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System Specifications C-9
Interrupt Requests (IRQs)
Interrupt Assignments
IRQ
NORMAL ASSIGNMENT
NMI
I/O channel check
0
Reserved, interval timer
1
Reserved, keyboard buffer
2
Reserved, cascade interrupt from slave PIC
3
COM2*
4
COM1*
5
LPT2 (Plug and Play option) / audio /user
available
6
Floppy Drive
7
Parallel Port 1 (LPT1)*
8
Real time clock
9
User available
10*
User available / USB
11*
Windows Sound System*/user available
12
On-board mouse port if mouse is present; else is
user available
13
Reserved, math coprocessor
14
Primary IDE channel
15
Secondary IDE channel or else user-available
*Default, but can be changed to another IRQ