The finished design is going to be quite big. It has to implement the 40 odd instructions of the RISC-V user level ISA as well as handle all the 32 bit data/address buses and connections. So creating it as a big breadboard project is out the window. No. We need to create some actual proper PCB designs that can then be connected together in a modular fashion.

So we need to use software to design the PCB and then have them manufactured. As a hobby project this needs to be a cheap service. So I have decided to use Eagle. If we stick to just 100mm x 80mm boards then the software is free. So that places a constraint on the maximum size on any of the boards we make. Looking at manufacturers I found a Chinese company called PCBWay that seems about the cheapest option. They can provide 100mm x 100mm boards at just $10 for 10 of them. Even when you factor in postage at $25 that is still only $35 for 10 boards of a professional quality. This is the cheapest way I can find and fits in with the hobby cost I can afford.

So all the components that make up the CPU need to be built from 100x80 PCB boards that can then be connected together using either simple ribbon cables or headers that directly plug together. In fact, this sounds ideal as each board can be designed and iterated quite cheaply until it works perfectly. All whilst keeping the cost down to a manageable level.