Assigning Irqs For Expansion Cards - Asus 850E - P4 ATX 533MHzFSB USB2 LAN User Manual

3. HARDWARE SETUP

3.6.2 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
0
1
2 N/A
3*
4*
5*
6
7*
8
9*
10*
11*
12*
13
14*
15*
*These IRQs are usually available for ISA or PCI devices.
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 —
PCI slot 2 —
PCI slot 3 —
AGP slot used
USB HC0 —
USB HC1 —
SMB —
AC'97 —
LAN —
IEEE 1394 —
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.
24
Standard Function
1 System Timer
2 Keyboard Controller
Programmable Interrupt
11 Communications Port (COM2)
12 Communications Port (COM1)
13 Sound Card (sometimes LPT2)
14 Floppy Disk Controller
15 Printer Port (LPT1)
3 System CMOS/Real Time Clock
4 ACPI Mode when enabled
5 IRQ Holder for PCI Steering
6 IRQ Holder for PCI Steering
7 PS/2 Compatible Mouse Port
8 Numeric Data Processor
9 Primary IDE Channel
10 Secondary IDE Channel
— — —
— — —
— — —
— — —
— — used
— — —
shared — —
shared — —
— — —
— used —
ASUS P4T-M User's Manual
— shared —
— — used
— — —
— — —
— — —
— — —
— — —
— — —
— shared —
— — —
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—
shared
—
—
shared
—
—
—
—