thumb|, , and floppy disks

thumb|, (full height), and drives

thumbnail|A floppy disk removed from its housing

A floppy disk, diskette, or floppy diskette is a type of disk storage made from a thin, flexible disk coated with a magnetic storage medium. It is enclosed in a square or nearly square plastic shell lined with fabric to help remove dust from the spinning disk. Floppy disks store digital data, which can be read or written when inserted into a floppy disk drive (FDD) connected to or built into a computer or other device.

, and drives were manufactured in a variety of sizes, most to fit standardized drive bays. Alongside the common disk sizes were non-classical sizes for specialized systems.

History

thumb| floppy disk,<br /> inserted in drive,<br />( floppy diskette,<br /> in front, shown for scale)

8-inch

thumb|upright| floppy disk

The first commercial floppy disks, developed in the late 1960s, were in diameter; None of these ever reached the point where it could be assumed that every current PC would have one, and they were later largely replaced first by optical disc burners and then by flash storage.

In 1990, an attempt was made to standardize details for a 20MB 3½-inch format floppy. At the time, "three different technologies that are not interchangeable" existed. One major goal was that the to-be-developed standard drive be backward compatible: that it be able to read 720 KB and 1.44 MB floppies.

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Nevertheless, the 5¼- and 3½-inch sizes remain to this day as the standards for drive bays in computer cases, the former used for optical drives (including Blu-ray), and the latter for hard disk drives.

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Variants

Other smaller floppy sizes were proposed, especially for portable or pocket-sized devices that needed a smaller storage device.

  • 3¼-inch floppies otherwise similar to 5¼-inch floppies were proposed by Tabor and Dysan.
  • Three-inch disks similar in construction to 3½-inch were manufactured and used for a time, particularly by Amstrad computers and word processors.
  • A two-inch nominal size known as the Video Floppy was introduced by Sony for use with its Mavica still video camera.

Use in Japan's government ended in 2024.

  • Zip disk

: Physically both the media and cartridge were slightly larger but similar to other 3½-inch media and cartridges. A linear actuator positioned flying heads over high-capacity media that started at 100 MB and grew to 700 MB. It was offered in a variety of interfaces including PATA.

  • LS-120/LS-240

:LS, for LASER-servo, uses a LED to generate light that allows the drive to align its heads on high capacity FD media, initially at 120 MB and subsequently at 240 MB. The drive read and write 3½-inch 1,440 KB floppy disks, and some versions of the drive can write 32 MB onto a 3½-inch 1,440 kB disk albeit not too reliably. It was offered in a variety of interfaces including PATA.

  • Sony HiFD

: Structurally similar to the Floptical and initially at 150&nbsp;MB, it was removed from the market and subsequently reintroduced at 200&nbsp;MB

  • Caleb UHD144

: Structurally similar to the Floptical it provides 144&nbsp;MB of storage and is capable reading and writing 720&nbsp;kB and 1.44&nbsp;MB 3½-inch disks.

Variants

In addition to the four generations of floppy disks and drives covered in this article there were various other floppy disks (and drives) offered, some were failed attempts to establish a standard for a generation while others were for special applications.

Operation

thumb|How the read-write head is applied on the floppy

A spindle motor in the drive rotates the magnetic medium at a certain speed, while a stepper motor-operated mechanism moves the magnetic read/write heads radially along the surface of the disk. Both read and write operations require the media to be rotating and the head to contact the disk media, an action originally accomplished by a disk-load solenoid.

Most home computers from that time have an elementary OS and BASIC stored in read-only memory (ROM), with the option of loading a more advanced OS from a floppy disk.

By the early 1990s, the increasing software size meant large packages like Windows or Adobe Photoshop required a dozen disks or more. In 1996, there were an estimated five billion standard floppy disks in use.

Further reading

  • Weyhrich, Steven (2005). "The Disk II": A detailed essay describing one of the first commercial floppy disk drives (from the Apple II History website).
  • Immers, Richard; Neufeld, Gerald G. (1984). Inside Commodore DOS: The Complete Guide to the 1541 Disk Operating System. Datamost & Reston Publishing Company (Prentice-Hall). .
  • Englisch, Lothar; Szczepanowski, Norbert (1984). The Anatomy of the 1541 Disk Drive. Grand Rapids, Michigan, USA, Abacus Software (translated from the original 1983 German edition, Düsseldorf, Data Becker GmbH). .
  • Hewlett Packard: 9121D/S Disc Memory Operator's Manual; printed 1 September 1982; part number 09121-90000.
  • HowStuffWorks: How Floppy Disk Drives Work
  • Computer Hope: Information about computer floppy drives
  • NCITS (mention of ANSI X3.162 and X3.171 floppy standards)
  • The Floppy User Guide -historical technical material
  • Summary of Floppy Disk Types and Specifications