MESSAGE REJECT (Init Targ)

The MESSAGE REJECT message is sent from either the initiator or target to indicate that the last message or 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 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 and interlock so that the initiator can determine which message byte is rejected.

After a target sends a MESSAGE REJECT message and if the ATN signal is still asserted, then it shall return to the MESSAGE OUT phase. The subsequent MESSAGE OUT phase shall begin with the first byte of a message.

NO OPERATION (Init Targ)

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if the target does not respond to the attention condition until a later phase and at that time the original message is no longer valid the initiator may send the NO OPERATION message when the target enters the MESSAGE OUT phase.

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M3099GX/GH OEM Manual