no, sounds like your memory is working better than mine. He thinks he has one with a printer and I will try to grab it. On Mon, Oct 12, 2015 at 11:32 PM, Nigel Williams < nw at retrocomputingtasmania.com> wrote:

On 13.10.2015 05:32, Nigel Williams wrote: I'm seeing one right now, as my VT52 has such an unit. Never seen one in action though. I can put up some pics if desired, let me know what you need. Jos Dreesen

On 10/13/2015 12:02 AM, tony duell wrote: I had a little Comprint printer in the 1970s/1980s that used something sort of like this. The paper was aluminum coated, thus conductive. The head was a high voltage electrode unit that burned away the aluminum layer. (I can't imagine any kind of deposition technology in that era...). The head flew back and forth really fast, doing one pixel-line at a time. JRJ

On Tue, Oct 13, 2015 at 11:25 AM, Paul Koning <paulkoning at comcast.net> wrote: That reminds me of a printer I worked with in 1986 or so, but this one had multi-layer paper that could be selectively burned for true 16-level grey-scale printing. It was expensive, but the customer needed to render ultrasonic scans in high fidelity, and even a laser printers wouldn't work in this application because the sample size/pixel size was too small for that to be effective. These days, an inkjet printer could probably dither small enough black dots to be a cost-effective alternative, or perhaps a 1200dpi laser printer. -ethan

On 10/13/2015 11:43 AM, Brent Hilpert wrote: My first contact with this paper wasn't printing, but rather in biology. You'd wrap the stuff around the drum of a kymograph, connect the (insulated) stylus to a HV (battery-powered induction coil setup) power source, and grounding the drum. Turn the power on and let 'er rip. I suspect that this technology probably goes back to the 20's at least. --Chuck

On Tue, 13 Oct 2015, tony duell wrote: That is how the Sinclair ZX printer works and also things like the Axiom EX820. Spark (about 80-100V IIRC) to aluminium-coated paper. Even Radio Shack had one of those! But not for long. Crumpling the paper could lose the image. ANd THERMAL printers couldn't handle leaving a printout in the sun. So, NOT the same.

I think it was electrostatic, using the aluminized paper. I don't imagine that electrostatic paper is still manufactured, is it? Even in different roll widths that might be cut down to support some old-timey computer printer? -- Mark J. Blair, NF6X <nf6x at nf6x.net> http://www.nf6x.net/

The tektronix printer (or 'copier' as they called it) was photographic. The paper was light-sensitive, and went past the screen of a 'flat' CRT (I think it only had deflection plates for one axis, the 'deflection' in the other direction coming from the paper movement). It really was an odd-looking tube. IIRC the image was developed by heating the paper. I don't remember any liquids involved, but it's been a long time since I looked at the manual for one and even longer since I've seen the actual device -tony

On 2015-10-13 12:06 PM, Paul Koning wrote: the 1970s in high end phototypesetting machines, such as the Autologic APS-5 and the Linotron 202. I think the idea was to make high resolution CRT display feasible by having to worry only about accuracy in one coordinate, not two. The film movement (actually paper, essentially a roll of photo-print paper) would provide the other coordinate. Unlike the Tektronix machine you describe, phototypesetter output was developed in essentially the same manner as photographic print, with developer and fixer chemicals, in a machine that would take the paper casette as input and produce the developed/fixed/dried roll of finished material coming out the other end. The roll of paper would then be cut to separate the individual columns and articles, and pasted onto cardboard page size boards to produce the finished layout. Excellent description. I spent a few years running a Linotronic L100, one of the first PostScript imagesetters, capstan feed. It worked on the same principle but instead of a CRT it used a laser and a fast rotating mirror to scan the paper in 1 dimension. It could, at a pinch, expose film directly, but struggled to get proper density. If I recall correctly the bromide paper roll was about 12" wide. A friend in Sydney, Australia, has this hardware now, but if there are serious collectors in that region who really want it, I think he could be persuaded to part with it. paper, but those were rather expensive and useful only once you got software to do the page layout on the computer instead of manually in the composing room. surprisingly long, certainly into the 1990s -- because laser printout was high enough resolution to read, but not good enough to use as the master for offset printing. I think phototypesetters were good to 1000 dpi or thereabouts, unlike the 300-600 dpi of the first decade or so of laser printers. The Linotronic series launched with PostScript by 1987 and produced "camera ready artwork" from the Macintosh printing system over AppleTalk (PageMaker, etc, or even MacWrite with its horrendous typography) or anything else over serial (FrameMaker, TeX, what-have-you). I just found an Australian Dollar price list from 1987 - * L100 AUD $69,250 * L300 AUD $96,000 The L100 had switchable resolutions up to 1270dpi and the L300 went up to 2540dpi - more than sufficient for offset. The subsequent generation of imagesetters exposed film (requiring higher exposure and allowing the re-photography step to be eliminated) and secured the film on a spinning drum, allowing industrial standard registration. The capstan feed setters could not offer very high registration accuracy. The first imagesetter I used of this type was the Scangraphic circa 1992 - apparently the first PostScript drum imported to Australia - and it was superb. --Toby

I wonder if the wet-paper printer that you remember used a similar process to the one that my folks' liquid toner photocopier did back in the 80s? It used an electrostatic toner adhesion process followed by a fuser. Just like contemporary laser printers and photocopiers, but with the toner particles suspended in a liquid carrier. The volatile carrier smelled awful, and the finished copies had a fingernails-on-chalkboard like gritty feel in the hands. I seem to recall that it needed specially prepared paper. -- Mark J. Blair, NF6X <nf6x at nf6x.net> http://www.nf6x.net/

