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Restore Pointers
(03
H )
This code is sent from the ACB-5500 to direct the Initiator to
restore the most recently saved pointers for
the particular
identified LUN to the active state.
Pointers to the COMMAND,
DATA, and STATUS locations for the LUN will be restored to the
active pointers.
COMMAND and STATUS pointers will be restored to
their value at the beginning of the present command.
The DATA
pointer shall be restored to the value at the beginning of the
command or at the value saved when the last SAVE DATA POINTER
message was executed.
Disconnect
(04
H)
This message is sent by the ACB-5500 to inform an Initiator that
the present physical path is going to be broken (the Target will
disconnect by releasing BSY), but that a later reconnect will be
required in order to complete the current operation.
By not
sending this message or the COMMAND COMPLETE message before going
to BUS FREE phase (other than as a result of reset), the Target
indicates that an error condition has occurred on the current
command.
This message does not save the DATA POINTER.
Initiator Detected Error
(05
H )
This message is from the Initiator to inform the ACB-5500 that an
Initiator-detected retryable error has occurred since the last
time the state of the DATA POINTER was saved.
Commonly, this is
for a data parity error.
The ACB-5500 will post error status
with an error code of 2D.
The message is sent from the Initiator to direct the ACB-5500 to:
o
Clear any operation for the specified LUN from the selecting
Initiator.
Only an operation for the selecting Initiator is
affected.
If no logical unit
has been selected by
the
IDENTIFY message, then only the operation in process on the
. bus will
be cleared by the Target.
o
Cause the bus to go to the BUS FREE phase.
No status or ending message shall be sent for the operation.
It
is not an error to issue this message to an LUN that is not
currently performing an operation for the Initiator.
4-14
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