I am wanting to create a functional OS from scratch like Terry A. Davis did that I can use on some raspberry pi/low powered device.That seems like a very rewarding process but I don't know where to start. If you recommend any materials it would be appreciated. I am limited in knowledge and understanding but I still would like to take a look. This is an example but I would like to see some more: https://samypesse.gitbooks.io/how-to-create-an-operating-system/
I want to go in deep with understanding which means understanding the hardware theory of it all as well. I know programming should come first- I can do that but I want to focus on creating a detailed timeline of this process/plan I have so I can actually see where I am relative to the goal.