Asus A7A266 3.7.2Assigning IRQs for Expansion Cards, Standard Interrupt Assignments, Interrupt Request Table for this Motherboard, IMPORTANT:, ASUS A7A266 User’s Manual

3.HARDWARE SETUP

3.7.2Assigning IRQs for Expansion Cards

Some expansion cards need an IRQ to operate. Generally, an IRQ must be exclusively 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 support “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	Standard Function	SETUP
0	1	System Timer
1	2	Keyboard Controller
2	N/A	Programmable Interrupt
			H/W
3*	11	Communications Port (COM2)
4*	12	Communications Port (COM1)	3.
5*	13	Sound Card (sometimes LPT2)
6	14	Floppy Disk Controller
7*	15	Printer Port (LPT1)
8	3	System CMOS/Real Time Clock
9*	4	ACPI Mode when used
10*	5	IRQ Holder for PCI Steering
11*	6	IRQ Holder for PCI Steering
12*	7	PS/2 Compatible Mouse Port
13	8	Numeric Data Processor
14*	9	Primary IDE Channel
15*	10	Secondary IDE Channel

*These IRQs are usually available for PCI devices.

Interrupt Request Table for this Motherboard

	INT-A INT-B		INT-C	INT-D	INT-E INT-F
PCI slot 1	shared	—	—	—	—	—
PCI slot 2	—	shared	—	—	—	—
PCI slot 3	—	—	shared	—	—	—
PCI slot 4	—	—	—	shared	—	—
PCI slot 5	—	—	—	—	—	shared
AGP Pro slot	shared	shared	—	—	—	—
Onboard PCI audio	—	—	—	—	—	shared
Onboard USB controller	—	—	—	—	used	—

Expansion Cards

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