Selection Phase - Fujitsu MAN3184 SERIES Specifications

1.6.3

SELECTION phase

An INIT selects a TARG (a single SCSI unit) in the SELECTION phase.
Note:
I/O signal is false during a SELECTION phase. (The I/O signal identifies the phase as
SELECTION or RESELECTION).
(1) Start sequence without ARBITRATION phase
In systems with the ARBITRATION phase not implemented, the INIT starts the SELECTION
phase in the following sequence (see Figure 1.23).
1) The INIT shall wait for at least Bus Clear Delay after BUS FREE phase detection.
2) Then the INIT asserts SCSI IDs of desired TARG and INIT itself on the DATA BUS.
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
(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 1.23).
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
wait at least Bus Settle Delay before looking for the response (BSY signal) from the TARG.
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2, the INIT asserts SEL signal and waits the response
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2. The INIT shall then