We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a SIMM?

By K. Powell
Updated May 17, 2024
Our promise to you
WiseGeek is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGeek, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

SIMM, which stands for single in line memory module, is a type of computer memory used in the x86 and Pentium family of computers, as well as selected laser printers. A SIMM consists of a small circuit board that holds from two to greater than 32 random access memory (RAM) chips and plugs into sockets that run an 8-bit or 32-bit bus. There are two distinct types: a 30-pin module for older x86 computers and a 72-pin module common in 486 and Pentium systems. Modules may contain parity or no parity.

The first SIMM module was created in 1983 by Wang Laboratories’ James Clayton and used exclusively in IBM PS/2 computers. Soon afterward, SIMMs became the standard for memory modules, replacing socketed DIP and SIPP memory chips which took up considerably more space on the motherboard. SIMMs were subsequently replaced by the dual in line memory module, or DIMM.

Of the two types of SIMMs, the older 30-pin module range in size from 256 kilobytes up to 16 Megabytes (MB). Each module provides for one byte, or 8 bits, plus one additional bit if parity chip is present, of data. In contrast, the 72-pin module can come in sizes from 1MB up to 2,048MB and provide four bytes, or 32 bits of data at a time. Two notches, one at the end and another in the middle, help guide the SIMM into the right location on the socket. Single-sided and double-sided configurations are available.

One of the primary differences between SIMMs and DIMMs lies in the location of the pins, or electrical contacts. The contacts along the front edge of a SIMM module are repeated again in the back. The contacts on DIMM modules differ for each side. Data path size is another notable difference between DIMMs and SIMMs. DIMMs use a 64-bit data path while SIMMs are limited to 32-bits. Finally, SIMMs must be installed in pairs to work correctly whereas only one DIMM module is required at a time.

Installing SIMMs as part of a computer memory upgrade is a fairly easy process. Always refer back to the technical manuals before performing any upgrades to verify the memory type.

First, turn off and unplug the computer. Remove the case and look for the memory slots on the motherboard. Dissipate extra static electricity by touching a metal object. Then, holding the memory module by the edges to avoid direct contact with the pins, insert the module into an empty socket at a 60° angle, and rotate it into place until the module is perpendicular to the motherboard. Replace the cover of the computer, reconnect the cables, and turn on the computer. In most cases, the system should recognize the new memory.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.