I had the privilege of taking two classes with Dr Shapiro while I was in undergrad. The second class revolved around a related operating system named Coyotos. One of the most memorable classes was a 3 hour session where we worked through the boot sequence step by step [1]. The single lecture helped us all appreciate the delicate dance to bring up an x86 processor, a history lesson in the various features that had been bolted onto x86 over time, and a bunch of helpful debugging tips when your options are limited (it prints "Co" "yo" and "tos" in different stages!).

This was easily one of my most memorable lectures from undergrad, and it really helped to show me that even your operating system is just more software that you can read and understand.

1. https://github.com/vsrinivas/coyotos/blob/c68719b851e253aa11...