True, but DIN is about as standard as it gets. http://en.wikipedia.org/wiki/Mini-din
That's what API design is so important, and so difficult. By analogy the DIN connector is simply calling convention and ADB the actual function calls.
Now, if you just wanted to hack peripheral hardware at the time, you would have invested in a lot cheaper (expendable) computer with a standard serial / parallel port, so I don't really understand what you are saying.