A fun overview of basic operating system development: https://stackoverflow.com/questions/22054578/how-to-run-a-program-without-an-operating-system/32483545#32483545
Related Posts
Today I learnt that the original name for DOS was QDOS, for "Quick and Dirty Operating System"! https://en.wikipedia.org/wiki/DOS#QDOS
(Seems rather unfortunate that they dropped the Q.)
Blogging about my programming language project: choosing the basic syntax!
https://www.garden-lang.org/blog/syntax.html
Learning software development through playing and contributing to a MUD: https://tashian.com/articles/how-i-learned-to-program/