KolibriOS – operating system written entirely in assembly language
I don't mean this as a slight because I love the project and other light fast OSes... but with modern compilers, what does assembly get you over just using C or another language and having it handle the translation? I was under the impression compilers nowadays have lots of optimizations that would take a lot of work for a human to do by hand, as well as creating less readable/maintainable code.