Chapter 2

Turning Data into Something You Can Use

© The McGraw-Hill Companies, Inc., 2000

Processing Hardware

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Overview

• Data and program representation

• Processor, main memory, registers

• RAM capacity, word size, processor speed

• Microcomputer

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Computers

• Programmed to learn and adapt

• High costs slowed initial adoption

• More than 15 billion microprocessors and microcontrollers in use at the turn of the century

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Data and Program Representation

• Binary system

• Two common schemes– EBCDIC– ASCII

• New scheme– Unicode

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The Parity Bit

• A parity bit is a check bit

• It is an extra bit attached to the end of a byte to check accuracy

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Capacity• Bit

– 0s and 1s

• Byte– 8 bits

• Kilobyte– about 1000 bytes

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Larger Capacity

• Megabyte– about one million bytes

• Gigabyte– about one billion bytes

• Terabyte– about a trillion bytes

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Processor

• Information– manipulates data into useful information

• Knowledge– results in reasoned analysis and

applications

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Processors, Main Memory, and Registers

• Processor– control unit– arithmetic/logic unit (ALU)

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Logical Operations

• Logical operations in the ALU are simple comparisons such as =, <, >, <=, or >=

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Boards and Chips

• Circuit boards

• Chips of silicon

• Use aluminum or copper to conduct electronic messages

• Semiconductor

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Specialized Systems

• Coprocessors– math– graphics

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Future

• PC on a chip

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CISC, RISC, MPP• CISC (“sisk”)

– complex instruction set, serially executed– most mainframes and PCs

• RISC (“risk”)– reduced instruction set, serially executed– cheaper and faster– shift some work to software

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MPP

• Massively parallel processing (MPP)– spreads calculations over many

computers or processors

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Main Memory

• Primary storage– RAM (random access memory)

• holds data

• instructions

• processed data for output

• is volatile

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Main Memory Facts

• Contents temporary

• Capacity varies according to installed amount of memory chips

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Registers

• High speed circuitry areas – store data and provide work areas– dedicated by function

• addition register

• subtraction register

• storage register

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Machine Cycle

• Compares a series of operations to perform a single program instruction

• During the instruction cycles, or I-cycles,– control unit fetches instructions from main

memory– decodes or interprets instruction

• During execution cycle, or E-cycle,– executes and stores result

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RAM Capacity, Word Size, Processor Speed

• RAM capacity– software determines capacity needed– older computers may not have enough– computer’s RAM capacity is limited by the

capacity of the motherboard

• Measured in megabytes, gigabytes, and terabytes – PCs to servers to mainframes, based on

programs and load capacity

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Word Size

• Number of bits computer can hold in its registers– sent through local bus

• 32-bit– most 486 PCs

• 64-bit– common PCs in CISC format

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Processing Speed

• System clock controls speed of operations

• Speeds measured in megahertz (MHz) are common

• Gigahertz (GHz) predicted in the near future

• MIPS and FLOPS not commonly used

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Focus on PC Purchasing– System unit

• Hard drive• Floppy drive

(except iMac)• Power supply• Motherboard• Microprocessor• Ram

• ROM• Cache• VRAM• Ports• Expansion

boards• Bus lines• PC slots• PC cards

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Power Supply

• Power supply– protected by power surge protector or

uninterrupted power supply unit (UPS)– voltage capacity can affect the ability to

support internal parts

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Motherboard

• Also called system board

• Includes CPU, memory chips (RAM, ROM), ports, coprocessors if not integrated on CPU, expansion slots

• Some boards have integrated sound, controller cards, and graphics

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Microprocessor• Intel (PC)

– X86– Celeron– Pentium

MMX– Pentium II/III

• AMD (PC)– K6-2– K6-3– Athlon

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Other Microprocessors

• Motorola (Mac)– 68000– 68020– 68040– PowerPC 601– PowerPC 604– PowerPC 620– PowerPC 750

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Compatibility

• Most software is backward compatible with new chips

• The older the hardware, the less the likely that it will install easily and function completely in new systems

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The Truth About RAM

• Generally, more is better– must match with motherboard and CPU

capabilities

• Software vendors traditionally understate software (RAM) requirements for a smooth operation of their software

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A Suggestion

– A computer running Microsoft Office 97 should have a minimum 32MB RAM for smooth performance

– Microsoft Office 2000 needs 64 to 128 MB RAM

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ROM Chips

• Read-only memory (ROM)

• Also known as firmware

• Helps boot the system

• BIOS– Basic Input Output System

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Other ROM

• PROM– programmable ROM

• EPROM– erasable programmable ROM

• EEPROM (flash)– electronically erasable programmable ROM– can be rewritten without special equipment

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Other Forms of Memory

• Cache memory (“cash”)– quick access memory, internal or external to the

processor– bridge between the processor and RAM– including pipeline-burst simultaneous

read/write

• Video memory– VRAM (“vee-ram”)– some graphic cards use other types of RAM

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Ports• External socket

– front or back of system unit

• Parallel– printers, some Zip drives, some scanners

• Serial port (RS-232)– modems, scanners, mice

• Video adapter– digital and analog, single or dual monitor

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More Ports

• SCSI: small computer system interface– fast– connected in daisy-chain fashion– originally used in Macs– can be internal or external– hard drives, tape backups, scanners, CD

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Less Common Ports

• Game ports– joystick

• Infrared– often used for keyboards, mice,

and printers

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Expansion Slots

• Bus slots– for expansion cards and adapter cards– memory – video– graphics– controller– internal modem

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Bus Designs

• ISA (“eye-suh”): Industry Standard Architecture– does not share common resources– 16-bit

• PCI: peripheral component interconnect– some cards do share resources, such as IRQs– 64-bit

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More Buses

• EISA (“ee-suh”) enhanced industry standard architect– 32-bit

• PCMCIA: Personal Computer Memory Card International Association– for PC cards on portable computers

• modems, hard drives, memory, Ethernet cards

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Newer Bus

• USB – Universal Serial Bus– printer, scanner, digital camera, joystick,

monitor– easy connection

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Newest Bus

• AGP: Advanced Graphics Port– dedicated for video use– speed and access to memory and CPU continue

to increase– more than double PCI rates– standards include 2X AGP, 4X AGP

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Standards and Options

• New boards often have ISA and PCI slots so close together that both cannot be available for expansion at the same time

• The PC-2000 computer standard calls for no ISA slots

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Future Processing Technologies

• Gallium arsenide– better conductor, fewer circuits than silicon

• Superconductors– electricity flows without resistance– 100 x faster– refrigerated system units already on market

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More of the Future

• Opto-electronic processing– use of light– in common with fiber optics

• Nanotechnology– nanometer = 1 billionth of a meter– molecules used to transform data or perform

tasks

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Future

• Biotechnology– use of bacteria for

on/off signals