Product Manual - Disc Drive SCSI-2/SCSI-3 Interface (Vol. 2; Ver. 2), Rev. E
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Message Reject (07h)
The MESSAGE REJECT message is sent from either the initiator or target to indicate that the last message
byte it received was inappropriate or has not been implemented.
In order to indicate its intentions of sending this message, the initiator shall assert the ATN signal prior to its
release of the ACK signal for the REQ/ACK handshake of the message byte that is to be rejected. If the target
receives this message under any other circumstance, it shall reject this message.
When a target sends this message, it shall change to MESSAGE IN phase and send this message prior to
requesting additional message bytes from the initiator. This provides an interlock so that the initiator can
determine which message byte is rejected.
Note. After a target sends a MESSAGE REJECT message and if the ATN signal is still asserted, then it
returns to the MESSAGE OUT phase. The subsequent MESSAGE OUT phase begins with the first
byte of a message, not the middle of the previous message.
Modify Data Pointer (01h)
See Paragraph 3.5.3.2 on Extended Messages
No-Operation (08h)
The NO OPERATION message is sent from an initiator in response to a target’s request for a message when
the initiator does not currently have any other valid message to send.
For example, if the target does not respond to the attention condition until a later phase and at that time the
original message is no longer valid the initiator may send the NO OPERATION message when the target
enters the MESSAGE OUT phase.
