She that had all Magnetique force alone,
To draw, and fasten sundred parts in one.

-John Donne

When considering Latin root words the term magnetic disk arrived in the English language from the ancient word magneticus implying a “mysterious flux.” Disk, on the other hand, derived from Latin as well, is diskae, denoting an object that is “shaped like a plate.” Within the realm of computer science a magnetic disk can also be called a hard disk or simply a disk. It’s typically a flat, rigid disk coated with magnetic material, on which data and programs can be formatted and stored. Since a RAM disk is not a true magnetic storage mechanism and because its contents vanish when the microcomputer is rebooted, any permanent data has to be duplicated on a magnetic disk for storage. Most hard disks on personal computers have storage capacities that range from 1 to 2.5 GB. A smaller form of magnetic disks that are practically outdated by today's standards is the floppy disk. In addition to floppies there are removable hard disks, zip disks, and removable cartridges. Many are cheaper and can store much larger quantities of data than RAM, however the trade off is a slower access time or the amount of time it takes the computer to read information from it. Ultimately technological progress makes it feasible to store ever-increasing amounts of information per square inch of disk space. For example, companies are now selling floppy 3 1/2" disk drives with a capacity of 100M per diskette.

A discussion at Wikipedia about the evolution of the word Disk or Disc? offers some interesting historical insights to the evolution of the second half of the term magnetic disk:

The divergence in spelling is due in part to the way in which the words originated. Disk came into the English language, an Indo-European language belonging to the West Germanic branch; the official language of Britain and the United States and most of the Commonwealth countries in the mid-17th century. It was modeled on words such as whisk; disc arose some time later, and was based on the original dialect of the language of ancient Rome, hence the Latin root word discus. In the 19th century, disc became the conventional spelling for audio recordings made on a flat plate, such as the gramophone record. This usage gave rise to the modern term disc jockey. Early BBC technicians differentiated between disks which were in-house transcription records and discs, the colloquial term for commercial gramophone records. By the 20th century, the c-spelling was more popular in British English, while the k-spelling was preferred in American English. In the 1940s, when the American company IBM pioneered the first hard disk storage devices, the k-spelling was used. In 1979 the European company Philips, along with Sony, developed the compact disc, a digitally encoded recording on an optical disk that is smaller than a phonograph record and played back by a laser. In this instance the c-spelling was chosen, possibly because of the predominating British spelling, or because the compact disc was seen as a successor to the analogue disc record. (paraphrased)

With this bit of history in mind, within the computer jargon of today it is generally accepted that the k-spellings refer chiefly to magnetic storage devices, while the c-spellings are routine for optical media like the compact disc and analogous technologies. Still in the computing field the terms are used erratically and software documents frequently utilizes the k-spelling entirely.

On the related topic of computer jargon, when a head crash or more commonly called "crash" occurs, it involves the destruction of data on the magnetic disk when the read/write head inadvertently comes in contact with the disk. The term for this sudden and drastic malfunction initially portrayed what happened when the air gap collapsed on a Winchester disk, a removable disk drive by IBM from the early 70’s.

These occasional failures of what were then huge clunky magnetic disks turned them into to walking drives. “Those old dinosaur parts carried terrific angular momentum; the combination of a misaligned spindle or worn bearings and stick-slip interactions with the floor could cause them to `walk' across a room, lurching alternate corners forward a couple of millimeters at a time. There is a legend about a drive that walked over to the only door to the computer room and jammed it shut; the staff had to cut a hole in the wall in order to get at it! Walking could also be induced by certain patterns of drive access (a fast seek across the whole width of the disk, followed by a slow seek in the other direction). Some bands of old-time hackers figured out how to induce disk-accessing patterns that would do this to particular drive models and held disk-drive races.”

If you’re interested in reading more about the history behind the development if the magnetic disk you may want to visit the Magnetic Disk Heritage Center on line.


Disk or Disc?:
Accessed May 26, 2005.

Geographic Information Science Glossary:
Accessed May 1, 2005.

The Hackers' Dictionary of Computer Jargon: computers/TheHackersDictionaryofComputerJargon/chap20.htm
Accessed May 1, 2005.

The Jargon File:
Accessed May 1, 2005.

Magnetic disks:
Accessed May 1, 2005.

Using Computers Today and Tomorrow:
Accessed May 1, 2005.

Technical Definitions and Descriptions (from Finkelstein's Pocket Book of Technical Writing):
Accessed: May 1, 2005.

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