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SCSI Description
Quantum DLT 7000 Tape System 3-15
The initiator asserts the RST signal and follows these steps:
a) Continues asserting the SEL and ATN signals and releases the DATA
BUS.
b) If it has not detected the BSY signal to be true after at least a selection
abort time plus two deskew delays, the drive releases the SEL and ATN
signals, allowing the SCSI bus to go to the BUS FREE phase.
When responding to selection, SCSI devices ensure that the selection was still
valid within a selection abort time of their assertion of the BSY signal. Failure
to comply with the requirement could result in an improper selection.
3.5.4 RESELECTION Phase
RESELECTION is an optional phase that allows a drive to reconnect to an
initiator to continue an operation that was previously started by the initiator
but was suspended by the drive.
The initiator determines that it is reselected when the SEL and I/O signals and
its SCSI ID bit are true, and the BSY signal is false for at least one bus settle
delay.
3.5.4.1 Reselection Sequence
The drive:
1. Upon completing the ARBITRATION phase, asserts both the BSY and SEL
signals.
2. Delays at least one bus clear delay plus one bus settle delay.
3. Asserts the I/O signal.
4. Sets the DATA BUS to the logical OR of its SCSI ID bit and the initiator’s
SCSI ID bit.
5. Waits at least two deskew delays.
6. Releases the BSY signal.
7. Waits at least one bus settle delay before looking for a response from the
initiator.
The initiator:
8. Determines that it is selected when the following occur for at least one bus
settle delay: SEL, I/O, and the initiator’s SCSI ID bit are true and BSY is
false.