the SCRIPTS processor is still executing a SCRIPTS program. If this bit is set when the Interrupt Status Zero (ISTAT0) or Interrupt Status One (ISTAT1) registers are read they are not automatically cleared. To clear this bit, write it to a one. The reset operation is self-clearing.

Note: If the INTF bit is set but SIP or DIP are not set, do not attempt to read the other chip status registers. An Interrupt-on-the-Fly interrupt must be cleared before servicing any other interrupts indicated by SIP or DIP.

This bit must be written to one in order to clear it after it has been set.

SIPSCSI Interrupt Pending1

This status bit is set when an interrupt condition is detected in the SCSI portion of the LSI53C875A. The following conditions cause a SCSI interrupt to occur:

A phase mismatch (initiator mode) or SATN/ becomes active (target mode)

An arbitration sequence completes

A selection or reselection time-out occurs

The LSI53C875A is selected

The LSI53C875A is reselected

A SCSI gross error occurs

An unexpected disconnect occurs

A SCSI reset occurs

A parity error is detected

The handshake-to-handshake timer is expired

The general purpose timer is expired

To determine exactly which condition(s) caused the interrupt, read the SCSI Interrupt Status Zero (SIST0) and SCSI Interrupt Status One (SIST1) registers.

DIPDMA Interrupt Pending0

This status bit is set when an interrupt condition is detected in the DMA portion of the LSI53C875A. The following conditions cause a DMA interrupt:

A PCI parity error is detected

4-50Registers

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LSI 53C875A technical manual Sipscsi Interrupt Pending1, Dipdma Interrupt Pending0