www.riscos.com Technical Support: 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.