[Hasith] sent in this project where he goes through the process of designing a one instruction CPU in Verilog. It may not win a contest for the coolest build on Hack A Day, but we really do appreciate the “applied nerd” aspect of this build.
With only one instruction, an OISC is a lot simpler than the mess we have to deal with today. There are a few instructions that by themselves are Turing-complete (like Subtract and branch if negative, and Move). Designing an OISC with one of these instructions means it can also emulate a Turing machine.
[Hasith]’s build log goes through the entire process of building a fully functional computer – the ALU, program counter, instruction register and RAM. There’s even Verilog code if you want to try this out for yourself.
This isn’t the first time we’ve read about a one-instruction set computer. Years ago, we saw a hardware version of a subtract and branch if negative computer. [Hasith] plans another how-to post on how to write a small compiler for his OISC. [Hasith] seems like a pretty cool guy, so we’re hoping it’s not a Brainfuck compiler; we wouldn’t want him to take up a drinking habit.