Fujitsu MAN3184 SERIES Specifications page 63

(3) Selection enabled parity protection and using/without using attention condition
1) The INIT sets the DATA BUS to a value that is the OR of INIT's SCSI ID bit, the TARG's
SCSI ID bit, and the appropriate parity bit(s) (i.e., DB(P_CRCA and/or P1)).
2) In the case of selection using attention condition, the INIT should create an attention condition
(indicating that a MESSAGE OUT phase is to follow the SLECTION phase).
But in the case of selection without using attention condition, the INIT should clear an
attention condition
3) The INIT waits at least two System Deskew Delays and releases the BSY signal.
4) The INT then wait at least one Bus Settle Delay before attempting to detect an assertion of the
BSY signal from the TARG.
(4) Response sequence
When an SCSI device (TARG) detects that the SEL signal and the data bus bit (DBn)
corresponding to the own SCSI ID are true and both BSY and I/O signals are false for at least Bus
Settle Delay, the SCSI device shall recognize that it is selected in the SELECTION phase. At this
time, the selected TARG may sample all bits on the SCSI bus to identify the INIT's SCSI ID.
The TARG must response to the INIT by asserting the BSY signal within Selection Abort Time
since the TARG detects that the TARG is selected. If the SCSI ID with three or more bits is
detected, or if a parity error is detected under the system that the parity bit is enabled, the TARG
shall not respond to the SELECTION phase.
At least Deskew Delay
release SEL signal. The values on the DATA BUS can be changed after this time.
Note:
When Selection without using attention condition, if an INIT detects an unexpected
COMMAND phase, it invalidates all prior negotiations with the selected TARG.
In this case, the INIT should create an attention condition and on the corresponding
MESSAGE OUT phase should issue an ABORT TASK message.
On the next selection of the TARG that received the ABORT TASK message the INIT
should do a selection using the attention condition.
2 after the BSY signal (asserted by the TARG) detection, the INIT shall
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