Author Topic: Digital LK250 Keyboard - Connect to PC  (Read 4688 times)

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Offline shmex

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Digital LK250 Keyboard - Connect to PC
« on: Mon, 30 May 2016, 21:33:01 »
Hello guys.
I was doing some cleaning on the attic yesterday and i found a Digital LK250 keyboard  :) 



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Its a pretty nice keyboard and i would like to test it on a PC, is this possible?
I have tried to search for some kind of converter on ebay but i didnt find anything ... I think the connection its SDL on one tip and RJ11 with 6 pins on the other.



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Any chance to convert this to PS2 or USB? Any converter or cable available to purchase?
Thanks in advance guys!

Offline BucklingSpring

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Offline shmex

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #2 on: Tue, 31 May 2016, 12:31:12 »

Offline Suruga Devil

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #3 on: Tue, 31 May 2016, 14:41:45 »
https://deskthority.net/workshop-f7/xt-at-ps2-terminal-to-usb-converter-with-nkro-t2510-330.html

Thanks for the URL, but i didnt find anything that could help me ... What exactly should i do?

You can write your own converting firmware and build a converter unit, but someone's already done it to perfection. Take a look at Soarer's converter (linked below). You will have a difficult path ahead of you if you decide not to use this converter, so I'd strongly advise you to do so.

https://geekhack.org/index.php?topic=17458.0

Offline Findecanor

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #4 on: Tue, 31 May 2016, 20:27:20 »
Wow. From the little I can find in a DuckDuckGo search, the DEC LK250 is supposed to be IBM-compatible somehow ...

DEC's more known keyboards, the LK201 and LK401 used another protocol.
For those, you could find schematics and source code on www.kbdbabel.org
Man must shape his tools lest they shape him
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Offline shmex

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #5 on: Wed, 01 June 2016, 19:20:20 »
https://deskthority.net/workshop-f7/xt-at-ps2-terminal-to-usb-converter-with-nkro-t2510-330.html

Thanks for the URL, but i didnt find anything that could help me ... What exactly should i do?

You can write your own converting firmware and build a converter unit, but someone's already done it to perfection. Take a look at Soarer's converter (linked below). You will have a difficult path ahead of you if you decide not to use this converter, so I'd strongly advise you to do so.

https://geekhack.org/index.php?topic=17458.0

Thank you so much for your help ... I really thought that a simple adapter would be enough to test this keyboard. It seems i was wrong  :D
Well, i will have to read all the guide and buy some cables and a  Teensy 2.0! Hope i can do it by myself.
Thanks once again for the URL!

Wow. From the little I can find in a DuckDuckGo search, the DEC LK250 is supposed to be IBM-compatible somehow ...

DEC's more known keyboards, the LK201 and LK401 used another protocol.
For those, you could find schematics and source code on www.kbdbabel.org

Ty so much for your help Findecanor.
When i read the guide i asked myself which of the schematics should i use for the connections ... The cable has 6 wires.
So, from this page (http://www.kbdbabel.org/conn/index.html), should i use the IBM Model-M Keyboard or the IBM Terminal shematic?






Offline shmex

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #6 on: Sun, 05 June 2016, 20:18:18 »
Could you anyone help me with the schematics please ... How can i know which wires should i connect to to the board (data, GND and VCC)?

Thanks!

Offline Findecanor

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #7 on: Sun, 05 June 2016, 20:52:10 »
I think you would have to inspect the PCB to see which is which and then trial and error.
GND is usually easiest to find because many circuits are often connected directly to GND. VCC likewise, but not as much.
GND often has a black cable, with VCC often white or red.

Do use a PS/2-to-USB converter when testing it.
Man must shape his tools lest they shape him
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Offline csmertx

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Offline shmex

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #9 on: Mon, 06 June 2016, 21:03:58 »
I think you would have to inspect the PCB to see which is which and then trial and error.
GND is usually easiest to find because many circuits are often connected directly to GND. VCC likewise, but not as much.
GND often has a black cable, with VCC often white or red.

Do use a PS/2-to-USB converter when testing it.

Well i would like to avoid that, but i guess it would be the only option. Maybe someone can help until the board arrives ...
Findecanor mentioned that this keyboard would be IBM compatible, so maybe the connections are identical to some connector on IBM keyboards right?
Regarding the PS2 converter, i guess i will buy a RJ12 adapter and connect all the wires directly to the board, thanks  :)

There are Soarer's converters for RJ45 on Ebay if you want to just buy one.

http://www.ebay.com/itm/NEW-RJ45-to-USB-Soarers-Converter-Model-M-Terminal-Keyboard-Remapping-Macros-/281476431381?hash=item41894d7e15:g:wwYAAOSwF1dUSZVm

Thanks for the help csmertx, but i cant use that converter on this keyboard ... The cable has two connectors, a RJ12 on one end that connects to the keyboard and a SDL on the other that should connect to the terminal i believe.
I think i will buy this adapter just to test if the keyboard works: http://www.ebay.com/itm/272118852476?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
With this adapter i can connects all the wires much more easily.

