UNIT-2, Introduction

Logic

• Formal logic is a branch of mathematics that deals with true and false values instead of numbers.

• In the mid-19th century, George Boole developed many Logic ideas.

• Boolean logic deals with equations where the operators are “AND” or “OR” instead of “add” and “multiply”.

Image: George Boole

Electric Logic

• Logical values can easily be expressed by an electrical circuit.

• “True” or “1” can be defined as voltage on a wire while “False” or “0” can be defined as  no voltage. We will use positive logic.

• Analog values can be anything while digital Analog values can be anything while digital only has discrete values, 0 or 1.

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   Boolean functions may be practically implemented by using electronic gates.

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Gate INPUTS are driven by voltages having two nominal values, e.g. 0V and 5V representing logic 0 and logic 1 respectively. 

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The OUTPUT of a gate provides two nominal values of voltage only, e.g. 0V and 5V representing logic 0 and logic 1 respectively.