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CUSTOM SCSI PACKETS
2-28
2
CT words $16 and $18: DATA LENGTH. The number of bytes to transfer
during either the data-in or the data-out phase. Not used if DMA is enabled
and SG bit is set in status/flag byte in word o.
CT words $1A and $1C: DATA POINTER. If a DATA-IN code is in the
TARGET script, the firmware starts transferring data FROM the contiguous
data buffer pointed to by this pointer. If a DATA-OUT code is in the TARGET
script, the firmware starts transferring data TO the contiguous data buffer
pointed to by this pointer. This pointer points to SG table if DMA SG is used.
CT word $1E: MESSAGE-IN LENGTH. Not used by the TARGET role
firmware for the message byte count in the message-in phase.
CT words $20 and $22: MESSAGE-IN POINTER. If a message-in code is in the
TARGET script, the firmware sends the messages from message-in buffer
where this pointer points.
CT word $24: MESSAGE-OUT LENGTH. Not used by the TARGET role
firmware.
CT words $26 and $28: MESSAGE-OUT POINTER. If the initiator that is
threaded to the MVME147 sends an extended message to the MVME147, the
firmware stores it in the message buffer that is pointed to by this pointer. (The
ATN condition is only serviced if the ATN signal is asserted during selection
or certain phases. The initial IDENTIFY message is handled internally by the
firmware for threading purposes. If the ATN condition arises during a phase
that can be serviced, the message that is received from the initiator is stored in
the buffer pointed to by this message-out pointer.)
CT word $64, even byte : TARGET role firmware SCSI status byte set by
firmware during target sequence packet execution..
The remaining bytes of the command table are reserved.
Packet word $0E=$8000:
This word classifies the custom SCSI packet as a TARGET sequence.
Packet word $14=$001C:
This word classifies the packet as a custom SCSI sequence.
Packet word $16:
The interrupt level must be non-zero because TARGET role is only supported
for interrupt mode. The vector number provides the return path for the
firmware to you.
Packet word $18: