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 <paulkon...@comcast.net> wrote: > > > On Oct 13, 2015, at 1:22 PM, tony duell <a...@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 > > >