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{{Short description|Printed circuit board for computer memory}}
[[File:DIMMs.jpg|frame|Two types of DIMMs (dual in-line memory modules): a 168-pin [[synchronous dynamic random access memory|SDRAM]] module (top) and a 184-pin [[DDR SDRAM]] module (bottom).]]

In [[computing]], a '''memory module''' or '''RAM stick''' is a [[printed circuit board]] on which [[Computer memory|memory]] [[integrated circuit]]s are mounted.<ref>Bruce Jacob, Spencer W. Ng, David T. Wang (2008). ''Memory Systems: Cache, DRAM, Disk''. Morgan Kaufmann Publishers. pp. 417–418.</ref>

Memory modules permit easy installation and replacement in electronic systems, especially computers such as [[personal computer]]s, [[workstation]]s, and [[Server (computing)|server]]s. The first memory modules were proprietary designs that were specific to a model of computer from a specific manufacturer. Later, memory modules were standardized by organizations such as [[JEDEC]] and could be used in any system designed to use them.

Distinguishing characteristics of computer memory modules include [[voltage]], capacity, speed (i.e., [[bit rate]]), and [[computer form factor|form factor]].

== Overview ==
Types of memory module include:
* [[TransFlash Memory Module]]
* [[SIMM]], a single in-line memory module
* [[DIMM]], dual in-line memory module
** [[Rambus]] memory modules are a subset of DIMMs, but are normally referred to as RIMMs
** [[SO-DIMM]], small outline DIMM, a smaller version of the DIMM, used in laptops
* [[CAMM (memory module)|Compression Attached Memory Module]], thinner than SO-DIMM

The large memories found in personal computers, workstations, and non-handheld game-consoles normally consist of [[Dynamic random-access memory|dynamic RAM]] (DRAM). Other parts of the computer, such as [[cache memory|cache memories]] normally use [[static RAM]]. Small amounts of SRAM are sometimes used in the same package as DRAM.<ref>{{cite web |date=21 July 1998 |title=Mitsubishi's 3D-RAM And Cache DRAM incorporate high performance, on-board SRAM cache |url=http://findarticles.com/p/articles/mi_m0EIN/is_1998_July_21/ai_50179297 |archiveurl=https://web.archive.org/web/20081224070955/http://findarticles.com/p/articles/mi_m0EIN/is_1998_July_21/ai_50179297 |archivedate=24 December 2008 |publisher=Business Wire}}</ref> However, since SRAM has high leakage power and low density, [[Three-dimensional integrated circuit|die-stacked]] DRAM has recently been used for designing multi-megabyte sized processor caches.<ref>S. Mittal et al., "[https://www.researchgate.net/publication/280577113_A_Survey_Of_Techniques_for_Architecting_DRAM_Caches A Survey Of Techniques for Architecting DRAM Caches]", IEEE TPDS, 2015</ref>

Physically, most DRAM is [[integrated circuit packaging|packaged]] in black [[Epoxy|epoxy resin]].

