Well, I don't know if there are scans of the documents or anything like that, but check on riocar.org for more information.

As for the control knob, that is if you had multiple tuners (don't forget, they also have add-on ports for stalks, and stuff like that), so that you could set your tuner's address.
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Paul Grzelak
200GB with 48MB RAM, Illuminated Buttons and Digital Outputs