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

2

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

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.

Putting it into context…
Task A:
Create a circuit to make the internal light come on when a car
door is opened.
5

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

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
7