Interrupts

• Usually several are provided.

  • You may have heard of IRQ lines in your PC
    • Early PCs limited to 8 IRQ because the microprocessor had 8 interrupt pins.
    • Later moved to 16
    • Now being replaced by more scalable architectures such as APIC controllers.
  • Normally Open-Collector and asserted low.

• Software interrupts or timers are also available and very useful on many microprocessors (eg. Watchdog timers)