The 6502 CPU's overflow flag explained at the silicon level
Very interesting<p>And this is 30 year old tech. The 6502, the processor in you cell phone is about 1000x faster than it (and much more capable)<p>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 <i>by hand</i> in the 6502, the drawings were done the size of a desk and reduced photographically. (IIRC)