The Decision Makers Inside Computers
The Decision Makers Inside Computers
AND gates are like security doors that need BOTH a keycard AND a fingerprint. Only when ALL inputs are 1 (true) does the output become 1. It's the strictest gate - everything must be true.
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Exam Tips - Logic Gates
Drawing gate symbols:
- AND gate: Draw a D-shape (flat back, curved front)
- OR gate: Draw a pointed shape (curved back, pointed front)
- NOT gate: Draw a triangle with a small circle (bubble) at the output
- The bubble ALWAYS means NOT (inversion)
Common exam mistakes to avoid:
- Forgetting that AND requires ALL inputs to be 1 - not just one!
- Confusing AND and OR symbols - remember AND is D-shaped, OR is pointed
- Missing the NOT bubble - it's essential for showing inversion
- Wrong truth table: AND has only ONE 1 (bottom row), OR has only ONE 0 (top row)
Quick truth table memory tricks:
- AND: Think "strict gate" - only 1,1 passes through → gives 1
- OR: Think "generous gate" - only 0,0 blocks → gives 0
- NOT: Think "flip gate" - whatever goes in, opposite comes out
Now try it yourself
Quiz · Question 1 of 16
An AND gate has inputs A=1 and B=0. What is the output?
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This topic in real past papers
Every real exam question we've found on logic gates, with a full worked answer.
AQA Paper 2
Both sittings we have full papers for test the XOR truth table with the identical stem, and both ask you to write a Boolean expression for a logic circuit.
OCR Paper 2
Boolean logic is tested on Paper 2, not Paper 1, for OCR's own J277 specification, unlike AQA's 8525 where logic gates sit on Paper 2 (Computing concepts). All three sittings we have full papers for include at least one logic-gate or truth-table question, worth 2 to 4 marks.