> no independent IO
I would challenge that! How is a smartcard different from a server in a qualitative sense? Both get all their I/O over the network.
Some cards even have a display, fingerprint reader, or can blink an LED (the latter unfortunately only indiscriminately when powered up, not in response to any computation, I'm afraid).
The interesting thing about this project is that this computer can function independently within a credit card sized space.
IO is of course required.
Perhaps the 'city block' heaters requiring similar sized AC condensors to provide control over Maxwell's daemon was the inspiration for the unix daemon process.
Optical computing makes fuzzy computations so much easier -> outgassing[2]
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[0] : https://spectrum.ieee.org/the-birth-of-ram
[1] : https://bunkerofdoom.com/lit/CRT-scopes/CRT_memory/index.htm...
[2] : https://spectrum.ieee.org/adhesive-outgassing-nasa-standards