What you are looking at is the underside of 260 Omron type MY4 relays, which I intend to build a CPU out of. The wire has yet to arrive, but I have made three of the registers using recycled wire from old projects.
The CPU is going to be based off Harry Porter’s relay computer, but with quite a few modifications to simplify it. I’ve decided to leave the instruction set as is because I couldn’t think of any need for other instructions. I am going to attempt to make 4096 bits of core memory instead of using SRAM, because I feel that SRAM is cheating on vintage computing projects. I have set a date of 1955 to use for components, meaning that anything that is a functional part of the CPU needs to have been available in 1955. This means that I cannot use any ICs, and amplifiers needed for the core memory will have to be vacuum tube based. Silicon transistors were available in 1954, but I am going to try not to use them. Also, any component that I can make myself will be homemade. I figure that should make this much more interesting.
Why am I doing this?
The main reason is so I have something to keep me entertained. I figure that a project of this magnitude should keep me busy for at least six months. The second reason is so I can further my knowledge. I wanted to learn more about the inner workings of computers, and this is the only practical way to do so. The third and final reason is because it is awesome. A huge machine clicking away with hundreds of blinky lights is much more satisfying than building a transistor-based CPU.
My wire should arrive in the next few days, so stay tuned for more details and a video.
EDIT 7/5/2011: This project is still underway, but I haven’t had much chance to work on it due to another project. Once I finish my current project, I will finish this one.
For years, I have had a dream of building a computer entirely out of electromechanical relays, but I have always been too busy. Recently, I have had a lot of time on my hands, so I decided to start designing it. Ten hours, 36 SPDT relays, and countless wires later, I ended up with this contraption. It is capable of adding four bit numbers, and it actually gives the right answer. I know it isn’t the 8-bit, turing complete CPU of my dreams, but it’s a start. Once I snag a deal on some 4PDT relays, the real fun will begin.