Nintendo released the Family Computer Disk System in Japan on 21 February 1986 as an expansion for the Famicom. It used rewritable magnetic Disk Cards instead of cartridges and connected to the console through a RAM Adapter inserted into the cartridge slot. The adapter added memory and an additional sound channel. The format allowed data to be saved directly in certain games, and Nintendo installed Disk Writer machines in Japanese shops so disks could be rewritten with new titles. The Legend of Zelda was released on the same day as the system as one of its first games.