2.5.3
Interrupt assignments
Standard interrupt assignments
* These IRQs are usually available for PCI devices.
IRQ
Priority Standard function
0
1
System Timer
1
2
Keyboard Controller
2
–
Redirect to IRQ#9
4
12
Communications Port (COM1)*
5
13
IRQ Holder for PCI Steering*
6
14
Floppy Disk Controller
7
15
Reserved
8
3
System CMOS/Real Time Clock
9
4
IRQ Holder for PCI Steering*
10
5
IRQ Holder for PCI Steering*
11
6
IRQ Holder for PCI Steering*
12
7
Reserved
13
8
Numeric Data Processor
14
9
Primary IDE Channel
ICH
A
B
C
D
E
F
G
H
LAN1 (8111C)
–
shared
–
–
–
–
–
–
LAN2 (8111C)
–
–
shared
–
–
–
–
–
Marvell 6121
–
–
–
shared
–
–
–
–
Marvell SAS
shared
–
–
–
–
–
–
–
PCI_1
shared
–
–
–
–
–
–
–
PCI-X_1
–
shared
–
–
–
–
–
–
PCI-X_2
–
–
shared
–
–
–
–
–
PCIE1_1
shared
–
–
–
–
–
–
–
USB controller 1
–
–
–
–
–
–
–
shared
USB controller 2
–
–
–
shared
–
–
–
–
USB controller 3
–
–
shared
–
–
–
–
–
USB controller 4
shared
–
–
–
–
–
–
–
USB controller 5
–
–
–
–
–
shared
–
–
USB controller 6
–
–
–
shared
–
–
–
–
USB 2.0 controller 1
–
–
–
–
–
–
–
shared
USB 2.0 controller 2
–
–
shared
–
–
–
–
–
SATA controller 1
–
–
–
–
shared
–
–
–
SATA controller 2
–
–
–
–
shared
–
–
–
Audio Azalia
–
–
–
–
–
–
shared
–
IRQ assignments for this motherboard
IOH
24
25
26
27
28
29
30
31
PCIE16_1
shared
–
–
–
–
–
–
–
PCIE16_2
–
–
–
–
–
–
shared
–
2-18
Chapter 2: Hardware information