
Operating Registers
5-24
SYM53C810A Data Manual
Bit 2
T E OP (SCSI true end of process)
T his bit indicates the status of the
SYM53C810A’s internal T EOP signal. T he
T EOP signal acknowledges the completion of
a transfer through the SCSI portion of the
SYM53C810A. When this bit is set, T EOP is
active. When this bit is clear, T EOP is inactive.
Bit 1
DRE Q (Data request status)
T his bit indicates the status of the
SYM53C810A’s internal Data Request signal
(DREQ). When this bit is set, DREQ is active.
When this bit is clear, DREQ is inactive.
Bit 0
DACK (Data acknowledge status)
T his bit indicates the status of the
SYM53C810A’s internal Data Acknowledge
signal (DACK /). When this bit is set, DACK / is
inactive. When this bit is clear, DACK / is
active.
Register 1B (9B)
Chip Test T hree (CT EST 3)
Read/Write
Bits 7-4 V3-V0 (Chip revision level)
T hese bits identify the chip revision level for
software purposes.
Bit 3
FLF (Flush DMA FIFO)
When this bit is set, data residing in the DMA
FIFO is transferred to memory, starting at the
address in the DNAD register. T he internal
DMAWR signal, controlled by the CT EST 5
register, determines the direction of the trans-
fer. T his bit is not self clearing; once the
SYM53C810A has successfully transferred
the data, this bit should be reset.
Note: polling of FIFO flags is allowed during
flush operations.
Bit 2
CLF (Clear DMA FIFO)
When this bit is set, all data pointers for the
DMA FIFO are cleared. Any data in the FIFO
is lost. T his bit automatically resets after the
SYM53C810A has successfully cleared the
appropriate FIFO pointers and registers.
Note: this bit does not clear the data visible at the
bottom of the FIFO.
Bit 1
FM (Fetch pin mode)
When set, this bit causes the FET CH/ pin to
deassert during indirect and table indirect read
operations. FET CH/ will only be active during
the op code portion of an instruction fetch.
T his allows SCRIPT S to be stored in a PROM
while data tables are stored in RAM.
If this bit is not set, FET CH/ will be asserted
for all bus cycles during instruction fetches.
V3
7
V2
6
V1
5
V0
4
FLF
3
CLF
2
FM
1
WRIE
0
Default>>>
X
X
X
X
0
0
0
0