Seagate Ultra160 Product Manual page 36

18
SCSI bus phase
COMMAND
ST DATA IN
ST DATA OUT
DT DATA IN
DT DATA OUT
STATUS
MESSAGE IN
MESSAGE OUT
Table abbreviations are defined as follows:
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
data bits shall be released (i.e., not driven) by this SCSI device. The P_CRCA and DB(P1) bit(s) may be
released or driven to the true state, but shall not 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 driven by any SCSI device. The bias circuitry of the bus termi-
nators 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.
PT: Target that initiated the QAS arbitration.
C/D, I/O,
BSY SEL MSG, REQ
Targ None Targ
Targ None Targ
Targ None Targ
Targ None Targ
Targ None Targ
Targ None Targ
Targ None Targ
Targ None Targ
SCSI Interface Product Manual, Rev. B
16 data bit (P) cable
8 data bit (A) cable
ACK, ATN DB(7-0)
Init Init
Init Targ
Init Init
Init Targ
Init Init
Init Targ
Init Targ
Init Init
DB(15-8),
P_CRCA DB(P1)
Init None
Targ Targ
Init Init
Targ Targ
Targ Init
Targ None
Targ None
Init None