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Hardware setup, 2 assigning irqs for expansion cards – Asus P4T-F User Manual

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ASUS P4T-F User’s Manual

3. HARDWARE SETUP

3. H/W SETUP

Expansion Cards

3.7.2 Assigning 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.

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 enabled

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.

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 inoperable.

Interrupt Request Table for this Motherboard

INT-A INT-B INT-C INT-D INT-E INT-F

INT-G INT-H

PCI slot 1

shared

PCI slot 2

used

PCI slot 3

shared

PCI slot 4

used

PCI slot 5

shared —

AGP slot

used

USB HC0

used

USB HC1

shared

SMB

shared —

AC’97

shared —