During the early 80's, I remember reading an article about HP working on a motorized calculator that held a plotter pen and literly drove over the sheet of paper while drawing the plot. They actually had a working prototype. I think the main reason for killing the project was that most people didn't have pool tables in their offices. Can you imagine the number of warranty claims stating that the calculator drove itself of the edge of the desk!
I think this article was in one of the HP Journals in a group of articles discussing their new moving paper ploters.
Bruce