BOS or Basic Operating System is an attempt to make a very simple operating system from scratch. It started with a simple bootloader and after several weeks ended in a small operating system which does nothing more than accept text input and react to some commands. More functions will come (maybe) in the future
You will find here two main files.
One is the os folder which contains everything to compile the operating system.
The other one is the examples folder where you can find some examples of bootloaders.
First of all you can find a lot of information and examples with google. But my two main sources of information were Stackoverflow and this PDF
Probably not. But if you are interested in the basic functioning of an operating system I can only recommend such a project.