This document discusses Boolean logic and logic gates. It defines logic gates, their notations, and truth tables. It provides examples of logic gates and circuits, including an incomplete truth table that needs to be filled in. It then gives three examples of real-world applications of logic gates and circuits: controlling an internal car light based on a door opening, launching missiles only when two keys are simultaneously turned on, and a burglar alarm that can be triggered by either a door or motion sensor once the main switch is turned on.

1. GCSE
Computer
Science (9-1)
Block1:
Understandingthemachine
CS1:
BooleanLogic
Name:……………………………….........
Class: ………………
Date: …………….....
Name:……………………………….........
Class: ………………
Date: …………….....

2. 2

3. Logic gates
3
Diagram
Gate
Notation
Boolean expression
Truth table
representation
A B Q A B Q A Y

4. Truth tables
4
A
B
C
X
A B C X
0 0 0
0 0 1
0 1 1
0 1 0
1 1 0
1 0 1
1 0 0 0
1 1 1
Write the Boolean expression for this logic circuit.
Complete the rest of the truth table.

5. Putting it into context…
Task A:
Create a circuit to make the internal light come on when a car
door is opened.
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6. Putting it into context…
Task B:
Create a circuit to launch nuclear missiles only when two
separate keys (A and B) are both turned to on at the same
time.
6

7. Putting it into context…
Task C:
A burglar alarm has 3 inputs -
• A (the main on/off switch)
• B (a door sensor)
• C (a motion sensor).
Once the alarm is set to ON, either sensor B or C can trigger
the alarm
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