Appendix D. Interrupt request and direct memory access
channel assignments
The following tables list the IRQ and DMA channel assignments.
IRQ System resource
NMI Critical system error
SMI System-management interrupt for power management
0 Timer
1 Keyboard
2 Cascade interrupt from slave PIC
3 COM2 (some models only)
4 COM1
5 Available to user
6 Diskette controller
7 LPT1
8 Real-time clock
9 Video, ACPI
10 Available to user
11 Available to user
12 Mouse port
13 Math coprocessor
14 Primary IDE (if present)
15 Secondary IDE (if present)
Note: The default settings for COM 1 (IRQ 4), COM 2 (IRQ 3), and LPT 1 (IRQ 7)
can be changed to another IRQ.
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
© Copyright IBM Corp. 2002 41