8'' floppy disk
A floppy disk is a data storage device that is composed of a circular piece of thin, flexible (i.e. "floppy") magnetic storage medium encased in a square or rectangular plastic wallet. Floppy disks are read and written by a floppy disk drive.
In 1967 IBM started developing a simple and inexpensive system for loading microcode into their System/370 mainframes. It should be faster and more purpose built than tape drives that could also be used to send out updates to customers for $5. The result of this work was a read-only, 8-inch (20 cm) floppy they called the "memory disk", holding 80 kilobytes in 1971.
So the first disks were designed for loading microcodes into the controller of the Merlin (IBM 3330) disk pack file (a 100 MB storage device). So, in effect, the first floppies were used to fill another type of data storage device. Overnight, additional uses for the floppy were discovered, making it the "new" program and file storage medium.