Ben Eater. He’s been explaining the low level details of how computers work. Literally building a functioning computer from nothing but a cpu and a breadboard. Incredibly good explanations.
In the same vein, check out CuriousMarc, especially the series about restoring an Apollo Guidance Computer to working order. (They actually finish up by simulating a moon landing.)
And for those who have watched all Ben Eater's videos, I highly recommend James Sharman's 8 Bit CPU from scratch playlist. I'ts a bit less step-by-step-tutorial, but it covers more ground than Ben.