CPU Components & Their Function (AQA GCSE Computer Science)

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Robert Hampton

Written by: Robert Hampton

Reviewed by: James Woodhouse

CPU Components & Their Function

What is the Von Neumann architecture?

  • The Von Neumann Architecture is a design of the CPU which was proposed by Mathematician John Von Neumann in the 1940s, which most general-purpose computers are built upon

  • The Von Neumann Architecture outlines how the computer memory, input / output devices and processor all work together 

What are the components of the CPU?

  • The CPU is made up of 5 key components

    • Arithmetic Logic Unit (ALU)

    • Control Unit (CU)

    • Clock

    • Registers

    • Bus

  • Each of the components sits within the CPU

the-cpu

What is the function of each component?

Arithmetic logic unit (ALU)

  • Performs arithmetic operations

  • Performs logical decisions

    • IF X > 5 THEN
            DO ……….

Control unit (CU)

  • Coordinates how data moves around the CPU by sending a signal to control the movement of the data 

  • Decodes the instructions fetched from memory

Clock

  • Keeps related components in sync by generating pulses at a constant rate

Registers

  • Extremely small, extremely fast memory located in the CPU

  • Hold small amounts of data needed as part of the fetch-execute cycle

  • Each register has its own specific purpose

    • Accumulator (ACC) - stores results of logical or arithmetic calculations carried out by the ALU

    • Memory address register (MAR) - stores the address of the next instruction to be fetched from RAM

    • Memory data register (MDR) - stores the data retrieved from RAM

    • Program counter (PC) - stores the memory address of the next instructions to be executed & Increments by 1 as the fetch-decode-execute cycle runs

Bus

  • A bus is a collection of wires through which data/signals are transmitted from one component to another

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Robert Hampton

Author: Robert Hampton

Expertise: Computer Science Content Creator

Rob has over 16 years' experience teaching Computer Science and ICT at KS3 & GCSE levels. Rob has demonstrated strong leadership as Head of Department since 2012 and previously supported teacher development as a Specialist Leader of Education, empowering departments to excel in Computer Science. Beyond his tech expertise, Robert embraces the virtual world as an avid gamer, conquering digital battlefields when he's not coding.

James Woodhouse

Author: James Woodhouse

Expertise: Computer Science

James graduated from the University of Sunderland with a degree in ICT and Computing education. He has over 14 years of experience both teaching and leading in Computer Science, specialising in teaching GCSE and A-level. James has held various leadership roles, including Head of Computer Science and coordinator positions for Key Stage 3 and Key Stage 4. James has a keen interest in networking security and technologies aimed at preventing security breaches.