13 Jul
2011
13 Jul
'11
2:37 p.m.
For all of its faults it was still the market leader.
Did you know you could plug a B&W TV camera into the back of a VT100 and see
the picture on the screen? I did it at Dec Park (Reading UK) one day and
drew a large crowd.
I can remember the tiny on/off switch and the vertical DB25 connector but that
is all I recall about the back of a VT100. I guess there must have been a BNC
connector? I do vaguely recall occasionally having to dissuade academic staff
from plugging their thinwire ethernet segment into the
back of their terminal but
I don't remember which type. I suppose it was
probably the VT100.
Did the terminal automatically sense an external video connection or was it
necessary to manually disable the video generated internally? I guess it was
probably expecting 525 lines, 60Hz but could cope with 625 lines, 50Hz?
My VT220 has a BNC connector on the back but in this case it is an output. It
produces a nice picture on a monochrome 625 line 50Hz monitor after adjusting
the vertical hold.
Regards,
Peter Coghlan.
14 Jul
14 Jul
3:03 a.m.
There were (still are) two BNC connectors on the back of the VT100.
One was video out which I used with the camera sync input and the other is
video in. This locked the picture to the data video.
Regards
?
Rod Smallwood
-----Original Message-----
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Peter Coghlan
Sent: 13 July 2011 19:37
To: cctech at classiccmp.org
Subject: Re: VT fixums
For all of its faults it was still the market leader.
Did you know you could plug a B&W TV camera into the back of a VT100 and
see
the picture on the screen? I did it at Dec Park
(Reading UK) one day and
drew a large crowd.
I can remember the tiny on/off switch and the vertical DB25 connector but
that
is all I recall about the back of a VT100. I guess there must have been a
BNC
connector? I do vaguely recall occasionally having to dissuade academic
staff
from plugging their thinwire ethernet segment into the
back of their
terminal but
I don't remember which type. I suppose it was probably the VT100.
Did the terminal automatically sense an external video connection or was it
necessary to manually disable the video generated internally? I guess it was
probably expecting 525 lines, 60Hz but could cope with 625 lines, 50Hz?
My VT220 has a BNC connector on the back but in this case it is an output.
It
produces a nice picture on a monochrome 625 line 50Hz monitor after
adjusting
the vertical hold.
Regards,
Peter Coghlan.
5:11 a.m.
There were (still are) two BNC connectors on the back
of the VT100.
One was video out which I used with the camera sync input and the other is
video in. This locked the picture to the data video.
???
What in the (insert your preffered expletives here, be criative!) a
VIDEO IN is doing behind an (old) terminal?! Watch NBC while working on the
company spreadsheet??? :oD
Hmmm...1984? :D INSOC watching you while you work? :D hahahahaha
8:10 a.m.
Easy - data on what you see on the screen. Say a picture of an extruder with
Temp and pressure on the screen. VT100 was black and white so the picture
replaced the black background. A modern security camera with a sync input
would probably work. Its good old 1v/75R Video. There's even a 50Hz option
in the setup.
Thirty five odd years and nobody has ever mentioned that one.
Regards
?
Rod Smallwood
?
-----Original Message-----
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Alexandre Souza - Listas
Sent: 14 July 2011 10:12
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: VT fixums
There were (still are) two BNC connectors on the back
of the VT100.
One was video out which I used with the camera sync input and the other is
video in. This locked the picture to the data video.
???
What in the (insert your preffered expletives here, be criative!) a
VIDEO IN is doing behind an (old) terminal?! Watch NBC while working on the
company spreadsheet??? :oD
Hmmm...1984? :D INSOC watching you while you work? :D hahahahaha
9:31 a.m.
On Thu, Jul 14, 2011 at 8:10 AM, Rod Smallwood
<rodsmallwood at btconnect.com> wrote:
VT100... the picture replaced the black background. A
modern security camera...
would probably work. Its good old 1v/75R Video.
Yep.
Thirty five odd years and nobody has ever mentioned
that one.
We knew about it in the 80s, but we never found a practical use for
the feature (we did software development and testing in the office -
manufacturing was done offsite at a wave solderer elsewhere in the
State, so there was really nothing going on that we cared to capture
on a video camera).
-ethan
15 Jul
15 Jul
4:04 p.m.
For all of its faults it was still the market leader.
Did you know you could plug a B&W TV camera into the back of a VT100 and see
the picture on the screen? I did it at Dec Park (Reading UK) one day and
drew a large crowd.
I can remember the tiny on/off switch and the vertical DB25 connector but that is all I recall about the back of a VT100. I guess
there must have been a BNC
connector? I do vaguely recall occasionally having to dissuade academic staff
There was of course also the mains input connector (IEC type, fuse and
votlage selector.A 3 contact jack socket (phone socket, like a hedphone
connector) for the keyboard. And 2 BNCs.
One was video output, and carried the composite video signal equivalent
to that shown on the built-in CRT. The frame rate was selectable as 50
ot 60Hz in the setup. The other was video input. This was just video (not
composite video and sync), you had to sync the extranl video source to
the sync signal appearing on the video output socket. This means
displaying live TV, etc was next-to-imposible.
from plugging their thinwire ethernet segment into the
back of their terminal but
I don't remember which type. I suppose it was probably the VT100.
MAybe a VT220, whcih ahd a (composite) video output BNC socket on the
back. No video input on that one, though. I remember when I was at
Bristol we had a thinwire segment go down. After checking for sillies, I
put a 'scope on it and found the unmistakable composite video signal.
