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[Acronym] for __A__dvanced __P__rogrammable __I__nterrupt Controller. The APIC is split into two parts, the Local APIC and the IO-APIC.

The Local APIC is found on uniprocessor and mulitprocessor systems and built into recent [x86] chips (Pentium Pro and up). The Local APIC can be used by the OS to program interrupts to wake up threads, on [SMP] machines it can be used to send interrupts to another processor. The Local APIC also has a handy timer in it, you can set the timer to whatever you want and it'll start generating interrupts.

The IO-APIC is only really useful for [SMP] systems. It is used for sending various interrupts to various [CPU]s in the system. Without an IO-APIC interrupts from hardware only get delivered to the boot [CPU]. Another advantage is that [PCI] interrupts can be sent around the system without overlapping [IRQ]s.

One page links to APIC:

TroubleshootingStartUp

Version 3, saved on Sunday, March 14, 2004 5:19:07 am by StuartYeates

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