◄ Wiki / OS

interrupt / IRQ

A hardware signal that yanks the CPU away from what it's doing to handle something urgent, like a keypress or timer.

Devices can't wait politely for the CPU to check on them, so they raise an interrupt request (IRQ) — an electrical signal that forces the processor to pause, jump to a handler, deal with the event, and resume. Because interrupts can fire at any moment, temporarily disabling them is one of the simplest ways to protect a critical section; in microZeus, disabling interrupts was the only real mutual exclusion x86 had.