IBM introduced the floppy disks in 1970                  ( 1970 )     

Floppy disks measured 8 inches and stored up to 100 kB.

Alan F. Shugart, an IBM engineer, left the company in 1973 to start up his own company, Shugart Associates. Three years later Shugart Associates launched the 5.25-inch disk, a smaller version of the 8-inch disk.

This became the standard size for storage devices on personal computers until the appearance of 3.5-inch disks in 1981. These disks could store up to 1.44 MB of information.