I got some serious deja vu reading that source code by the way. 24 years ago, as my senior year project I decided I would try to build a DOS-like OS that could boot from a floppy. I didn't get very far beyond a rudimentary CLI, some fun builtin commands and the beginnings of a FAT-like file system...

"hey, I made something that could boot from a 1981 PC, from scratch, and I understood it all the way.".

That's a pretty nice feeling - I think you probably felt the same way?