
Operating Registers
5-44
SYM53C810A Data Manual
Register 4C (CC)
SCSI Test Zero (ST EST 0)
Read Only
Bit 7
Reserved
Bits 6-4 SSAID (SCSI Selected As ID)
T hese bits contain the encoded value of the
SCSI ID that the SYM53C810A was selected
or reselected as during a SCSI selection or
reselection phase. T hese bits are read only and
contain the encoded value of 0-7 possible IDs
that could be used to select the
SYM53C810A. During a SCSI selection or
reselection phase when a valid ID has been put
on the bus, and the 53C810A responds to that
ID, the “selected as” ID is written into these
bits.
Bit 3
SLT (Selection response logic test)
T his bit is set when the SYM53C810A is ready
to be selected or reselected. T his does not take
into account the bus settle delay of 400 ns.
T his bit is used for functional test and fault
purposes.
Bit 2
ART (Arbitration Priority E ncoder
Test)
T his bit will always be set when the
SYM53C810A exhibits the highest priority ID
asserted on the SCSI bus during arbitration. It
is primarily used for chip level testing, but it
may be used during low level mode operation
to determine if the SYM53C810A has won
arbitration.
Bit 1
SOZ (SCSI Synchronous Offset
Zero)
T his bit indicates that the current synchronous
SREQ/SACK offset is zero. T his bit is not
latched and may change at any time. It is used
in low level synchronous SCSI operations.
When this bit is set, the SYM53C810A, as an
initiator, is waiting for the target to request
data transfers. If the SYM53C810A is a target,
then the initiator has sent the offset number of
acknowledges.
Bit 0
SOM (SCSI Synchronous Offset
Maximum)
T his bit indicates that the current synchronous
SREQ/SACK offset is the maximum specified
by bits 3-0 in the SCSI Transfer register. T his
bit is not latched and may change at any time.
It is used in low level synchronous SCSI opera-
tions. When this bit is set, the SYM53C810A,
as a target, is waiting for the initiator to
acknowledge the data transfers. If the
SYM53C810A is an initiator, then the target
has sent the offset number of requests.
RES
SSAID
2
6
SSAID
1
5
SSAID
0
4
SLT
ART
SOZ
SOM
7
3
2
1
0
Default>>>
X
X
X
X
0
X
1
1