Uni

vers

ity o

f Pun

e S.

E. I.

T.

Subj

ect c

ode:

214

442

Part

34

: PCI

and

SCS

I Bus

es

Com

pute

r Org

aniz

atio

n

UN

IT

V

Tush

ar B

. Kut

e,

Dep

artm

ent o

f Inf

orm

atio

n Te

chno

logy

, Sa

ndip

Inst

itute

of T

echn

olog

y &

Res

earc

h Ce

ntre

, Nas

hik.

ht

tp:/

/tus

hark

ute.

com

Stan

dard

I/O

Inte

rfac

es

Trad

ition

al (I

SA) (

with

cac

he)

High

Per

form

ance

Bus

PCI B

us

Perip

hera

l Com

pone

nt In

terc

onne

ct

In e

arly

199

2, th

e In

tel f

orm

ed a

n an

othe

r in

dust

rial g

roup

in re

latio

n to

the

PC b

us. T

he

mai

n ob

ject

ive

behi

nd th

e fo

rmat

ion

of th

e gr

oup

was

to o

verc

ome

the

wea

knes

s in

ISA

and

EISA

bu

ses.

Th

ey d

esig

ned

the

PCI s

peci

ficat

ions

in Ju

ne 1

992

and

upda

ted

in A

pril

1993

.

Feat

ures

Re

quire

s ver

y fe

w c

hips

to im

plem

ent.

Use

s the

syst

em b

us to

incr

ease

the

bus c

lock

spee

d.

Abili

ty to

func

tion

with

64-

bit d

ata

bus.

Hi

gh b

andw

idth

, 33

MHz

. Su

ppor

t of s

ingl

e an

d m

ultip

roce

ssor

syst

ems.

O

pera

te co

ncur

rent

ly w

ith th

e pr

oces

sor b

us.

Func

tion

as m

ezza

nine

or p

erip

hera

l bus

. Sy

nchr

onou

s tim

ings

. Be

tter

syst

em p

erfo

rman

ce fo

r hig

h sp

eed

I/O

subs

yste

ms

such

as A

GP,

NIC

, disk

cont

rolle

rs.

Plug

and

Pla

y.

PCI i

n sin

gle

proc

esso

r sys

tem

PCI i

n m

ulti

proc

esso

r sys

tem

PCI C

onne

ctor

PCI B

us L

ines

(req

uire

d)

Syst

ems l

ines

In

clud

ing

cloc

k an

d re

set

Addr

ess &

Dat

a 32

tim

e m

ux li

nes f

or a

ddre

ss/d

ata

Inte

rrup

t & v

alid

ate

lines

Inte

rfac

e Co

ntro

l Ar

bitr

atio

n N

ot sh

ared

Di

rect

conn

ectio

n to

PCI

bus

arb

iter

Erro

r lin

es

PCI B

us L

ines

(Opt

iona

l)

Inte

rrup

t lin

es

Not

shar

ed

Cach

e su

ppor

t 64

-bit

Bus E

xten

sion

Addi

tiona

l 32

lines

Ti

me

mul

tiple

xed

2 lin

es to

ena

ble

devi

ces t

o ag

ree

to u

se 6

4-bi

t tra

nsfe

r

JTAG

/Bou

ndar

y Sc

an

For t

estin

g pr

oced

ures

PCI C

omm

ands

Tran

sact

ion

betw

een

initi

ator

(mas

ter)

and

ta

rget

M

aste

r cla

ims b

us

Dete

rmin

e ty

pe o

f tra

nsac

tion

e.g.

I/O

read

/writ

e

Addr

ess p

hase

O

ne o

r mor

e da

ta p

hase

s

PCI R

ead

Tim

ing

Diag

ram

PCI B

us A

rbite

r

PCI B

us A

rbitr

atio

n

SCSI

Smal

l Com

pute

r Sys

tem

Inte

rfac

e, o

r SCS

I (p

rono

unce

d sc

uzzy

), is

a se

t of s

tand

ards

for

phys

ical

ly co

nnec

ting

and

tran

sfer

ring

data

bet

wee

n co

mpu

ters

and

per

iphe

ral d

evic

es.

The

SCSI

stan

dard

s def

ine

com

man

ds, p

roto

cols,

and

el

ectr

ical

and

opt

ical

inte

rfac

es.

