It’s been a really long time since I did any work on my Relay Computer (older posts here). In fact, it’s been almost 2 years. For whatever reason I finally got inspired again and I got back to work. The next step was to start laying out the actual schematic for the ALU. So I chose a PCB manufacturer pretty much at random and downloaded their toolkit and started building out the schematic.
My vision is to have 4 identical boards each filled with an identical copy of the 1 Bit ALU. Once they are all wired together I will then have the 4bit ALU module which will be the heart of my Relay Computer. So I needed to come up with a design for the PCB. Step one in the PCB creation process is to have an actual schematic mapped out with all the connections between all the components that will be on the board. In my case the only component is the relay I chose so setting up the software was pretty easy. I just had to draw out one relay component and then start wiring them all up and placing them in an organized layout. The schematic took up 5 pages. Here they are if you’re curious : ALU-a ALU-b ALU-c ALU-d ALU-e .
Next up, I needed to make sure my schematic was good so I had to whip out the breadboard and start building the circuit. It was surprisingly easy work and there were only a couple of bugs in the schematic (very minor ones and they aren’t reflected in the PDFs above). Here are a few pics of the building as it was progressing along.
Next I needed to wire up some simple switches and an LED array for the output and then I needed to test it all out. Once I was done I made a little video for you all to see. Until next time!