I/O interrupt subclasses

An input/output (I/O) interrupt subclass is specified for a symbolic device address (SDA) when you use the MSDAC macro to mount the SDA.

Control register 6 contains I/O interrupt subclass masks. The z/TPF system uses the subclass masks to enable I/O interrupts for different types of devices on various I-streams.

The following table describes I/O interrupt subclass usage.

Table 1. I/O interrupt subclass usage
Subclass Enabled on I-stream Usage
0 I-stream 1
  • Tape
  • SNA
  • Unit record
  • Multi-processor interconnect facility (MPIF), if there is only 1 I-stream
1 I-stream 2 MPIF, if there are 2 or more I-streams
2   Not used
3 As many as 4 I-streams.

Subclass 3, 4, 5, and 6 are enabled across in-use I-streams on a round-robin basis.

DASD
4 As many as 4 I-streams.

Subclass 3, 4, 5, and 6 are enabled across in-use I-streams on a round-robin basis.

DASD
5 As many as 4 I-streams.

Subclass 3, 4, 5, and 6 are enabled across in-use I-streams on a round-robin basis.

DASD
6 As many as 4 I-streams.

Subclass 3, 4, 5, and 6 are enabled across in-use I-streams on a round-robin basis.

DASD
7 As many as 4 I-streams.

This subclass is enabled on the first 4 I-streams

 OSA