Chapter 3 BIOS Setup
42
EC71817LNAR
u
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 distributed. The ISA devices
claim to engross the interrupt. Only the plug and play ISA devices can be distributed
by the UEFI or the OS. And several PCI devices share one interrupt through the
distribution of UEFI or OS. The diagram below shows parts of the interrupt
distribution under X86 platform, 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 Natural Keyboard
IRQ2
Reserved
IRQ3
COM2
IRQ4
COM1
IRQ5
Reserved
IRQ6
Reserved
IRQ7
Reserved
IRQ8
System CMOS/Real Time Clock
IRQ9
ACPICompliant System
IRQ10
Reserved
IRQ11
Reserved
IRQ12
Microsoft PS/2 Mouse
IRQ13
Numeric data processor
IRQ14
Reserved
IRQ15
Reserved
