2 May
2016
2 May
'16
3:59 p.m.
Yet another nice color brochure.
https://dl.dropboxusercontent.com/u/96935524/Datormusuem/lab11.pdf
Has anyone seen a VR20 in real? Rather interesting to be able to do a red
and green X/Y screen based on different energy levels. Someone care to
explain how that works?
If I read the fine print on the back correctly (and comparing with the
others) I would guess that this brochure is from 1971.
2 May
2 May
4:21 p.m.
On May 2, 2016, at 3:59 PM, Mattis Lind <mattislind
at gmail.com> wrote:
Yet another nice color brochure.
https://dl.dropboxusercontent.com/u/96935524/Datormusuem/lab11.pdf
Has anyone seen a VR20 in real? Rather interesting to be able to do a red
and green X/Y screen based on different energy levels. Someone care to
explain how that works?
See https://en.wikipedia.org/wiki/Penetron. The idea is that there are two layers, and a
high voltage beam pokes through the first to activate the second.
I think Tektronix made monitors of this type, but apparently GE invented them. I remember
hearing about that technology in the 1970s; I never actually saw one in the wild (from any
manufacturer).
If I read the fine print on the back correctly (and
comparing with the
others) I would guess that this brochure is from 1971.
Assuming that 00771 is a date code, yes. The cover photo is interesting (PDP11 with PDP12
color scheme!) but the console looks like an LA30. I didn't know those were out in
1971. The first (and fortunately only) one I encountered was in 1974.
paul
4:32 p.m.
On 5/2/16 1:21 PM, Paul Koning wrote:
I think Tektronix made monitors of this type
Tek 1241
http://www.barrytech.com/tektronix/logic_analyzers/tek1241.html
and DAS 9100 logic analyzers used them.
You could get red, green, and yellow
4:35 p.m.
On 5/2/16 1:32 PM, Al Kossow wrote:
On 5/2/16 1:21 PM, Paul Koning wrote:
http://www.barrytech.com/tektronix/logic_analyzers/tekdas9100.html
I think Tektronix made monitors of this type
Tek 1241
http://www.barrytech.com/tektronix/logic_analyzers/tek1241.html
and DAS 9100 logic analyzers used them.
You could get red, green, and yellow 
5:39 p.m.
On Mon, May 2, 2016 at 1:21 PM, Paul Koning <paulkoning at comcast.net> wrote:
I'm not sure that the Penetron is what DEC was using; according to
http://homepage.cs.uiowa.edu/~jones/pdp8/man/vc8e.html:
"If the CO (color) bit changes because of the value loaded, and if the VC8E
is equipped to handle this option, a timer will be started to set the DN
(done) bit after either 300 microseconds (green to red) or 1600
microseconds (red to green). These delays correspond to the time taken by
the VR20 display for these color changes."
According the Penetron wiki page, additional activation energy was provided
by a "set of fine wires placed behind the screen"; whereas the VC8E
apparently is setting the color by timing the beam.
So yes, it seems to be an activation energy phenomenon, but not
specifically the Penetron technology. My physics fu isn't good enough to
explain how, but I would guess at some very non-linear phosphorescence
response.
-- Charles
On May 2, 2016, at 3:59 PM, Mattis Lind
<mattislind at gmail.com> wrote:
Yet another nice color brochure.
https://dl.dropboxusercontent.com/u/96935524/Datormusuem/lab11.pdf
Has anyone seen a VR20 in real? Rather interesting to be able to do a red
and green X/Y screen based on different energy levels. Someone care to
explain how that works?
See https://en.wikipedia.org/wiki/Penetron. The idea is that there are
two layers, and a high voltage beam pokes through the first to activate the
second.
6:19 p.m.
On 2016-May-02, at 2:39 PM, Charles Anthony wrote:
On Mon, May 2, 2016 at 1:21 PM, Paul Koning
<paulkoning at comcast.net> wrote:
I'm not sure that the Penetron is what DEC was using; according to
http://homepage.cs.uiowa.edu/~jones/pdp8/man/vc8e.html:
"If the CO (color) bit changes because of the value loaded, and if the VC8E
is equipped to handle this option, a timer will be started to set the DN
(done) bit after either 300 microseconds (green to red) or 1600
microseconds (red to green). These delays correspond to the time taken by
the VR20 display for these color changes."
According the Penetron wiki page, additional activation energy was provided
by a "set of fine wires placed behind the screen"; whereas the VC8E
apparently is setting the color by timing the beam.
So yes, it seems to be an activation energy phenomenon, but not
specifically the Penetron technology. My physics fu isn't good enough to
explain how, but I would guess at some very non-linear phosphorescence
response.
