What is Interrupt in OS: Definition and Examples

An interrupt in an operating system is a signal that temporarily stops the current running process to allow the OS to handle important tasks immediately. It helps the system respond quickly to events like input from a keyboard or hardware requests.

How It Works

Imagine you are reading a book, and someone suddenly calls your name. You stop reading to listen, then go back to your book. An interrupt works similarly in a computer. When the CPU is busy running a program, an interrupt signal tells it to pause and pay attention to something urgent.

The operating system uses interrupts to manage many tasks efficiently. When an interrupt happens, the CPU saves its current work, handles the urgent task (like reading a key press), and then resumes what it was doing. This way, the system can react quickly without waiting for the current task to finish.

Example

This simple example simulates an interrupt using Python to show how a program can be paused to handle an event.

python

import time
import threading

# This function simulates an interrupt handler
def interrupt_handler():
    print("Interrupt received! Handling urgent task...")

# This function simulates the main program running
def main_program():
    for i in range(5):
        print(f"Main program running step {i+1}")
        time.sleep(1)

# Simulate an interrupt after 2 seconds
threading.Timer(2, interrupt_handler).start()

main_program()

Output

Main program running step 1
Main program running step 2
Interrupt received! Handling urgent task...
Main program running step 3
Main program running step 4
Main program running step 5

When to Use

Interrupts are used whenever a computer needs to respond quickly to events without wasting time waiting. For example:

• When you press a key on the keyboard, an interrupt tells the CPU to read that input immediately.
• When a printer finishes printing, it sends an interrupt to notify the system.
• Hardware devices like network cards use interrupts to signal data arrival.

Using interrupts helps computers multitask smoothly and efficiently.

Key Points

• An interrupt temporarily stops the CPU to handle urgent tasks.
• It allows quick response to hardware or software events.
• The CPU saves its state before handling the interrupt and resumes afterward.
• Interrupts improve multitasking and system efficiency.

Key Takeaways

An interrupt signals the CPU to pause and handle urgent tasks immediately.

Interrupts enable fast response to hardware events like keyboard input.

The CPU saves its current work before handling an interrupt and resumes it later.

Interrupts help the operating system manage multiple tasks efficiently.