LSI 53C875A User Manual
Page 166
4-74
Registers
CMP
Function Complete
6
Indicates full arbitration and selection sequence is
completed.
SEL
Selected
5
Indicates the LSI53C875A is selected by a SCSI initiator
device. Set the Enable Response to Selection bit in the
register for this to occur.
RSL
Reselected
4
Indicates the LSI53C875A is reselected by a SCSI target
device. Set the Enable Response to Reselection bit in the
register for this to occur.
SGE
SCSI Gross Error
3
The following conditions are considered SCSI Gross
Errors:
•
Data underflow – reading the SCSI FIFO when no
data is present.
•
Data overflow – writing to the SCSI FIFO while it is
full.
•
Offset underflow – receiving a SACK/ pulse in target
mode before the corresponding SREQ/ is sent.
•
Offset overflow – receiving an SREQ/ pulse in the
initiator mode, and exceeding the maximum offset
(defined by the MO[3:0] bits in the
register).
•
A phase change in the initiator mode, with an
outstanding SREQ/SACK/ offset.
•
Residual data in SCSI FIFO – starting a transfer other
than synchronous data receive with data left in the
SCSI synchronous receive FIFO.
UDC
Unexpected Disconnect
2
This condition only occurs in the initiator mode. It
happens when the target to which the LSI53C875A is
connected disconnects from the SCSI bus unexpectedly.
See the SCSI Disconnect Unexpected bit in the
register for more information on
expected versus unexpected disconnects. Any
disconnect in low level mode causes this condition.