Chapter 3 BIOS Setup
EC0-1814(B)
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IRQ Assignment Table
There are 15 interrupt sources of the system. Some are occupied by the system
devices. Only the ones that are not occupied can be assigned to other devices. ISA
device requests exclusive use of its interrupt. Only the plug and play ISA devices can
be assigned by the BIOS or the OS. And several PCI devices share one interrupt,
which is assigned by BIOS or OS. Interrupt assignment of some devices of X86
platform is shown in the table below, but it does not show the interrupt source
occupied by the PCI devices.
Level
Function
IRQ0 System
Timer
IRQ1
Standard 101/102 Key or Microsoft Keyboard
IRQ2 Reserved
IRQ3 COM#2
IRQ4 COM#1
IRQ5 Reserved
IRQ6
Standard Floppy Disk Controller
IRQ7 Parallel
Port#1
IRQ8
System CMOS/Real Time Clock
IRQ9 Microsoft
ACPI-Compliant
System
IRQ10
COM#3 ~ COM#6
IRQ11
Reserved
IRQ12
Reserved
IRQ13
Numeric data processor
IRQ14 Master
IDE
IRQ15 Slave
IDE
