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

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 Yes, I had a bunch of Versatec 1200A's with the Tektronix hard copy feature. the Versatec was the greatest graphics printer until laser printers came out, then they became instant boat anchors. Here's the process. There is a double-sided PC board that touches the face of the paper end-on, so the traces just come to the end of the board and make contact with the paper. On the 1200A, that was a 200 DPI printer, so each side of the PC board had 100 traces/inch, and they were interleaved, so you got to paint 200 raster lines/inch along the axis of the paper. The back side of the paper had wide electrodes that defined zones. One of these backplate electrodes was charged at a time to the opposite polarity of the front electrodes. I seem to remember there were +800, -200 and -800 V power supplies. The raster line was written about one inch at a time across the page, then the next backplate was charged and the next inch was written, etc. Once the whole line was written electrostatically on the paper, a stepper motor advanced the paper and the next line was written. About an inch from the writing electrodes, there was a toner applicator that produced a fountain of this hydrocarbon-smelling solventy stuff with the carbon toner suspended in it. The charge on the paper would attract the toner particles, and when the solvent dried (assisted by a blower) it pretty well stuck to the paper. The paper had this awful chalky feel on the print side, the toner smelled like printer's ink, and when it was working really well, the paper came out gray with fairly decent print. But, it was FAST!!! It could print at about 1000 LPM in print mode, and if your computer could feed it, it could plot images (black and white only) at better than a page every 10 seconds or so. So, it could actually run faster than most of today's laser printers - although the print quality, of course, was WAY worse. And, with the Tek hardcopy board, it could hardcopy a Tek storage tube terminal in less than 30 seconds. I still have some Versatec printed output, as I ran one here at my house for a couple years, from my MicroVAX. We did have a TEK hard copy unit before the Versatecs. That was a pretty awful unit. it had a line-scan CRT with a fiber optic faceplate that exposed the image onto thermal-developing silver paper-film that rolled past the CRT. It also made bad smells, and the paper came out brown with dark brown images on them. In normal fluorescent lighting, the hard copies started turning totally brown after just a day or two. Also, the silver paper was QUITE expensive, maybe close to a Dollar a page or something, even back in the 1970's. Jon