I'm not sure on this, but from what I've read in this thread, you can buy either a serial or usb cable for this dive computer. If that is the case, the circuit you see in the picture above is probably mostly for adapting serial levels from the dive computer to the usb port on your pc. If anyone has ever taken a look inside a "simple" serial to usb adapter, there is a lot of stuff on one of those boards... The serial version of this cable may be quite simple and could be built and fitted with a serial to usb adapter. Just a thought.