LSI LSI53C1000, Technical Manual

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SCSI Registers 4-33
arbitrating for the SCSI bus. The IDs that the LSI53C1000
responds to when selected or reselected are configured
in the
Response ID Zero (RESPID0) and Response ID
One (RESPID1) registers. The priority of the 16 possible
IDs, in descending order is:
Register: 0x05
SCSI Transfer (SXFER)
Read/Write
This register is automatically loaded when a Table Indirect Select or
Reselect SCRIPTS instruction is executed.
R Reserved [7:6]
MO[5:0] Max SCSI Synchronous Offset [5:0]
These bits describe the maximum SCSI synchronous
offset used by the LSI53C1000 when transferring
synchronous SCSI data in either the initiator or target
mode.
Table 4.3 describes the possible combinations and
their relationship to the synchronous data offset used by
the LSI53C1000. These bits determine the LSI53C1000
method of transfer for ST/DT Data-In and ST/DT
Data-Out phases only; all other information transfers
occur asynchronously. Please note that the SCSI offset
for Ultra160 transfers is counted as the maximum number
of data transfers allowed to be outstanding, not the
maximum REQ pulses allowed to be outstanding.
During ST Data-In or ST Data-Out transfers the
maximum supported offset is 31 (MO[5:0] = 0x1F).
During DT Data-In or DT Data-Out transfers the
maximum supported offset is 62 (MO[5:0] = 0x3E).
Setting offset values outside the allowable range will
result in data corruption.
Highest Lowest
7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8
7 6 5 0
R MO[5:0]
0 0 0 0 0 0 0 0