Assigning Irqs For Expansion Cards - Asus A7A266-E User Manual

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.
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.
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
PCI slot 4
PCI slot 5
AGP Pro slot
Onboard PCI audio
Onboard USB controller
ASUS A7A266-E 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 INT-C
shared — —
— shared —
— — shared
— — —
— — —
shared shared —
— —
— — —
INT-D INT-E
— —
— —
— —
shared —
— —
— —
— — —
— used
INT-F
—
—
—
—
shared
—
shared
—
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