Part of the Microprocessors glossary:

A context switch is a procedure that a computer's CPU (central processing unit) follows to change from one task (or process) to another while ensuring that the tasks do not conflict. Effective context switching is critical if a computer is to provide user-friendly multitasking.

In a CPU, the term "context" refers to the data in the registers and program counter at a specific moment in time. A register holds the current CPU instruction. A program counter, also known as an instruction address register, is a small amount of fast memory that holds the address of the instruction to be executed immediately after the current one.

A context switch can be performed entirely in hardware (physical media). Older CPUs, such as those in the x86 series, do it that way. However, most modern CPUs perform context switches by means of software (programming). A modern CPU can perform hundreds of context switches per second. Therefore, the user gets the impression that the computer is performing multiple tasks in a parallel fashion, when the CPU actually alternates or rotates between or among the tasks at a high rate of speed.

 

Continue reading about context switching:

OSDev.org offers a concise explanation of how context switching works.

This was last updated in April 2012
Contributor(s): Stan Gibilisco
Posted by: Margaret Rouse

Related Terms

Definitions

  • embedded device

    - An embedded device is an object that contains a special-purpose computing system. The system, which is completely enclosed by the object, may or may not be able to connect to the Internet. (WhatIs.com)

  • segmented memory

    - Segmented memory is a system of addressing computer memory, which may be physical or virtual and may be operating in real or protected mode. The segmented memory system was used to expand the 64KB... (WhatIs.com)

  • Intel 8086

    - The Intel 8086 was Intel’s first x86 processor. Released in 1978, the 8086 began the long line of Intel’s most successful architecture, which eventually included the 80286, 80386 and 80486. (WhatIs.com)

Glossaries

  • Microprocessors

    - Terms related to microprocessors, including definitions about silicon chips and words and phrases about computer processors.

  • 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. Find an Answer.Powered by ITKnowledgeExchange.com

Ask An IT Question

Get answers from your peers on your most technical challenges

Ask Question

Tech TalkComment

Share
Comments

    Results

    Contribute to the conversation

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