Editing Apple Desktop Bus

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[[File:ADB plug.jpg|250px|thumb|ADB plug]]

'''Apple Desktop Bus''', or '''ADB''', is a serial interface developed by [[Apple]] for connecting peripherals such as keyboards, mice and graphics tablets to computers. ADB uses a mini-DIN 4 connector, identical to that used by S-video.

ADB was developed by Steve Wozniak for the Apple IIgs, and it was later introduced to the Macintosh II to replace the original Mac's keyboard-specific connector. ADB allows up to 16 devices to be "daisy-chained"—connected in series—to the host computer. ADB on the Macintosh was a hot-swap interface: [[Mac OS]] would scan the bus periodically during vertical blank interrupts for new devices. Nevertheless, Apple failed to provide surge protection on the bus, and hot-swapping ADB devices carried the risk of damaging the motherboard; as such, hot-swapping is widely proscribed.

Macintosh computers typically only provided one ADB port. The keyboard would connect to the computer, and the keyboard provided a downstream port for the mouse, which typically had a short cable. Early Macintosh ADB keyboards featured two bidirectional female ports, one on either side, and a detachable keyboard cable: the cable could be connected either port, and the port on the opposite side would be used for the mouse.

Apple discontinued the use of ADB with the transition to [[Universal Serial Bus|USB]], starting with the first ''Apple iMac''. The last computer with an ADB port was the blue-and-white 1999 Power Macintosh G3, which also had USB ports.


==Converters==

===ADB peripheral to USB host===

* Belkin/Griffin iMate: ADB to USB keyboard and mouse [[converter]]
* [https://geekhack.org/index.php?topic=14290.0 Hasu's ADB to USB keyboard converter]. The firmware is part of the [https://github.com/tmk/tmk_keyboard TMK Keyboard Firmware Collection], designed to use an 8-bit AVR microcontroller such as in the [[Teensy]] 2.0 or a [[Pro Micro]] boards. Several ready-made converters have also been sold.
* [https://www.drakware.com/shop/p/adb2usb Drakware ADB2USB]

===Bidirectional===

*[http://www.bigmessowires.com/usb-wombat/ ADB-USB Wombat Input Converter] — ADB to USB or USB to ADB. On-board [[power button]]. USB input can be a bus-powered hub with both mouse and keyboard.

===Honourable mentions===

* The [http://www.astrospark.com/adbbusboy/ ADB bUSBoy] would have connected two USB peripherals to a ADB port. It never went into production because the USB Wombat had been introduced at a lower price.


==Gallery==
<gallery widths="250" heights="187">
File:PS-2 and ADB connectors.jpg | [[PS/2]] and ADB ports on a Motorola StarMax 4000/200 computer
File:ADB downstream port.jpg     | Downstream ADB port on the bottom of the AppleDesign Keyboard
</gallery>

==See also==
* [[:Category:Apple keyboards]]
* [[:Category:Apple mice]]

[[Category:Keyboard terms]]
[[Category:Pointing device terms]]
[[Category:Keyboard protocols and interfaces]]
[[Category:Pointing device protocols and interfaces]]