Wrong, games are saved on the cartridge. Some games do use memory cards (off the top of my head, Turok did), but I guess that depends on the data needed... I guess the cartridge is very limited. For example, Mariokart saves progress on the cartridge, but if you want to save ghosts of your time trials, you need a memory pak. I guess it just caches most of the disk in its memory before starting it or something