Tektronix Hard Copy Unit (Was: Phototypesetters and imagesetters - Re: VT52s, VT61s lots of DEC and DG keyboards)

[Rick Bensene]

> >
> >> On Oct 13, 2015, at 11:52 AM, tony duell <ard at p850ug1.demon.co.uk>
> wrote:
> >>
> >>> The only other terminal I worked
> >>> with that could do that was a Tektronix storage scope terminal
(4010
> >>> or 4014, IIRC).  The Tek printer wasn't built-in, but it did take
a
> >>> scan of the live screen, so that was similar.  The paper was
> >>> silver-grey and I remember it coming out wet too.  Everything else
I
> >>> worked with was either thermal or dot-matrix impact, and could
only
> >>> capture text as it arrived at the terminal, not a screen image.
> >>

AFAIK, the Tektronix external "hard copy units" for their DVST display
terminals (4002A, 4010, 4012, 4014, and others that were integrated into
various systems (e.g., the 4081 computer system, and 4051/4052/4054
desktop computers))  were dry-process devices.  The paper was a
dry-silver paper that was photosensitive, but it was developed by heat
rather than by chemicals.

It is possible, in the very early days of the DVST terminals, that some
kind of wet-process hard copy may have been used...or that perhaps a
third party developed a wet-process hard copy unit, but my only
experience was with the thermal-developing dry-silver paper hard copy
units.

I used these devices extensively in my time at Tektronix, and became
quite expert at troubleshooting/adjustment  of the hard copy units.
There were no chemicals or toners involved.  The paper would come out of
the machine quite warm from the developing process.  

The tube in these hard copy devices was indeed weird...wide, but not
very tall.  It produced a single scan line that was synchronized with
the motion of the paper through the machine.   The scan line was driven
by the terminal, which used a low-intensity scanning beam to "read" the
charge on the storage element of the display screen, and sent the analog
signal from the read-out image to the hard copy unit. 

The DVST technology that Tektronix created for these terminals was very
much an example of the extreme levels of CRT technology and knowledge
that existed within Tektronix during those days.   Just about every tube
they used for oscilloscopes, scan converters,  and all of the DVST tubes
were designed and manufactured in-house  at TektroniX HQ in Beaverton,
Oregon.  The CRT building was one of the earlier buildings on the
Tektronix campus there. It was quite a place to visit.   Even in the
late 1970's, there was amazing CRT development going on there for
building things like the tube for the first 1GHz (analog) oscilloscope.

Rick Bensene
The Old Calculator Museum
http://oldcalculatormuseum.com