Browse Definitions :
Definition

extended memory

Extended memory, also known as XMS (eXtended Memory Specification) is a technology that enables capacity above the 640KB standard MS-DOS limit of main memory.

Extended memory was introduced in the Intel 80286 processor, increasing the amount of addressable memory beyond what was introduced in the similarly named expanded memory (EMS). Prior to XMS, expanded memory was used to increase the 640KB upper limit of DOS to 1MB using a gated memory card riser.

Extended memory initially boosted the addressable memory to 16MB. XMS 2.0 extended the capacity to 64GB and XMS 3.0 to up to 4GB. Beyond XMS 3.0, AMD64, the de facto x86-64 standard, expands maximum memory to 256TB.

Programs written to use expanded memory would be redirected by driver emulation to use extended memory’s upper memory area instead. This process involved no special hardware, just increased RAM and support in the processor design.

Extended memory can only be addressed by software running in protected mode as all but the small portion of upper memory are unreadable by programs running in standard real mode.

Fun fact: The 640KB upper limit of DOS is the alleged source of the often-quoted but steadfastly denied Bill Gates statement: “640KB ought to be enough for anyone.”

This was last updated in February 2014

SearchCompliance

  • information governance

    Information governance is a holistic approach to managing corporate information by implementing processes, roles, controls and ...

  • enterprise document management (EDM)

    Enterprise document management (EDM) is a strategy for overseeing an organization's paper and electronic documents so they can be...

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

SearchSecurity

  • cyber espionage

    Cyber espionage, also called cyber spying, is a form of cyber attack that is carried out against a competitive company or ...

  • virus (computer virus)

    A computer virus is malicious code that replicates by copying itself to another program, computer boot sector or document and ...

  • honeypot (computing)

    A honeypot is a network-attached system set up as a decoy to lure cyber attackers and detect, deflect and study hacking attempts ...

SearchHealthIT

SearchDisasterRecovery

  • risk mitigation

    Risk mitigation is a strategy to prepare for and lessen the effects of threats faced by a business.

  • call tree

    A call tree is a layered hierarchical communication model that is used to notify specific individuals of an event and coordinate ...

  • Disaster Recovery as a Service (DRaaS)

    Disaster recovery as a service (DRaaS) is the replication and hosting of physical or virtual servers by a third party to provide ...

SearchStorage

  • dropout

    Dropout refers to data, or noise, that's intentionally dropped from a neural network to improve processing and time to results.

  • cloud storage

    Cloud storage is a service model in which data is transmitted and stored on remote storage systems, where it is maintained, ...

  • cloud testing

    Cloud testing is the process of using the cloud computing resources of a third-party service provider to test software ...

Close