Tech moves fast! Stay ahead of the curve with Techopedia!
Join nearly 200,000 subscribers who receive actionable tech insights from Techopedia.
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.
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.