Asus A7M266-D User Manual download pdf (Page 25)

ASUS A7M266-D User’s Manual 25

3. HARDWARE SETUP

Expansion Cards

3. H/W 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 Standard Function

0 1 System Timer

1 2 Keyboard Controller

2 N/A Programmable Interrupt

3* 11 Communications Port (COM2)

4* 12 Communications Port (COM1)

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

PCI slot 3 — shared ——

PCI slot 4 ——used —

PCI slot 5 ———used

AGP Pro slot shared shared ——

Onboard PCI audio — shared ——

1 ... 24 25 26 ... 98

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Asus A7M266-D User Manual Page 25