10 Boolean logic

By the end of this section you should be able to

• 10.1 Identify the standard logic gate symbols
• 10.2 Describe NOT, AND, OR, NAND, NOR and XOR
• 10.3 Draw logic circuits from statements, expressions and truth tables
• 10.4 Complete truth tables
• 10.5 Write logic expressions

Lessons

1. Logic gates
2. Truth tables
3. Logic circuits and expressions
4. Universal gates

Key vocabulary

Logic gate

An electronic component that produces an output from one or more binary inputs.

NOT

Outputs the opposite of its single input.

AND

Outputs 1 only when both inputs are 1.

OR

Outputs 1 when either or both inputs are 1.

NAND

Outputs 0 only when both inputs are 1.

NOR

Outputs 1 only when both inputs are 0.

XOR

Outputs 1 when the inputs are different.

Truth table

A table showing the output for every possible combination of inputs.