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dynamic RAM
main memory
tag RAM
Von Neumann machine

Pronounced ramm, acronym for random access memory, a type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the preceding bytes. RAM is the most common type of memory found in computers and other devices, such as printers.

There are two basic types of RAM:

  • dynamic RAM (DRAM)
  • The two types differ in the technology they use to hold data, dynamic RAM being the more common type. Dynamic RAM needs to be refreshed thousands of times per second. Static RAM does not need to be refreshed, which makes it faster; but it is also more expensive than dynamic RAM. Both types of RAM are volatile, meaning that they lose their contents when the power is turned off.

    In common usage, the term RAM is synonymous with main memory, the memory available to programs. For example, a computer with 8M RAM has approximately 8 million bytes of memory that programs can use. In contrast, ROM (read-only memory) refers to special memory used to store programs that boot the computer and perform diagnostics. Most personal computers have a small amount of ROM (a few thousand bytes). In fact, both types of memory (ROM and RAM) allow random access. To be precise, therefore, RAM should be referred to as read/write RAM and ROM as read-only RAM.

    For pages about RAM, . Also, check out the following links!

    More Information

    Outstanding Page A Guide to RAM
    Discusses how memory works, what applications use the most of it, how to shop for it., and how to install it.

    Outstanding Page Building Your Own PC
    What hard-core techies and companies like Dell and Compaq have been doing for years is what any computer user can learn how to do - build a computer from scratch. Let SE take you on a stroll through the park and ease the pain of building a DIY PC.

    Outstanding Page DRAM: The Next Generation
    Excellent article (June, 1997) from Computer Shopper that describes all the current varieties of DRAM, as well as future architectures, including Rambus. Updated on May 12, 1998

    Outstanding Page Kingston Memory Guide
    Home page of a detailed site that described how memory works and discusses the differences between different types of memory. Includes descriptions of SIMMS, DIMMS, EDO DRAM, SDRAM, and more.

    Outstanding Page RAM information page
    This site hosts an extensive collection of information on RAM. Included are explanations on the different types of RAM, with links to related sites. Updated on Aug 4, 1998

    Outstanding Page System Memory Overviews
    Describes memory technology types, memory speed, access and timing, DRAM technologies, memory size and packaging, errors, detection and correction, and logical memory layout. This page is from "The PC Guide".

      A RAM Primer
    PC Magazine tutorial article that presents a description of the various types of RAM. Also contains an explanation of how RAM works, as well as the relationship between RAM and the CPU. Updated on Aug 4, 1998

      An Illustrated Guide to RAM
    Describes what RAM is and includes a brief explanation of DRAM types. Also provides descriptions for SIMMs, DIMMs, PC100 RAM, Rambus and DDR RAM.

      Installing RAM
    Explains each of the five categories of RAM chips for PCs with a section on problems associated with RAM and possible solutions. Updated on May 20, 1998

      Logical Memory Layout
    Describes how memory is allocated and how it is used within the PC. This page is from "The PC Guide".

      Memory Speed, Access and Timing
    Describes how the system memory works. Includes details on how memory is accessed and important issues related to system timing. This page is from "The PC Guide".

      Memory Technology Types
    Describes the main types of memory used in PCs (ROM, RAM, SRAM, and DRAM) and how they differ from each other. This page is from "The PC Guide".

      Parity FAQ
    Answers common questions about parity and ECC SIMMs. Updated on Mar 5, 1998

      PC Guide's system memory reference
    Extensive reference covering the system memory. Covers technology types, memory speed and timing, packaging, error detection and correction, and the logical memory layout.

      SDRAM vs. RDRAM, Facts and Fantasy
    In-depth analysis of Rambus' RDRAM aims to find its technological advantages and disadvantages, as well as reach a verdict on the SDRAM vs. RDRAM issue.

      Ultimate Memory Guide - How Memory Works
    Describes how memory works and the main differences between different varieties of memory modules, including SIMMs, DIMMs, and SO DIMMs.



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