LSI LSI53C895A, Technical Manual

Page: 185 / 364

SCSI Registers 4-77
R Reserved 3
STO Selection or Reselection Time-out 2
The SCSI device which the LSI53C895A is attempting to
select or reselect does not respond within the
programmed time-out period. See the description of the
SCSI Timer Zero (STIME0) register bits [3:0] for more
information on the time-out timer.
GEN General Purpose Timer Expired 1
The general purpose timer is expired. The time measured
is the time between enabling and disabling of the timer.
See the description of the
SCSI Timer One (STIME1)
register, bits [3:0], for more information on the general
purpose timer.
HTH Handshake-to-Handshake Timer Expired 0
The handshake-to-handshake timer is expired. The time
measured is the SCSI Request-to-Request (target) or
Acknowledge-to-Acknowledge (initiator) period. See the
description of the
SCSI Timer Zero (STIME0) register,
bits [7:4], for more information on the handshake-
to-handshake timer.
Register: 0x42
SCSI Interrupt Status Zero (SIST0)
Read Only
Reading the SIST0 register returns the status of the various interrupt
conditions, whether they are enabled in the
SCSI Interrupt Enable Zero
(SIEN0) register or not. Each bit set indicates occurrence of the
corresponding condition. Reading the SIST0 clears the interrupt status.
Reading this register clears any bits that are set at the time the register
is read, but does not necessarily clear the register because additional
interrupts may be pending (the LSI53C895A stacks interrupts). SCSI
interrupt conditions are individually masked through the
SCSI Interrupt
Enable Zero (SIEN0) register.
7 6 5 4 3 2 1 0
M/A CMP SEL RSL SGE UDC RST PAR
0 0 0 0 0 0 0 0