Interrupts

Interrupts

An interrupt occurs when an event needs attention while a computer is running. The machine automatically pauses the running program and transfers control to a program that handles the event. After handling it, execution normally returns to the paused program.

Interrupt sources include mouse movement, mouse clicks, keyboard input, and a printer requesting service or reporting completion.

Modern computers use interrupt systems mainly to:

• Improve computer-system efficiency: processors work much faster than peripherals, and interrupts coordinate their operation. When a peripheral needs to exchange information with the processor, it sends an interrupt request, which the processor handles promptly.

• Maintain reliable operation: applications cannot perform privileged operations directly and must request them through system calls. Out-of-bounds memory access could disrupt a program or corrupt another program's information. Memory-management hardware detects such access and raises an exception so the processor can take protective action.

• Meet real-time requirements: monitoring and control devices send interrupt requests, and the processor responds and handles them within the system's real-time constraints.

• Support fault handling: fault-detection and diagnostic components raise interrupts or exceptions when they detect a fault or error, allowing the system to record and isolate the fault as a basis for further handling.