The IBM PC supports 3 standard diskette formats on a 5.25 inch drive:
* The earliest IBM PCs used single-sided, double density, 40 cylinders, 300 RPM, floppy drives which yield a capacity of 160KB 160 KB per side. And MS-DOS 1.0 only supports single-sided drives. * Double-sided drives were introduced in the IBM PC in 1982 and are supported in MS-DOS 1.1. They originally had a capacity of 320KB 320 KB per diskette. MS-DOS 2.0 extended the capacity to 360 KB with a new disk format. [https://minuszerodegrees.net/5150/early/5150_early.htm Source]
* A new floppy drive was introduced with the PC/AT in 1984. It is double sided, quad density, 80 cylinders, with a total capacity of 1.2 MB. The high density drive rotates at '''360 RPM''', so only 15 sectors can be written on a track instead of 18.