28
Product Manual - Disc Drive SCSI-2/SCSI-3 Interface (Vol. 2; Ver. 2), Rev. E
_____________________________________________________________________________________
Abort Tag (0Dh)
The ABORT TAG message shall be implemented if tagged queuing is implemented. The target shall go to the
BUS FREE phase following successful receipt of this message. The target shall clear the current I/O process
for the I T L nexus. If the target has already started execution of the I/O process, the execution shall be
halted. The medium contents may have been modified before the execution was halted. In either case, any
pending status or data for the I/O process shall be cleared and no status or ending message shall be sent to
the initiator. Pending status, data, and commands for other queued or executing I/O processes shall not be
affected. Execution of other I/O processes queued for the I T L nexus shall continue in the normal manner.
Bus Device Reset (0Ch)
The BUS DEVICE RESET message is sent from an initiator to direct a target to clear all current I/O pro-
cesses on that SCSI device. This message forces a hard reset condition to the selected SCSI drive. The
target shall go to the BUS FREE phase following successful receipt of this message. The target shall create
a Unit Attention condition for all initiators (See 4.6).
Clear Queue (0Eh)
The CLEAR QUEUE message shall be implemented if tagged queuing is implemented and may be imple-
mented if untagged queuing is implemented. The target shall go to the BUS FREE phase following success-
ful receipt of this message. The target shall perform an action equivalent to receiving a series of ABORT
messages from each initiator. All I/O processes, from all initiators, in the queue for the specified logical unit
shall be cleared from the queue. All executing I/O processes shall be halted. The medium may have been
altered by partially executed commands. All pending status and data for that logical unit for all initiators shall
be cleared. No status or ending message shall be sent for any of the outstanding I/O processes. A unit
attention condition shall be generated for all other initiators with I/O processes that either had been executing
or were queued for execution for that logical unit. When reporting the Unit Attention condition the additional
sense code shall be set to TAGGED COMMANDS CLEARED BY ANOTHER INITIATOR.
Command Complete (00h)
The COMMAND COMPLETE message is sent from a target to an initiator to indicate that the execution of a
command (or series of linked commands) has terminated and that valid status has been sent to the initiator.
After successfully sending this message, the target shall go to the BUS FREE phase by releasing BSY. The
target shall consider the message transmission to be successful when it detects the negation of ACK for the
COMMAND COMPLETE message with the ATN signal false.
Notes: The command may have been executed successfully or unsuccessfully as indicated in the status.
