---
title: "Components of CPU"
subject: "Computer Organization and Architecture"
chapter: 2
key: "semester_5/computer_organization_and_architecture:cpu-components"
source: https://www.bctengineer.com/q/semester_5/computer_organization_and_architecture/cpu-components
site: BCT Engineering
---

# Components of CPU

Computer Organization and Architecture · Chapter 2: Central Processing Unit

- Asked in: 2078 Bhadra, 2 marks
- Video: [CPU and Its Components|| Components of MIcroprocessor](https://www.youtube.com/watch?v=VgSbiNRIpic) — Professor  Computer
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/computer_organization_and_architecture/cpu-components
- Whole chapter: https://www.bctengineer.com/md/semester_5/computer_organization_and_architecture/chapter-2

## Question

Explain the components of CPU.

## Short answer

The CPU consists of the ALU for arithmetic/logic operations, the control unit which fetches/decodes instructions and generates control signals, and registers (PC, IR, AC, etc.) for fast storage. They are linked by internal buses.

## Answer

The CPU has three main components:
1. **ALU (Arithmetic Logic Unit):** performs arithmetic and logic operations on data.
2. **Control unit (CU):** fetches and decodes instructions and generates the control signals that direct the ALU, registers, memory and I/O.
3. **Registers:** fast on-chip storage, including PC, IR, AR, DR, AC, flags and general-purpose registers.

They are connected by internal buses.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which are the three main components of the CPU?
   A. ALU, control unit and registers
   B. ALU, memory and I/O
   C. Control unit, cache and bus
   D. Registers, RAM and ROM
   Answer: A. The CPU consists of the ALU, the control unit and registers, linked by internal buses. (Key point: Main components)

2. What does the control unit do?
   A. Performs arithmetic and logic operations
   B. Stores data in fast on-chip storage
   C. Fetches and decodes instructions and generates control signals
   D. Holds the program permanently
   Answer: C. The CU directs the ALU, registers, memory and I/O through control signals. (Key point: Control unit role)

3. What is the function of the ALU?
   A. Decodes the opcode
   B. Performs arithmetic and logic operations on data
   C. Holds the next instruction address
   D. Controls the buses
   Answer: B. The ALU carries out arithmetic and logic operations; decoding belongs to the control unit. (Key point: ALU role)