Making a Magnetic Core Memory USB Drive
Article excerpt
Some of us have felt somewhat nervous about the collapse of DRAM and NAND Flash memory supply in the consumer market, while others seem to have fully embraced it. Someone …read more
Some of us have felt somewhat nervous about the collapse of DRAM and NAND Flash memory supply in the consumer market, while others seem to have fully embraced it. Someone like [polymatt] for example, whose recent project entails a USB drive that skips back quite a few decades and opts to use a glorious 64-bit core memory device for storage.
To really embrace the DIY spirit here, the PCBs were milled using a small CNC router before the core memory was assembled alongside the other components, including apparently L293 H-bridge ICs as the drivers, along with an ESP32 module for the brains and USB interface.
Core memory relies on sensing the state of a cell through a destructive read action, which thus requires a fair bit of surrounding logic to set up read and writes, parse sense line values and restore any read value after said destructive read. Determining the right voltage to use during read and write actions is essential, and here determined experimentally.
The final build contains two PCBs inside an enclosure that’s filled with silicone oil. Other than looking cool through the acrylic window, it also helps to keep the individual cores at a fairly consistent temperature, which is helpful with reliable bit flipping, even if it’s probably overkill here.
Ignoring for a moment that just the memory required for the USB stack in the ESP32 module is many times the size of this core memory device, it’s still a very cool project whose appeal goes far beyond mere practicality.