5 1/4 floppy
In 1976 Alan Shugart developed a new floppy disk. The main reason for this development was that the normal 8 inch floppy disk was to large for using it in desktop computers. So the new 5.25 inch floppy disk was born. Its storage capability was 110 kilobytes. These new floppy disk drives were cheaper than the ones for 8 inch floppy disks and replaced them very quickly.
At this time only one side of the floppy disk was used. So in 1978 a double-sided drive for reading 5.25 inch floppy was introduced. So the storage capability was increased again to 360 kilobytes.