Message Explanation; Task Complete Message: X'00'(T I); Save Data Pointer Message: X'02'(T I); Restore Pointers Message: X'03' (T 1) - Fujitsu MAN3184 SERIES Specifications

2.3

Message Explanation

This section explains the function of each message. The following symbols are used for message
identification.
Symbols:
(I T): The message which can be sent from the INIT to the TARG only.
(T I): The message which can be sent from the TARG to the INIT only.
(I T): The message which can be sent between the INIT and TARG in any direction.
2.3.1

TASK COMPLETE message: X'00'(T I)

The TASK COMPLETE message indicates that an unlinked command or a series of linked
commands have been executed and that a valid status information has been posted to the INIT.
This message notifies the INIT the validity of status information but the command may or may not
have been executed normally. The command completion status is indicated by the status byte
which is sent in the STATUS phase prior to this message.
When the TARG sends the status byte to the INIT, the TARG always sends this message after the
STATUS phase even if the normal command (CDB) transfer has failed (due to a parity error of
SCSI data bus in MESSAGE OUT or COMMAND phase).
When the TARG completes normal message transfer, it enters the BUS FREE phase. The TARG
determines that the message transfer has completed normally if the ATN signal is false when the
ACK signal becomes false.
2.3.2

SAVE DATA POINTER message: X'02'(T I)

The SAVE DATA POINTER message requests the INIT to save the current data pointer. When
receiving this message, the INIT stores the value of current data pointer into the Saved pointer for
the currently connected LUN. For the disconnection message, see Section 2.3.3.
2.3.3

RESTORE POINTERS message: X'03' (T 1)

The RESTORE POINTERS message requests the INIT to restore the current SCSI pointers. If this
message is received, the INIT restores the value of Current SCSI pointers with the value of the
Saved pointers for the corresponding I/O process. For the SCSI Pointers, see Section 2.2.
2.3.4

DISCONNECT message: X'04' (T I)

The DISCONNECT message informs to the INIT that the TARG disconnects the SCSI bus
temporary. After the TARG has sent this message, it enters the BUS FREE phase and the
disconnection completes. The TARG determines that the message transfer has completed normally
if the ATN signal is false when the ACK signal becomes false.
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