Andy Geppert's Core 64 Interactive Core Memory Boards Get a Final Design and 3D-Printed Weaving Jig

Designed to bring back a classic from the early days of computing in interactive form, the new Core 64 boards will form a stack eight deep.

Gareth Halfacree
4 years agoRetro Tech

Andy Geppert has unveiled the latest entry in the Core 64 family, a range of badge boards designed to bring back a classic of early computing: hand-woven magnetic core memory.

While modern computers and microcontrollers run from dynamic RAM, static RAM, flash RAM, or most commonly a combination thereof, that technology wasn't always available. Early computers had to rely on other forms of random access memory, with one of the most widespread being magnetic core — toroidal magnets suspending in a hand-woven grid of copper wire.

Today, the only time a programmer will likely be reminded of magnetic core memory is when a system saves a "core dump" — unless you're Andy Geppert, who's been bringing the technology back with the Core 64 family of interactive badges powered by hand-woven magnetic core.

The Core 64 design centers around making the core memory a form of user interface: A grid of magnetic cores are suspended over an LED matrix, and the user "draws" with a magnetic stylus — flipping each toroidal bit as the stylus tip passes over and lighting up the LED that lies beneath.

"This what I think will be the final core board configuration," Geppert writes of the latest design. "All of the functionality is tested, except I haven't physically made a core stack yet. I'm happy with the ambient light sensor and Hall sensor 'buttons' hiding under M - + S. The layer select function works well too, composed of solder jumpers and the two big chips.

"I'm also quite happy with the weaving in this one. This is my best one yet thanks to a 3D-printed assembly fixture. The fixture helps guide the sense wire crisply. My vision of making the cores easier to thread by placing the fixture on from both sides of the PCB has not yet been realized, but manually weaving plane isn't too bad... after some practice on the first two."

While Geppert has already demonstrated earlier prototypes working in a simple single-board two-dimensional fashion, his vision is larger: Putting eight of the boards together into a core memory stack which will allow for 3D art and visualization. "This board WILL have the ability to drive all 8 layers of core planes," he explains, "and that is going to be fun when I get all the core planes visualized in real-time on an LCD!"

More details on the project, including the latest design, can be found on the Core 64 page.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire:
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