Literature that explains operating system code

[SactoMike711]

My goal is to understand the operating system code that controls the console, or the hard drive, or the various peripherals, or all of the above. I think the most practical way of understanding such code would be to study FreeDos. Does anyone know of any literature in print, or on the internet, that explains exactly how such code functions?

Thanks

[nil]

I believe that you want to research "How to create a simple x86 32-bit bootloader."

From what I've read, start with 32-bit bootloader if you want to learn. The 64-bit is more advanced.

Here is a sample tutorial that was highly rated, and is fairly recent:

http://3zanders.co.uk/2017/10/13/writing-a-bootloader/

This one is also really neat, someone wrote a bootloader and video game, and it fits in a single tweet:

https://www.quaxio.com/bootloader_retro_game_tweet/