Anyone who really wants to dig into this, and is willing to be a bit scared, should review the materials for the 15-410 operating systems course at Carnegie Mel

Anyone who really wants to dig into this, and is willing to be a bit scared, should review the materials for the 15-410 operating systems course at Carnegie Mellon University. The fall edition of the page isn't up yet but there are probably some older versions kicking around. If you are at CMU you should definitely take this course, as long as your pain tolerance is high. This course teaches students to write a preemptive operating systems kernel from scratch. It is quite an experience (I TA'd it after finishing my PhD while trying to figure out what to do next). The kernels the students wrote used to be able to boot on standard (but old) PC hardware. Sadly the modern USB stack is so complex that a conformant thing to talk to a USB keyboard is pretty much as complex as the student's whole project (but less educational). So non-legacy hardware that lacks a PS/2 keyboard no longer has this nice easy path to read/write stuff to console without a lot of setup.