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3. HARDWARE SETUP
3.7.2 Assigning IRQs for Expansion Cards
Some expansion cards need an IRQ to operate. Generally, an IRQ must be exclu-
sively assigned to one use. In a standard design, there are 16 IRQs available but
most of them are already in use, leaving 6 IRQs free for expansion cards. If your
motherboard has PCI audio onboard, an additional IRQ will be used. If your moth-
erboard also has MIDI enabled, another IRQ will be used, leaving 4 IRQs free.
The following table lists the default IRQ assignments for standard PC devices. Use
this table when configuring your system and for resolving IRQ conflicts.
Standard Interrupt Assignments
IRQ
Priority
0
1
1
2
2
N/A
3*
11
4*
12
5*
13
6
14
7*
15
8
3
9*
4
10*
5
11*
6
12*
7
13
8
14*
9
15*
10
*These IRQs are usually available for PCI devices.
Interrupt Request Table for this Motherboard
PCI slot 1
PCI slot 2
PCI slot 3
AGP slot
Onboard USB controller
Onboard Audio/SMBus
Onboard LAN (optional)
IMPORTANT: If using PCI cards on shared slots, make sure that the drivers sup-
port "Share IRQ" or that the cards do not need IRQ assignments. Conflicts will
arise between the two PCI groups that will make the system unstable or cards inop-
erable.
ASUS A7VI-VM User's Manual
Standard Function
System Timer
Keyboard Controller
Programmable Interrupt
Communications Port (COM2)
Communications Port (COM1)
Sound Card (sometimes LPT2)
Floppy Disk Controller
Printer Port (LPT1)
System CMOS/Real Time Clock
ACPI Mode when used
IRQ Holder for PCI Steering
IRQ Holder for PCI Steering
PS/2 Compatible Mouse Port
Numeric Data Processor
Primary IDE Channel
Secondary IDE Channel
INT-A
INT-B
shared
—
—
shared
—
—
shared
—
—
—
—
—
—
shared
INT-C
INT-D
—
—
—
—
used
—
—
—
—
shared
—
shared
—
—
23
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