> In my 6502 hacking days, the presence of an exclusive OR was a sure-fire indicator you’d either found the encryption part of the code, or some kind of sprite routine.

Meanwhile, people like me who got started with a Z80 instead immediately knew why, since XOR A is the smallest and fastest way to clear the accumulator and flag register. Funny how that also shows how specific this is to a particular CPU lineage or its offshoots.