Memory module

Incomputing,amemory moduleorRAM stickis aprinted circuit boardon whichmemoryintegrated circuitsare mounted.

Two types of DIMMs (dual in-line memory modules): a 168-pinSDRAMmodule (top) and a 184-pinDDR SDRAMmodule (bottom).

Memory modules ofSK Hynix

Memory modules permit easy installation and replacement in electronic systems, especially computers such aspersonal computers,workstations,andservers.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 asJEDECand could be used in any system designed to use them.

Distinguishing characteristics of computer memory modules include voltage, capacity, speed (i.e.,bit rate), andform factor.

Overview

Types of memory module include:

• TransFlash Memory Module
• SIMM,a single in-line memory module
• DIMM,dual in-line memory module
  • Rambusmemory 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 ofdynamic RAM(DRAM). Other parts of the computer, such ascache memoriesnormally usestatic 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-stackedDRAM has recently been used for designing multi-megabyte sized processor caches.

Physically, most DRAM ispackagedin black epoxy resin.

General DRAM formats

A256 x 4Kibit20-pin DIP DRAM on an early PC memory card, usuallyIndustry Standard Architecture

Common DRAM packages. From top to bottom: DIP, SIPP, SIMM (30‑pin), SIMM (72‑pin), DIMM (168‑pin), DDR DIMM (184‑pin).

16GiBDDR4-2666 288-pin 1.2 VUDIMMs

Dynamic random access memory is produced asintegrated circuits(ICs)bondedand 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 themotherboardor onISAexpansion 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)
  • Dual In-line Memory Module (DIMM)
  • Rambus In-line Memory Module (RIMM), technicallyDIMMsbut 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 asMini-ITXmotherboards), 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 standard developed byDell,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 olderTSOPor the newerBGAstyle IC chips. Silicon dies connected with olderwire bondingor newer TSV.
  • Several proposed stacked RAM approaches exist, with TSV and much wider interfaces, including Wide I/O, Wide I/O 2,Hybrid Memory CubeandHigh 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-fast page mode DRAM(FPRAM))
• SIPP 30-pin (usually FPRAM)
• SIMM 30-pin (usually FPRAM)
• SIMM 72-pin (oftenextended data out DRAM(EDO DRAM) but FPRAM is not uncommon)
• DIMM168-pin (mostSDRAMbut some wereextended data out DRAM(EDO DRAM))
• DIMM 184-pin (DDR SDRAM)
• RIMM 184-pin (RDRAM)
• DIMM 240-pin (DDR2 SDRAMandDDR3 SDRAM)
• DIMM 288-pin (DDR4 SDRAMandDDR5 SDRAM)

Common SO-DIMM DRAM modules:

• 72-pin (32-bit)
• 144-pin (64-bit) used for SO-DIMMSDRAM
• 200-pin (72-bit) used for SO-DIMMDDR SDRAMand SO-DIMMDDR2 SDRAM
• 204-pin (64-bit) used for SO-DIMMDDR3 SDRAM
• 260-pin used for SO-DIMMDDR4 SDRAM
• 262-pin used for SO-DIMMDDR5 SDRAM