Resume; Scsi Bus Reset Handling; Reset Initiated By The Host - Adaptec AHA-1740A Technical Reference Manual

adaptec

Resume

F E D
Fields that are empty are reserved and should be set to zero.
This command is used to clear an extended contingent allegiance condition. The host
adapter notifies the host that a target is in a state of extended contingent allegiance
by setting bit 14 in the status word. After issuing this command, all queued opera-
tions for the target specified in the Attention register will no longer be suspended
and normal operation is resumed.
If the host adapter receives this command for a target that is not in a state of ex-
tended contingent allegiance, this situation is not considered an error, and the com-
mand is treated as a No-Op.
Bit 5 in byte 2 provides the option of whether an interrupt should be issued upon com-
pletion of this command. Setting this bit to one, disables the interrupt. If this bit is
set to zero, an interrupt will be reported.
Possible errors:
Code Description
08 Firmware not downloaded
20 Host adapter hardware failure

SCSI Bus Reset Handling

A SCSI bus reset can occur in several ways. The following describes what can cause
the reset and how the host adapter will respond to the condition.

Reset Initiated by the Host

Hard Reset. When the host adapter is reset via hardware control and the RSTPWR
flag (SCSIDEF Register, bit 4) is set to one, the SCSI bus will be reset by the host
adapter as part of its power-on sequence. There will be no notification of the SCSI re-
set since it is implied by the Hard Reset.
Soft Reset. When the host adapter is reset via software control (Immediate Reset com-
mand) and the Adapter Reset Option flag is set to zero, the SCSI bus will be reset by
the host adapter as part of its reinitialization. There will be no notification of the
SCSI reset since it is implied by the Soft Reset.
6-46
C B A 9 8
AHA-1740A/1742A/1744
7 6 5 4 3
1 0 0 1 0
1
2 1 0 Byte
Offset
0 0 0 00
02