5-6 Operating Registers
Register: 0x01 (0x81)SCSI Control One (SCNTL1)
Read/Write
EXC Extra Clock Cycle of Data Setup 7
When this bit is set, an extra clock period of data setup
is added to each SCSI data transfer.The extra data setup
timecan provide additional system design margin, though
it affectsthe SCSI transfer rates. Clearing this bit disables
the extra clock cycle of data setup time. Setting this bit
only affects SCSI send operations.
ADB Assert SCSI Data Bus 6
When this bit is set, the LSI53C810A drives the contents
of the SCSI Output Data Latch (SODL) register onto the
SCSI data bus. When the LSI53C810A is an initiator,the
SCSI I/O signal must be inactive to assert the SCSI Out-
put Data Latch (SODL) contents onto the SCSI bus.
When the LSI53C810A is a target, the SCSI I/O signal
must be active to assert the SCSI Output Data Latch
(SODL) contents onto the SCSI bus. The contents of the
SCSI Output Data Latch (SODL) register can be asserted
at any time,even before the LSI53C810A is connected to
the SCSI bus. Clear this bit when executing SCSI
SCRIPTS. It is normally used only for diagnostics testing
or operation in low level mode.
DHP Disable Halt on Parity Erroror ATN (Target Only) 5
The DHP bit is only deļ¬ned for target mode. When this
bit is cleared, the LSI53C810A halts the SCSI data
transfer when a parity error is detected or when the
SATN/signal is asser ted. If SATN/or a parity error is
receivedin the middle of a data transfer, the LSI53C810A
may transferup to three additional bytes before halting to
synchronize between internal core cells. During
synchronous operation, the LSI53C810A transfers data
until there are no outstanding synchronous offsets. If the
LSI53C810A is receiving data, any data residing in the
DMA FIFO is sent to memory before halting.
76543210
EXC ADB DHP CON RST AESP IARB SST
00000000