A dongle (center, in white) allowing anethernet cable (left, in grey) to be connected to aThunderbolt port on a laptop (right).
Adongle is a small piece of computer hardware that connects to aport on another device to provide it with additional functionality, or enable a pass-through to such a device that adds functionality.[1]
In computing, the term was initially synonymous withsoftware protection dongles—a form of hardwaredigital rights management in which a piece ofsoftware will only operate if a specified dongle—which typically contains alicense key or some other cryptographic protection mechanism—is plugged into the computer while it is running.
The term has since been applied to other forms of devices with a similar form factor, such as:
adapters that convert ports to handle different types of connectors (such asDVI toVGA for displays,USB-to-serial data communication, and in modern computing,USB-C to other types of ports, andMobile High-Definition Link),[2]
USB wireless adapters for standards such asBluetooth andWi-Fi
USB flash drives (more commonly described as "USB stick" or "USB key")
small form-factordigital media players that plug intoHDMI ports (most commonly described as a "media player dongle" or "media player stick")
There are varying accounts on the etymology of the word "dongle"; in a 1999 paper, P. B. Schneck stated that the origin was unclear, but that it was possibly a corruption of the word "dangle" (since these devices "dangle" from a port on a PC).[3]
A 1992Byte magazine advertisement byRainbow Technologies claimed that dongles were invented by and named after a person named "Don Gall", one of Andrew Fuschi's best friends, which spawned anurban legend. LinguistBen Zimmer noted that the claim was likely a by-product of their "tongue-in-cheek" marketing style, and "was so egregiously false that the company happily owned up to it as a marketing ploy when pressed byEric S. Raymond, who maintains theJargon File, an online lexicon of hacker slang."[3][4]
Very short cables that connect relatively large jacks to smaller plugs allow cables to be easily installed and removed from equipment with limited space available for connectors.
IDE/PATA connectivity can be re-channeled with some dongles:
Bothfloppy disk andhard disk drives have been emulated on solid-state "dongles" to ensure legacy recognition, allowing SD cards to serve software to oldCommodore 64 andApple II era computers.
Older cars that "externalized" their CD players and changers from the head unit can now use "emulators" that allow USB and SD cards withMP3s and other audio files to be recognized as "tracks" to the CD control unit circuitry.
Adapters that convert miniature implementations of an interface to the full-sized equivalent, or are required to provide the electrical and mechanical interfaces for expansion cards that cannot physically accommodate them (such as PCMCIA, Compact Flash and ExpressCard expansion cards which are just millimetres thick, too small for a standard connector without having the connector and housing extend beyond the dimensions specified by the standard). Although commonly referred to as "dongles", the alternative term "Pig-tail" is favoured by some in the IT industry, due to the appearance of a full-sized connection element, with a short, thin wire extending, somewhat reminiscent of the rear of porcine animals. The term is somewhat descriptive, and allows one to avoid using the word dongle except for its original meaning.[citation needed]
^Schneck, P.B. (July 1999). "Persistent access control to prevent piracy of digital information".Proceedings of the IEEE.87 (7):1239–1250.doi:10.1109/5.771075.
