I got those boards today Sean, thanks. I should be able to dump the three of them (MM7x and the D557), but the other two probably not. I can't find a single shred of info about them except this thread and a calculator website saying "yup, this chip is in a blackjack playing calculator!".

I will poke on them a little but probably won't spend a lot of time on them since even if I do get data out, it probably won't be useful.