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ALU - GCSE Computer Science Definition

Reviewed by: Robert Hampton

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What is the ALU?

In GCSE Computer Science, the ALU (Arithmetic Logic Unit) is defined as a component of the CPU, responsible for performing arithmetic operations and logical decisions.

  • Arithmetic operations - performing operations and calculations on numbers (e.g. addition or subtraction)

  • Logical decisions - making decisions on a set of predefined conditions (e.g. comparisons)

The ALU plays a crucial role in the execute stage of the fetch-decode-execute cycle.

Diagram of a computer system architecture with an ALU, CU, registers (ACC, MDR, PC, MAR), and cache, highlighting data flow connections.
Illustration of the internal components of a CPU

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Robert Hampton

Reviewer: 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.

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