Specifications

System Macros Invoked by Drivers
SPI$SENSE_PHASE
SPI$SENSE_PHASE
Returns the current phase of the SCSI bus.
Format
SPI$SENSE_PHASE
Description
The SPI$SENSE_PHASE macro allows the host to read the current SCSI bus
phase, and the state of the ATN signal, while using the asynchronous event
notification feature.
A class driver must supply the address of the SPDT in R4 as input to the
SPI$SENSE_PHASE macro.
The port driver returns the following values to the class driver, destroying R2,
and preserving all other registers:
Location Contents
R0 SS$_NORMAL.
R1 SCSI bus phase (and ATN signal). This SCSI-defined
longword has the format illustrated in Figure 2–1.
Figure 2–1 SCSI Bus Phase Longword Returned to SPI$SENSE_PHASE
ZK−1377A−GE
0 MSG C/D I/O
31 3 2 1 0
ATN
30
2–90