Incandescent RAM - Refresh Circuit functions-ish!
Incandescent Light Bulbs have a sort of "Memory," in that their resistance increases dramatically with heat.
Here I've made a circuit that stores 4 bits of binary data in lightbulbs!
This circuit measures the resistance of each of four bulbs in sequence to determine whether they're hot (1) or cold (0), then "Refreshes" them so their "value" can be stored indefinitely, requiring fewer relays than data bits.
DRAM, as used in modern computers, works similarly. Instead of storing bits in lightbulbs, they store bits in capacitors. Those capacitors eventually lose their charge, so must be refreshed regularly, just as I've done, here.
Capacitors large-enough to trigger relays like this would be quite large, and lightbulbs come in many sizes! I imagine "grain of wheat" bulbs, or certainly festive string-lights, could store quite a bit of data, rivalling early magnetic core memory in density, but 100 years earlier!
If you're curious, I've got a few more vids on Incandescent RAM! And many writings which can be found alongside the Schematics and thoughts for this one at https://hackaday.io/project/162351-in...