What a massive project!!! Thousands of solder join. Need to take time after assemby to debug it. The PC bits relay and Carry are very sensitive and need to be switched with other at the begining for finding the perfect match. And after that if still some troubles , reduce speed to 4 or 3.
If you ever wanted to have or play with a relay based computer this is a good kit. It includes the computer PCB, programmed PIC chips (the other electronic components can be sourced via Digikey or Mouser). It well rounded with a single pass assembler, dis-assembler, and debugger. Input and output can be handled through the hex keypad and LED's, four bit relay I/O, in addition to TTL serial. It has a decent set of instructions and not hard to learn assembly with all of the built in tools. Its generally not a hard build, but I wouldn't recommend it for your first kit. The only real thing to watch for is some VIA's are close a couple of the components through-hole locations. Have patience double components polarity and verify solder joints, and you'll be fine. Overall a cool computer, and well worth the time to build and learn on... and its RELAY's need i say more :-)
This is a great little relay computer demonstrator! I got the bare board here on Tindie, ordered the parts from Mouser and Digi-Key directly from the BOM in the documentation, and had no trouble at all with the build. Awesome watching/listening to it click-clack away running calculations.