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Arithmetic Logic Unit (ALU)

The ALU is the part of the CPU that does all the calculations and logical decisions.

It performs two key types of tasks:

  • Arithmetic operations – like addition, subtraction, multiplication, and division.

  • Logical operations – like comparing numbers (e.g. is one number bigger, smaller, or equal to another?).

The ALU is essential for carrying out instructions and making decisions in a program.

National 5 Target

You should be able to describe the role of the ALU and give examples of the tasks it performs.

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