floppy disk

<hardware, storage> A small, portable plastic disk coated in a magnetisable substance used for storing computer data. The physical size of disks has shrunk from the early 8 inch, to 5 1/4 inch ("minifloppy") to 3 1/2 inch ("microfloppy") while the data capacity has risen.

These disks are known as "floppy" disks (or diskettes) because the disk is flexible and the read/write head is in physical contact with the surface of the disk in contrast to "hard disks" (or winchesters) which are rigid and rely on a small fixed gap between the disk surface and the heads. Floppies may be either single-sided or double-sided.

3.5 inch floppies are less floppy than the larger disks because they come in a stiff plastic "envelope" or case, hence the alternative names "stiffy" or "crunchy" sometimes used to distinguish them from the floppier kind.

The following formats are used on IBM PCs:

 Capacity  Density  Width
   360K	   double   5 1/4"
   720K	   double   3 1/2"
   1.2M	   high	    5 1/4"
  1.44M	   high	    3 1/2"