X1 is a very small operating system meant to introduce students to low-level system programming. As a result, it focuses on clarity of explanation. It’s not meant to demonstrate state-of-the-art methods and algorithms, but rather simple, naive ones that do the job, while providing pointers and references to the more modern ways.
X1 was written with the help of Jerko Lenstra (Github page).
Matthew Leach uses X1 for his personal network stack project (Github page).
Source code : https://git.sceen.net/rbraun/x1.git/
GitHub mirror : https://github.com/richardbraun/x1