Scsi status one (sstat1), Register: 0x0e – LSI 53C875A User Manual
Page 135
SCSI Registers
4-43
AIP
Arbitration in Progress
4
Arbitration in Progress (AIP = 1) indicates that the
LSI53C875A has detected a Bus Free condition, asserted
SBSY, and asserted its SCSI ID onto the SCSI bus.
LOA
Lost Arbitration
3
When set, LOA indicates that the LSI53C875A has
detected a bus free condition, arbitrated for the SCSI bus,
and lost arbitration due to another SCSI device asserting
the SSEL/ signal.
WOA
Won Arbitration
2
When set, WOA indicates that the LSI53C875A has
detected a Bus Free condition, arbitrated for the SCSI
bus and won arbitration. The arbitration mode selected in
the
register must be full
arbitration and selection to set this bit.
RST
SCSI RST/ Signal
1
This bit reports the current status of the SCSI RST/
signal, and the SRST signal (bit 6) in the
register. This bit is not latched and may
change as it is read.
SDP0
SCSI SDP0/ Parity Signal
0
This bit represents the active HIGH current status of the
SCSI SDP0/ parity signal. This signal is not latched and
may change as it is read.
Register: 0x0E
SCSI Status One (SSTAT1)
Read Only
FF[3:0]
FIFO Flags
[7:4]
These four bits, along with
bit 4, define the number of bytes or words that currently
reside in the LSI53C875A’s SCSI synchronous data FIFO
as shown in
. These bits are not latched and
they will change as data moves through the FIFO. The
SCSI FIFO can hold up to 31 bytes for narrow SCSI
7
4
3
2
1
0
FF[3:0]
SDP0L
MSG
C_D
I_O
0
0
0
0
x
x
x
x