LSI LSI53C1000, Technical Manual

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SCSI Functional Description 2-25
Note: For DT mode or when the Protocol Options field is nonzero,
the Transfer Width Exponent must be one indicating a SCSI
width of 16 bits.
Note: The Table Indirect data (used during selection/reselection)
must be updated to enable certain control bits in the
SCNTL4 register. Specific bits to look at include: bit 7,
U3EN (Ultra160 Transfer Enable); bit 6, AIPEN
(Asynchronous Information Protection Enable); and
bits [3:0] (Extra Clock Setup/Hold).
Protocol Options (Byte 7) – A bus or device reset, power cycle, or
change between LVD/SE modes invalidates these settings. A
renegotiation resets the Protocol Options.
2.2.5.3 Asynchronous Information Protection (AIP)
The AIP feature provides error checking for asynchronous, nondata
phases through BCH encoding. During the command, status, message
in/out phases, the BCH code is transferred on the upper SCSI data bus.
For details on the BCH code, see T10 119 document "Protection for the
Asynchronous Phases".
QAS_REQ DT_REQ IU_REQ Description
0 0 0 Use ST Data-In and ST Data-Out phase
to transfer data
0 1 0 Use DT Data-In and DT Data-Out phase
to transfer data with CRC
0 1 1 Use DT Data-In and DT Data-Out phase
to transfer data with information units
1 1 0 Use DT Data-In and DT Data-Out phase
to transfer data with CRC and use the
QAS method for arbitration
1 1 1 Use DT Data-In and DT Data-Out phase
to transfer data with information units and
use the QAS method for arbitration