Might have had to do with the time taken to switch the HV supply (for a Penetron) for the
different penetration levels rather than a different phosphor-exciting scheme. Although,
is that interface even at the scan level relating directly to the display tube, or at a
controller level where it might be an artifact of the controller electronics?
On May 2,
2016, at 3:59 PM, Mattis Lind <mattislind at gmail.com> wrote:
Yet another nice color brochure.
https://dl.dropboxusercontent.com/u/96935524/Datormusuem/lab11.pdf
Has anyone seen a VR20 in real? Rather interesting to be able to do a red
and green X/Y screen based on different energy levels. Someone care to
explain how that works?
See https://en.wikipedia.org/wiki/Penetron. The idea is that there are
two layers, and a high voltage beam pokes through the first to activate the
second.
7:36 p.m.
On Mon, May 2, 2016 at 3:19 PM, Brent Hilpert <hilpert at cs.ubc.ca> wrote:
On 2016-May-02, at 2:39 PM, Charles Anthony wrote:
VC8E
Context: I have never seen any of these beasts, and I am a s/w guy that
dabbles in h/w. All of my opinions herein are derived from my reading DEC
documents to write vector display emulators. I may talking through my hat
here....
http://bitsavers.informatik.uni-stuttgart.de/www.computer.museum.uq.edu.au/…
"3.4.6.2 Green Mode -- ... The intensify pule is used to intensify the
point on the scope. ... approximately 1 us."
"3.4.6.2 Red Mode -- ... 6 us."
I can't locate any VR20 documentation, so other than pulse width input to
the VR20 I am unable to speculate further; it may well be that Penetron
technology was used, but the wording of the controller made it seem to me
otherwise, but I am more than prepared to be wrong -- it is perfectly
possible that the VR20 is controlling a Penetron based on the pulse width.
-- Charles
On Mon, May 2, 2016 at 1:21 PM, Paul Koning
<paulkoning at comcast.net>
wrote:
>> On May 2, 2016, at 3:59 PM, Mattis Lind
<mattislind at gmail.com> wrote:
>>
>> Yet another nice color brochure.
>>
>> https://dl.dropboxusercontent.com/u/96935524/Datormusuem/lab11.pdf
>>
>> Has anyone seen a VR20 in real? Rather interesting to be able to do a
red
>> and green X/Y screen based on different
energy levels. Someone care to
>> explain how that works?
>
> See https://en.wikipedia.org/wiki/Penetron. The idea is that there are
> two layers, and a high voltage beam pokes through the first to activate
the
second.
I'm not sure that the Penetron is what DEC was using; according to
http://homepage.cs.uiowa.edu/~jones/pdp8/man/vc8e.html:
"If the CO (color) bit changes because of the value loaded, and if the is equipped to handle this option, a timer will
be started to set the DN
(done) bit after either 300 microseconds (green to red) or 1600
microseconds (red to green). These delays correspond to the time taken by
the VR20 display for these color changes."
According the Penetron wiki page, additional activation energy was
provided
by a "set of fine wires placed behind the
screen"; whereas the VC8E
apparently is setting the color by timing the beam.
So yes, it seems to be an activation energy phenomenon, but not
specifically the Penetron technology. My physics fu isn't good enough to
explain how, but I would guess at some very non-linear phosphorescence
response.
Might have had to do with the time taken to switch the HV supply (for a
Penetron) for the different penetration levels rather than a different
phosphor-exciting scheme. Although, is that interface even at the scan
level relating directly to the display tube, or at a controller level where
it might be an artifact of the controller electronics?
7:46 p.m.
On Mon, May 2, 2016 at 4:36 PM, Charles Anthony <charles.unix.pro at gmail.com>
wrote:
I can't locate any VR20 documentation, so other than pulse width input to
the VR20 I am unable to speculate further; it may well be that Penetron
technology was used, but the wording of the controller made it seem to me
otherwise, but I am more than prepared to be wrong -- it is perfectly
possible that the VR20 is controlling a Penetron based on the pulse width.
Hmm. The Rhode Island Computer Museum has a working VR20. We need to get
them to
take a look inside it to see what kind of CRT tube is in there....
-- Charles
3 May
3 May
12:50 a.m.
On Mon, May 2, 2016 at 5:46 PM, Charles Anthony
<charles.unix.pro at gmail.com> wrote:
Hmm. The Rhode Island Computer Museum has a working
VR20. We need to get
them to take a look inside it to see what kind of CRT tube is in there....
It hardly matters, since it's a beam penetration CRT that was custom
made for DEC and isn't used in *anything* else. Barring a major
miracle, the only way you'll ever get another suitable tube is out of
another VR20.
2 May
2 May
5:40 p.m.
