Browse Definitions:
Definition

segmented memory

Contributor(s): Matthew Haughn

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 limit on first-generation flat address space. Computers made prior to segmented memory used a flat addressing system based on a four-digit hexadecimal code. With hexadecimal, the highest 4-digit number you can create is FFFF (or 65535), which equals 64KB.

Segmented memory addressing, the alternative to the flat scheme, is used in 16-bit systems such as MS-DOS Windows 3.1, to address 64KB segments of memory with an offset to specify within the segment.

The Intel 8086 processor generation was designed to address as much as 1MB of memory but was hampered by the limits of flat address space. Rather than redesign the entire memory system, Intel modified it to achieve the greater capacity through a two-part, compound 16-bit address.

The MMU (memory management unit) would then interpret the segment, as well as its offset, to find the physical address. Once the address was located, the MMU would enquire if the memory permissions allowed the request and, if they did, perform it.

Strictly speaking, flat address space used in 32-bit computing is actually segmented. However, the entire space is a single segment addressing the entirety of the 32-bit segment or 4GB memory space.

This was last updated in March 2014

Continue Reading About segmented memory

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

  • PCAOB (Public Company Accounting Oversight Board)

    The Public Company Accounting Oversight Board (PCAOB) is a Congressionally-established nonprofit that assesses audits of public ...

  • cyborg anthropologist

    A cyborg anthropologist is an individual who studies the interaction between humans and technology, observing how technology can ...

  • RegTech

    RegTech, or regulatory technology, is a term used to describe technology that is used to help streamline the process of ...

SearchSecurity

  • Advanced Encryption Standard (AES)

    The Advanced Encryption Standard, or AES, is a symmetric block cipher used by the U.S. government to protect classified ...

  • identity theft

    Identity theft, also known as identity fraud, is a crime in which an imposter obtains key pieces of personally identifiable ...

  • spear phishing

    Spear phishing is an email-spoofing attack that targets a specific organization or individual, seeking unauthorized access to ...

SearchHealthIT

SearchDisasterRecovery

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

  • mass notification system (MNS)

    A mass notification system is a platform that sends one-way messages to inform employees and the public of an emergency.

  • disaster recovery as a service (DRaaS)

    One approach to a strong disaster recovery plan is DRaaS, where companies offload data replication and restoration ...

SearchStorage

  • CIFS (Common Internet File System)

    CIFS (Common Internet File System) is a protocol that gained popularity around the year 2000, as vendors worked to establish an ...

  • GlusterFS (Gluster File System)

    GlusterFS (Gluster File System) is an open source distributed file system that can scale out in building-block fashion to store ...

  • virtual memory

    Virtual memory is a memory management capability of an OS that allows a computer to compensate for physical memory shortages by ...

SearchSolidStateStorage

  • Tier 0

    Tier 0 (tier zero) is a level of data storage that is faster, and perhaps more expensive, than any other level in the storage ...

  • PCIe SSD (PCIe solid-state drive)

    A PCIe SSD (PCIe solid-state drive) is a high-speed expansion card that attaches a computer to its peripherals.

  • SSD caching

    SSD caching, also known as flash caching, is the temporary storage of data on NAND flash memory chips in a solid-state drive so ...

SearchCloudStorage

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

  • Zadara VPSA and ZIOS

    Zadara Storage provides block, file or object storage with varying levels of compute and capacity through its ZIOS and VPSA ...

Close