Asus PCI-DA2100 Manual do Utilizador descarregar pdf (Página 10)

US

6,173,344

B1

5

detrimentally

affected

When

non-Ultra2

target

devices

are

connected

through

the

Ultra or Ultra

Wide

buses

(i.e.,

having

cable

102

and

connectors

104).

The

protection

provided

to

the

Ultra2

bus

and

Ultra2

target

devices

is

a

result

of

electrically

isolating

the

Ultra

bus

from

the

Ultra2

bus

during

their

respective

operation.

As

shoWn

in

FIG.

3,

a

transceiver

unit

302

is

strategically

connected

betWeen

an

internal

SCSI

bus

segment

(i.e.,

3126)

for

Ultra

target

devices

and

an

internal

SCSI

bus

segment

(i.e.,

312a, 312b,

312c,

and

312a)

for

Ultra2

target

devices.

Preferably,

the

transceiver

unit

302

is

coupled

to

the

internal

SCSI

bus

segment

312c,

Which

is

in

turn

coupled

to

the

internal

SCSI

bus

segment

312a

that

is

coupled

to

the

internal

Ultra2-LVD/SE

connector

204b.

The

internal

SCSI

bus

segment

312a

is

also

coupled

to

the

external

Ultra2

LVD/SE

connector

204a

through

the

internal

SCSI

bus

segment

312b.

Furthermore,

the

transceiver

unit

302

is

also

coupled

to

a

SCSI

host

adapter

chip

304

through

the

internal

SCSI

bus

segments

312c

and

312d.

In

this

embodiment,

the

SCSI

host

adapter

chip

is

a

ACI-7890A

packaged

semicon

ductor

device,

Which

is

available

from

Adaptec

Inc.,

of

Milpitas,

Calif.

The

transceiver

unit

302

is

also

coupled

to

the

Ultra

bus

through

the

internal

SCSI

bus

3126.

In

this

example,

both

a

50

pin

Ultra

SCSI/SE

connector

207

and

an

Ultra

Wide

connector

206

are

provided,

hoWever,

either

one

may

be

omitted

depending

on

the

desired

application.

Accordingly,

either

one

or

both

of

the

Ultra

Wide

connector

206

and

the

Ultra

connector

207

may

be used

to

connect

to

the

Ultra

bus

cables

102

and

connectors

104.

The

host

adapter

202

also

includes

a crystal

oscillator

(clock)

306

Which

is

con?gured

to

provide

the

appropriate

clock

“CLK”

timing

to

both

the

transceiver

unit

302

and

the

SCSI

host

adapter

chip

304.

Also

included

is

a

standard

programmable

logic

device

(PLD)

308,

Which

is

pro

grammed

With

the

identi?cation

codes

“IDs”

to

operate

as

an

initiator,

as

opposed

to

a

terminator.

The

host

adapter

202

also

has

a

EEPROM

310

memory

device,

Which

is

con?g

ured

to

store

the

initialiZation

code

that

Will

be used

during

the

host

computer’s

boot-up

process.

As

shoWn,

the

transceiver

unit

302

is

in

communication

With

the

SCSI

host

adapter

chip

304

via

a

target

information

signal

(TIS)

line

320,

in

accordance With

one

embodiment

of

the

present

invention.

As

mentioned

above,

the

transceiver

unit

302

is

capable

of

isolating

the

Ultra2

bus

from

the

Ultra

bus

When

processing

a

data

transfer

in

accordance

With

the

SCSI

Ultra2

protocol,

and

respectively

isolating

the

Ultra

bus

from

the

Ultra2

bus

When

processing

a

data

transfer

in

accordance With

the

SCSI

Ultra2

protocol.

To

further

elaborate

on

the

functionality

of

the

transceiver

unit

302,

reference

is

made

to

a

state

machine

diagram

400

of

FIG.

4,

in

accordance

With

one

embodiment

of

the

present

invention.

When

the

transceiver

unit

302

is

in

an

idle

state

402,

the

state

machine

400

Will

be

set

to

a

logical

state

Zero

(0),

Which

is

communicated

via

the

TIS

line

320

to

the

SCSI

host

adapter

chip

304.

Upon

the

utiliZation

of

the

Ultra2

bus,

either

through

the

Ultra2-LVD/SE

connector

204b

or

the

Ultra2-LVD/SE

connector

204a,

the

internal

SCSI

bus

lines

312a,

312b

and

312d

Will

be

utiliZed

to

communicate

With

the

SCSI

host

adapter

chip

304,

Which

in

turn

communicates

With

the

host

210

via

the

PCI

connector

208.

Therefore,

during

an

Ultra2

transaction,

the

state

machine

400

Will

proceed

to

a

state

406.

In

state

406,

the

target

information

signal

(TIS)

is

held

at

a

logical

state

Zero

(0),

and

the

state

machine

proceeds

to

a

state

408

Where

the

transaction

of

the

current

SCSI

protocol

is

complete.

