Woven Rings Hold Data in This Hand-Built Magnetic Memory Module

Polymatt grew tired of watching memory prices climb. Instead of buying another expensive chip, he reached back to the 1960s and built storage the way engineers once did. Tiny ferrite rings now sit inside a compact case. Each ring stores one bit by holding a magnetic field in one direction or the other. Sixty-four rings together hold eight characters of text. Remove all power and the information stays exactly where it is.

The finished unit simply plugs into any modern computer using a standard USB cable, and you’re ready to go. You simply open that single file, type a few words or a short sentence, save it, and the rest is history. The text is then turned into magnetism patterns inside the rings, and when you view that file again later, the original characters seem exactly the same – there’s no end to this sort of thing.

The build began with a modest test board sporting only one ring. Polymatt then ran two drive wires and one sense wire through it before firing a current pulse through the drive wires and watching an oscilloscope for a slight voltage fluctuation on the sense wire. When he saw that tiny spike, he realized the ring had changed its magnetic condition. That was a watershed moment; only after he’d established the proper voltage and timing did he consider spreading it to the entire array.

The rings were made from recycled Soviet equipment. Each ring received three wires; horizontal lines crisscrossed an 8 by 8 grid in one direction, while vertical lines did the same in the opposite direction. A single sensing wire wound its way through every ring. To modify a specific ring, the electronics would send half the required current down one horizontal line and half down a vertical line, with just the ring where those two lines intersect receiving the entire dose and switching state. Every other ring stays in place, but threading all those wires through the matrix was no easy process, requiring sewing needles and lengthy stretches of precise, tedious work. Wires were passed through the center hole and around the outer edge one ring at a time, following a specific pattern. Once the entire grid was threaded, it was placed on a special circuit board. The motor driver chips handle the real current pulses used for writing and reading.

The translation layer is powered by an ESP32 microcontroller. When you save that text file, it converts each character to binary and determines which rings need to point north or south, then sends the command to the drivers to fire off the exact pulses required, and when you read it, it works in reverse, with the chip looking at the state of each ring through the sense wire and a tiny amplifier that boosts the faint signals. The data is subsequently transferred back to the text file displayed on screen.

Because temperature fluctuations can cause problems with the rings, the board and matrix are coated with clear silicone oil. The oil acts as a heat buffer, allowing you to keep the ideal switching pattern. Finally, everything is held together in a 3D printed container with clear windows that show the complete woven structure. Two printed circuit boards were assembled by hand to support the full electronics system. One board holds the core array and driving bits, while the other houses the ESP32, power regulation, and sensing amplifier.

The finished device can store those 8 characters all by itself, without the need for a battery or flash memory. If you turn off the power, the data remains entirely intact and appears exactly the same on the next read. The experiment emphasizes how much effort and elbow grease once went into even the smallest bits of computer memory. Modern components such as the ESP32 and USB interface are essentially a nicely packaged version of the previous magnetic technology that now plugs directly into a laptop or desktop computer.
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