[Geekos-devel] defs.h

[Sergey L. <ioa...@ya...>]

Hi Behrang,
Although Dave's answer is absolutely correct,
I wanna explain it in more details.

CPU may be interrupted in 2 ways: programmatically or by the
hardware. Every such case has the associated number, called
'interrupt number'. CPU then searches special table, called
IDT (interrupt descriptor's table), and uses the interrupt number
as an index to find the handler: a function to call to handle the
interrupt.
(there are different IDT formats for real and protected mode,
but the concept remains the same).

Programmatically, you issue an interrupt by instruction INT XX,
where XX is an interrupt number (index in IDT).

All interrupts from real hardware go to a chip called 'programmable
interrupt controller', or PIC. PIC then sends an interrupt to a 
processor: so PIC is an 'interrupt router'.
PIC has 8 'pins', or lines, callePOST /ym/ComPOST /ym/Compose?YY=46200
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