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The VT-100 Keyboard

D

David Irish

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Feb 7, 2018
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I really want to add a VT-100 to my vintage computer collection, but I also want to put it to work, connecting it to my DEC PDP minicomputer emulators, and setting up demos to show what old school computing was all about. However, not only are DEC terminals rare, but every time I find a VT-100, it's missing the keyboard, and they still want $200-$300 for it. The VT-100 has a unique interface cable that has a 1/4" Audio cable -- the type you use to plug in your MIC or musical instrument pickup into a mixer. This is an unusual thing, and it means that you can't just take an old keyboard with a RJ-11, RJ-45, DIN, Mini-DIN, or USB connector and hook it up. You need to make a box that converts a modern keyboard's signal into the correct ANSI signal and pass it through the cable so that the terminal understands it.

I have seen one person who made a box that converts the VT-100 keyboard into USB. I have not seen anyone do the reverse -- allow you to use a USB keyboard on a VT-100.

The prospects of my getting a VT-ANYTHING are slim, but if I am to get a DEC terminal that fits the correct time period, This may be the only option. So does anyone know if it can be done, or if it's already been done, and I haven't found the dude selling the box yet?

Also -- besides Ebay and Craig's list, are there any other resources for finding old DEC equipment?

THanks!
 
I can't offer any advice on how to get a VT100. A VT220, VT240 or VT320 might be easier to acquire (and the LK201 keyboards for them are easier to get as well).

Also, I don't know if you are aware of it but I've written a VT52 emulator that you might find useful. I've tried to give it a look similar to what you would have seen on real hardware:

RawTCP.JPG
 
Does it have to be DEC-branded? Back in the day, we used C. Itoh and Beehive VT-220 terminals with our VAX, which were every bit as nice as the DEC ones. I think even Tab offered one, as well as Televideo and Wyse.
 
Yes, the VT-100 keyboard is a strange beast indeed. There is a bunch of analog mojo going on in
the communication between the keyboard and the terminal. You can read all about it in the VT100
technical manual. That is the source material (along with schematics) that the YouTuber Seth Morabito
used to create the USB interface he describes in this series of videos:

https://www.youtube.com/watch?v=tRf1zCHlj6o
https://www.youtube.com/watch?v=35Bptrf9BMA
https://www.youtube.com/watch?v=QW_uu-B1kbg
https://www.youtube.com/watch?v=i03rmPtuJZ4

I contacted the author regarding his circuit and he will gladly respond with any information that might be missing from his posts.
You can find a link to his blog posts and his firmware repository on github in the external links section of the VT100 entry on
the terminals wiki:

https://terminals-wiki.org/wiki/index.php/DEC_VT100#External_Links

I was interested in taking his circuit and making it more compact by using a modern USB interfacing microcontroller and
a boost converter to get the 12 V needed to drive the keyboard from the 5 V supply of the USB. I don't think the keyboard
draws so much current that it would exceed the power provided by a USB connection. It just needs the higher voltage in
order to do its analog tricks that it uses to communicate to the terminal. This would give you a much smaller dongle into
which you plug the VT100 keyboard and then connect to a regular host by USB. Seth's project used an external power
supply to get the 12 V and a fairly large breadboard setup with a Teensy microcontroller. I think the whole thing could
be reduced significantly in size and then fabricated using one of the maker board service houses into a small dongle.
 
Also, if you camp on ebay long enough you will eventually find either
a) a VT100 with keyboard, or b) just the keyboard for sale. Even though
they are getting harder to find, they were made in sufficient quantities
that they are still out there semi-regularly.

Also, be on the lookout for the C. Itoh CIT-10x series of terminals which
were blatant copies of the DEC VT100, including the funky keyboard
jack.
 
David Irish said:
I really want to add a VT-100 to my vintage computer collection, but I also want to put it to work
every time I find a VT-100, it's missing the keyboard, and they still want $200-$300 for it.
Click to expand...

So what are you willing to spend for a working VT100 with a keyboard?
 
Here's a C. Itoh CIT-101:

800px-C._Itoh_CIT-101_191388350368-1.jpg


Look vaguely familiar?
 
What do people use to replace the plastic snap rivets that hold the terminal shell together when those get broken? Can you get identical replacements for those somewhere?

I have one where the top of the shell is mostly flapping around in the breeze instead of being latched to the bottom of the shell.
 
gslick said:
What do people use to replace the plastic snap rivets that hold the terminal shell together when those get broken? Can you get identical replacements for those somewhere?
Click to expand...
It has been decades. but IIRC they were regular center-pin expanding rivets like this (not my image):

shopping


These are used on a lot of things, from car body trim to PCB heatsinks.
 
gslick said:
What do people use to replace the plastic snap rivets that hold the terminal shell together when those get broken? .
Click to expand...

I use rubber expansion nuts and a mating machine screw. Tighten the screw and the rubber expands, similar to the way the wings flare out when you push the plunger on the plastic snap rivet. However, the plastic rivet does lock tighter (do not pick the VT100 up by the top lid when using the expansion nuts!!)

Lou
 
Terry Kennedy said:
Does it faithfully replicate the melodic sound of the VT-52's feeper? :sarcasm:
Click to expand...
It doesn't, for either key click or the "bell", mostly because I don't have a good recording of what they sound like. "good" referring to a combination of sound quality, provenance, and usage licensing.

-ken
 
kgober said:
It doesn't, for either key click or the "bell", mostly because I don't have a good recording of what they sound like. "good" referring to a combination of sound quality, provenance, and usage licensing.

-ken
Click to expand...

I recently got a VT62 terminal. I might be able to help you out there. I'm sure there are other VT[56]x owners out there would be willing to help out as well.
 
i have a VT-100 with keyboard for $250. Pickup in Tyngsboro, Ma. call 978-649-1353.
 
that's not a terrible price. Anyone selling them will want market prices. If you bought a VT 100 (or 101 or 102) for $250 you could always resell it if you come across a donation/traded terminal.

VT 220's are a lot more practical albeit newer and less kitsch.

b
 
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