Things You'll Need
Instructions
Boot up your PlayStation 3 and let it load to the XMB (Cross Media Bar). Navigate to the Game heading in the XMB.
Select "Memory Card Utility" from the given options. You will then be shown 2 options: PS1 and PS2. Choose "PS1" from the given options and allow the PlayStation 3 to format the data.
Exit out of the Memory Card Utility to finish formatting your game. From here, saving a game will work the same as it would on an actual PS1.