If you have no experience in digital electronics at all, I would actually start with a book like Code by Charles Petzold. It's a pop-science book about electron

If you have no experience in digital electronics at all, I would actually start with a book like Code by Charles Petzold. It's a pop-science book about electronics and goes from light bulbs and switches to simple logic blocks like adders. It covers the basic building blocks of virtually every cpu in existence - how to turn transistors into calculators. It's well written and provides some context to otherwise pretty dry textbooks. There is quite a bit of difference between how an FPGA works and is programmed versus a totally custom chip. You could also take a look at reverse engineering walkthroughs eg Ken Shirrif has a few on his blog. Nand2tetris is another good thing to look at. Finally, reverse engineering the MOS6502: https://m.youtube.com/watch?v=fWqBmmPQP40 https://m.youtube.com/watch?v=fWqBmmPQP40