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🔌 How Do Computers Make Decisions? — Logic Gates

Toggle inputs on interactive logic gates or build expressions to generate truth tables automatically.

Designed with the WJEC specification in mind
CS GCSE §1.6CS A-Level Unit 1CS A-Level Unit 3

🤔 What are logic gates?

Logic gates are the building blocks of all computer circuits. They take electrical inputs (on/off) and produce outputs based on simple rules. Every decision your computer makes uses these basic gates!

🍕 Analogy: Think of them like automatic doors with different rules — some need BOTH sensors triggered (AND), others need just one (OR), and some do the opposite of what you'd expect (NOT)!
🎛️ Interactive Gates
📋 Truth Tables
✍️ Expression Builder
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Select a gate to see its truth table

✍️

Boolean Expression → Truth Table

Type a Boolean expression using variables A, B, C and operators AND, OR, NOT, XOR, NAND, NOR. Use brackets for grouping.

Examples:
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Exam Tips

  • GCSE: Know the symbols and truth tables for AND, OR, NOT gates
  • A-Level: Include XOR, NAND, NOR gates and be able to simplify Boolean expressions
  • Key point: NAND = NOT AND, NOR = NOT OR (they're the opposites)
  • Remember: Use brackets carefully in expressions — (A AND B) OR C is different from A AND (B OR C)