[Dr. Cockroach]’s goal was to build a four-bit computer out of recycled and repurposed junk. The resulting computer, called IO, consists of a single 555, around 230 PNP and NPN transistors, 230 diodes, and 460 resistors. It employs RISC architecture and operates at a speed of around 3 Hz.
He built IO out of cardboard for a good reason: he didn’t have a big budget for the project and he could get the material for free from his workplace. And because it was built so cheaply, he could also build it really big, allowing him to be able to really see each circuit close up and repair it if it wasn’t working right. You can really see the architecture very well when it’s this big—no tangle of wires for [Dr. Cockroach]. He uses over sixty blue LEDs to help monitor the system, and it doesn’t hurt that they look cool too. One of our favorite parts of the project is how he used copper fasteners to both manage the cardboard and serve as wiring points.