On 2015-10-13 18:20, Paul Koning wrote: Electrostatic printers... I've dumped a few in my lifetime. Never tried get any of them working, and the last one was like 30 years ago... Smell of the liquids were bad, and you had a couple of bottles inside the printer... Johnny

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. 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. -tony

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:

Only in the sense that a PDP11, or a VAX, or a PERQ, or a <insert your favourite classic computer> is a boatanchor. My view is that a computer is a lot more than the processor, and that the peripherals should be preserved too. Yes the processor runs the old software, but emulators do that too, If you are interested (as I am) in the hardware then the peripherals are as interesting as the processor in a lot of cases That's it. IIRC that was the 'Nib electrode' in Versatec manuals. Somewhere I have a spare one for the V80 series. It's been a long time since I looked at the manuals, but IIRC the width of the back electrodes was half what you might expect -- half the 'repeat distance' of the nibs. The reason was to prevent edge effects between nibs and the adjacent back electrodes. Was it a stepper motor? I am sure mine uses a permanent magnet DC motor. I do remember that the paper feed roller is in 2 parts with a differential gear between them. It's called the 'toner fountain' in the manuals, but it actually works below atmospheric pressure. The results are that (a) the paper is sucked down onto the toner fountain and (b) if the paper is torn or runs out you don't get toner sprayed all over the machine room. The toner is circulated by a little electromangnetic pump. The toner system tends to block, I found that what we call 'white spirit' was a suitable solvent to unblock it. One time I tried the old 'suck it and see' method to get the pump valves working and found that the toner tastes horrible! [...] I don't have a Tektronix hard copy unit (one of the few oddball printers I've not managed to obtain) but I am told that the paper goes off with time, and that it unlikely there's any useable paper left for them ;-( -tony

[Versatec paper feed motors] You've got me worried now... I have V80. Actually, it's ICL-badged, and has a GPIB adapter board at the back connected to the normal parallel port [1]. I was prepared to swear the motor in that is a normal DC motor, but perhaps I have misremembered it. I really don't want to strip it down tonight, and finding the manuals [2] Is an even bigger job. [1] This is a really odd board. It contains about 4 chips, one is a Fairchild thing that does the GPIB handshake, etc. Another is (IIRC) 48 pins, and is some kind of custom interface chip. I have never found out quite how the thing responds to GPIB data, one day I will set it up with the PERQ (which I have software to drive it on) and my HPIB analyser and take a look... The GPIB cable it came with had a 'barrier box' halfway along it. This was something more commonly used with modems in the UK (in fact when you had to rent the modem of zeners and 24 fuses to mke darn sure you coudn't overvoltage any pin on the modem. Quite why it was needed here I don't know... [2] Still unpacking after the housemove a year ago. Need to get the bookshelves up so I can unpack the 100-200 boxes of books... Yes, that's like the V80, but I am pretty sure on that machine the 'fountain' is on the suction side of the pump, that is it sucks from the outer region. When there is paper present this causes toner to flow from the bottle up through the middle bit, then back round the outside to the pump and back to the bottle. Again I might be mis-remembering things... Got any better ways to unclog the pump? -tony

Ok, but for screen hardcopy, the question is how the image on the screen is read out so it can be fed to the printer. For the Tek storage tube case, that presumably is done by scanning the screen with the beam, which will produce the stored image in the same way as a TV camera tube works. But how would you do that in a plasma panel? paul

Really? PLATO terminals? Or some other kind? I have a Carroll PLATO terminal at home. If you have one, you can connect it to the cyber1 PLATO system. paul

Thanks Jos, Tony and Rod - you've neatly highlighted why I found the screen printer so curious and fascinating, an oddball feature in the terminal world and seemingly a simple mechanism to render the screen. If anyone with access to one has the interest and time I'd appreciate pictures and any additional detail of how it works; if you can make one print, pictures of what it can produce would be great too. It has always struck me that VT52 screen printer has never been fully described or experienced, and I don't know of any other display devices that had it built-in (I'm ignoring later devices like the Sony screen-printers that rendered to thermal paper etc.) Some years ago I expended some effort and scoured the internet for a picture of the output and I vaguely recall I found a single image, but it appears I filed it too well and now can't find it.

Its called a Hellschreiber http:// www.nonstopsystems/radio/pdf-hell/hell-g5xb.pdf Regards Rod On 13/10/2015 06:20, Nigel Williams wrote: -- Wanted : KDJ11-E M8981 KK8-E M8300 KK8-E M8310 KK8-E M8320 KK8-E M8330

-----Oorspronkelijk bericht----- From: Nigel Williams Sent: Tuesday, October 13, 2015 12:32 PM To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: VT52s, VT61s lots of DEC and DG keyboards- return trip through Maine, MA, NY, PA, OH, IN to IL Fixed URL: http://www.nonstopsystems.com/radio/pdf-hell/hell-g5xb.pdf ========= I have one VT55-FB which has "the toilet paper dispenser" at the right side. There is some paper in it too. I never tried it though. At the moment (and probably for quite some time to come) I will be busy with repairs and getting the systems running. And I already notice that planned activities take much more time :-/ The VT55-FB will be "checked" when the 11/35 is on the top of the list. The 11/35 has a 20mA current loop console M7800-YA, and connects to the VT55. BTW, Hellschreiber is known in the HAM radio amateur world. AFAIK, invented by the Germans, hence its name. The nice thing about this principle is that text stays readable, even when the receiver is not in sync (within acceptable limits). - Henk