Core memory, magnetised memory using tiny magnetic rings suspended on a grid of wires, is now more than five decades obsolete, yet it exerts a fascination for hardware hackers still. Not least [Andy Geppert], who’s made a nibble, four bits of it, complete with interactive LED illumination to show state. Best of all, it’s on a SAO for fun and games on a badge.
Aside from it being a fun project, perhaps the most interesting part comes in the GitHub repository, where can be found the schematic for the device. He’s built all the drive and sense circuitry himself rather than finding an old-stock core memory driver chip, which gives those of us who’ve never worked with this stuff the chance to understand how it works. Beyond that it takes the a2c from the Stemma or SAO ports to a GPIO expander, which provides all the lines necessary to drive it all.
To show it in action he’s posted a video which we’ve placed below the break. Particularly interesting is the use of a magnet to flip bits, something we guess is obvious, but was new to us. If you’re hungry for more, it’s not [Andy]’s first outing into core memory.