==General DRAM formats==
[[Image:256Kx4 DRAM.JPG|thumb|A {{nowrap|256 x 4}} [[Kibibit|Kibit]] 20-pin DIP DRAM on an early PC memory card, usually [[Industry Standard Architecture]]]]
[[Image:RAM n.jpg|thumb|Common DRAM packages. From top to bottom: DIP, SIPP, SIMM (30{{nbhyph}}pin), SIMM (72{{nbhyph}}pin), DIMM (168{{nbhyph}}pin), DDR DIMM (184{{nbhyph}}pin).]]
[[File:16 GiB-DDR4-RAM-Riegel RAM019FIX Small Crop 90 PCNT.png|thumb|16 [[Gibibyte|GiB]] DDR4-2666 288-pin 1.2 V [[UDIMM]]s]]
Dynamic random access memory is produced as [[integrated circuit]]s (ICs) [[adhesive|bonded]] and mounted into plastic packages with metal pins for connection to control signals and buses. In early use individual DRAM ICs were usually either installed directly to the [[motherboard]] or on [[Industry Standard Architecture|ISA]] expansion cards; later they were assembled into multi-chip plug-in modules (DIMMs, SIMMs, etc.). Some standard module types are:
* '''DRAM chip (Integrated Circuit or IC)'''
** Dual in-line Package ([[Dual in-line package|DIP]]/DIL)
** Zig-zag in-line package ([[Zig-zag in-line package|ZIP]])
* '''DRAM (memory) modules'''
** Single In-line Pin Package ([[SIPP memory|SIPP]])
** Single In-line Memory Module ([[SIMM]])
** Dual In-line Memory Module ([[DIMM]])
** Rambus In-line Memory Module ([[RDRAM|RIMM]]), technically [[DIMM]]s but called RIMMs due to their proprietary slot.
** Small outline DIMM ([[SO-DIMM]]), about half the size of regular DIMMs, are mostly used in notebooks, small footprint PCs (such as [[Mini-ITX]] motherboards), upgradable office printers and networking hardware like routers.
** Small outline RIMM (SO-RIMM). Smaller version of the RIMM, used in laptops. Technically SO-DIMMs but called SO-RIMMs due to their proprietary slot.
** Compression Attached Memory Module ([[CAMM (memory module)|CAMM]]), a standard developed by [[Dell]], which uses a land grid array instead of the more common edge connector.
* '''Stacked vis-à-vis non-stacked RAM modules'''
** {{anchor|Stacked RAM module}}Stacked RAM modules contain two or more RAM chips stacked on top of each other. This allows large modules to be manufactured using cheaper low density wafers. Stacked chip modules draw more power, and tend to run hotter than non-stacked modules. Stacked modules can be packaged using the older [[Thin small-outline package|TSOP]] or the newer [[Ball grid array|BGA]] style IC chips. Silicon dies connected with older [[wire bonding]] or newer TSV.
** Several proposed stacked RAM approaches exist, with TSV and much wider interfaces, including Wide I/O, Wide I/O 2, [[Hybrid Memory Cube]] and [[High Bandwidth Memory]].

==Common DRAM modules==
Common DRAM packages as illustrated to the right, from top to bottom (last three types are not present in the group picture, and the last type is available in a separate picture), this list is in roughly chronological order:
* DIP 16-pin (DRAM chip, usually pre-[[Dynamic_random-access_memory#Page_mode_DRAM|fast page mode DRAM]] (FPRAM))
* SIPP 30-pin (usually FPRAM)
* SIMM 30-pin (usually FPRAM)
* SIMM 72-pin (often [[#Extended data out DRAM (EDO DRAM)|extended data out DRAM]] (EDO DRAM) but FPRAM is not uncommon)
* [[DIMM]] 168-pin (most [[SDRAM]] but some were [[#Extended data out DRAM (EDO DRAM)|extended data out DRAM]] (EDO DRAM))
* DIMM 184-pin ([[DDR SDRAM]])
* RIMM 184-pin ([[RDRAM]])
* DIMM 240-pin ([[DDR2 SDRAM]] and [[DDR3 SDRAM]])
* DIMM 288-pin ([[DDR4 SDRAM]] and [[DDR5 SDRAM]])

Common SO-DIMM DRAM modules:
* 72-pin (32-bit)
* 144-pin (64-bit) used for SO-DIMM [[SDRAM]]
* 200-pin (72-bit) used for SO-DIMM [[DDR SDRAM]] and SO-DIMM [[DDR2 SDRAM]]
* 204-pin (64-bit) used for SO-DIMM [[DDR3 SDRAM]]
* 260-pin  used for SO-DIMM [[DDR4 SDRAM]]
* 262-pin  used for SO-DIMM [[DDR5 SDRAM]]

== References ==
{{reflist}}
{{DRAM}}

[[Category:Computer memory]]
[[Category:Modularity]]

Memory module - Revision history

imported>Dr. Abdullah Atiq: added a wiki link