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 from 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 Magnetic Drum?

By H.R. Childress
Updated May 17, 2024
Our promise to you
About Mechanics 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 About Mechanics, 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.

Two different types of equipment are referred to as magnetic drums. One type is a data storage device used in early computers, also known as drum memory. The other is a magnetic drum separator, a tool used in the recycling industry to separate metals from other materials.

The magnetic drum used for computer memory was invented in 1932. It was the main working memory in most computers during the 1950s and 1960s. Core memory, the forerunner of random access memory (RAM), gradually replaced drum memory as the primary memory, though magnetic drums continued to be used as secondary storage for a while.

In the computer industry, a magnetic drum consisted of a hollow metal cylinder covered with a magnetizable material. Read and write heads recorded data on the drum as it rotated by emitting electromagnetic pulses to magnetize tiny spots to record a binary value of zero or one. The same heads could "read" the recorded data by sensing the magnetized spots. A drum surface was divided into tracks and sectors so users could indicate where information should be stored and avoid writing over previous data.

Compared to more modern storage methods, magnetic drums could store a very small amount of data. A drum that was 4 inches (about 10 cm) in diameter and 8 inches (about 20 cm) long could hold about 500 bits. There are eight bits in a byte, the basic unit of digital information, so the drum could hold about 62 bytes. Most computer memory in the early 21st century is measured in gigabytes, a unit of 10^6 bytes. Drum storage was many orders of magnitude smaller than its modern counterparts, but it was the standard type of memory for early computers.

In the recycling industry, a magnetic drum separator may be used to help sort materials. Recycled materials are fed through a chute at either the top or bottom of the drum. The metal scraps stick to the drum, while the other, non-magnetic materials fall out of the drum. The drums are designed so that one side is constantly magnetized, while the other is not; when the metal scraps get to the non-magnetized side, they drop off to a different location than the other materials.

Magnetic drum separators consist of a rotating magnetic cylinder that can capture the metal coming through. To attract the metal scraps, they may use electromagnetic circuits; magnetic fields; or rare earth materials, which are a group of magnetic metals. Magnetic drum separators come in a variety of sizes to accommodate varying volumes of materials.

About Mechanics 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

About Mechanics, in your inbox

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

About Mechanics, in your inbox

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