I really enjoy core memory, my PDP 8's have 24K words and 32K words. There is a great process for tuning the drivers in the PDP 8 maintenance manual which resul

I really enjoy core memory, my PDP 8's have 24K words and 32K words. There is a great process for tuning the drivers in the PDP 8 maintenance manual which results in a matched set of driver boards to a core-plane board. I built a small 4 bit (2 x 2) using #2 iron nuts and LM293D H-bridges as the drivers. The hysteresis band of the nuts was really small so it made it pretty unreliable sadly. Perhaps the most interesting fallout from core memory was the invention of FRAM which looks like a serial EEPROM (in 8 pin PDIPs) but are in fact small ferro-magnetic memories. Unlimited writes and all that.