It’s a certain kind of itch that drives people to voluntarily build their own CPU. We start thinking about the papered-over gap in our understanding, the one that lurks between how logic gates and flip-flops work individually and how machine code controls a fully assembled processor. What exactly happens in the magic zone where hardwired circuits start dancing to software’s ever-changing tune?
It turns out this itch afflicts enough people that there are commercial kits for makers who want to put a CPU together to see (or hear) it tick, and the Web is littered with home-brewed 4-bit and 8-bit CPUs with architectures that would be familiar to an engineer from the 1970s. I should know—I made one myself. But then I began to wonder: Could I build my own CPU featuring some of the latest technology? Could I design my own fully compliant 32-bit RISC-V central processing unit?