2.5.3

Interrupt assignments

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 ISA or PCI devices.

IRQ assignments 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

—

—

—

used

PCI slot 5

shared

—

—

—

Gigabit LAN

—

shared

—

—

Onboard RAID

—

—

shared

—

Onboard 1394

shared

—

—

—

Serial ATA

—

—

shared

—

AGP slot

shared

—

—

—

When using PCI cards on shared slots, ensure that the drivers support “Share IRQ” or that the cards do not need IRQ assignments. Otherwise, conflicts will arise between the two PCI groups, making the system unstable and the card inoperable.

2-16

Chapter 2: Hardware information