Asus TR-DLSR TR-DLSR User Manual - Page 25

Assigning IRQs for Expansion Cards

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3. HARDWARE SETUP 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 the motherboard has PCI audio onboard, an additional IRQ will be used. If the motherboard also has MIDI enabled, another IRQ will be used, leaving 4 IRQs free. The following table lists the default IRQ assignments for standard PC devices. Use this table when configuring your system and for resolving IRQ conflicts. ISA Interrupt (IRQ) Assignments ISA INT ISA 00 ISA 01 ISA 02 ISA 03* ISA 04* ISA 05* ISA 06 ISA 07* ISA 08 ISA 09* ISA 10* ISA 11* ISA 12* ISA 13 ISA 14* ISA 15* Priority 1 2 N/A 11 12 13 14 15 3 4 5 6 7 8 9 10 Standard Function System Timer Keyboard Controller Programmable Interrupt Communications Port (COM2) Communications Port (COM1) Sound Card (sometimes LPT2) Floppy Disk Controller Printer Port (LPT1) System CMOS/Real Time Clock ACPI Mode when used IRQ Holder for PCI Steering IRQ Holder for PCI Steering PS/2 Compatible Mouse Port Numeric Data Processor Primary IDE Channel Secondary IDE Channel *These IRQs are usually available for PCI devices. 3. H/W SETUP Expansion Cards ASUS TR-DLSR User's Manual 25

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ASUS TR-DLSR User’s Manual
25
3. HARDWARE SETUP
Expansion Cards
3. H/W SETUP
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 the motherboard has
PCI
audio onboard, an additional IRQ will be used. If the motherboard also has
MIDI
enabled, another IRQ will be used, leaving 4 IRQs free.
The following table lists the default IRQ assignments for standard PC devices. Use this
table when configuring your system and for resolving IRQ conflicts.
ISA Interrupt (IRQ) Assignments
ISA INT
Priority
Standard Function
ISA 00
1
System Timer
ISA 01
2
Keyboard Controller
ISA 02
N/A
Programmable Interrupt
ISA 03*
11
Communications Port (COM2)
ISA 04*
12
Communications Port (COM1)
ISA 05*
13
Sound Card (sometimes LPT2)
ISA 06
14
Floppy Disk Controller
ISA 07*
15
Printer Port (LPT1)
ISA 08
3
System CMOS/Real Time Clock
ISA 09*
4
ACPI Mode when used
ISA 10*
5
IRQ Holder for PCI Steering
ISA 11*
6
IRQ Holder for PCI Steering
ISA 12*
7
PS/2 Compatible Mouse Port
ISA 13
8
Numeric Data Processor
ISA 14*
9
Primary IDE Channel
ISA 15*
10
Secondary IDE Channel
*These IRQs are usually available for PCI devices.