It’s been two years since I started working as a software engineer. I sometimes tell my colleagues about a student project I did in my junior year of university, and it’s so well-received that I’m writing this post.

Now, let me ask you a question. Have you ever designed your own ISA, built a processor of that ISA on FPGA, and built a compiler for it? Furthermore, have you run an operating system on that processor? Actually, we have.

In this post, I’m going to talk about my undergraduate days in 2015, our four months of building a home-built CPU of a home-built RISC ISA, building a home-built C toolchain, and porting Xv6, a Unix-like OS, to that CPU.