Boolean Logic

Logic Gates

Allows an electronic system to make a decision based on its inputs

True

1

False

0

Truth Tables

Diagrams that show all possible inputs and their associated outputs, for logic gates

NOT gate

A gate that will produce the opposite of the input

AND gate

For A AND B to be TRUE both A and B must occur

OR gate

For A OR B to be TRUE either A or B must occur or both

NOT gate symbol

AND gate symbol

OR gate symbol

Boolean Logic

A branch of computer science that uses the logical operators OR, AND, and NOT.

Security Light

Example of an AND gate when both the sensor needs to be active and dark outside

Automated Central Heating

Example of a NOT gate when if it is too hot then the central heating is not on

Smartphone Unlock

Example of an OR gate when a thumbprint or passcode will unlock the device

NAND gate symbol

NOR gate symbol

XOR gate symbol

NAND gate

For A NAND B to be TRUE either A or B or neither A AND B must occur

NOR gate

For A NOR B to be TRUE neither A or B must occur

XOR gate

FOR A XOR B to be TRUE either A or B must occur but not neither or both

Logic proposition

A statement that is either TRUE or FALSE

Logic expression

Logic propositions combined using Boolean operators, which may be written with a defined outcome