LSI LSI53C895A, Technical Manual

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SCSI Registers 4-49
1. Set this bit.
2. Wait for an interrupt.
3. Read the Interrupt Status Zero (ISTAT0) and
Interrupt Status One (ISTAT1) registers.
4. If the SCSI Interrupt Pending bit is set, then read the
SCSI Interrupt Status Zero (SIST0) or SCSI Interrupt
Status One (SIST1) register to determine the cause
of the SCSI Interrupt and go back to Step 2.
5. If the SCSI Interrupt Pending bit is clear, and the
DMA Interrupt Pending bit is set, then write 0x00
value to this register.
6. Read the DMA Status (DSTAT) register to verify the
aborted interrupt and to see if any other interrupting
conditions have occurred.
SRST Software Reset 6
Setting this bit resets the LSI53C895A. All operating
registers are cleared to their respective default values
and all SCSI signals are deasserted. Setting this bit does
not assert the SCSI RST/ signal. This reset does not
clear the ID Mode bit or any of the PCI configuration
registers. This bit is not self-clearing; it must be cleared
to clear the reset condition (a hardware reset also clears
this bit).
SIGP Signal Process 5
SIGP is a R/W bit that is writable at any time, and polled
and reset using
Chip Test Two (CTEST2) . The SIGP bit
is used in various ways to pass a flag to or from a running
SCRIPTS instruction.
The only SCRIPTS instruction directly affected by the
SIGP bit is Wait for Selection/Reselection. Setting this bit
causes that instruction to jump to the alternate address
immediately. The instructions at the alternate jump
address should check the status of SIGP to determine
the cause of the jump. The SIGP bit is usable at any time
and is not restricted to the wait for selection/reselection
condition.