SCSI

is m

ost c

omm

only

use

d fo

r har

d di

sks a

nd ta

pe

driv

es, b

ut it

can

con

nect

a w

ide

rang

e of

oth

er

devi

ces,

incl

udin

g sc

anne

rs a

nd C

D dr

ives

.

Back

grou

nd

SCSI

was

der

ived

from

"SAS

I", t

he "S

huga

rt

Asso

ciat

es S

yste

m In

terf

ace"

, dev

elop

ed c

. 197

8 an

d pu

blic

ly d

isclo

sed

in 1

981.

[2] A

SAS

I con

trol

ler

prov

ided

a b

ridge

bet

wee

n a

hard

disk

driv

e's l

ow-

leve

l int

erfa

ce a

nd a

hos

t com

pute

r, w

hich

nee

ded

to

read

blo

cks o

f dat

a.

Larr

y Bo

uche

r is c

onsid

ered

to b

e th

e "f

athe

r" o

f SAS

I an

d SC

SI d

ue to

his

pion

eerin

g w

ork

first

at S

huga

rt

Asso

ciat

es a

nd th

en a

t Ada

ptec

. Dal

Alla

n pr

onou

nced

the

new

acr

onym

as "

scuz

zy" a

nd th

at

stuc

k.

SCSI

Inte

rfac

e

SCSI

Inte

rfac

e

SCSI

Con

trol

ler

SCSI

-1

This

was

evo

lved

from

SAS

I in

1979

. it w

as

appr

oved

by

ANSI

in 1

986

as X

3.13

1-19

86.

SCSI

def

ines

the

basis

for f

irst S

CSI b

uses

in

clud

ing

cabl

e le

ngth

, sig

nalin

g fe

atur

es,

com

man

d an

d tr

ansf

er m

odes

. It

uses

onl

y a

8-bi

t bus

, with

5 M

B/s d

ata

tran

sfer

rate

.

SCSI

-2

The

exte

nsio

n of

orig

inal

SCS

I app

rove

d by

AN

SI in

19

94 a

nd re

leas

ed a

s X3.

131-

1994

. Fa

st S

CSI,

10 M

Hz, 1

0 M

B/s,

8bi

t reg

ular

SCS

I. W

ide

SCSI

, 16/

32 b

its.

Mor

e de

vice

s per

bus

: 16

Impr

oved

cabl

e an

d co

nnec

tors

(50

in S

CSI-1

) Ac

tive

term

inat

ion.

Di

ffere

ntia

l Sig

nalin

g, to

allo

w lo

ng c

able

leng

ths.

Co

mm

and

Que

uing

: allo

w m

ultip

le re

ques

ts o

n th

e bu

s Ad

ditio

nal C

omm

and

Set:

for C

DRO

Ms,

Sca

nner

SCSI

-3

Devi

sed

in 1

993.

Kn

own

as S

CSI-3

par

alle

l int

erfa

ce S

PI.

It de

fines

mec

hani

cal,

elec

tric

al p

roto

col l

ayer

s of t

he

inte

rfac

e.

Data

tran

sfer

rate

: 8-b

its a

t 20

MB/

s ove

r 50

pin

conn

ecto

r. 16

-bits

at 4

0 M

B/s o

ver 6

8 pi

n co

nnec

tor.

Th

e ca

pabi

litie

s of I

EEE-

1394

and

Fib

er C

hann

el w

ere

incl

uded

.

SCSI

Spe

eds

SCSI

Bus

term

inat

ion

Pass

ive

Term

inat

ion

Activ

e Te

rmin

atio

n Fo

rced

Per

fect

Term

inat

ion

High

Vol

tage

Diff

eren

tial

Low

Vol

tage

Diff

eren

tial

Data

tran

sfer

on

SCSI

bus

Initi

ator

Ta

rget

SCSI

Bus

Sig

nals

Refe

renc

es

Web

sites

: ht

tp:/

/en.

wik

iped

ia.o

rg

Com

pute

r Arc

hite

ctur

e an

d O

rgan

izatio

n

By A

. P. G

odse

(fro

m b

ooks

.goo

gle.

com

)

Com

pute

r Org

aniza

tion

By

Ham

ache

r and

Zak

y