@revk I've been around long enough to have used core memory systems (early GEC 4000 series). I had to do some bug fixing around switching the systems off and back on and continue running from where they were. The system power supplies were fun - on mains fail, the computer supply rails were crowbared in a strict sequence at the end of running the current instruction to prevent any core memory corruption during power down or subsequent power up.
I do have a PDP8 core memory card in the garage, although I never used PDP8s.
@AndrewG very cool. Modern chips also need some stupidly strict power rail up/down sequences, as we are finding in our current hardware designs - enough to make it worth a separate MCU with a chunk capacitor to manage them! I also had fun managing power up/down on an ASR-33 to avoid printing a gash character. That was fun too.