An 8 MB removable solid state memory card can be plugged into the controller in a manner similar to that of the Dreamcast’s VMU. Game saves can either be copied from the hard drive when in the Xbox dashboard’s memory manager or saved during a game whenever the memory card is inserted. Most Xbox game saves can be copied to the memory unit and moved to another console but some Xbox saves are digitally signed; each console has a unique signing key, and some games (e. g. Ninja Gaiden and Dead or Alive Xtreme Beach Volleyball) will not load saved games signed by a different Xbox, limiting the utility of the memory card. Some game saves can be tagged as uncopyable (like Burnout 3: Takedown) or simply padded to over 8 MB (Star Wars: Knights of the Old Republic). The signing mechanism has been reverse-engineered by the Xbox hacking community, who have developed tools to modify savegames to work in a different console, though the signing key of the recipient Xbox (the “HDkey”) and the ramped-up title key of the game (the “authkey”) must be known.