LSI LSI53C896, Technical Manual

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4-28 Registers
byte boundary, the LSI53C896 SCSI function stores the
last byte in the
SCSI Wide Residue (SWIDE) register
during a receive operation, or in the SCSI Output Data
Latch (SODL) register during a send operation. This byte
is combined with the first byte from the subsequent
transfer so that a wide transfer is completed.
SLPMD SLPAR Mode 5
If this bit is cleared, the SCSI Longitudinal Parity (SLPAR)
register functions as a byte-wide longitudinal parity
register. If this bit is set, the SLPAR functions as a
word-wide longitudinal parity function. The high or low
byte of the SLPAR word is accessible through the SLPAR
register. Which byte is accessible is controlled by the
SLPHBEN bit.
SLPHBEN SLPAR High Byte Enable 4
If this bit is cleared, the low byte of the SLPAR word is
accessible through the
SCSI Longitudinal Parity (SLPAR)
register. If this bit is set, the high byte of the SLPAR word
is present in the SLPAR register.
WSS Wide SCSI Send 3
When read, this bit returns the value of the Wide SCSI
Send (WSS) flag. Asserting this bit clears the WSS flag.
This clearing function is self-clearing.
When the WSS flag is HIGH following a wide SCSI send
operation, the SCSI core is holding a byte of “chain” data
in the
SCSI Output Data Latch (SODL) register. This data
becomes the first low-order byte sent when married with
a high-order byte during a subsequent data send transfer.
Performing a SCSI receive operation clears this bit. Also,
performing any nonwide transfer clears this bit.
VUE0 Vendor Unique Enhancements, Bit 0 2
This bit is a read only value indicating whether the group
code field in the SCSI instruction is standard or vendor
unique. If cleared, the bit indicates standard group codes;
if set, the bit indicates vendor unique group codes. The
value in this bit is reloaded at the beginning of all
asynchronous target receives.
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