LSI 53C810A - Manual (Page 98)

5-24 Operating Registers
Register: 0x0E (0x8E)
SCSI Status One (SSTAT1)
Read Only
FF[3:0] FIFO Flags [7:4]
These four bits define the number of bytes that currently
reside in the LSI53C810A’s SCSI synchronous data
FIFO. These bits are not latched and they will change as
data moves through the FIFO. The FIFO can hold up to
9 bytes. Values over nine will not occur.
[
SDPL Latched SCSI Parity 3
This bit reflects the SCSI parity signal (SDP/),
corresponding to the data latched in the
SCSI Input Data
Latch (SIDL) . It changes when a new byte is latched into
the SCSI Input Data Latch (SIDL) register. This bit is
active high, in other words, it is set when the parity signal
is active.
7 4 3 2 1 0
FF[3:0] SDPL MSG C/D I/O
0 0 0 0 x x x x
FF3 FF2 FF1 FF0
Bytes or Words in
the SCSI FIFO
0 0 0 0 0
0 0 0 1 1
0 0 1 0 2
0 0 1 1 3
0 1 0 0 4
0 1 0 1 5
0 1 1 0 6
0 1 1 1 7
1 0 0 0 8
1 0 0 1 9