wires

Hi Guys, need your help with my restoration. I am looking to install a new radio and sound system in my E9. I bought the car with a missing radio however it had wiring for speakers. I am not sure what these cables are, but i think they could be for the radio, can anyone confirm...

So, I've had the opportunity to putz around with the wires while the ignition switch is out. Before now I had believed that the Green wire was the Starter Wire, while Red was Power, Black ground, and Violet Accessory. However, by mere accident I discovered that Black appears to be the starter...