Once

15

35

45

55

65

6

complete,

the

state

machine

400

Will

move

to

a

state

410

in

Which

the

TIS

is

set

to

a

logical

state

Zero

HoWever,

because

the

Ultra2

transaction

maintains

the

TIS

signal

320

that

is

transferred

from

the

transceiver

unit

302

to

the

SCSI

host

adapter

chip

304

at

a

logical

state

Zero

(0),

the

state

410

Will

not

change

the

state

of

the

TIS

signal

320.

After

the

Ultra2

transaction

is

complete,

the

state

machine

400

Will return

to

the

idle

state

402.

Once

at

the

idle

state

402,

a

next

transaction,

Which

could

be

an

Ultra

transaction

may

begin.

When

an

Ultra

transaction

begins,

the

internal

SCSI

bus

3126

Will

be

used

to

communicate

betWeen

one

of

the

Ultra

Wide

connector

206

and

the

Ultra

connector

207

and

the

transceiver

unit

302.

At

the

point

the

transceiver

unit

302

receives

the

Ultra

signal

over

the

internal

SCSI

bus

3126,

the

state

machine

400

Will

move

from

the

idle

state

402

to

a

state

404.

In

state

404,

the

TIS

signal

320

is

set

to

a

logical

state

one

(1)

and

passed

to

the

SCSI

host

adapter

chip

304.

Next,

the

state

machine

400

Will

move

to

the

state

408

Where

the

SCSI

Ultra

transaction

protocol

is

processed

to

completion.

In

this

embodiment,

the

Ultra

signal

is

processed

by

being

passed

through

the

transceiver

unit

302,

onto

the

internal

SCSI

buses

312c

and

312d,

and

to

the

SCSI

host

adapter

chip

304

for

processing.

At

that

point,

the

data

can

be

communicated

to

the

host

210.

FIG.

5

is

?oWchart

diagram

500

illustrating

one

exem

plary

method

for

con?guring

a

computer

system

that

includes

a

host

adapter

having

connectors

to

both

an

Ultra2

bus and

a

non-Ultra2

bus,

in

accordance

With

one

embodi

ment

of

the

present

invention.

The

method

begins

at

an

operation

502,

Where

a

computer

system

that

has

a

host

adapter

that

includes

a

transceiver

unit

is

booted

up.

In

this

embodiment,

the

transceiver

unit

is

preferably

connected

to

both an

Ultra2

bus and

a

non-Ultra2

(i.e.,

single

ended

Ultra)

bus,

Which

have

target

devices

connected

to

the

respective

buses.

During

the

boot-up

process,

the

SCSI

host

adapter

chip

304

Will

scan

the

SCSI

buses

to

detect

all

of

the

target

devices

that

may

be

connected

to

the

respective buses.

From

operation

502,

the

method

Will

proceed

to

an

operation

504

Where

the

ID

numbers

and

the

type of

target

devices

that

are

connected

to

the

Ultra2

and

the

non-Ultra2

buses

are dis

played

to

the

user.

To

illustrate

the

boot-up

and

display

process

in

greater

detail,

reference

is

made

to

FIGS.

6A

and

6B.

In

table

600,

an

exemplary

case

in

Which

tWo

Ultra2

target

devices

having

ID

numbers

“3”

and

“9”,

and

one

Ultra

target

device

“*”

having

ID

number

“1”

are

connected

to

an

Ultra2

bus.

Also

shoWn

is

an

Ultra

target

device

having

ID

number

“7”

that

is

connected

to

an

Ultra

bus.

By

examining

the

table

600,

it

is

evident

that

the

boot-up

process has

detected

that

the

Ultra

target

device

having

ID

number

“1”

is

connected

to

the

Ultra2

bus.

As

discussed

above,

this

connection

con?gura

tion

Will

have

the

detrimental

effect

of

substantially

reducing

the

maximum

SCSI

bust

rate

(i.e.,

speed) of

all

of

the

Ultra2

target

devices

that

are

connected

to

the

Ultra2

bus.

Reference

is

noW

draWn

back

to

FIG.

5,

Where

the

method

proceeds

to

a

decision

operation

506.

In

decision

operation

506,

it

is

determined

Whether

there

is

a

non-Ultra2

device

connected

to

the

Ultra2

bus.

As

illustrated

in

the

example

case

of

FIG.

6A,

a

non-Ultra2

target

device

(i.e.,

Ultra

target

device

having

ID

number

“1”)

is

connect

to

the

Ultra2

bus.

At

this

point,

the

method

proceeds

to

an

operation

508,

Where

the

non-Ultra2

target

device

is

removed

from

the

Ultra2

bus.

Once

removed,

the

method

proceeds

to

an

operation

510 Where

the

non-Ultra2

target

device

is

con

nected

to

the

non-Ultra2

bus

(i.e.,

Ultra

bus),

Which

is

connected

to

the

transceiver

unit.

NoW

that

the

target

devices

have

been

connected

in

an

optimum

orientation

on

either

1 2 ... 5 6 7 8 9 10 11 12

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