How the CPU Works

CPU stands for Central Processing Unit. It is the most important chip inside a computer. Every task you do on a computer goes through the CPU.

The CPU follows three steps for every task. This is called the IPO Cycle — Input, Process, Output.

INPUT

You type or click.
Data enters the computer.

PROCESS

The CPU thinks and calculates the result.

OUTPUT

The result appears on your monitor or printer.

IPO Cycle: You type 2+2, CPU calculates, Monitor shows 4

The CPU chip has two important parts that work together.

The ALU does all maths and comparisons. Adding numbers, subtracting, checking "is this bigger?" — all these jobs go to the ALU.

The Control Unit manages all other parts. It tells the ALU what to calculate, fetches data from memory, and sends results to the output device.

Inside the CPU: CU and ALU work as a team

CPU speed is measured in GHz (Gigahertz). A 3 GHz CPU can do 3 billion steps every second! More GHz usually means a faster computer.

💡 Fun Fact: If the human brain were a CPU, it would run at about 1 exahertz — that is 1,000,000,000 GHz. Computers still have a long way to go!

Q1. What does CPU stand for?

✅ CPU stands for Central Processing Unit.

Q2. Write the three steps of the IPO cycle in order.

✅ Input → Process → Output

Q3. Which part of the CPU does maths calculations?

✅ The ALU (Arithmetic Logic Unit) does maths calculations.

Q4. In what unit is CPU speed measured?

✅ CPU speed is measured in GHz (Gigahertz).