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4-26
Registers
the arbitration sequence is complete. If a sequence is
aborted, check bit 4 in the
SCSI Control One (SCNTL1)
register to verify that the SYM53C1010 is not connected
to the SCSI bus.
WATN
Select with SATN/ on a Start Sequence
When this bit is set and the SCSI function is in the
initiator mode, the SATN/ signal is asserted during
selection of a SCSI target device. This is to inform the
target that the SYM53C1010 SCSI function has a
message to send. If a selection time-out occurs while
attempting to select a target device, SATN/ is deasserted
at the same time SSEL/ is deasserted. When this bit is
cleared, the SATN/ signal is not asserted during
selection. When executing SCSI SCRIPTS, this bit is
controlled by the SCRIPTS processor, but manual setting
is possible in the low level mode.
4
EPC
Enable Parity/CRC/AIP Checking
When this bit is set and the SCSI transfers are
asynchronous or ST synchronous, the SCSI data bus is
checked for odd parity when data is received from the
SCSI bus in either the initiator or the target mode. If a
parity error is detected, bit 0 of the
SCSI Interrupt Status
Zero (SIST0)
register is set and an interrupt may be
generated.
3
When this bit is set SCSI transfers are DT synchronous,
the CRC is checked when the target requests a CRC
transfer using the DP0 signal on the SCSI bus. If a CRC
error is detected, bit 0 of the
SCSI Interrupt Status Zero
(SIST0)
register is set and an interrupt may be
generated.
If the SYM53C1010 SCSI function is operating in the
initiator mode and a parity error or CRC error is detected,
SATN/ can optionally be asserted, but the transfer
continues until the target changes phase or the block
move in which the parity error was detected completes.
When this bit is clear, parity and CRC errors are not
reported.
CRCRP
CRC Request Pending
When this bit is set, the SYM53C1010 SCSI function has
an outstanding CRC request pending. When this bit is set
and the SYM53C1010 is in target mode, a Block Move of
2