![DIMMs](https://upload.wikimedia.org/wikipedia/commons/b/bc/DIMMs.jpg)
In
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, e ...
, a memory module or RAM (
random-access memory
Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A Random access, random-access memory device allows data items to b ...
) stick is a
printed circuit board
A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in Electrical engineering, electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a L ...
on which
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
integrated circuit
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
s are mounted. Memory modules permit easy installation and replacement in electronic systems, especially computers such as
personal computer
A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...
s,
workstation
A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating systems. The term ''workstat ...
s, and
server
Server may refer to:
Computing
*Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients
Role
* Waiting staff, those who work at a restaurant or a bar attending customers and su ...
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
The JEDEC Solid State Technology Association is an independent semiconductor engineering trade organization and standardization body headquartered in Arlington County, Virginia, United States.
JEDEC has over 300 members, including some of the w ...
and could be used in any system designed to use them.
Types of memory module include:
*
TransFlash Memory Module
Secure Digital, officially abbreviated as SD, is a proprietary non-volatile flash memory card format developed by the SD Association (SDA) for use in portable devices.
The standard was introduced in August 1999 by joint efforts between SanDis ...
*
SIMM
A SIMM (single in-line memory module) is a type of memory module containing random-access memory used in computers from the early 1980s to the early 2000s. It differs from a dual in-line memory module (DIMM), the most predominant form of memory ...
, a single in-line memory module
*
DIMM
A DIMM () (Dual In-line Memory Module), commonly called a RAM stick, comprises a series of dynamic random-access memory integrated circuits. These memory modules are mounted on a printed circuit board and designed for use in personal compute ...
, dual in-line memory module
**
Rambus
Rambus Incorporated, founded in 1990, is an American technology company that designs, develops and licenses chip interface technologies and architectures that are used in digital electronics products. The company is well known for inventing RDR ...
memory modules are a subset of DIMMs, but are normally referred to as RIMMs
**
SO-DIMM
A DIMM () (Dual In-line Memory Module), commonly called a RAM stick, comprises a series of dynamic random-access memory integrated circuits. These memory modules are mounted on a printed circuit board and designed for use in personal computers, ...
, small outline DIMM, a smaller version of the DIMM, used in laptops
Distinguishing characteristics of computer memory modules include voltage, capacity, speed (i.e.,
bit rate
In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time.
The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction w ...
), and
form factor.
For economic reasons, the large (main) memories found in personal computers, workstations, and non-handheld game-consoles (such as PlayStation and Xbox) normally consist of dynamic RAM (DRAM). Other parts of the computer, such as
cache memories normally use
static RAM
Static random-access memory (static RAM or SRAM) is a type of random-access memory (RAM) that uses latching circuitry (flip-flop) to store each bit. SRAM is volatile memory; data is lost when power is removed.
The term ''static'' differen ...
(
SRAM). 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.
[S. Mittal et al., ]
A Survey Of Techniques for Architecting DRAM Caches
, IEEE TPDS, 2015
Physically, most DRAM is
packaged in black epoxy resin.
General DRAM formats
![16 GiB-DDR4-RAM-Riegel RAM019FIX Small Crop 90 PCNT](https://upload.wikimedia.org/wikipedia/commons/8/85/16_GiB-DDR4-RAM-Riegel_RAM019FIX_Small_Crop_90_PCNT.png)
Dynamic random access memory is produced as
integrated circuit
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
s (ICs)
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
A motherboard (also called mainboard, main circuit board, mb, mboard, backplane board, base board, system board, logic board (only in Apple computers) or mobo) is the main printed circuit board (PCB) in general-purpose computers and other expand ...
or on
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 (
DIP/DIL)
** Zig-zag in-line package (
ZIP)
* DRAM (memory) modules
** Single In-line Pin Package (
SIPP)
** Single In-line Memory Module (
SIMM
A SIMM (single in-line memory module) is a type of memory module containing random-access memory used in computers from the early 1980s to the early 2000s. It differs from a dual in-line memory module (DIMM), the most predominant form of memory ...
)
** Dual In-line Memory Module (
DIMM
A DIMM () (Dual In-line Memory Module), commonly called a RAM stick, comprises a series of dynamic random-access memory integrated circuits. These memory modules are mounted on a printed circuit board and designed for use in personal compute ...
)
** Rambus In-line Memory Module (
RIMM), technically
DIMM
A DIMM () (Dual In-line Memory Module), commonly called a RAM stick, comprises a series of dynamic random-access memory integrated circuits. These memory modules are mounted on a printed circuit board and designed for use in personal compute ...
s but called RIMMs due to their proprietary slot.
** Small outline DIMM (
SO-DIMM
A DIMM () (Dual In-line Memory Module), commonly called a RAM stick, comprises a series of dynamic random-access memory integrated circuits. These memory modules are mounted on a printed circuit board and designed for use in personal computers, ...
), about half the size of regular DIMMs, are mostly used in notebooks, small footprint PCs (such as
Mini-ITX
Mini-ITX is a motherboard form-factor, developed by VIA Technologies in 2001. They are commonly used in small-configured computer systems. Originally, they were a niche product, designed for fan-less cooling with a low power consumption archit ...
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), a proprietary
Dell
Dell is an American based technology company. It develops, sells, repairs, and supports computers and related products and services. Dell is owned by its parent company, Dell Technologies.
