saving psx1 games on a chipped psx2

[squonk]

I have a NEO4 chipped psx2 which works fine when saving Psx2 games to a psx2 memory card.

When I play psx1 games on it, they will not save to the psx2 memory card. Do I need a psx1 type memory card or is it a downfall that chipping a psx2 means you can no longer save osx1 games played on it?

David