I’ve responded to you on the support ticket. For the record, here is what I said (in case other users need to know):
If you do want to use your current RPi, note that the 2×20 pins are backward compatible with the original 2×13 pins — specifically, the first 2×13 pins on the new RPis exactly match the 2×13 pins on the old RPi.
It’s a bit tricky to explain the wiring without holding one at hand. So I will try my best:
First, open the OSPi user manual:
On page 3, look at the ‘Plus’ version. That’s how the RPi is plugged into the pin headers. Your model B would be plugged in the same way, except that the yellow RCA connector would block it i the way. Anyways, this gives you an idea of which pin should go to which pin.
In fact, OSPi really only uses the first 2×8 pins (go to page 10, look at the Pin Use graph, that shows which pins OSPi uses). So you just need to get either one 2×8 ribbon cable (male to femal) or two 1×8 ribbon cables to make the connections as described above. That’s all. Hope this makes sense.