DS game saves -- on card or in system?

[norkusa]

I rented Mario DS or whatever it's called from Gamerush when I got my system from there. I'm just wondering....will my game be saved in my system, or is it saved in the card? I know the DS has an internal battery, but no idea if the game save uses it.

[postulio]

saved on card

[Lone_Monster]

It saves on the card. When my friend wanted to play my Super Mario 64 DS, he put the game in his DS, and when he tried to play, it went to a data corrupted screen, and turned off. He tried again, and the same thing. He tried one more time, and when he went to slect a file, my file was gone. I tried it on my DS, and my file was there. Once again, we tried it on his DS again, and my file was finally there. Why would this happen?