What is combinatorial logic? - Definition from WhatIs.com

Definition

combinatorial logic

Part of the Electronics glossary:

Combinatorial logic is a concept in which two or more input states define one or more output states, where the resulting state or states are related by defined rules that are independent of previous states. Each of the inputs and output(s) can attain either of two states: logic 0 (low) or logic 1 (high). A common example is a simple logic gate .

In combinatorial logic, the output is a function of the input at a specific time. An example is the AND gate. Suppose an AND gate has two inputs, X and Y, and one output, Z. The AND operation is symbolized by an asterisk (*). The operation of the two-input AND gate can be represented by the following truth table:

X Y X * Y
1
1
1 1 1

The output of this logic gate is high if and only if both inputs are high. If either or both of the inputs are low, the output is low. If the states of the inputs change periodically, the output always obeys the rules depicted in the above truth table. The current state of the device is not affected by preceding states. This contrasts combinatorial logic with sequential logic , in which the current state of the device is affected by previous states.

Logic gates are one of several types of devices that use combinatorial logic. Other forms include encoders, decoders, multiplexer s, comparators, and latches.

This was last updated in September 2005
Contributor(s): Matthew Berggren
Posted by: Margaret Rouse

Related Terms

Definitions

  • Faraday constant

    - Faraday's constant, symbolized by the italic uppercase letter F, is the physical constant representing the electric charge in a mole. The unit is named for Michael Faraday, an early 19th century in... (WhatIs.com)

  • farad (F)

    - The farad is the standard international unit of capacitance. Both the farad and Faraday's constant are symbolized by the capital letter F; however they are different. Faraday's constant is a measur... (WhatIs.com)

  • ARM processor

    - An ARM processor is any of several 32-bit RISC (reduced instruction set computer) microprocessors developed by Advanced RISC Machines, Ltd. The ARM architecture was originally developed by Acorn Co... (WhatIs.com)

Glossaries

  • Electronics

    - Terms related to electronics, including definitions about electrical components and words and phrases about computers, laptops parts, digital cameras, televisions and home appliances.

  • Internet applications

    - This WhatIs.com glossary contains terms related to Internet applications, including definitions about Software as a Service (SaaS) delivery models and words and phrases about web sites, e-commerce ...

Ask a Question About combinatorial logicPowered by ITKnowledgeExchange.com

Get answers from your peers on your most technical challenges

Tech TalkComment

Share
Comments

    Results

    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.