Playing backup games with no modding

[Cyber Akuma]

I remember hearing long ago about this method involving the memorycard, however, the information was rather scarse and didnt make it very clear.

From what I recall, you load some special save onto a PS2 memorycard, then load an original PSX game, itll cause some buffer overrun or something and allow you to then insert a backup PSX game.

Did I get it right? Does anyone have any more info on this method? On what exactly it can do, how to do it, and technical info on it?

Thanks in advance