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Programmer's Reference Manual

 

Interrupts


Introduction and Overview

The new IOMD or ARM 7500 chips used under RISC OS 3.5 and 3.6 use new device numbers (see Device numbers). These are:

0 Printer interrupt from controller
1 Unused
2 Floppy disc Index
3 VSync Pulse
4 Power on reset - this should never appear in normal use
5 IOC Timer 0
6 IOC Timer 1
7 FIQ Downgrade - reserved for the use of the current owner of FIQ
8 Expansion card FIQ Downgrade - this should normally be masked off
9 IDE hard disc interrupt
10 Serial port interrupt from controller - also mapped to FIQ device 4
11 Network card interrupt
12 Floppy disc interrupt from controller
13 Expansion card interrupt
14 Keyboard serial transmit register empty
15 Keyboard serial receive register full
16 DMA channel 0
17 DMA channel 1
18 DMA channel 2
19 DMA channel 3
20 DMA sound channel 0
21 DMA sound channel 1
22 ARM 7500 mouse port receive register full
23 ARM 7500 mouse port transmit register empty
24 ARM 7500 joystick A-to-D completion
25 ARM 7500 event 1
26 ARM 7500 event 2

Note that device numbers 22 - 26 are available with an ARM 7500, but not with an IOMD.

This edition Copyright © 3QD Developments Ltd 2015
Last Edit: Tue,03 Nov 2015