I can heartedly recommend this one NandToTetris.

In this course gives you a complete understanding of how computers and programming qorks from first principle.

You’ll start by (virtually) making chips with just a nand chip, than you’ll make a cpu, ram and rom, evetually on to a full fletched computer. Than you’ll write your own assembly language, parser and compiler for that computer. You’ll write your own OS and your own higher level language (OOP) and eventually you’ll write a geme (tetris) in that language.

This is of course all very simplified, but very educational.