Single Inline Memory Module

What Does Single Inline Memory Module Mean?

Single inline memory module (SIMM) is a type of RAM (random access memory) that was popular in the early 1980s to late 1990s. SIMMs have 32-bit data paths and were standardized under the JEDEC JESD-21C standard. Non-IBM PC computers, UNIX workstations and the Mac IIfx used the non-standard SIMMS.


Techopedia Explains Single Inline Memory Module

Wang Laboratories invented and patented the SIMM in 1983. SIMMs with 30-pin variants were used in 386, 486, Macintosh Plus, Macintosh II, Quadra and Wang VS systems. The 72-pin variant was used in IBM PS/2, 486, Pentium, Pentium Pro and some Pentium II systems.

Dual inline memory module (DIMM) has replaced SIMM beginning with the Intel P-5 Pentium processors. SIMMs have redundant contacts on both sides of the module, whereas DIMMS have separate electrical contacts on each side. DIMMS have 64-bit data paths, as opposed to SIMMS which had 32-bit data paths. Intel Pentiums required that SIMMs be installed in pairs and DIMMs eliminated that requirement.


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Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…