At least for normal kids back in the day, you got little booklets with codes printed in them and they were pretty opaque as to how they were obtained. There wa

At least for normal kids back in the day, you got little booklets with codes printed in them and they were pretty opaque as to how they were obtained. There was a guide with it that more or less said to try random things and that maybe F would have more effect than 0 but it gave no indication that I can recall of how the device worked or why F might do more than 0. Of course now I know that it's just modifying bits of memory (and how that can screw things up...) and that if you're doing a life counter or something, F is a bigger number, but yeah, it was never remotely clear to me as a kid what it was doing.