OEM MANUAL:K6602924
3 SCSI BUS
Revision: 1 / Date: 2003.03.06
Page: 36 / 273
Extended Message (01
H
)
This message is sent from either the host computer or the controller as the first
byte of a multiple-byte message. ( see 3.2.3 for description of extended
messages.)
Save Data Pointer (02
H
)
This message is issued by the controller to direct the host computer to save the
copy of the current active data pointer of the currently connected logical unit.
The data to be transferred after this message will be the following part to the
data already
transferred, that is, the already transferred data won't be transferred again
after this message.
Restore Pointers (03
H
)
This message is issued by the controller to direct the host computer to restore
the last saved pointers (for the currently connected logical unit) to the active
state. This message is used to restore the pointers in case of other than a
reconnection after a disconnection.
Precautions to observe on the host computer side;
The pointers to the command to the logical unit, data, and status must be
restored to the active pointer.
The pointers to the command and status must be restored at the beginning of
the current command and status areas.
The data pointer shall be restored at the beginning of the data area if no Save
Data Pointer message has been issued and otherwise in the pointer area
indicated in the last Save Data Pointer message for the current logical unit.
Disconnect (04
H
)
This message is sent from the controller to the host computer to indicate that
the current physical path is being disconnected (the controller is about to
disconnect from the SCSI bus by releasing the BSY signal) but that a later
reconnection is required to complete the current operation.
Note : To split a long sequence of transfer data into two or more shorter blocks
of transfer data with the Disconnect message (include the cases caused
by error retries), the controller sends a Save Data Pointer message
prior to the Disconnect message.