Reselection Phase - Fujitsu MAW3073 SERIES Specifications

1.6.4

RESELECTION phase

The SCSI device operated as a TARG selects an INIT in the RESELECTION phase. This phase is
an option for the system, and this phase can only be used in systems with the ARBITRATION
phase implemented.
When the TARG re-starts the command processing under the disconnection on the SCSI bus, the
TARG reconnects with the INIT using this phase.
(1) Start sequence
A TARG performs the RESELECTION phase in the following sequence after obtaining control of
the SCSI bus through the ARBITRATION phase (see Figure 1.29).
(a) Parity Protection is disabled
1) TARG waits at least Bus Clear Delay + Bus Settle Delay after asserting the SEL signal in
the ARBITRATION phase.
2) The TARG asserts the I/O signal with sending the SCSI IDs of the TARG itself and INIT
to the SCSI bus (the SCSI device that gets the bus usage right by asserting the I/O signal is
recognized as a TARG).
3) The TARG releases the BSY signal after waiting at least Deskew Delay × 2, and the
TARG shall then wait the response (BSY signal) from the INIT after at least Bus Settle
Delay passed.
(b) Parity Protection Enabled
1) The SCSI device that won arbitration has both the BSY and SEL signals asserted and has
delayed at least one Bus Clear Delay plus one Bus Settle Delay before ending the
ARBITRATION phase.
2) The SCSI device that won arbitration identifies itself as a TARG by asserting the I/O
signal.
3) The TARG also sets the DATA BUS to a value that is the logical OR of TARG's SCSI ID
bit, the INIT's SCSI ID bit and the appropriate parity bit(s).
4) The TARG waits at least two System Deskew Delays and releases the BSY signal.
5) The TARG then waits at least one Bus Settle Delay before attempting to detect an assertion
of the BSY signal by the INIT.
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