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Messages

4-10 Quantum DLT 8000 Tape System

4.2.8 LINKED COMMAND COMPLETE Message (0Ah)

This message is sent from a target to an initiator to indicate that the execution of a

linked command (with the FLAG bit set to zero) is complete and that status has been

sent. The initiator then sets the pointers to the initial state for the next command.

If received by a target, this message is handled as an illegal message; the drive enters the

MESSAGE IN phase and returns MESSAGE REJECT.

4.2.9 LINKED COMMAND COMPLETE, with Flag Message (0Bh)

This message is sent from a target to an initiator to indicate that the execution of a

linked command (with the FLAG bit set to one) is complete and that status has been

sent.

4.2.10 MESSAGE PARITY ERROR Message (09h)

This message is sent from the initiator to tell the drive that the last message byte the

drive passed on 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 target can determine which message has the parity

error. If the target receives this message under any other condition, it proceeds directly

to the BUS FREE state by releasing the BSY signal, signifying a catastrophic error.

The target’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.

4.2.11 MESSAGE REJECT Message (07h)

This message is sent from the initiator or target to indicate that the last message

received was inappropriate 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.

MESSAGE REJECT is issued in response to any message the drive considers to be illegal

or not supported. When sending to the initiator, the tape drive does so before requesting

any additional message bytes.

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Quantum DLT 8000 Manual Página 140