Standard interrupt assignments

IRQ

Standard function

0

System Timer

1

Keyboard Controller

2

Programmable Interrupt

4

Communications Port (COM1)

6

Floppy Disk Controller

7

Printer Port (LPT1)*

8

System CMOS/Real Time Clock

9

ACPI mode when used*

10

IRQ Holder for PCI Steering*

11

IRQ Holder for PCI Steering*

12

PS/2 Compatible Mouse Port*

13

Numeric Data Processor

14

Primary IDE Channel*

* These IRQs are usually available for ISA or PCI devices.

IRQ assignments for the system motherboard

PCI Slot 1

A

B

C

D

E

F

G

H

-

-

-

-

-

used

-

-

PCI Slot 2

-

-

-

-

-

-

used

-

PCI Express x16 slot

shared

-

-

-

-

-

-

-

PCI Express x1 slot

-

shared

-

-

-

-

-

-

USB controller 1

-

-

-

-

-

-

-

shared

USB controller 2

-

-

-

shared

-

-

-

-

USB controller 3

-

-

shared

-

-

-

-

-

USB controller 4

shared

-

-

-

-

-

-

-

USB 2.0 controller

-

-

-

-

-

-

-

shared

LAN controller

-

-

-

-

shared

-

-

-

Audio controller

shared

-

-

-

-

-

-

-

When using a PCI card 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.

2-14

Chapter 2: Basic installation