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Which goes from bits on up without shying away from circuit diagrams. It's also really well written and you can read it from start to finish.

It puts it in a historical context too which makes it fun to read.

Once you read that, they'll be fewer unknown unknowns.

This is a far better idea than "Operating Systems: Three Easy Pieces" as suggested by the OP.

A great place to start before diving into books would be Ben Eater's videos on YouTube.

Please feel free to privmail me and I will try to share some ideas.