Dual In-line Memory Module

storage Small circuit boards carrying memory integratedcircuits, with signal and power pins on both sides of the

board, in contrast to single-in-line memory modules (SIMM).

The individual gold or lead connectors (pins) on SIMMs,

although they are on both sides of the chip, are connected to

the same memory chip, while on a DIMM, the connections on each

side of the module connect to different chips. This allows

for a wider data path, as more modules can be accessed at

once. DIMM pins are arranged in a zigzag design to allow PCB

tracks to pass between them.

The 8-byte DIMM format with dual-sided contacts can

accommodate 4- and 16-megabit dynamic RAM chips, and is

predicted to handle 64- and 256-Mbit devices. The 8-byte DIMM

will hold up to 32 megabytes of memory using 16-Mbit DRAMs,

but with the 256-Mbit future-generation DRAM, it will be able

to hold a 64-Mx64 configuration. Another variation, the

72-pin SO-DIMM, is designed to connect directly to 32 bit

data buses, and is intended for use in memory-expansion

applications in notebook computers.

A Dual in-line memory module (DIMM), as opposed to SIMMs (used

by the majority of the PC industry) allows for a 128-bit data

path by interleaving memory on alternating memory access

cycles. SIMMs on the other hand, have a 64-bit data path.

Suppliers are unanimous in their belief that the DIMM will

eventually replace the SIMM as the market's preferred memory

module.

(1996-01-28)