The 6502 CPU's overflow flag explained at the silicon level
Very interestingAnd this is 30 year old tech. The 6502, the processor in you cell phone is about 1000x faster than it (and much more capable)To me the hardest part (apparently) is converting the electronic circuit to the actual chip drawings. Not sure how this is done (how do you route it). And this was done by hand in the 6502, the drawings were done the size of a desk and reduced photographically. (IIRC)