In digital circuit theory, **combinational logic** (sometimes also referred to as **combinatorial logic** or **time-independent logic** ) is a type of digital logic which is implemented by boolean circuits, where the output is a pure function of the present input only. This is in contrast to sequential logic, in which the output depends not only on the present input but also on the history of the input. In other words, sequential logic has *memory* while combinational logic does not.

Combinational logic is used in computer circuits to do boolean algebra on input signals and on stored data. Practical computer circuits normally contain a mixture of combinational and sequential logic. For example, the part of an arithmetic logic unit, or ALU, that does mathematical calculations is constructed using combinational logic. Other circuits used in computers, such as half adders, full adders, half subtractors, full subtractors, multiplexers, demultiplexers, encoders and decoders are also made by using combinational logic.

Read more about Combinational Logic: Representation, Logic Formulas Minimization, Terminology

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### Famous quotes containing the word logic:

““... We need the interruption of the night

To ease attention off when overtight,

To break our *logic* in too long a flight,

And ask us if our premises are right.””

—Robert Frost (1874–1963)