Avago Technologies LSI8751D - Manual (Page 177)

5-61
A one in any bit position of the final SLPAR value would indicate a
transmission error.
The SCSI Longitudinal Parity (SLPAR) register is also used to generate
the check bytes for SCSI send operations. If the SCSI Longitudinal Parity
(SLPAR) register contains all zeros prior to sending a block move, it
contains the appropriate check byte at the end of the block move. This
byte must then be sent across the SCSI bus.
Note: Writing any value to this register resets it to zero.
The longitudinal parity checks are meant to provide an added measure
of SCSI data integrity and are entirely optional. This register does not
latch SCSI selection/reselection IDs under any circumstances. The
default value of this register is zero.
Register: 0x45 (0xC5)
SCSI Wide Residue (SWIDE)
Read/Write
SWIDE SCSI Wide Residue [7:0]
After a wide SCSI data receive operation, this register
contains a residual data byte if the last byte received was
never sent across the DMA bus. It represents either the
first data byte of a subsequent data transfer, or it is a
residue byte which should be cleared when an Ignore
Data Bytes Running SLPAR
– 00000000
1. 11001100 11001100 (XOR of word 1)
2. 01010101 10011001 (XOR of word 1 and 2)
3. 00001111 10010110 (XOR of word 1, 2 and 3) Even Parity
4. 10010110 00000000
7 0
SWIDE
x x x x x x x x