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1976 Videoton VT-340 keyboard

This beefy keyboard was part of the Videoton VT-340 display terminal, manufactured from 1972. Check out this picture-heavy disassembly post full of surprises.

KBD.news
Published October 19, 2023
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I was fairly sure that this beast will have some surprises in store for me but I wasn't expecting a considerable amount of yarn, nor sewing, stitching and book binding techniques applied to the PCB beneath the hood. :D And it seems I "discovered" a yet undocumented switch variant.

But let's get a few weeks back when I came across this dirty Videoton in a classified ad, instantly falling in love with the industrial look without knowing anything about this particular model.

Pic:

As already teased in issue #137, the case of this hefty bad boy is made of 5 mm thick metal, too heavy for the small laboratory scales I had laying around my office (3.86 kg). And it's ridiculously high, about 11 cm.

In this photo you can see it next to a compact low-pro Bancouver40 (just for fun) and the Intergraph, featured recently, which is more in the same league.

Pic: Intergraph vs Bancouver40 vs Videoton

Intergraph vs Bancouver40 vs Videoton

This was one of those fortunate situations when I could source a rare artifact which not many of you will have the opportunity to grab, especially on the other side of the pond, given it was manufactured in the socialist Hungary in relatively low number.

However, it was referenced in a lot of NASA documents so maybe it's not impossible to find one in the US.

Listed as "could make use of some cleaning" – meaning get your hazmat suit or run for your life –, I didn't even want to put this filthy thing on my desk. That's why some of the early photos (only for tough-nerved readers) were shot on the floor.

Honestly, I've seen some dirty keyboards during my collector "career", but pieces of plaster were falling out of this one… I've stumbled upon another specimen listed with a thick splash of plaster hardened on the housing which may originate from the same lot, probably sourced from an abandoned factory or other industrial building.

Data sheet

  • Model: Videoton EC-7168 (VT-430)
  • Manufacturer: Videoton / TKI
  • Items manufactured: 10-15K (90K?!)
  • Manufacturing period: 1972-1984
  • Layout: 73 keys
  • Switches: RAFI early RC 72 Hall effect?
  • Keycaps: RAFI doubleshot, uniform spherical
  • Weight: 3.86 kg
  • Height: 10.5 cm

Most sources indicate there were 10-15,000 items manufactured of the VT-340, and one single source mentions 90K terminals, which is probably incorrect. Based on the sticker (below), the factory's output was about 60 devices per month in the fifth year of production (-> 720/year), which is about 10K projected for the whole manufacturing period of 1972-1984.

Labels & Age

Originally, all I supposed based on the layout was that I'm dealing with a pre-standard, pre-'84 keyboard, probably terminal. I'd never thought this would be almost 50 years old, manufactured in 1976. Only ofter the purchase looked I up what the listing stated was a Videoton Computer EC-7168 (VT-430) (sic!) keyboard.

Pic: Videoton VT 340 (not 430…) (photo: holdcomputers.com)

Videoton VT 340 (not 430…) (photo: holdcomputers.com)

PCB and plate frame: 1976 JAN 27 (stamped) 54 (scratched). PCB: VD-43:

Pic:

TKI Tip: T5112. No: 0057/76 (sticker):

Pic:

Case: Videoton Computer Typ: 48000 No: 601/09

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The only photos I could find about the whole terminal (I have only the keyboard) where this and this:

Pic:

Then I realized there was a typo in the listing and it's not VT-430 but 340. This opened up a whole new world, and most of the photos here come from a great site called holdcomputers.com – which is an abbreviation for Hungarian Old Computers. Site runner and renowned local collector Zsolt Vidvenyecz gave permission to use his photos of the whole display terminal:

Pic: Videoton VT 340 (photo: holdcomputers.com)

Videoton VT 340 (photo: holdcomputers.com)

…and also of his photo archive with some VT-340s in action:

Pic: Videoton VT 340 (source: holdcomputers.com)

Videoton VT 340 (source: holdcomputers.com)

Pic:

Pic: In the back

In the back

…and being built:

Pic:

Pic:

Videoton VT 340

Famous for its radios and TVs, Videoton was a big name in the 1980s in Hungary but also well-known in most countries of the Eastern Block. Display terminals being almost CRT TVs in those days, it was probably a natural move for the company to dip their toes into computing. The Videoton VT 340 display terminal, one of their earliest models manufactured from 1972, was compatible with the DEC VT-52 and other typewriters and interfaces of the 1960-70s.

