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SDLT 600 SCSI Interface Guide Chapter 3: SCSI Messages

81-81200-02 REV A01 January 2005 3-9

3.2.9 MESSAGE PARITY ERROR (09h)

The initiator sends this message to tell the SDLT tape drive that the last message byte the drive passed

to the initiator contained a parity error.

To indicate that it intends to send the message, the initiator sets the ATN signal before it releases ACK

for the REQ/ACK handshake of the message that has the parity error. This provides an interlock so that

the drive can determine which message has the parity error. If the drive receives this message under

any other condition, it proceeds directly to the BUS FREE phase by releasing the BSY signal,

signifying a catastrophic error.

The drive’s response to this message is to switch to the MESSAGE IN phase and re-send from the

beginning all the bytes of the message that precipitated the MESSAGE PARITY ERROR message.

3.2.10 MESSAGE REJECT (07h)

The initiator or SDLT tape drive sends this message to indicate that the last message received was

illegal or has not been implemented.

To indicate its intention to send 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 drive issues the

MESSAGE REJECT message in response to any message it considers to be illegal or not supported.

The drive sends this message to the initiator before requesting any additional message bytes.

3.2.11 NO OPERATION (08h)

If the SDLT tape drive requests a message, the initiator sends a NO OPERATION message if it does

not currently have any other valid message to send. The drive ignores the NO OPERATION message.

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