Quantum 10K II - Manual (Page 345)

Appendix B. SCSI Bus Signal Timing
B–24 Quantum Atlas 10K II Ultra 160/m SCSI Hard Disk Drives
The initiator keeps the ATN signal asserted if more than one byte is to be
transferred. The initiator can negate the ATN signal at any time, except it does not
negate the ATN signal while the ACK signal is asserted during a MESSAGE OUT
phase. Normally, the initiator negates the ATN signal while the REQ signal is true
and the ACK signal is false during the last REQ/ACK handshake of the MESSAGE
OUT phase.
B.6.2 Reset Condition
The drive employs the hard reset alternative for bus RESET processing. Write cache
data is preserved across a SCSI reset and will be flushed to the media.
The hard reset means that upon detection of the reset condition, the disk drive
follows these steps:
1. Clears all tasks, including task sets (queues).
2. Releases all SCSI device reservations.
3. Returns any SCSI device operating modes to their appropriate initial conditions,
similar to those conditions that would be found after a normal power-on reset.
MODE SELECT conditions are restored to their last saved values, if saved
values have been established. MODE SELECT conditions for which no values
have been saved are returned to their default values.
4. Sets unit attention condition.