already available Self contained, PSU,UHF modulator, and cassette Simply plugs into videomonitor or UHF TV Full expansion to disks and printer Absolutely complete - lust fit into mains plug.The Video Genie is a complete computer system, requiringonly connection to a domestic 625 line TV set to be fullyoperational; or if required a video monitor can be connectedto provide the best quality display. 51 key typewriter stylekeyboard, which features a 10 key rollover. Supplied withthe following accessories:- BASIC demonstration tape; Video lead; Second cassetee lead; Users manual; BASIC manual; Beginners programming manual. Writeuseful programs in the BASIC computer language yourself.

10,1 VIDEO GENIEEXPANSION BOX

Complete with RS232 interface and floppy disc controller.0 memory. E225 + VAT.

Memory expansion card (5100) 16K E110 32K £159 + VATFurther S100 cards available later in the year.

PRACTICAL COMPUTING May 1981

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Ass&

..:Ft("St Add a powerful, doubledensity, mini floppy disc to

your Nascom system. Disc Controller Card linclud,Nasbus 6 S100 interface Will control 4 Drives. CPM operating system. Extended Disc BasicCompiler. Power supply included

One Disc System - £499 + VATAdditional Disc Unit - + VAT

NASCOM 2 DISC DRIVES

NASCOM 2 GAMES TAPEfeaturing Space Invaders and Android Nim, Re -numbering

program and other goodies!

£7,59 +VAT

NEW REDUCEDPRICES

8K £39916K £449 VAT _41,___4111111141Mal

32K £499RRP £795 for 32K

Very popular forThe PEDIGREE PETS home Et businessuse. 8K Microsoft Basic in ROM. 8K Pet 32K 8 16K withnew improved keyboard. All with green screen.

Cassette Deck £55 extra Full range of software available.

Interface PET IEEE - Centronics Parallel

Decoded £77.00 + VAT

GET YOURSELFA NEW MX80

PRINTER AND SAVEA FORTUNE

only £299 + VATInterface Cards for Apple,Pet, TRS80, Nascom andCompukit - RS232 Interface ,,xrCards not necessary for parallel.

EAR + VAT

Full TRS80/Genie Graphics including cables.Ready to go EX -STOCK.

COMP POCKET COMPUTERGREATEST BREAKTHROUGH

YET.". £79.90,...A.A3wrissublat + VAT

OW. COMPUTERPOWER THAT

ONCE FILLED A ROOMCAN NOW BE CARRIED IN YOUR POCKET,

Programs in BASIC "OWERTY" AlphabeticKeyboard 1.9K Random Access Memory Long Battery Life.

Computer power that once filled a room can now be carriedin your pocket! It's easy to load with ready -to -run softwarefrom cassette tape (interface and recorder optional) orprogram it yourself in easy -to -learn BASIC. 24 -characterliquid crystal readout displays one line at a time. Specialfeature is advanced non-volatile memory allows you topower on and off without losing the contents of memory.Note: Memory must be transferred to tape before changingbatteries. Automatic statement compaction squeezes everyounce of memory space. Features power -off retention ofprograms and data. Powerful resident BASIC languageincludes multiple statements, math functions, editing,strings, arrays and much more. Multiple program loadingcapability subject to RAM availability. Carrying case andbatteries included.

r

ompuKIT UK101*6502 based system - best value formoney on the market. * Powerful 8KBasic - Fastest around * Full QwertyKeyboard *4K RAM Expandable to 8Kon board. * Power supply and RFModulator on board. * No Extrasneeded - Plug-in and go * Kansas CityTape Interface on board. * FreeSampler Tape including powerfulDissassembler and Monitor with eachKit. * If you want to learn aboutMicros, but didn't know which machineto buy then this is the machine for you.

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Color a\\ OV2, 511'

NE VV ISSUECONIPUKITWITH ALL THE

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MARKET.Now VVITH FREENEIN EXTENDEDMONITOR(a saving

ofWhichCursor, includesScreen

EditiSave Data on Tape ,

DEALERENQUIRIES

INVITED

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FOR THE COMPUKIT - Assembler Editor £14.90 Screen Editor Tape £1.90 4K Upgrade £15.90GAME PACKS - 11. Four Games £5.00 21. Four Games E5.00 31. Three Games 8K only £5.00Super Space Invaders 18K1 £6.50 Space Invaders £5.00 Chequers £3.00 Realtime Clock £3.00

Case for Compukit £29.50 40 pin Expansion Jumper Cable £8.50 All Prices exclusive VAT

TV GAME BREAK OUTHas got to be one of the 11111211rak

world's greatest TV games.You really get hooked. Asfeatured in ETI. Has also 4

other pinball games and lotsof options. Good kit for

up -grading old amusementgames.

MINI NIT - PCB, sound & vision modulator, memory chipand de -code chip. Very simple to construct. £14.90 + VAT

OR PCB £2.90 MAIN LSI £8.50 Both plus VAT

A SELECTION OF APPLE INTERFACESARE NOW AVAILABLE AT OUR NEW

SHOWROOM.

