First I thought it might be a floppy interface; Then I thought it might be a parallel port.
Now, I am not sure at all! I tried a straight through adapter I made with a parallel port to a 26 pin 2mm header, that didn't work. I rechecked what pins I could, pins 1 & 2 are 5 volt, 15 & 16 are ground. To the best of my knowledge and pinouts references that I could find, this doesn't match any type of floppy or parallel port. The only other type of common interface using 26 pins is the feature connecter on some video cards.
Isn't anyone else interested in finding out what this is??