Reply To: Beosound 1 (CD version) data link???

[B3OHACK3R]

You can see something similar in the BS9000 service manual. On the connector board those pins are labeled with “data” but if you follow the path they are then marked with N.C. (not connected).
Interesting that they actually routed it to the MCU on BS1. What confuses me a bit is that they are marked with “IN” and “OUT”. Datalink is bi-directional / half-duplex. So there are no separate signals for in/out. Could also be that it’s an undocumented service port.
I have no BS1 unfortunately but you could hook up an oscilloscope to see if there is being some data transmitted.