It appears the original users at the University of Washington used narrow paper in this plotter and the plots ran off the edge. You can see the remnants of several plots on the drum and the outlines of the pin feed holes. I've been removing the ink when I run off the paper so these are from when the plotter was originally in use.
Feel free to contact me, David Gesswein email@example.com
with any questions, comments on the web site, or if you have related equipment,
documentation, software etc. you are willing to part with. I am
interested in anything PDP-8
related, computers, peripherals used with them, DEC or third party, or