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Read/Write Packet
7-9
7
DMA Scatter/Gather Table Entry
Each scatter/gather table entry has two longwords: first one is DMA memory
address, second is control/byte count.
310
|function code (3 bits)
1 = link to next entryFor example $5 is
0 = no link, last entryused here (supervisory
data space)
NOTE
S:
1. Refer to Chapter 3.
2. Refer to the following scatter/gather table format.
3. The interrupt level of this firmware can be from level 0 to 7. It should be
kept the same throughout the firmware execution; i.e., when the user has
chosen a specific interrupt level, it must not be changed until there is no
outstanding command.
4. The return vector should point to the user return routine at all times for
the proper return path.
5. Because both the interrupt vector and the return vector use the Vector
Base Register (VBR) to locate the proper address to resume the operation,
the VBR should not be changed if there are any outstanding SCSI
commands.
6. During scatter/gather operation, no automatic RETRY is performed by
SCSI firmware and the scatter/gather table contents could be modified by
the firmware when the command is completed.
DMA MEMORY ADDRESS (32-BIT)
X0000101XXXX
XXXX
XXXX
XXXX
XXXX
XXXX