ATA: You are operating under a really big misconception.
I have a full computer, running Windows XP with a music/video/navigation/network scanner etc etc etc running, and that computer also hooks into the OBD-II port on my car and also logs/analyzes the output of the computer that's built into the car in the factory.
Does that make sense now? I think you are very confused, but it's ok, it's Christmas.