dongle

dongle /dong'gl/ n.  1. A security or {copy protection}
   device for commercial microcomputer programs consisting of a
   serialized EPROM and some drivers in a D-25 connector shell, which
   must be connected to an I/O port of the computer while the program
   is run.  Programs that use a dongle query the port at startup and
   at programmed intervals thereafter, and terminate if it does not
   respond with the dongle's programmed validation code.  Thus, users
   can make as many copies of the program as they want but must pay
   for each dongle.  The idea was clever, but it was initially a
   failure, as users disliked tying up a serial port this way.  Almost
   all dongles on the market today (1993) will pass data through the
   port and monitor for {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.  The devices are still not
   widely used, as the industry has moved away from copy-protection
   schemes in general.  2. By extension, any physical electronic key
   or transferable ID required for a program to function.  Common
   variations on this theme have used parallel or even joystick ports.
   See {dongle-disk}.

   [Note: in early 1992, advertising copy from Rainbow Technologies (a
   manufacturer of dongles) included a claim that the word derived
   from "Don Gall", allegedly the inventor of the device.  The
   company's receptionist will cheerfully tell you that the story is a
   myth invented for the ad copy.  Nevertheless, I expect it to haunt
   my life as a lexicographer for at least the next ten years. ---
   ESR]