3Expansion

H/W .

SETUPCards

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 motherboard 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 arise between the two PCI groups that will make the system unstable or cards inoperable.

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

AIC7899 (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 (LAN Intel 82559)

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 ISA or PCI devices.

NOTE: IRQ settings vary with different operating systems. Refer to the actual condition of your system when changing the settings.

Interrupt Request Table for this Motherboard

 

 

INT-A

INT-B

INT-C

INT-D

 

PCI slot 1

—

—

—

shared

 

PCI slot 2

shared

—

—

—

 

 

 

 

 

 

 

PCI slot 3

—

shared

—

—

 

 

 

 

 

 

 

PCI slot 4

—

—

shared

—

 

 

 

 

 

 

 

PCI slot 5

—

—

—

shared

 

 

 

 

 

 

 

AGPPro slot

shared

—

—

—

 

 

 

 

 

 

 

Onboard USB controller

—

—

—

shared

 

 

 

 

 

 

 

Onboard SCSI controller

—

shared

shared

—

 

 

 

 

 

 

 

Onboard LAN controller

—

—

—

shared

 

 

 

 

 

 

 

 

 

 

 

 

28

ASUS CUV266-DLS User’s Manual