Computer Basics - Arithmetic Logic Unit
What Is an Arithmetic Logic Unit (ALU)?
The Arithmetic Logic Unit (ALU) is a core component of the CPU (Central Processing Unit). It is responsible for performing all arithmetic and logical operations in a computer.
Think of it as the “calculator” of the CPU — it handles the actual computation.
Main Functions of the ALU
1. Arithmetic Operations
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These include basic mathematical operations such as:
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Addition
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Subtraction
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Multiplication
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Division
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2. Logical Operations
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These involve decision-making and comparisons, such as:
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AND
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OR
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NOT
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XOR
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Comparisons (e.g., greater than, less than, equal to)
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3. Bitwise Operations
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Operations that work on individual bits of binary numbers.
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Example: Shifting bits left or right
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How the ALU Works
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The ALU receives data (operands) and instructions from the Control Unit.
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It performs the operation and sends the result back to the CPU registers or memory.
Importance of the ALU
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It is essential for all types of computing tasks, from simple math in a calculator app to complex algorithms in scientific computing.
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Every operation a program runs that involves logic or math goes through the ALU.
Simple Example
If you type 5 + 3
into a calculator:
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The Control Unit sends the numbers and the operation (+) to the ALU.
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The ALU performs the addition.
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The result (8) is sent back to be displayed as output.