Appendix C. IRQ and DMA channel assignments

Appendix C. IRQ and DMA channel assignments

The following figures list the interrupt request (IRQ) and direct memory access (DMA) assignments.

Figure

38. IRQ channel assignments

 

 

 

 

 

 

 

IRQ

 

System

resource

 

 

 

 

 

 

 

 

NMI

 

Critical

system

error

 

 

 

SMI

 

System management interrupt — power management

 

 

 

 

 

0

 

Reserved

(interval

timer)

 

 

 

 

1

 

Reserved

(keyboard)

 

 

 

 

 

2

 

Reserved,

cascade

interrupt from slave PIC

 

 

 

 

 

 

 

 

 

3

 

COM2

3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4

 

COM1

3

 

 

 

 

 

 

 

 

 

 

5

 

LPT2/audio

(if

present)

 

 

 

 

 

 

6

 

Diskette

 

controller

 

 

 

 

 

 

 

 

 

 

7

 

LPT1

3

 

 

 

 

 

 

 

 

 

 

 

8

 

Real-time

clock

 

 

 

 

 

 

 

 

 

 

9

 

Video

 

 

 

 

 

 

 

 

 

 

 

 

10

 

Available

 

to

user

 

 

 

 

 

 

 

 

11

 

Available

 

to

user

 

 

 

 

 

 

 

 

12

 

Mouse

port

 

 

 

 

 

 

 

 

13

 

Reserved

(math

coprocessor)

 

 

 

 

 

14

 

Primary

IDE

(if present)

 

 

 

 

 

 

15

 

Secondary

IDE

(if

present)

 

 

 

 

 

 

 

 

 

Figure

39. DMA channel assignments

 

 

 

 

 

 

DMA channel

 

Data width

System resource

 

 

 

 

 

 

0

 

8

bits

Open

 

 

 

 

 

 

 

1

 

8

bits

Open

 

 

 

 

 

 

 

2

 

8

bits

Diskette

drive

 

 

 

 

 

3

 

8

bits

Parallel port (for ECP or EPP)

 

 

 

 

 

 

4

 

 

Reserved

(cascade channel)

 

 

 

 

 

 

5

 

16

bits

Open

 

 

 

 

 

 

 

6

 

16

bits

Open

 

 

 

 

 

 

 

7

 

16

bits

Open

 

 

 

 

 

 

 

3 Default, can be changed to another IRQ.

40

Copyright IBM Corp. September 1999

Page 48
Image 48
IBM PC 300PL manual Appendix C. IRQ and DMA channel assignments, IRQ channel assignments, Data width System resource