VT52s, VT61s lots of DEC and DG keyboards- return trip through Maine, MA, NY, PA, OH, IN to IL

tony duell ard at p850ug1.demon.co.uk
Tue Oct 13 12:22:03 CDT 2015

> That sounds correct.  Versatec made printers that used that process, I used one
>  (attached to the CDC 6500 at U of Illinois PLATO).  Very nice for continuous roll
> full bitmap graphics.

The Versatec electrostatic plotters are not the same as the VT52 printer, they are
yet another process. WIth those the paper passes between a set of electrodes that
build up a charge image on the paper. I beleive the paper is specially treated to 
make it more resistive so the charge doesn't leak away too quickly, and there is 
a clever multiplexing scheme for the electrodes to reduce the number of HV drivers
needed (IIRC there is around 600V between the electrodes on the 2 sides of the 

The paper then passes over a stream of liquid toner, which is attracted to the charge
image. The liquid evaporates leaving the toner on the paper. That's it, no further

FWIW, apart from the Tektronix photgraphic one, I have examples of all the printers
mentioned (aluminium-coated paper, Olivetti Sparkjet, Versatexc, VT52 copier) here.
Some need minor repairs, but I will get them all going.


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