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)
DMA channel
0
1
2
3
4
5
6
7
© Copyright IBM Corp. 2002
can be changed to another IRQ.
Data width
8 bits
8 bits
8 bits
8 bits
16 bits
16 bits
16 bits
System resource
Open
Open
Diskette drive
Parallel port (for ECP or EPP)
Reserved (cascade channel)
Open
Open
Open
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