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Common CPU Components & Their Function

Computer Science: OCR GCSE, topic 1.1.2

Common CPU Components & Their Function

All modern Central Processing Units (CPUs) are based on the Von Neumann architecture. The components of this architecture are:

Arithmetic and Logic Unit (ALU)

Arithmetic and Logic Unit (ALU)

  • The ALU performs all of the arithmetic and logical operations of the CPU, including:
  • Addition and subtraction, multiplication and division.
  • Comparisons such as whether numbers are equal or if one is greater than another.
  • Boolean operations (e.g. AND, OR, NOT).
Control Unit (CU)

Control Unit (CU)

  • The Control Unit transmits control signals to other components of the CPU.
  • The Control Unit follows the fetch-decode-execute cycle to execute program instructions.
  • There are two main components of the Control Unit:
  • The clock, which coordinates the CPU's activity.
  • The decoder, which decodes program instructions.

Common CPU Components & Their Function

Registers

Registers

  • Registers are tiny amounts of super-quick memory within the CPU.
  • They are used to hold information needed for the CPU to work.
  • Each register holds a specific piece of information.
  • They are used for temporary storage of data/instructions during the FDE cycle.
Cache

Cache

  • Cache is a small, fast type of memory located inside or close to the CPU.
  • It stores the most frequently used instructions/data so the CPU can access them more quickly than from RAM.
  • This reduces the time taken during the fetch stage.
  • It helps prevent the CPU from sitting idle while waiting for data to arrive from slower memory (RAM).
  • Cache memory is organised into levels (L1, L2, L3), from small but fast to large but slow.

Test yourself on Common CPU Components & Their Function

  • This is the common architecture for what feature of computers?

  • Which of the following are examples of Boolean operators?

  • What is the name of the Control Unit component that coordinates the CPU's activity?

  • Which of the following are components of the Von Neumann architecture?

  • What is the name of the Control Unit component that coordinates the CPU's activity?

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