Browse Definitions:
Definition

combinatorial logic

Contributor(s): Matthew Berggren

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

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

  • smart contract

    A smart contract, also known as a cryptocontract, is a computer program that directly controls the transfer of digital currencies...

  • risk map (risk heat map)

    A risk map, also known as a risk heat map, is a data visualization tool for communicating specific risks an organization faces. A...

  • internal audit (IA)

    An internal audit (IA) is an organizational initiative to monitor and analyze its own business operations in order to determine ...

SearchSecurity

SearchHealthIT

SearchDisasterRecovery

  • incident management plan (IMP)

    An incident management plan (IMP), sometimes called an incident response plan or emergency management plan, is a document that ...

  • crisis communication

    Crisis communication is a method of corresponding with people and organizations during a disruptive event to provide them with ...

  • Zerto

    Zerto is a storage software vendor that specializes in enterprise-class business continuity and disaster recovery in virtual and ...

SearchStorage

  • SSD write cycle

    An SSD write cycle is the process of programming data to a NAND flash memory chip in a solid-state storage device.

  • data storage

    Data storage is the collective methods and technologies that capture and retain digital information on electromagnetic, optical ...

  • hard disk

    A hard disk is part of a unit -- often called a disk drive, hard drive or hard disk drive -- that stores and provides relatively ...

SearchSolidStateStorage

  • hybrid hard disk drive (HDD)

    A hybrid hard disk drive is an electromechanical spinning hard disk that contains some amount of NAND Flash memory.

Close