“A pain to run” and “tense” indeed! The Dover printing system was an Alto (6 MIPs <microinstructions>) driving “Orbit” hardware about half the size of the Alto itself*, driving the raster video to the printer. The hardware was called “orbit” because it could directly “OR” bits into the raster image, rather than requiring read-modify-write cycles. “Spruce” was the spooler and printer driver that ran on the Alto. Evidently the hardware is a typical Butler Lampson knife edge design up in the corner of what was possible, implemented by Bob Sproull and Severo Ornstein. Additional software by Dan Swinehart. There’s a page about this in https://bwlampson.site/38-AltoSoftware/Abstract.html <https://bwlampson.site/38-AltoSoftware/Abstract.html> and a patent https://patents.google.com/patent/US4203154 <https://patents.google.com/patent/US4203154>. I have a feeling I’ve seen a longer description of Orbit somewhere but I can’t remember where. Like most Stanford folks of the era I printed my thesis on one, assisted about 1 AM by Lyle Ramshaw who knew where to get a new drum for the printer. In any event, a vast improvement over the XGP and a godsend for those of us who <didn’t> have a phototypesetter. * An earlier one-off called EARS had printer hardware about 3 times the size of the attached Alto. That one was font-image based. To do things like lines and graphics the software constructed custom font glyphs to make up the image.