Quantum 10K II - Manual (Page 337)

Appendix B. SCSI Bus Signal Timing
B–16 Quantum Atlas 10K II Ultra 160/m SCSI Hard Disk Drives
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.
9. Examines the DATA BUS to determine the SCSI ID of the reselecting drive.
10. Asserts the BSY signal within a selection abort time of its most recent detection
of being reselected.
The initiator does not respond to a RESELECTION phase if bad parity is
detected or if more than two SCSI ID bits are on the DATA BUS.
The drive:
11. Detects the BSY signal is true.
12. Asserts the BSY signal.
13. Waits at least two deskew delays.
14. Releases the SEL signal.
The drive can then change the I/O signal and the DATA BUS.
The initiator:
15. Detects the SEL signal is false.
16. Releases the BSY signal.
The drive:
17. continues asserting the BSY signal until it relinquishes the SCSI bus.
Reselection Time-Out
The Atlas 10K IIdrive performs the following recovery procedure in order to clear the
SCSI bus in response to a reselection time-out. The drive waits a minimum of a
selection time-out delay before initiating this procedure.
1. The drive continues asserting the SEL and I/O signals and releases the data bus
signals.
2. The drive waits a for a total of a selection abort time plus two deskew delays.
3. The drive tests BSY. If it is asserted, the drive completes the reselection
protocol.
4. If BSY is not asserted, the drive releases the SCSI bus.