DIMMs (Dual In-line Memory Module) were a 1990s upgrade for SIMMs (Single In-line Memory Modules) as Intel P5-based Pentium processors began to gain market share. The Pentium … See more

There are numerous DIMM variants, employing different pin-counts:
DIMM 100-pin: printer SDRAM and printer ROM (e.g., PostScript) 168-pin: SDR SDRAM, sometimes used for FPM/EDO DRAM in workstations or servers, may be 3.3 or 5 V 184-pin: … See more

On the bottom edge of 168-pin DIMMs there are two notches, and the location of each notch determines a particular feature of the module. The first notch is the DRAM key position, which represents RFU (reserved future use), registered, and unbuffered See more

ECC DIMMs are those that have extra data bits which can be used by the system memory controller to detect and correct errors. There are numerous ECC schemes, but … See more

A SO-DIMM (pronounced "so dim" /ˈsoʊdɪm/, also spelled SODIMM) or small outline DIMM, is a smaller alternative to a DIMM, being roughly half the physical size of a regular DIMM. … See more

DDR, DDR2, DDR3, DDR4 and DDR5 all have different pin counts and/or different notch positions, and none of them are forward compatible See more

A DIMM's capacity and other operational parameters may be identified with serial presence detect (SPD), an additional chip which contains information about the module type and … See more