As the inaugural game of The Legend Of Zelda series, it was first released in Japan as a launch title for the Famicom's Disk System peripheral, a year and five months before it was released in the United States. Because the Famicom Disk System was not released outside Japan, the game was published internationally on the Nintendo Entertainment System's cartridge format in 1987, with an internal battery to facilitate data saving. Nintendo released the game in Japan in 1994 on cartridge format for the Famicom.   Wikipedia