Cartridge Unit was a robot who lived in a community of outdated robots who refused to upgrade to newer technology. This community preferred to live a simpler existence on a little island, free of technology. The speech of Cartridge Unit is merely a playback of selected cassettes, although the selection is always made by Cartridge Unit itself. Although it is unknown how many cartridges Cartridge Unit owned exactly, he appeared to have a cartridge for speech applying to every possible situation.