There are a lot of designs out there of modern home made relay computers (not just ALUs but real computers -let's call them Turing complete, although Turing complete is not enough for having an operational usable machine nowadays-)
I'm looking for the absolute minimum modern/hobby/home-made relay computer in the relay retro computers known uniserse. I will be as specific as I can, since my project is very specific:
- By "pure" I mean no cheating with modern RAM chips, nor transistors. LEDs are acceptable (most of the designs I've seen use LEDs for output) but diode logic should be avoided. No modern oscillators.
- At least 4-bits as the size of its data words.
- I don't care about program word size if it's a Harvard architecture.
- If its a machine with very small amount of data memory it does not matter (a lot of microcontrollers a few years ago used to have 32 bytes of RAM and that was enough for some applications).
- It can even have a motorized clock (like old Harvard Mark computers, for example).
- By minimum, I'm measuring it in relay-count.
For example, the following computers are awesome, but look at their relay counts:
- https://hackaday.io/project/18599-brainfuckpc-relay-computer: 800 relays, but using a RAM IC (so it doesn't count).
- https://hackaday.com/2012/01/16/the-tim-8-is-the-smallest-8-bit-relay-computer-ever/: 152 relays
- http://web.cecs.pdx.edu/~harry/Relay/: 415 relays, although also using SRAM chip.
One more thing: I don't care about the amount of poles in the relays.
So does anyone know of the smallest one of this kind of machine? (I want to build it!). Thanks!