Yeah, I guess it depends on what legacy you're willing to part from. Something like https://www.amazon.com/Elements-Computing-Systems-Building-Principles/dp/02

Yeah, I guess it depends on what legacy you're willing to part from. Something like https://www.amazon.com/Elements-Computing-Systems-Building-Principles/dp/0262640686/ https://www.amazon.com/Elements-Computing-Systems-Building-P... is not hard, but it's arguably a toy system. IMO Project Oberon starts from the same principles and builds up to a productive enironment including text processing, a compiler, very basic hypertext, basic networking and hardware to run it on.