Reference Manual

PMAC 2 Software Reference

PMAC I-Variable Specification 41

I56 DPRAM ASCII Communications Interrupt Enable

Range

0 .. 1

Units

none

Default

Remarks

I56 enables or disables the interrupt feature for the dual-ported RAM (DPRAM) ASCII

communications function that is enabled with I58=1. When I56=1, PMAC will generate

an interrupt to the host computer each time it loads a line into the DPRAM ASCII buffer

for the host to read. When I56=0, it will not generate this interrupt.

For PMAC(1)-PC, PMAC(1)-Lite, PMAC(1)-PCI, and PMAC(1)-PCI-Lite, the interrupt

line used is the EQU4 interrupt. For this to reach the host, the E55 jumper must be ON,

and E54, E56, and E57 must be OFF (E54 and E56 do not exist on PMAC-Lite). When

using this feature, do not use the EQU4 line for any other purpose, including position

compare.

For the regular (non-Ultralite) ISA-bus and PCI-bus versions of PMAC2 (PMAC2-PC,

PMAC2-Lite, Mini-PMAC2, PMAC2-PCI, PMAC2-PCI-Lite), the interrupt line used is

the EQU1 interrupt. When using this feature, do not use the EQU1 line for any other

purpose, including position compare.

For the PMAC2-PC Ultralite and PMAC2-PCI Ultralite, the interrupt line used is the

CTRL0 line, which has no other functions.

For the VME-bus versions (PMAC(1)-VME, PMAC2-VME, PMAC2-VME Ultralite), the

interrupt line used is the normal communications interrupt (the only interrupt available).

This line – IRQn on the VME bus, is determined by the VME setup value in register

X:$0788. The interrupt vector provided to the host is one greater than the value in setup

will provide an interrupt vector of $A2.