On Monday, May 2, 2016 1:21 PM, Paul Koning <paulkoning at comcast.net> wrote:
On May 2, 2016, at 3:59 PM, Mattis Lind <mattislind
at gmail.com> wrote:
Yet another nice color brochure.
https://dl.dropboxusercontent.com/u/96935524/Datormusuem/lab11.pdf
Has anyone seen a VR20 in real? Rather interesting to be able to do a red
and green X/Y screen based on different energy levels. Someone care to
explain how that works?
See https://en.wikipedia.org/wiki/Penetron. The idea is that there are two layers, and a
high voltage beam pokes through the first to activate the second.
I think Tektronix made monitors of this type, but apparently GE invented them.? I remember
hearing about that technology in the 1970s; I never actually saw one in the wild (from any
manufacturer).
If I read the fine print on the back correctly (and
comparing with the
others) I would guess that this brochure is from 1971.
Assuming that 00771 is a date code, yes.? The cover photo is interesting (PDP11 with PDP12
color scheme!) but the console looks like an LA30.? I didn't know those were out in
1971.? The first (and fortunately only) one I encountered was in 1974.
??? paul
I believe they used a beam penetration tube in the VR20. I have an HP 1338A that uses that
technology.Google it, it's interesting.
Bob
3 May
3 May
12:48 a.m.
On Mon, May 2, 2016 at 2:21 PM, Paul Koning <paulkoning at comcast.net> wrote:
See https://en.wikipedia.org/wiki/Penetron. The idea
is that there are two layers, and a high voltage beam pokes through the first to activate
the second.
I think Tektronix made monitors of this type, but apparently GE invented them. I
remember hearing about that technology in the 1970s; I never actually saw one in the wild
(from any manufacturer).
I'd never heard it called a "Penetron" before; I'm not sure if that
was a trademark (perhaps of GE), but the generic term was "beam
penetration CRT". I've never seen the DEC VR20, but I have an HP
1338A color XY display that uses this technology to produce multicolor
displays with red, green, and yellow. Although the technology was
invented for color TV, I've never seen a beam penetration CRT with any
blue phosphor.
I hadn't heard of it being used in Tektronix oscilloscopes, but I'm
not surprised. They also used it in the DAS9120 series logic
analyzers, with the DAS9129 mainframe being the color display versions
of the more common DAS9100, and in the later 1241 logic analyzer. As
with the HP 1338A, the colors are red, green, and yellow.
12:54 a.m.
On May 2, 2016 9:48 PM, "Eric Smith" <spacewar at gmail.com> wrote:
I hadn't heard of it being used in Tektronix oscilloscopes, but I'm
not surprised. They also used it in the DAS9120 series logic
analyzers, with the DAS9129 mainframe being the color display versions
of the more common DAS9100, and in the later 1241 logic analyzer. As
with the HP 1338A, the colors are red, green, and yellow.
I thought the 1241 used a conventional CRT with a Liquid Crystal Color
Shutter in front of it.
1:22 p.m.
On Mon, May 2, 2016 at 10:54 PM, Glen Slick <glen.slick at gmail.com> wrote:
On May 2, 2016 9:48 PM, "Eric Smith"
<spacewar at gmail.com> wrote:
I think you're right. I remembered that the 1241 had an unusual
display, but forgot the details.
I hadn't heard of it being used in Tektronix oscilloscopes, but I'm
not surprised. They also used it in the DAS9120 series logic
analyzers, with the DAS9129 mainframe being the color display versions
of the more common DAS9100, and in the later 1241 logic analyzer. As
with the HP 1338A, the colors are red, green, and yellow.
I thought the 1241 used a conventional CRT with a Liquid Crystal Color
Shutter in front of it. 
2:23 a.m.
On Mon, May 02, 2016 at 04:21:09PM -0400, Paul Koning wrote:
The cover photo is interesting (PDP11 with PDP12 color scheme!)
It's the "LAB" color scheme. There was a LAB-8/e which has the same
colors. And there was at least one blue PDP-12 and one orange. I think
the market segment or purpose dictated the color more than anything.
/P
2:19 a.m.
On Mon, May 02, 2016 at 09:59:08PM +0200, Mattis Lind wrote:
Yet another nice color brochure.
https://dl.dropboxusercontent.com/u/96935524/Datormusuem/lab11.pdf
Has anyone seen a VR20 in real? Rather interesting to be able to do a red
and green X/Y screen based on different energy levels. Someone care to
explain how that works?
Unfortunately not. The printset that came with my GAMMA-11 suggests that it should be
used with a three color scope. Unfortunately I didn't get the scope.
/P
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14 comments
9 participants
participants (9)
-
aek＠bitsavers.org -
bobalan＠sbcglobal.net -
charles.unix.pro＠gmail.com -
glen.slick＠gmail.com -
hilpert＠cs.ubc.ca -
mattislind＠gmail.com -
paulkoning＠comcast.net -
pontus＠Update.UU.SE -
spacewar＠gmail.com