Outline Of Command Processing; Single Commands - Fujitsu MAX3073NC - SCSI,80, Dell DC961,Hard Drive Scsi Logical Interface Specifications

Command Processing
(6) INTERMEDIATE CONDITION MET Status
This status is reported when it is possible to secure the cache memory area necessary to read all the
logical data blocks specified in a PRE-FETCH command which specifies a link (in the case of "Immed =
1"), or when reading of all the specified logical data blocks is completed (in the case of "Immed = 0").
The IDD does not support the PRE-FETCH command. Therefore, this status is not reported.
(7) RESERVATION CONFLICT status
This status indicates that the IDD is reserved by another INIT, and that use is impossible until the
reserved status is canceled. Normally, an INIT which receives this status reissues the original command
after waiting an appropriate period of time.
(8) COMMAND TERMINATED status
This status is reported when the IDD has completed the executing input/output operation when it received
a TERMINATE I/O PROCESS message from the INIT.
The IDD does not support the TERMINATE I/O PROCESS message. Therefore, this status is not
reported.
(9) TASK SET FULL status
This status is reported if the IDD cannot register a received tagged command in the command queue
because there is no empty space in the command queue.
1.3

Outline of Command Processing

1.3.1

Single commands

Following shows single command processing examples which are the most basic operations on the SCSI
bus. Furthermore, if disconnect processing is permitted, it may be accompanied by disconnect/reconnect
processing during the command execution, depending on the type of command, but this operation is
omitted in the following explanation. The disconnect function is described in Section 1.3.3.
1) The INIT sets the initial values for the command in the command pointer, data pointer and status
pointer.
2) The INIT selects the TARG in the SELECTION phase after obtaining the SCSI bus usage in the
ARBITRATION phase. After the SELECTION phase is ended, the SCSI bus control is entrusted to
the TARG.
3) If the ATTENTION condition exists when the TARG responds to the SELECTION phase, the TARG
executes the MESSAGE OUT phase. Normally, the INIT sends the IDENTIFY message as the initial
message and specifies the device (LUN) that is the object of the operation.
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