Interrupts are used, like the word says, to interrupt the processor from it's regular work to do something that is time critical.

When interrupts happen, the processor jumps to a specific memory location where the interrupt subroutine occurs.

Interrupt routines need to be very, very optimized since other interrupts may be disabled while the routine is running.

IRQ routines need to use the RTI? instruction to go back to regular processing, where the processor will keep going like nothing ever happened.

TODO: Need more information here on IRQ masks, clearing them, what happens on the stack, etc.

-- AlexHarford - 30 Jun 2006