Table 6
+==============-=====================================-========================+
| Bus phase | A cable signals | B cable signals |
| |-------------------------------------+------------------------|
| | | | C/D, | | | | | DB(31-8) |
| | | | I/O, | | | | | DB(P1) |
| | | | MSG, | ACK, | DB(7-0) | | | DB(P2) |
| | BSY | SEL | REQ | ATN | DB(P) | REQB | ACKB | DB(P3) |
|--------------+------+------+------+------+---------+------+------+----------|
| BUS FREE | None | None | None | None | None | None | None | None |
| ARBITRATION | All | Win | None | None | S ID | None | None | None |
| SELECTION | I&T | Init | None | Init | Init | None | None | None |
| RESELECTION | I&T | Targ | Targ | Init | Targ | None | None | None |
| COMMAND | Targ | None | Targ | Init | Init | None | None | None |
| DATA IN | Targ | None | Targ | Init | Targ | Targ | Init | Targ |
| DATA OUT | Targ | None | Targ | Init | Init | Targ | Init | Init |
| STATUS | Targ | None | Targ | Init | Targ | None | None | None |
| MESSAGE IN | Targ | None | Targ | Init | Targ | None | None | None |
| MESSAGE OUT | Targ | None | Targ | Init | Init | None | None | None |
|-----------------------------------------------------------------------------|
| |
|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. |
| |
|I&T: 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. |
+=============================================================================+