Quantum ATL SuperLoader ATL, User Manual

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Chapter 2 Messages
Supported SCSI Messages
20 Quantum ATL SuperLoader Software Interface Guide
No Operation (08h)
2
If a target requests a message, the initiator sends a NO
OPERATION message if it does not currently have any other valid
message to send. The message is accepted when the SuperLoader
is acting as a target and may be sent when it is an initiator. If a NO
OPERATION message is received during a selection, the
SuperLoader proceeds to the COMMAND phase, provided ATN
does not continue as asserted; the NO OPERATION message is
ignored by the SuperLoader.
Restore Pointers
(03h)
2
The RESTORE POINTERS message is sent from the SuperLoader
to the initiator to direct the initiator to copy the most recently
saved command, data, and status pointers for the I/O process to
the corresponding current pointers. The command and status
pointers are restored to the beginning of the present command and
status areas. The data pointer is restored 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 point at which the last
SAVE DATA POINTER message occurred for that logical unit.
When the RESTORE POINTERS message is received as a target,
the target switches to the MESSAGE IN phase and returns
MESSAGE REJECT.
Save Data Pointer
(02h)
2
The SAVE DATA POINTER message is sent from the SuperLoader
to direct the initiator to copy the current data pointer to the saved
data pointer for the current I/O process.
When functioning as a target, the SuperLoader sends this message
before a DISCONNECT message during a data transfer. It does not
send a SAVE DATA POINTER message if it intends to move
directly to STATUS phase. When received as a target, it switches to
MESSAGE IN phase and returns MESSAGE REJECT.