l, dawng‑] 
| a hardware device attached to a computer without which a particular software program will not run: used to prevent unauthorized use. |
don·gle  (dôn'gəl, dŏng'-) n. A hardware device that serves as copy protection for certain software by rendering the software inoperable when the device is not plugged into a printer port. [Probably arbitrary coinage.] |
dongle hardware
/dong'gl/ (From "dangle" - because it dangles off the computer?)
1.
One common form consisted of a serialised EPROM and some drivers in a D-25 connector shell.
Dongles attempt to combat software theft by ensuring that, while users can still make copies of the program (e.g. for backup), they must buy one dongle for each simultaneous use of the program.
The idea was clever, but initially unpopular with users who disliked tying up a port this way. By 1993 almost all dongles passed data through transparently while monitoring for their particular magic codes (and combinations of status lines) with minimal if any interference with devices further down the line. This innovation was necessary to allow daisy-chained dongles for multiple pieces of software.
In 1998, dongles and other copy protection systems are fairly uncommon for Microsoft Windows software but one engineer in a print and CADD bureau reports that their Macintosh computers typically run seven dongles: After Effects, Electric Image, two for Media 100, Ultimatte, Elastic Reality and CADD. These dongles are made for the Mac's daisy-chainable ADB port.
The term is used, by extension, for any physical electronic key or transferable ID required for a program to function. Common variations on this theme have used the parallel port or even the joystick port or a dongle-disk.
An early 1992 advertisment from Rainbow Technologies (a manufacturer of dongles) claimed that the word derived from "Don Gall", the alleged inventor of the device. The company's receptionist however said that the story was a myth invented for the ad.
[The Jargon File]
(1998-12-13)
2. A small adaptor cable that connects, e.g. a PCMCIA modem to a telephone socket or a PCMCIA network card to an RJ45 network cable.
(2002-09-29)