Ben Eater's Youtube series "Building an 8-bit Breadboard Computer" is a really good introduction to the lowest levels of how a computer works: https://www.youtube.com/playlist?list=PLowKtXNTBypGqImE405J2... I recommended it to my daughter when she was taking a class in R and asked "But how does the COMPUTER know what to do?"
>But how does the COMPUTER know what to do? Ben Eater is amazing, but his series in my very humble opinion isn't the best answer to this question. I found the emphasis on the breadboard and the particulars of physical implementation getting in the way of a clean pedagogical introduction to logic circuits as a DAG of abstract computational elements implementing function from {0,1}^n -> {0,1}^m (which we then implement…
The first gives a great overview, and the latter deep dives into some of the architectural concerns around building computers (which are mostly ignored in the course), like understanding buses, running assembly on actual hardware. The most important bit for me was learning how to read data sheets to figure out how to use chips.