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Wanted: Digital LK421-AA (DEC's UNIX keyboard)

hackerb9

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Jul 14, 2015
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Earth, currently.
Hiya! Does anyone have or know where I can find an LK421-AA?

Alternately, can anyone point me to a USB or PS/2 keyboard that is laid out in a similar fashion? I can make an adapter using an Arduino so it'll work in my VT340. Unfortunately, it's been hard for me to find any keyboard that is right. The LK421-AA has the control key directly to the left of the letter A, and one-story Return key. It's also cute and small because it omits the application keypad. The "Happy Hacking" keyboard is the closest I've found, but I don't think I'd be very happy with the Backspace key being in a different location.
 

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kgober

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A USB keyboard meeting your needs shouldn't be hard to find. Google for "TKL keyboard", TKL standing for Ten Key Less, i.e. having no number pad. There are also keyboards without the cursor keys, these are generally referred to as "60%". If the Ctrl key isn't already where you want it, then look for a model with customizable firmware. The QMK firmware is very popular and with it, changing the keyboard layout is just a matter of generating a new firmware image and reflashing the keyboard. If you change the layout this way, you may need replacement keycaps if, for example, the CapsLock and Ctrl keycaps are different sizes. If you get a keyboard using something popular like Cherry MX keyswitches then finding replacement keycaps that fit the MX stems won't be difficult.

I have a Drop CTRL keyboard (https://drop.com/buy/drop-ctrl-high-profile-mechanical-keyboard) that lacks the number pad but has the arrow keys, using the 'standard' layout. I do have a replacement keycap set that includes a larger Ctrl keycap that will fit the space where Caps Lock is, but it doesn't have a smaller Caps Lock key. I'm sure there are keycap sets out there that will have both.

If you aren't interested in the fancy RGB lighting, there is also the Drop ENTR keyboard: https://drop.com/buy/drop-entr-mechanical-keyboard.

While searching I found this keycap set that you might find interesting: https://drop.com/buy/drop-matt3o-mt3-3277-custom-keycap-set
These keys don't have translucent legends allowing individual keyswitch lighting to shine through, but this set does include Ctrl keys in a variety of widths as well as a number of other interesting terminal keys (more IBM-ish than UNIX-ish, alas).
 

hackerb9

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Thanks for the super informative help! I had not known about "TKL" or "QMK".

And that "Drop ENTR" keyboard looks very close to perfect! So, I would just need to flash the firmware to get rid of capslock and then buy a control key that would fit in its place? The kit you linked to with the red buttons has everything I'd need?

I've also found something called the "Mini Model M" by Unicomp that looks like a good contender if I can't find an LK421-AA.
 

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kgober

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Yes, updating the firmware would allow you to change the scan code generated by each key, and yes, getting another Ctrl keycap of the appropriate size would be needed if it bothers you to have your Ctrl key physically labeled "CapsLock" on the keycap.

If you go the Unicomp route, they do sell replacement keycap sets for exactly this purpose, although you will probably need to do the scan code swap in the Arduino because I don't know if Unicomp lets you modify the firmware.
Unicomp, Inc.: Alternative Ctrl-Caps Lock Buckling Spring Keys (pckeyboard.com)

Keep in mind that Unicomp keycaps are different from and not compatible with the Cherry MX style so you shouldn't expect to be able to mix and match replacement Unicomp keycaps onto a keyboard using Cherry MX keyswitches.

If you care about the feel of the keys, the Model M has a clicky feel (and sound) *very* different from DEC keyboards. I don't happen to have an LK421, but I did have an LK401 handy and the keyswitches on my LK401 are mushy and silent, with a slight tactile bump at the top of the key movement (like a rubber dome keyboard). I tested a bunch of different Cherry MX and MX-clone keyswitches and the ones I have that feel most similar to the LK401 are Cherry MX Clear, Cherry Tactile Gray, Zealios 78g, and Kailh Box Royal.
 

hackerb9

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Messages
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Location
Earth, currently.
If you go the Unicomp route, they do sell replacement keycap sets for exactly this purpose, although you will probably need to do the scan code swap in the Arduino because I don't know if Unicomp lets you modify the firmware.
Unicomp, Inc.: Alternative Ctrl-Caps Lock Buckling Spring Keys (pckeyboard.com)

Thanks for the link! It looks like Unicomp's Mini M isn't reprogrammable, unlike their Model F keyboards. Fortunately, the swap should be easy in the Arduino. The styling isn't as pretty as Drop, but I think it would match the VT340 better. Especially since I'll probably end up repainting the cases, à la ModRadio:

JonAlmeda (ModRadio) - A retro radio that has been repainted and retrofitted


If you care about the feel of the keys, the Model M has a clicky feel (and sound) *very* different from DEC keyboards. I don't happen to have an LK421, but I did have an LK401 handy and the keyswitches on my LK401 are mushy and silent, with a slight tactile bump at the top of the key movement (like a rubber dome keyboard). I tested a bunch of different Cherry MX and MX-clone keyswitches and the ones I have that feel most similar to the LK401 are Cherry MX Clear, Cherry Tactile Gray, Zealios 78g, and Kailh Box Royal.

"Clicky" versus "mushy", I get. When I hear “Zealios 78g” orKailh Box Royale”... I don't know if we're talking high-end perfumes or expensive cigars, but I know I'm in over my head.:lol:

Thank you for all the helpful information and sorry I'm not at the level where I can completely appreciate it.
 
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kgober

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They are just names of different models of keyswitches. Keyboards like the Drop CTRL allow you to swap out the keyswitches with different types, based on your preferences. The problem then becomes, how do you choose? It's not like you can go to your local keyswitch store and try them all out. So for the benefit of anyone who is building a USB mechanical keyboard that wants to replicate the feel of an LK401 I tested the ones I happen to have to see which ones felt similar.

Naturally if you are going the Unicomp route you won't need to worry about any of this.
 

Kadar3337

New Member
Joined
Nov 23, 2022
Messages
5
Hiya! Does anyone have or know where I can find an LK421-AA?

Alternately, can anyone point me to a USB or PS/2 keyboard that is laid out in a similar fashion? I can make an adapter using an Arduino so it'll work in my VT340. Unfortunately, it's been hard for me to find any keyboard that is right. The LK421-AA has the control key directly to the left of the letter A, and one-story Return key. It's also cute and small because it omits the application keypad. The "Happy Hacking" keyboard is the closest I've found, but I don't think I'd be very happy with the Backspace key being in a different location.
Hope you are still alive, I have found what u r looking for the LK421-AA.

(Edited by ajacocks) please don’t publicly post your contact info. @hackerb9 can PM you.
 
Last edited by a moderator:

sorphin

Experienced Member
Joined
Feb 11, 2014
Messages
259
Hope you are still alive, I have found what u r looking for the LK421-AA.

(Edited by ajacocks) please don’t publicly post your contact info. @hackerb9 can PM you.
I sent you a pm incase they no longer need it (and since you're under the post count to send).
 
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