Understanding Truth Tables

Truth tables help understand the behaviour of logic gates.

Truth Table Diagram

Drawing Truth Tables for Combined Gates

Truth tables can also help understand the behaviour of combinations of logic gates linked together.

The following example shows the steps for drawing up a truth table for a combined gate configuration.

Example 

 

Exercise

See if you can draw the truth table for the following logic circuit and find the output expression. What gate does the expression represent? When you have done this, you check with the answers.

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Richard Bigwood 2005