> likely reverse engineered Probably some of this had to be done (specs never quite match implementation), but the ADB protocol and hardware interface was quit

> likely reverse engineered Probably some of this had to be done (specs never quite match implementation), but the ADB protocol and hardware interface was quite well documented by Apple in Inside Macintosh and Guide to Macintosh Hardware which I’m sure the Linux devs availed themselves of. There was also an Apple KB article (written mostly for hardware and driver developers) with the charming title of “Help! Space Aliens Ate My Mouse!” which detailed all of the things that could go wrong with ADB that Apple hadn’t thought of when they wrote the original documentation.