Dell sells personal computers (PCs), servers, data ...
format which they expect to be adopted as a standard.
* Stacked vs. 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
Wire bonding is the method of making interconnections between an integrated circuit (IC) or other semiconductor device and its packaging during semiconductor device fabrication. Although less common, wire bonding can be used to connect an IC ...
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
High Bandwidth Memory (HBM) is a high-speed computer memory interface for 3D-stacked synchronous dynamic random-access memory (SDRAM) initially from Samsung, AMD and SK Hynix. It is used in conjunction with high-performance graphics accelerators ...
.
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):
* DIP 16-pin (DRAM chip, usually pre-
fast page mode DRAM (FPRAM))
* SIPP 30-pin (usually FPRAM)
* SIMM 30-pin (usually FPRAM)
* SIMM 72-pin (often
extended data out DRAM
Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access memory, random-access semiconductor memory that stores each bit of data in a memory cell (computing), memory cell, usually consisting of a tiny capacitor and a tr ...
(EDO DRAM) but FPRAM is not uncommon)
*
DIMM
A DIMM () (Dual In-line Memory Module), commonly called a RAM stick, comprises a series of dynamic random-access memory integrated circuits. These memory modules are mounted on a printed circuit board and designed for use in personal compute ...
168-pin (most
SDRAM
Synchronous dynamic random-access memory (synchronous dynamic RAM or SDRAM) is any DRAM where the operation of its external pin interface is coordinated by an externally supplied clock signal.
DRAM integrated circuits (ICs) produced from the ...
but some were
extended data out DRAM
Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access memory, random-access semiconductor memory that stores each bit of data in a memory cell (computing), memory cell, usually consisting of a tiny capacitor and a tr ...
(EDO DRAM))
* DIMM 184-pin (
DDR SDRAM
Double Data Rate Synchronous Dynamic Random-Access Memory (DDR SDRAM) is a double data rate (DDR) synchronous dynamic random-access memory (SDRAM) class of memory integrated circuits used in computers. DDR SDRAM, also retroactively called DDR1 ...
)
* RIMM 184-pin (
RDRAM
Rambus DRAM (RDRAM), and its successors Concurrent Rambus DRAM (CRDRAM) and Direct Rambus DRAM (DRDRAM), are types of synchronous dynamic random-access memory (SDRAM) developed by Rambus from the 1990s through to the early 2000s. The third-generati ...
)
* DIMM 240-pin (
DDR2 SDRAM
Double Data Rate 2 Synchronous Dynamic Random-Access Memory (DDR2 SDRAM) is a double data rate (DDR) synchronous dynamic random-access memory (SDRAM) interface. It superseded the original DDR SDRAM specification, and was itself superseded by DDR3 ...
and
DDR3 SDRAM
Double Data Rate 3 Synchronous Dynamic Random-Access Memory (DDR3 SDRAM) is a type of synchronous dynamic random-access memory (SDRAM) with a high bandwidth (" double data rate") interface, and has been in use since 2007. It is the higher-speed ...
)
* DIMM 288-pin (
DDR4 SDRAM
Double Data Rate 4 Synchronous Dynamic Random-Access Memory (DDR4 SDRAM) is a type of synchronous dynamic random-access memory with a high bandwidth (" double data rate") interface.
Released to the market in 2014, it is a variant of dynamic rand ...
)
Common SO-DIMM DRAM modules:
* 72-pin (32-bit)
* 144-pin (64-bit) used for SO-DIMM
SDRAM
Synchronous dynamic random-access memory (synchronous dynamic RAM or SDRAM) is any DRAM where the operation of its external pin interface is coordinated by an externally supplied clock signal.
DRAM integrated circuits (ICs) produced from the ...
* 200-pin (72-bit) used for SO-DIMM
DDR SDRAM
Double Data Rate Synchronous Dynamic Random-Access Memory (DDR SDRAM) is a double data rate (DDR) synchronous dynamic random-access memory (SDRAM) class of memory integrated circuits used in computers. DDR SDRAM, also retroactively called DDR1 ...
and SO-DIMM
DDR2 SDRAM
Double Data Rate 2 Synchronous Dynamic Random-Access Memory (DDR2 SDRAM) is a double data rate (DDR) synchronous dynamic random-access memory (SDRAM) interface. It superseded the original DDR SDRAM specification, and was itself superseded by DDR3 ...
* 204-pin (64-bit) used for SO-DIMM
DDR3 SDRAM
Double Data Rate 3 Synchronous Dynamic Random-Access Memory (DDR3 SDRAM) is a type of synchronous dynamic random-access memory (SDRAM) with a high bandwidth (" double data rate") interface, and has been in use since 2007. It is the higher-speed ...
* 260-pin used for SO-DIMM
DDR4 SDRAM
Double Data Rate 4 Synchronous Dynamic Random-Access Memory (DDR4 SDRAM) is a type of synchronous dynamic random-access memory with a high bandwidth (" double data rate") interface.
Released to the market in 2014, it is a variant of dynamic rand ...
* 262-pin used for SO-DIMM
DDR5 SDRAM
Double Data Rate 5 Synchronous Dynamic Random-Access Memory (DDR5 SDRAM) is a type of synchronous dynamic random-access memory. Compared to its predecessor DDR4 SDRAM, DDR5 was planned to reduce power consumption, while doubling bandwidth. The ...
References
{{reflist
Computer memory
Modularity