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

Paul Anderson useddec at gmail.com
Tue Oct 13 22:02:07 CDT 2015

Do you remember Carrol Touch terminals made in the area? I just picked up 2
still in the box!

On Tue, Oct 13, 2015 at 1:32 PM, Paul Koning <paulkoning at comcast.net> wrote:

> > On Oct 13, 2015, at 1:22 PM, tony duell <ard at p850ug1.demon.co.uk> wrote:
> >
> > 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
> > paper.
> >
> > 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
> > processing.
> Speaking of Versatec: at University of Illinois, there was a PLATO
> terminal that had a "Versatec screen printer".  I never understood how that
> worked.  It smelled like the same electrostatic liquid toner technology.
> But how the image got from the terminal to the printer is unclear.
> Remember that these were plasma panel displays, where the graphics state
> exists only inside the gas pixels in the panel.  I wonder if they read out
> the on/off state of the pixels somehow, but how to do that when there's a
> 100 volt or so square wave voltage across the panel is not obvious.  I have
> never seen any documentation of this machine.
>         paul

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