MEMORY UPGRADES16K (8 x 4116) £15.90 VAT

Compukit (8 x 2114) £15.90

WHETHER OR NOT YOUPURCHASE YOUR

PRODUCTS FROM US ORNOT - OUR STAFF OF

HIGHLY TRAINEDENGINEERS WILL BE ONLY

TO PLEASED TO CARRY OUTANY REPAIRS NECESSARY

"Europes Largest DiscountPersonal Computer Stores"

OUR SHOWROOMEt SALES CENTRE AT

311 Edgware Road, London W2

8MHz Super Quality Modulators E4.90

6MHz Standard Modulators £2.90

C12 Computer Grade Cassettes 10 for £4.00

Anadex Printer Paper - 2000 sheets £25.00

Floppy Discs 53/4" Hard and Soft Sectored £3.50

Floppy Disc Library Case 51/4" £3.50

Verocases for Nascom 1 Er 2 etc. £24.90

SPECIAL OFFERWe will part exchangeyour Sinclair ZX80

for any ofour products.

Refurbished ZX80's fullyRefurbished MicroAces guaranteed}

I(Supply dependant upon stocks). +

ENGLISH COLOUR TV/AMERICAN NTSC

COLOUR MONITORSuitable for Apple, Atari and Texas 99/4 £295 VAT

FANTASTIC FOR FILE HANDLING

ACULABFLOPPY

TAPEThe tape that behaves

like a disc, forTRS-80 LEVEL 2.

£169 + VATThe Aculab Floppy Tape for the TRS-80 and Video Genie is ahighly reliable digital storage system that provides many ofthe advantages of floppy disks at less cost. Automaticdebounce routine for the Level 2 keyboard.Connects directly to TRS-80 Level 2 Keyboard. Operatingand file handling software in ROM. 8 commands add 12powerful functions to Level 2 BASIC.

Delivery is added at cost. Please make cheques and postal orders payable to COMPSHOP LTD., or phone your orderquoting BARCLAYCARD, ACCESS, DINERS CLUB or AMERICAN EXPRESS number.

CREDIT FACILITIES ARRANGED - send S.A.E. for application form.MAIL ORDER AND SHOP:148 Station Road, New Barnet, Hertfordshire, EN5 1QW (Close to New Barnet BR Station - Moorgate Line).Telephone: 01-441 2922 (Sales) 01-449 636 Telex: 298755 TELCOMOPEN (BARNET) - 10am - 7pm - Monday to SaturdayNEW WEST END SHOWROOM:311 Edgware Road, London W2. Telephone: 01-262 0387OPEN (LONDON) - 10am - 6pm - Monday to Saturday* IRELAND: 80 Marlborough Street, Dublin 1. Telephone: Dublin 7499331. COMPSHOP USA, 1348 East Edinger, Santa Ana, California, Zip Code 92705.

Telephone: 0101 714 5472526

PRACTICAL COMPUTING May 1981

TELEPHONE SALESOPEN 24 hrs. 7 days a week

01-441 2922tusamcuts

VISA E<PRESS

omn.nownt.

219

w

Outside of the gardenyou need a computer that can grow.For the common or garden hobbyist, a high quality personalcomputer is a real temptation. But let's face it: in the worldof business, engineering and scientific applications, youneed a system that has been designed from the ground up toallow flexibility and expansion.Providing flexibility and expandability today allows themicro to move up to and beyond the level of yesterdays mini.Hard disks for big system memory; more peripherals for bigsystem flexibility; more number crunching capability andprogramming power can all be added when you need them.And without the feeling that you are turning a good naturedtoytown machine into a disproportionate monster.The Ithaca InterSystems DPS1 has the power and flexibilityof the IEEE 696 S100 bus with 20 slots of expandability for upto 16 individually addressable DMA devices and up to 1MegaByte direct addressing from our Z80 board with itsunique memory management system.For really serious computing, our optional hardware front -panel provides a powerful diagnostic tool for debugging anddevelopment. Among its many features are the ability todeposit into and examine memory and set hardware break-points. Coupled with an oscilloscope, many other activitiesusually associated with expensive logic analyzers arepossible. No wonder it's fast becoming the chosen develop-ment system in laboratories everywhere. And the recentlyannounced system without the hardware frontpanel sets newstandards for target systems too.On the subject of standards, Ithaca InterSystems Series II isthe most complete line of IEEE 696 5100 boards . . . easilyupgradeable to the Z8000 or other 16 bit processors as theybecome available ... so you never get locked out of rapid

expansion, or locked into obsolesence, by depending on asingle manufacturer.But beware: IEEE 696 is an 8 bit AND 16 bit standard, not 8bit only as some would have you believe. True compatabilityand later upgrade to 16 bits means you need to stick to thefull IEEE 696 5100 standard from the start.So if you've left the common or garden variety applicationsbehind, come to Ithaca InterSystems and get a system thatwill grow as big as your next idea. Whether starting out witha basic low cost system or needing a sophisticated fullfeature multiuser system or anything in between . . . you'llfind a solution to your problem with Ithaca InterSystems.With a choice of 5" or 8" drives, hard disks and CPIM orMPIM, and the full range of CPIM compatible software,including the excellent PASCAL/Z native code compiler, weprobably have what you need.Why not contact us to discuss your requirement? Call todayfor a catalogue of our products which also contains details ofthe IEEE S100 bus.

Coleridge Lane, Coleridge Road,London N8 8ED. England.Telephone: 01-341 2447Telex: 299568

IT H ACA On iteirt2g2 DO (UK) Ltd.

"MAKING MICROCOMPUTERS FOR THE '80s"12-0