Table 3.4 Signal Source

 

 

 

 

C/D, I/O,

 

 

 

 

 

 

MSG,ACK,DB(7,0)
Bus PhaseBSYSELREQATNDB(P)

 

 

 

 

 

 

BUS FREE

None

None

None

None

None

ARBITRATION

All

Win

None

None

S ID

SELECTION

I&T

Init

None

Init

Init

RESELCTION

I&T

Targ

Targ

Init

Targ

COMMAND

Targ

None

Targ

Init

Init

DATA IN

Targ

None

Targ

Init

Targ

DATA OUT

Targ

None

Targ

Init

Init

STATUS

Targ

None

Targ

Init

Targ

MESSAGE IN

Targ

None

Targ

Init

Targ

MESSAGE OUT

Targ

None

Targ

Init

Init

 

 

 

 

 

 

 

All:

The signal shall be driven by all SCSI devices that are actively

 

arbitrating.

 

 

 

 

 

S ID:

A unique data bit (the SCSI ID) shall be driven by each SCSI

 

device that is actively arbitrating; the other seven data bits shall be

 

released (i.e., not driven) by this SCSI device. The parity bit

 

(DB(P)) may be released or driven to the true state, but shall never

 

be driven to the false state during this phase.

 

 

 

The signal shall be driven by the initiator, target or both, as

 

specified in the SELECTION phase and RESELECTION phase.

Init:

If driven, this signal shall be driven only by the active initiator.

None: The signal shall be released; that is, not be driven by any SCSI

 

device. The bias circuitry of the bus terminators pulls the signal to

 

the false state.

 

 

 

 

 

Win:

The signal shall be driven by the one SCSI device that wins

 

arbitration.

 

 

 

 

 

Targ:

If the signal is driven, it shall be driven only by the active target.

 

 

 

 

 

 

 

3-10

M3099GX/GH OEM Manual