Avago Technologies LSI53C876E - Manual (Page 120)

4-26 Registers
LSI53C876 SCSI function may transfer up to three
additional bytes before halting to synchronize between
internal core cells. During synchronous operation, the
LSI53C876 SCSI function transfers data until there are
no outstanding synchronous offsets. If the LSI53C876
SCSI function is receiving data, any data residing in the
DMA FIFO is sent to memory before halting.
When this bit is set, the LSI53C876 SCSI function does
not halt the SCSI transfer when SATN/ or a parity error is
received.
CON Connected 4
This bit is automatically set any time the LSI53C876
SCSI function is connected to the SCSI bus as an initiator
or as a target. It is set after the LSI53C876 SCSI function
successfully completes arbitration or when it has
responded to a bus initiated selection or reselection. This
bit is also set after the chip wins simple arbitration when
operating in low level mode. When this bit is cleared, the
LSI53C876 SCSI function is not connected to the SCSI
bus.
The CPU can force a connected or disconnected
condition by setting or clearing this bit. This feature is
used primarily during loopback mode.
RST Assert SCSI RST/ Signal 3
Setting this bit asserts the SRST/ signal. The SRST/
output remains asserted until this bit is cleared. The
25
µ
s minimum assertion time defined in the SCSI
specification must be timed out by the controlling
microprocessor or a SCRIPTS loop.
AESP Assert Even SCSI Parity (force bad parity) 2
When this bit is set, the LSI53C876 SCSI function
asserts even parity. It forces a SCSI parity error on each
byte sent to the SCSI bus from the chip. If parity checking
is enabled, then the LSI53C876 SCSI function checks
data received for odd parity. This bit is used for diagnostic
testing and is cleared for normal operation. It is useful to
generate parity errors to test error handling functions.
IARB Immediate Arbitration 1
Setting this bit causes the SCSI core to immediately
begin arbitration once a Bus Free phase is detected