Pic:

Disassembly

One of the impressive parts about this keyboard is the thick and very high cast(?) aluminum case with about 5 mm wall thickness and almost 11 cm in height.

Pic:

Pic:

Here it is again with a bancouver40 for scale: :D

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To assemble such a high keyboard you need some long screws:

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Keycaps

Nice doubleshot keycaps in two colors. The profile is high, uniform, spheical, like an all-R3 SA. As you'll see later, these were part of RAFI's keyboard framework:

Pic:

Some legends are crisp, some others not so nice with considerable bleeding.

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By the way, you can easily remove the keycaps, they come off without any resistance, in contrast to many similar vintage caps/switches with these square stems. E.g. seen on the Orion and also my Datacoops from a good decade later.

Spacebar

I'm always cautious when removing spacebars of old keyboards. You never know what to expect and the last thing I want to do is to break something. But after taking a quick look at this one I realized there's no stabilizer or any similar mechanism. Instead, two dummy switches on the flanks.

Pic:

And a pencil mark indicating the year? 75 or 76, or 75 corrected to 76. (The PCB was made in 1975 December, the whole keyboard was assembled in 1976 January.)

Pic:

Switches

RAFI switches, probably Hall effect. Again? Linears for sure, but some older variant, not listed on Deskthority. Huge bulky housing, four long pins in a row on the PCB side. Despite no visible branding this time, they are RAFIs for sure.

Pic:

Unfortunately, I can't desolder or further disassemble this thing until I make some special tools to remove the strange screws holding the frame together.

Anyway, RAFI is a German switch manufacturer, starting development of keyswitches in 1968 and launching the firts RAFI keyboard in 1970 – so we are in the right period. These are probably some early RAFIs, but not the contactless magnetoresistive switches, like e.g. in this patent.

According to this source, these switches had 3 or 5 pins and were only current for around three years, before RAFI introduced RC 72 Hall effect switches.

Pic: Four pins

Four pins

My switches are probably between the two models or some very early RC 72s, without branding on the top. The same source also states that RAFI switches were favoured by TKI (Távközlési Kutatóintézet which roughly means Telecommucation Research Institute in Hungarian), and that's exactly what's indicated on one of the stickers. (And seeing kbd.news referenced on that site is just surreal. :D)

That said, I will desolder one switch for the sake of science and keyboard archeology, but it will require some special tools to disassemble the RAFI frame, holding together the whole contraption.

Pic:

A RAFI advertisement describes this modular system:

The contactless keyboards are built according to a modular system. They comprise rails and end-pieces, which are preassembled as a frame, as well as contactless switches, signal lamps and snap-in covers for empty positions. Frames can be manufactured with up to 30 units in each vertical or horizontal row (1 unit = 19.05 x 19.05 mm). The position of the contactless switches and signal lamps can be offset by a quarter unit (4.76 mm) or multiples thereof.

PCB

This is the crazy part with threads, sewing, and the two PCBs stitched together like you do book binding.

Pic:

As fanf pointed out, this technique is called cable lacing, and it was (is?) a cable management method taught to generations of lineworkers, used in telecommunication, naval and aerospace applications.

Cable lacing uses a thin cord to bind together a group of cables using a series of running lockstitches. As outdated as this technique may seem, it also used on Mars rovers.

There are two PCBs which you can open up like a book:

Pic:

Thanks to this connection strenghtened by threads:

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The result:

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In fact, the PCB is even older, I guess this is "1975 DEC 03":

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Connector

First it looks each key has its own wire (not true):

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I counted 24 wires that make it into the cable and right to the giant connector. Again, faf came up with a possible solutions: this may be a Centronics parallel port, some kind of micro ribbon, maybe this IEEE 1284 (TypeB?).

Pic:

The connector has room for 36 so that should be about right.

Results

If you dared to check out the original photos, the cleaned version may come as a relief:

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Resources

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Published on Thu 19th Oct 2023. Featured in KBD #140.


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