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3. HARDWARE SETUP
3.7.2Assigning IRQs for Expansion Cards
This is applicable only when MPS 1.4 Support is Disabled in section 4.6 Boot Menu.
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
ISA 00
1
ISA 01
2
ISA 02
N/A
ISA 03*
11
ISA 04*
12
ISA 05*
13
ISA 06
14
ISA 07*
15
ISA 08
3
ISA 09*
4
ISA 10*
5
ISA 11*
6
ISA 12*
7
ISA 13
8
ISA 14*
9
ISA 15*
10
*These IRQs are usually available for PCI devices.
PCI Interrupt (IRQ) Assignments
PCI Slot
PCI INTA PCI INTB PCI INTC PCI INTD
64-bit
PCI 0
D1260 CUR-DLSR User's Manual
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
PCI 3
PCI 4
PCI 5
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