• Please review our updated Terms and Rules here

Keyboard-less VT10x terminals

Redirected here from the VT125 thread...

Question about the PS/2 keyboard - Have you tried a DEC LK411/412 PS/2 keyboard with your interface? I ask because, DEC being who they are, used a slightly different keycode schema in their keyboards. I think they had alternate code to use the normal PC type scheme also but I don't recall. And I've forgotten the technical term for it until I reference my past notes... Ah, here it is. Scancode sets. The DEC LK411/412 PS/2 keyboard is a scancode set 3 keyboard ( https://www.scs.stanford.edu/10wi-cs140/pintos/specs/kbd/scancodes-5.html#ss5.10 ) but I think they can revert to scancode set 2 under certain circumstances. I did a lot of research into this back in the early 2000's when I was looking for a KVM that worked with DEC/Compaq keyboards (hint: not many do. Raritan does and Compaq had a re-badged KVM from someone that did).

Edit: It seems this was more important in the early 2000's than now. Apparently most new keyboards are scan set 3

Anyway, has anyone tried? If not, I'll buy one and give it a shot.
 
Last edited:
I have only tried keyboards from regular PC's. - the $25 ones you can get on Amazon. The key code conversion is table-based, so it could probably be adapted.
 
jmdhuse said:
Hello All,

I've noticed that there any number of VT10x monitors for sale on Ebay, but without the standard VT100 keyboard to go with them, and if you can find a keyboard, they are pretty pricey. I managed to get my hands on a VT101 monitor (no keyboard), and I decided to design a board that would connect to the monitor on one end and a PS/2 keyboard on the other end. The keyboard interface is adapted directly from the DEC schematics for the VT100 keyboard, and uses a microcontroller to receive inputs from the PS/2 keyboard and mimic key switch presses and releases on the VT100 key scan lines. I have it working at this point, and I wondered if there was any interest in such a thing among the community here.

Here is a photo of the current prototype - the final version will have a 1/8" stereo jack so you can use an audio cable (1/4" stereo jack to 1/8" stereo jack) to connect the board to the monitor.
View attachment 1273072
I have tested it quite a bit, and all the functions seem to work correctly. I mapped special keys, like SETUP, PF1 - PF4, etc. to function keys on the PS/2 keyboard - the mapping is done in a table that gets compiled into the firmware, so it can be changed to match your whimsey. I'd be glad to provide the PCB files, parts list, and compiled firmware.

Let me know if you are interested - cheers, Jon.
Click to expand...
Im suffering from 2 vt-100 series keyboard failures. Do you have any more of these ? Thank you.
 
jmdhuse said:
Once I get some feedback from a few people and I am sure the design is stable, I will be glad to share that information.
Click to expand...
That would be great, thank you. "Are we there yet" :-}?
jmdhuse said:
I don't have any built at the moment, but I can do assembly this week...
Click to expand...
Are these partially-assembled (SMD stuff) kits or completely assembled? I'm still interested, and like @Macdoctor have some "shortfalls"!
 
pbirkel@gmail.com said:
That would be great, thank you. "Are we there yet" :-}?

Are these partially-assembled (SMD stuff) kits or completely assembled? I'm still interested, and like @Macdoctor have some "shortfalls"!
Click to expand...
These are bare PCBs that I assemble by hand... They are mostly SMD, with just a few through-hole items like the 6402 UART and the sockets for the cable and keyboard. The only challenging SMD device to assemble is the STM32F302C8 - it is an LQFP48 package with 0.50mm pitch leads., but I've gotten pretty good at it.

I have three units under assembly right now - should be done with testing later this week.
 
DeltaDon said:
Do you program the STM32 on this pcb or prior to soldering to the pcb?
Click to expand...
I program it after it is soldered on to the board... there is a connection for the ST-LINK V2 interface. I still uncover the odd firmware bug, so it needs to be updateable.
 
Macdoctor said:
Im suffering from 2 vt-100 series keyboard failures. Do you have any more of these ? Thank you.
Click to expand...
Hi Macdoctor - I have one of these assembled and tested, if you are interested. I'm asking $40 for it, plus whatever it costs to ship it. Let me know and I will reach out to you via a DM to get the details.
 
VERAULT said:
Would this board work as a replacement for the DEC rainbow?
Click to expand...
I wouldn't think so... the VT100 keyboard interface was very unique and they switched to fairly standard keyboard interfaces after that. The rainbow uses an LK201 keyboard, right?
 
jmdhuse said:
I wouldn't think so... the VT100 keyboard interface was very unique and they switched to fairly standard keyboard interfaces after that. The rainbow uses an LK201 keyboard, right?
Click to expand...
Yes lk201 or lk401. I was hoping it was a similar protocol as i keep buying terrible keyboard with bad membranes.
 
VERAULT said:
Yes lk201 or lk401. I was hoping it was a similar protocol as i keep buying terrible keyboard with bad membranes.
Click to expand...
The VT100 protocol mixes clock and bi-directional data on a single wire... I think the later keyboards used two-wire async-serial protocol.
 
You must log in or register to reply here.
Back
Top