Magnetic core memory reborn

Core memory board (1960s)

Arduino core memory shield (2011)

Welcome! You have arrived at a website dedicated to the lost art of magnetic core memory manufacture. This site came about following our success building an Arduino-based magnetic core memory module.

Building a core memory shield was a great learning experience and a lot of fun, so we thought it would be worth writing up some details for anyone else who might like to do something similar. As well as the report, we provide all the resources (EAGLE files, gerber files, parts list, etc.) necessary to build this Arduino shield.

We couldn’t resist the temptation to publish our report on May 11th, 2011 — the 60th anniversary of the original core memory patent. Although the report contains everything you need to know to build the Arduino shield, there is a lot more we would like to say about our experience building the shield. We may one day post a more detailed build log.

We hope you enjoy reading about the core memory shield and would be delighted to hear any feedback.

Full report on the core memory shield[PDF]

Eagle files, Gerber files, parts list, and Arduino code for the boards

(Hardware design files licensed under the TAPR OHL; software under the GNU GPL; details in zip-file.)

News

• The core memory shield as a science project, by Joshua Silver (20250824)
• Another successful replication of the core memory shield, by Michael Seedman (20240928)
• Article in Make: magazine about the shield (20211021)
• Jussi Kilpeläinen's redesigned core memory shield (20160502, 20201112, 20241024)
• Successful replication of the core memory shield by two Italian students (20150729)

Other resources

• Philips Product Book "Magnetic Core Memories: What they are and how they function", giving a good description of the theory of operation, and containing some cool photographs of people constructing and testing core planes. Thanks to Ite Weide for sending on this link!
• Philips Data Handbook "Components and Materials" from June 1971. The "Memory Products" section (pp.9–285 of the PDF) is described as follows in its preface. "The following pages describe a complete range of memory products, from individual ferrite cores to complete assemblies comprising stacked matrix planes and their associated driving circuits. Cores with switching times ranging from 0·1µs to 10µs and cores with low temperature coefficients, as well as a complete selection of matrices based on these cores, are listed. Besides, relatively slow memories for industrial use as well as fast memories for computers are offered." Thanks to Ite Weide for sending on this link!
• Excerpt from a TI Series 74 Designers Manual from 1973, showing TI's range of specialised ICs for creating core memory modules. Lots of good circuit and construction details. Many thanks to Andy Warner for sending this on!
• Talk given by Jay Forrester on the Whirlwind Computer, including a section on memory systems in general, and core memory in particular, at around 36:20–50:00.
• The Amazing IBM 1620 Magnetic Core Memory Stack Design. Write-up of a circuit design for using an auxiliary switching core as a transformer to switch the actual memory cores.
• Our shield's page on Jonathan Oxer's Arduino Shield List.