I'm not too familiar with the FDAMS unit, but from what I know, the card is a standard PCMCIA card, as would fit in the side of most laptops. this is totally different from most flash memory cards, which are a good bit smaller. PCMCIA is just about credit card sized, and about 1/8th inch think.
PCMCIA cards are usually used to 'interface' between bits of hardware that you can plug in, and the computer itself, and actually using them as storage is less common, and there aren't many similar ones available. from memory (hazy today!), the FDAMS disk sizes aren't standard either, which may be critical when plugging a different sort in.
Without knowing the system at all, I'm not in a position to give much help, but would probably advise sticking to the standard spec. card you get with the unit, unless somebody knows better. Any slight change in all sorts of things can cause problems with those cards....
dh-d.