Memory module

In computing, a memory module or RAM stick is a printed circuit board on which memory integrated circuits are mounted.
Memory modules permit easy installation and replacement in electronic systems, especially computers such as personal computers, workstations, and servers. 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, and 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
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 RAM. Other parts of the computer, such as cache memories normally use static RAM. Small amounts of SRAM are sometimes used in the same package as DRAM. However, since SRAM has high leakage power and low density, die-stacked DRAM has recently been used for designing multi-megabyte sized processor caches.
Physically, most DRAM is packaged in black epoxy resin.

General DRAM formats

Dynamic random access memory is produced as integrated circuits 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 ISA expansion cards; later they were assembled into multi-chip plug-in modules. Some standard module types are:

DRAM chip
* Dual in-line Package
* Zig-zag in-line package
DRAM modules
* Single In-line Pin Package
* Single In-line Memory Module
* Dual In-line Memory Module
* Rambus In-line Memory Module, technically DIMMs but called RIMMs due to their proprietary slot.
* Small outline DIMM, about half the size of regular DIMMs, are mostly used in notebooks, small footprint PCs, upgradable office printers and networking hardware like routers.
* Small outline 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, 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
* 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 TSOP or the newer 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, this list is in roughly chronological order:

DIP 16-pin
SIPP 30-pin
SIMM 30-pin
SIMM 72-pin
DIMM 168-pin
DIMM 184-pin
RIMM 184-pin
DIMM 240-pin
DIMM 288-pin

Common SO-DIMM DRAM modules:

72-pin
144-pin used for SO-DIMM SDRAM
200-pin used for SO-DIMM DDR SDRAM and SO-DIMM DDR2 SDRAM
204-pin used for SO-DIMM DDR3 SDRAM
260-pin used for SO-DIMM DDR4 SDRAM
262-pin used for SO-DIMM DDR5 SDRAM

Memory module

Overview

General DRAM formats

Common DRAM modules