Ok well I bought Soul Blade that originally came out on Playstation pre PSone.
But I have a new slim Playstation 2. The Soul Blade game works and I have 2 PS2 memory cards that both have lots of space but the game doesn't seem to recognize them as even being in the console. What should I do?
Buy a playstation 1 memory card?

hey spawn you cannot save ps1 games on ps2 memory canrds and visa versa

Yeah, you need a PS1 memory card in order to save your PS1 games.

It's the same with PS2 games. You need the PS2 memory card.

If you're playing a PS1 game but have a PS2 memory card in the slot, the console won't pick it up because it's the wong format.

I had that trouble when I was playing Final Fantasy VIII. I had to go and buy a memory card especially for it.

Gotcha. Thank you for that insight. I figured as much but at the same time I found it kinda absurd.

actually i just thought about it you can save your ps1 games on the memory card you just won't be able to play it off that memory card duh i can't believe i forgot that.

it simple start your ps2 with no disk and the memory cards go to memory card copy ps1 data and paste on the ps2 card and their you go i can't geruntee that it will work if you recopy and then paste it over again

Well it will be ok. Thank you for the idea man. I think I'll try that. Though I first need to get a PS1 card anyway.