Reset Host Adapter - Adaptec AHA-1740A Technical Reference Manual

EISA-to-Fast SCSI Host Adapter
returned will reflect that the command was aborted by the host adapter (error
code = 05). Any commands received after the acknowledgment of the Asynchro-
nous Event Notification interrupt will be operated on normally.

Reset Host Adapter

If the Attention register contains the SCSI ID of the host adapter, then this com-
mand is intended to reset the SCSI subsystem to a known state.
On receiving this command, the host adapter will clear its internal memory of all out-
standing control blocks and queued interrupts for all targets on the SCSI bus. The ac-
tion taken on the SCSI bus depends on the setting of the Adapter Reset Option Flag
(byte 2, bit 3).
If the Adapter Reset Option flag is set to zero, the host adapter will assert the Reset
signal on the SCSI bus, thus initializing all devices on the bus.
If the Adapter Reset Option flag is set to one, the host adapter will attempt to abort
all outstanding operations for all targets without resetting the SCSI bus. If a target
is currently active, the host adapter will assert the Attention signal and send an
Abort message. If the target does not respond to the Attention signal within 250 milli-
seconds, the host adapter will reset the SCSI bus and report an error. If a target re-
connects with an operation that was cleared by this command, the host adapter will
respond with an Abort (or Abort Tag) message.
The Device Reset Option flag (byte 2, bit 2) is ignored by the host adapter for host
adapter reset operations.
Possible errors:
Code Description
08 Firmware not downloaded
20 Host adapter hardware failure
21 Target did not respond to Attention: SCSI Bus reset by host adapter
If the host adapter resets the SCSI bus because the device did not respond to Atten-
tion, the result of the command will be as if the host adapter reset was issued with
Adapter Reset Option Flag set to zero.
Enhanced Mode Firmware Description
6-45