David Butleradded May 26, 2019

This is the biggest most elaborate electronic kit that i have ever assembled. The Single Board Relay Computer, produced by Joe Allen around 2017, was an experiment in building a computer in which the main processing was done with electromechanical relays. While the numner entry and memory (ROM and RAM) use more modern parts in the form of PIC microcontrollers, the main processing relies on the 83 relays on the board (the little black AXICOM boxes. These make clicking noises whenever the system is processing, and the speed of processing can be adjusted. The board was also designed to allow the relays to go into standard 16 pin IC sockets for easy replacement.
The inspiration was Konrad Zuse's Z3 computer from 1941. It was the world's first programmable computer, and consisted of 2600 relays.
Im not entirely sure what i can do with it, as i only recently finished building it. Also, my unit has a problem in which the demo program gets stuck in a loop. I'm still investigating why this happening. However, my current power supply is only 12V at 1.2A. Joe Allen recommends at least 1.5A, so it may be that the relays are trying to draw more power than i can currently give. In addition to pictures of the board, i have included pictures of a serial terminal connection to this computer.
This kit was very expensive and time consuming. While i do recommend people try it out, it should not be the first kit for a beginner. The board itself is huge, and it is sold by Joe Allen on eBay and other sites for around $120. He does not sell finished kits He only includes the bare board and the two pre-programmed PIC microcontrollers. The rest of the parts should be obtained through other sources. I used both Digi-key and Mouser. Including shipping and taxes the parts cost me around $420. The big killer was the relays. They are around $1.50 to $2.50 apiece which sounds small until you have to buy at least 83 of them. It also took a few days with me spending a few hours each day.