Yes, you're right. For my OS class when I was in school, instead of doing the proposed homework, I convinced the professor to let me do a x86 OS. We were a group of 3. I started doing everything in C with as little as assembly as possible, but the other two decidet to do an all-assembly little monster.

At the end of the course, we had only the boot loader and a little command interpreter, aside from FAT-12 support.

Then, much later, I messed with OS by playing with the code from the Minix Book [1].

Last year I wrote a little emulator for a virtually unknown architecture that can run uClinux on a modern browser (i.e., Chrome)[2].

[1] Operating System Design and Implemenation: http://www.amazon.com/Operating-Systems-Design-Implementatio...

[2] https://github.com/ubercomp/jslm32/