In 1986, Nintendo released the Famicom Disk System (FDS) in Japan, a type of floppy drive that uses a single-sided, proprietary 5 cm (2") disk and plugs into the cartridge port. It contains RAM for the game to load into and an extra single-cycle wavetable-lookup sound chip. The disks were originally obtained from kiosks in malls and other public places where buyers could select a title and have it written to the disk. This process would cost less than cartridges and users could take the disk back to a vending booth and have it rewritten with a new game. The disks were used both for storing the game and saving progress and total capacity was 128k (64k per side).
 How were the disks sold?