Quantum DLTtape DLT1, Interface Manual

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DLT1/VS80 SCSI Interface Guide
81-81276-01 Rev A01 July 2004 3-7
3.2.12 MESSAGE REJECT (07h)
The initiator or target sends this message to indicate that the last message received was inappropriate
or remains not implemented.
To indicate its intentions of sending this message, the initiator asserts the ATN signal before it releases
ACK for the REQ/ACK handshake of the message that is to be rejected.
The tape drive issues MESSAGE REJECT in response to any messages the tape drive considers to be
illegal or not supported. When sending to the initiator, the tape drive issues a MESSAGE REJECT
before requesting any additional message bytes.
3.2.13 NO–OPERATION (NO–OP, 08h)
If a target requests a message, the initiator sends NO–OP if it does not currently have any other valid
message to send. The tape drive accepts the message when acting as a target and can send the message
when acting as an initiator. If the tape drive receives NO–OP during a selection operation, the tape
drive proceeds to the COMMAND phase, provided ATN does not continue being asserted. The tape
drive ignores and discards the NO–OP message.
3.2.14 RESTORE POINTERS (03h)
A target sends this message to direct the initiator to restore the most recently saved pointers for the
currently attached logical unit. When it receives the RESTORE POINTERS message, the initiator
performs the following tasks:
•
Restores pointers to the command, data, and status locations for the logical unit to the active
pointers
•
Restores Command and Status pointers to the beginning of the present Command and Status areas
•
Restores the Data pointer to the value at the beginning of the data area in the absence of a SAVE
DATA POINTER message, or to the value at the last SAVE DATA POINTER message that
occurred for that logical unit.
When a target receives the RESTORE POINTERS message, the target switches to the MESSAGE IN
phase and returns MESSAGE REJECT.