CPU Components & Their Function (AQA GCSE Computer Science)

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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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