Offline csmertx

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #10 on: Mon, 06 June 2016, 21:25:29 »
I think you would have to inspect the PCB to see which is which and then trial and error.
GND is usually easiest to find because many circuits are often connected directly to GND. VCC likewise, but not as much.
GND often has a black cable, with VCC often white or red.

Do use a PS/2-to-USB converter when testing it.

Well i would like to avoid that, but i guess it would be the only option. Maybe someone can help until the board arrives ...
Findecanor mentioned that this keyboard would be IBM compatible, so maybe the connections are identical to some connector on IBM keyboards right?
Regarding the PS2 converter, i guess i will buy a RJ12 adapter and connect all the wires directly to the board, thanks  :)

There are Soarer's converters for RJ45 on Ebay if you want to just buy one.

http://www.ebay.com/itm/NEW-RJ45-to-USB-Soarers-Converter-Model-M-Terminal-Keyboard-Remapping-Macros-/281476431381?hash=item41894d7e15:g:wwYAAOSwF1dUSZVm

Thanks for the help csmertx, but i cant use that converter on this keyboard ... The cable has two connectors, a RJ12 on one end that connects to the keyboard and a SDL on the other that should connect to the terminal i believe.
I think i will buy this adapter just to test if the keyboard works: http://www.ebay.com/itm/272118852476?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
With this adapter i can connects all the wires much more easily.

Oh ok, the RJ12 connects to the keyboard gotcha. That's a shame, at least you found something that could possibly get the keyboard to output some characters.
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Offline hasu

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #11 on: Mon, 06 June 2016, 23:36:52 »
Found these info. It seems like the keyboard supports both "LK250" codes and  "industry-standard" codes and they are very similar with PS/2 and XT respectively but some keys are different. Not sure existent conveter works with this keyboard.

http://labs.hoffmanlabs.com/node/19
Quote
LK250 — LK-style layout with PC compatibility (dual-mode), PC DIN connector

... the LK250 and LK450, which are LK-style keyboards intended for use on Microsoft Windows systems. These keyboard provide the LK-style layout, and can select PC-style operations and LK-style operations.

See Chapter 8 for keyboard DEC extended commands, you can even control fourth LED using them.
http://manx.classiccmp.org/collections/hcps/jp76ath.pdf

Offline aylfit

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #12 on: Thu, 06 September 2018, 14:13:28 »
Hi Guys. Have you found a converter online yet or really needs to built it ?

Thanks!

Offline wsr80913

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #13 on: Mon, 01 April 2019, 22:46:59 »
DEC has made physically compatible and electrically incompatible devices, so make sure your part number matches and/or test at your own risk.

My keyboard is an LK250 (not an LK250.AA or whatever) and came to me with a PS/2 connector on its cord.

The keyboard end of the cord has an RJ12 (6p6c) connector with six pins, and looking at the plug with the key up, and pin 1 on the left, pin 2 is Data, pin 3 is Clock, pin 4 is +5v, and pin 5 in ground.

Alt-F17 swaps between DEC and "Industry Standard" mode.  I have it hooked up to a Soarer's Converter, and the attached .sc file works with the "Special" LED off.

There are commands to control the mode in the document Hasu posted, so it should be possible to adjust the tmk converter to set it up automatically.

Offline obsysteme

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Re: Digital LK250 Keyboard - Connect to PC
« Reply #14 on: Sat, 26 June 2021, 22:42:31 »
Hi,
Joining in on this past conversation. I have such keyboard that I am trying to make work on a windows PC, but of model LK250-aa, which based on the 6p6c cable photos as posted on the original post by Shmex, appears to be the same model as his. I nonetheless built a Cable with ps2 outlet plugged into a Soarer’s converter, with pinout as described by WRS80913 (but as he mentions, his keyboard is LK250, not LK250-aa).

What I get when I plug it into the PC with such a cable, is that the keyboard makes a kind of boot noise, and then the “special” LED is on. I can switch on/off special LED with ALT+F17 and when I type I hear beeper sound for each key pressed (internal beeper function of this terminal keyboard?). So it seems voltage reaches the keyboard appropriately, but data does not reach the PC, as when I type, no character registers. I am wondering if I maybe only have partially correct pin-out for the LK250-aa. Is ti possible it uses 1 and/or 6 position of the 6 wire cables, and so is different pinout than LK250? I can’t find any pinout info on LK250-aa anywhere?

Cheers