Interrupts Revisited (see Fig. 10)

Figure 10: How interrupts happen. The connections between devices and interrupt controller actually use interrupt lines on the bus rather than dedicated wires.

• CPU interrupt request line triggered by I/O device
• Interrupt handler receives interrupts
• Maskable to ignore or delay some interrupts
• Interrupt vector to dispatch interrupt to correct handler based on priority some unmaskable
• Interrupt mechanism also used for exceptions, traps