Fujitsu MBA3073 SERIES Technical Manual page 73

Note:
If single INIT operates without the RESELECTION phase, it is allowed to assert only the
TARG's SCSI ID.
3) After waiting at least Deskew Delay × 2, the INIT asserts SEL signal and waits the response
(BSY signal) from the TARG.
(2) Start sequence with ARBITRATION phase
In systems with ARBITRATION phase implemented, the INIT starts the SELECTION phase in
the following sequence (see Figure 1.28).
1) The INIT shall wait for at least Bus Clear Delay + Bus Settle Delay after turning SEL signal
on during the ARBITRATION phase.
2) Then the INIT asserts SCSI IDs of the desired TARG and INIT itself on the DATA BUS.
Note:
If single INIT operates without RESELECTION phase, it is allowed to assert only the TARG's
SCSI ID.
3) The INIT releases BSY signal after waiting at least Deskew Delay × 2. The INIT shall then
wait at least Bus Settle Delay before looking for the response (BSY signal) from the TARG.
(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 SELECTION 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.
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