I haven't thought of that, it would make sense, especially since they reset the board revision counter to 0 as well, in the middle of the MD1 production. But that would mean that they reset twice in two years, since they definitely did reset around when the Master System came out (SG-1000 and SG-1000 II use different syntax, Mark III seem to follow it but without the board revision, Master System in Japan seems to have board versions but with nonsequential numbers...). However I think we just don't have enough samples for the post Megadrive models. I know that I have extremely few USA Genesis samples. Any system released from 1990 and up (minus Dreamcast) will definitely use the serial format we have cracked, however. Starting from the Game Gear, at the very least. And in that format, the OEM codes go from 0-9, then A-Z, then AA, AB, AC, etc up to AG.