I dug up my old ERGO 301-C134 Terminal, but in the various house-moves, the keyboard has gone missing. I searched and searched the roof-cavity, but it has probably been lost.

ERGO 301 Terminal Back View ERGO 301 Terminal Front View
Click to embiggen

My intention is to re-use the terminal, however without a keyboard, it's basically e-waste. (I'm getting pressure from my SO to either use it, or recycle it.) So I would like to know what is possible in terms of replacing the keyboard with a modern one. Or perhaps a reference to some kind of circuit that will translate PS/2 USB Keyboard codes to whatever this terminal needs.

Reading about other terminals seems to indicate that the keyboards sometimes used a simple serial protocol. but I can find no such information for this terminal.

I am seeking information on what I may be able to replace the keyboard with? It seems to use an RJ11 jack for attaching the keyboard. But I'm not even sure if the keyboard was just a keyboard, or if it included the terminal processor or further circuitry.

So far I have been able to find:

Any help gratefully appreciated.

Some further background reading on Dumb Terminals.

  • 1
    What exactly is the question? It would be helpful to exactly specify the goal you're going for and what information you assume missing. After all, the linked information seems rather sufficient (maybe in combination with opening the unit) to make it work again/create a compatible keyboard. After all, it seems rather closely following it's DEC antetype . with the keyboard obviously being just that.
    – Raffzahn
    Commented Apr 21, 2022 at 23:25
  • 1
    Just a guess but since the external connection and printer port are both serial the keyboard probably is as well. From the looks of it the keyboard uses a 6-pin connector and has a 8048 MCU. I'd guess that the 6 pins are ground, power, TX, RX, bell, and keyboard lock (for flow control as mentioned in the manual); probably 7-bit ASCII on the wire since the rest seems to be 7-bit. Probing the port with with a multimeter and an oscilloscope could be informative. Commented Apr 21, 2022 at 23:30
  • @Raffzahn Unrelated to this question, do you know what the word frei means on a German schematic? Specifically in the context of a transformer. (I pinged you over on this question but I don't think pings are sent if the person's not commenting in the thread.) Commented Apr 21, 2022 at 23:36
  • @AlexHajnal Oops, haven't seen that, answered over there. (Also, I wouldn't be so sure about the keyboard being 7 bit.
    – Raffzahn
    Commented Apr 22, 2022 at 0:09
  • From the dirt/dust on it, you might actually have dug it up…
    – Jon Custer
    Commented Apr 23, 2022 at 17:46


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