Yes, sombody had plugged a spare T-piece into the back of a VT220.
Did the terminal automatically sense an external video connection or was it
necessary to manually disable the video generated internally? I guess it was
probably expecting 525 lines, 60Hz but could cope with 625 lines, 50Hz?
My VT220 has a BNC connector on the back but in this case it is an output. It
produces a nice picture on a monochrome 625 line 50Hz monitor after adjusting
the vertical hold.
I thought hte VT220 had a setup option for 50 or 60Hz vertical too. If
so, in the former setting, it should display fien on a 625 line monitor
without any adjustments.
-tony
16 Jul
16 Jul
2:29 p.m.
There was of course also the mains input connector (IEC type, fuse and
votlage selector.A 3 contact jack socket (phone socket, like a hedphone
connector) for the keyboard. And 2 BNCs.
Its been over 15 years since I last saw the back of a VT100 and my feeble
memory doesn't recall the details. However, now that you mention it, I do
remember the keyboard jack. In the event of getting a working display but
no response from the keyboard, standard procedure was to reach behind the
terminal and wiggle the keyboard connector until a click was heard from
the speaker and then try again.
One was video output, and carried the composite video signal equivalent
to that shown on the built-in CRT. The frame rate was selectable as 50
ot 60Hz in the setup. The other was video input. This was just video (not
composite video and sync), you had to sync the extranl video source to
the sync signal appearing on the video output socket. This means
displaying live TV, etc was next-to-imposible.
It never dawned on me that the 50/60Hz selection in setup was for the video
output frame rate. I assumed it was supposed to be set to the frequency of
the mains supply but I never bothered to figure out exactly what effect it
might have or why not having it set correctly didn't seem to make any great
difference. If it was marked frame rate or something like that, I would
probably have figured it out.
from plugging their thinwire ethernet segment
into the back of their terminal but
I don't remember which type. I suppose it was probably the VT100.
MAybe a VT220, whcih ahd a (composite) video output BNC socket on the
back. No video input on that one, though. I remember when I was at
Bristol we had a thinwire segment go down. After checking for sillies, I
put a 'scope on it and found the unmistakable composite video signal.
Yes, sombody had plugged a spare T-piece into the back of a VT220.
I thought hte VT220 had a setup option for 50 or 60Hz vertical too. If
so, in the former setting, it should display fien on a 625 line monitor
without any adjustments.
I just had a hunt through setup on my VT220 and I can't find a 50/60Hz option.
Regards,
Peter Coghlan.
17 Jul
17 Jul
6:42 p.m.
Well, no one came to claim any of the VT fixums on Saturday, so they
went to the MIT flea, and a few folks walked away with one.
There are still more we need to get rid of. Next month!
The triage session at RCS yielded 6-8 good VT100oids, which we intend
to keep. One of the VT100s is one of the R at Re! green screen variants.
--
Will
18 Jul
18 Jul
1:39 p.m.
Its been over 15 years since I last saw the back of a
VT100 and my feeble
In my case, s/years/minutes/ :-)
memory doesn't recall the details. However, now
that you mention it, I do
remember the keyboard jack. In the event of getting a working display but
no response from the keyboard, standard procedure was to reach behind the
terminal and wiggle the keyboard connector until a click was heard from
the speaker and then try again.
I see... Of course the speaker was in the keyboard unit, so I guess the
click yuo heard was the keyboardelectorncis powering up or being
initialisd when the faulty contact at the plug was no longer faulty.
It never dawned on me that the 50/60Hz selection in
setup was for the video
I wonder what else it could be fore :-)
output frame rate. I assumed it was supposed to be set
to the frequency of
the mains supply but I never bothered to figure out exactly what effect it
You are. It also sets, of cource the frame rate for the internal display
(same videO0. The problem with getting ir wrong is that that the screen
image can strobe aginst mains powered lights and you get a very annoying
10Hz filcker. I have never managed to get this effect, but I am told it
can happen.
Setiting it wrongly won't do anay damage, of course.
As an aside, I have a Fluke data logger which has 2 internal 50/60Hz
selection swtiches. One sets the division ration for the real time clock
counter (which takes the mains as its frequency reference), the otehr
cotnrols the timing of the ADC so that it integrates the input signal
over a whole number of mains cycles, effectively eleimantate
mains-frequency noise. But that's anot a particualrly common reason for
having rreqeucny selection
[Yes this is sort-of on-topic. The unit is controlled by 2 4040
microprocessors, one for system control and one on the paper tape output PCB,
might have or why not having it set correctly
didn't seem to make any great
difference. If it was marked frame rate or something like that, I would
probably have figured it out.
I am surte it's in one of the fine manuals....
I just had a hunt through setup on my VT220 and I
can't find a 50/60Hz option.
I may have been msitaken. Alas I don;t have a VT220 or any later DEC
terminal, so I can't fire one up and look for it. The only real DEC
termianls I have are a VT55, VT100 (2 or 3) and a VT105.
-tony
4753
days inactive
4758
days old
8 comments
6 participants
participants (6)
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ard＠p850ug1.demon.co.uk -
CCTECH＠beyondthepale.ie -
ethan.dicks＠gmail.com -
pu1bzz.listas＠gmail.com -
rodsmallwood＠btconnect.com -
wdonzelli＠gmail.com