|This article does not cite any references (sources). (April 2014)|
A dongle is a small piece of hardware that attaches to a computer, TV, or other electronic device in order to enable additional functions such as copy protection, audio, video, games, data, or other services. These services are available only when the dongle is attached.
"Attached" does not need to involve a wired connection. The dongle may communicate wirelessly with the device it enables via NFC, for example.
The term "dongle" originally addressed a software protection device. The construct is now more broadly used especially for
- licensing purposes,
- cryptology purposes,
- identifying purposes.
Examples of dongles
- The CD-based parts catalog (known as "ETKA") used by Volkswagen Group used since 1989 requires a coded dongle be plugged into a host computer's port in order to run.
- Some professional digital audio workstation packages on the Atari TOS platform required the presence of the supplied dongle in the computer's cartridge port in order to run. Steinberg's Cubase range and C-Lab's Creator and Notator packages frequently send data to the dongle, which sends a response determined by the electronics inside the cartridge.
(The additional expense of producing the dongle was justified by the high purchase price of the software (hundreds of British pounds) and the tendency for unprotected software to be subject to piracy. To ensure compatibility with MIDI and other audio expansion units that also occupy the single cartridge port, some dongles had a pass-through connector to accommodate them. Some expanders were also designed with backplane sockets to host the different dongles unique to a specific set of packages. Eventually, software pirates were able to circumvent the dongle scheme by modifying the program's binary to accept simulated dongle responses, at the expense of stability and performance.)
Copy protection circumvention
- Some unlicensed game cartridges have a "daisy chain" that allows licensed games to pass along their authorization, for instance to circumvent the 10NES chip on the Nintendo Entertainment System.
Small peripheral appliances
- Small devices that plug into other equipment to add functionality are often referred to as dongles; for example the infrared remote control adapters available for "smart" mobile phones, or internet content streaming devices such as the WiDi / Chromecast.
- MHL. A dongle enables adaptation to legacy standards such as HDMI via conversion circuitry contained in the dongle itself. MHL dongles often allow USB connections and/or device charging as well.
- Smart TV dongle, such as Apple TV.
- Very short cables that connect relatively large jacks to smaller plugs allowing cables to be easily installed and removed from equipment with limited space available for connectors. The Chromecast device mentioned above, for example, comes with a short HDMI extension cable to allow its use in cramped quarters.
- Cassette adapters enable cassette-radios to allow AUX in, like with iPod/MP3 player/smartphone (portable CD players before 2000)
- Personal FM transmitters allow content from a portable media player, portable CD player, smartphone, portable cassette player, or other portable audio system to be heard on an FM radio.
- IDE/PATA connectivity can be re-channeled with some dongles:
- Old school video game consoles:
- The Everdrive series of game cartridges has enabled classic systems such as the Sega Megadrive and Nintendo 64 to allow one cartridge to have a number of games that were formerly on multiple cartridges of their own, by use of an SD card with ROMs on them; since it can allow a real game console to access ROMs, which an emulator would normally do.
- The Sega 32X was an add-on for the Sega Megadrive which allowed a 32-bit library of games to play on a system that was normally just 16-bit, though it suffered from having its own video output, and its own AC adapter in order to work.
- USB host connectivity grants more flexibility to computer-based devices
- Older cars that "externalized" their CD players and changers from the head unit can now use "emulators" that allow USB and SD cards with MP3s and other audio files to be recognized as "tracks" to the CD control unit circuitry.
- Adaptors 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.