geekhack Community > Keyboards
Reverse engineering a Vector Graphic 4 Key Tronic kb
dplass:
--- Quote from: ErgoMacros on Sun, 27 September 2020, 20:45:50 ---Hi,
Did you see this?
https://www.old-computers.com/museum/computer.asp?st=1&c=799
--- Quote ---Terminal only had a parallel keyboard, and a B/W monitor. All video and keyboard interface was via S-100 card called Flashwriter, with all power signals passed via a DB-25 connector.
--- End quote ---
Or this?
https://deramp.com/vector_graphic.html
--- Quote ---The keyboard in the Vector 3 is a capacitive keyboard made by Keytronics These keyboards have a great feel, but unfortunately, the foam pad present in each key deteriorates over time and virtually all keyboards of this type and vintage do not work properly (if at all). A good source for replacement pads is a Sun "Type 4" keyboard. Even though the Sun keyboards are just ten or so years newer than the Vector keyboard, they use a different type of foam that doesn't break down so quickly. Search the internet for "Sun keyboard" followed by "320-1018". This is a French Canadian version of the keyboard and is the most readily available and least expensive version. In addition to replacing the foam pads, I gently sanded the key "capacitors" on the bare PCB with a very fine grit sandpaper (600) and then wiped the board clean. Based on past experience, this step reduces the likelihood that some of the key positions may still not work. (photo courtesy of sol20.org)
--- End quote ---
With 4(?) wires to connect the keyboard I'd guess serial communications.
My first guess would be 1200 baud, but in those days the choices were anywhere between 110 and no more than 9600 baud.
The large chip above F7, F8, and F9 has got to be the microcontroller. (8048 was a common type back then, but I can't read the numbers). 40 pins.
The keyboard is almost certainly done as a matrix. Possibly extended with a shift register (below Z5 on the PCB.)
If you can give us the numbers printed on the chips that may help. Certainly it will tell you the required voltages needed. (Probably 5V)
To re-purpose it to modern (as opposed to restore for old) I would:
* Pull the 40 pin chip out
* Test for continuity between every 2 pins. If you find any ignore them in the next steps
* Press a key. Inserting a coin between 2 keycaps can hold it down
* Test for continuity between every 2 pins. When you find some write it down.
* Repeat for all keys
A pattern will emerge. That's your matrix.
Program a ProMicro to match the matrix, wire it to a 40-pin header, and insert into the old microcontroller socket.
Power and communicate with the ProMicro.
Success. (Well, I could have missed a few steps.)
--- End quote ---
--- Quote from: ErgoMacros on Sun, 27 September 2020, 20:45:50 ---Hi,
Did you see this?
https://www.old-computers.com/museum/computer.asp?st=1&c=799
--- Quote ---Terminal only had a parallel keyboard, and a B/W monitor. All video and keyboard interface was via S-100 card called Flashwriter, with all power signals passed via a DB-25 connector.
--- End quote ---
Or this?
https://deramp.com/vector_graphic.html
--- Quote ---The keyboard in the Vector 3 is a capacitive keyboard made by Keytronics These keyboards have a great feel, but unfortunately, the foam pad present in each key deteriorates over time and virtually all keyboards of this type and vintage do not work properly (if at all). A good source for replacement pads is a Sun "Type 4" keyboard. Even though the Sun keyboards are just ten or so years newer than the Vector keyboard, they use a different type of foam that doesn't break down so quickly. Search the internet for "Sun keyboard" followed by "320-1018". This is a French Canadian version of the keyboard and is the most readily available and least expensive version. In addition to replacing the foam pads, I gently sanded the key "capacitors" on the bare PCB with a very fine grit sandpaper (600) and then wiped the board clean. Based on past experience, this step reduces the likelihood that some of the key positions may still not work. (photo courtesy of sol20.org)
--- End quote ---
With 4(?) wires to connect the keyboard I'd guess serial communications.
My first guess would be 1200 baud, but in those days the choices were anywhere between 110 and no more than 9600 baud.
The large chip above F7, F8, and F9 has got to be the microcontroller. (8048 was a common type back then, but I can't read the numbers). 40 pins.
The keyboard is almost certainly done as a matrix. Possibly extended with a shift register (below Z5 on the PCB.)
If you can give us the numbers printed on the chips that may help. Certainly it will tell you the required voltages needed. (Probably 5V)
To re-purpose it to modern (as opposed to restore for old) I would:
* Pull the 40 pin chip out
* Test for continuity between every 2 pins. If you find any ignore them in the next steps
* Press a key. Inserting a coin between 2 keycaps can hold it down
* Test for continuity between every 2 pins. When you find some write it down.
* Repeat for all keys
A pattern will emerge. That's your matrix.
Program a ProMicro to match the matrix, wire it to a 40-pin header, and insert into the old microcontroller socket.
Power and communicate with the ProMicro.
Success. (Well, I could have missed a few steps.)
--- End quote ---
Thanks for your input! I've got a lot to go on now, and have made progress since my last post. It's likely 9600 baud, and is sending back LSB-first-ASCII on the one and only serial line. The F&F are all dead.
I'm documenting it a little more on my YT: https://www.youtube.com/playlist?list=PLYa0BHE_u5gvDV8tXLj0zJBWFPb6pN-zy
ErgoMacros:
Here's a link to XR 22-950-3Bs in stock. Still no datasheets.
https://www.digchip.com/datasheets/quote.php?action=search&pn=22-950-3B
Here's someone trying to restore a similar keyboard. He/She has more info on the XR22-950-3b scan driver, and XR 22-908-03 sense amp.
http://www.vcfed.org/forum/archive/index.php/t-22356.html
More pinout info here:
https://groups.google.com/g/alt.sys.perq/c/QtjOXZbrEOk
And this is a huge text file:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiDy7z2y43sAhUErJ4KHdyRDuwQFjALegQIBBAB&url=ftp%3A%2F%2Fbitsavers.informatik.uni-stuttgart.de%2Fmailing_lists%2Fcctalk_mailing_list%2F1997-July.txt&usg=AOvVaw1zQ0wpH9JC9FYPoHokb-dY
that says (search for 950):
-----> So, What are the Custom Chips ?
There are, in general 2 off 20 pin custom chips in a keytronics keyboard (some
later ones have a single 40 pin chip, but I know nothing about that).
22-908-3B
8-channel sense amplifier
More1 : Row 0
2 : Row 1
3 : Row 2
4 : Row 3
5 : Reset/sync output
6 : Row 4
7 : Row 5
8 : Row 6
9 : Row 7
10 : Ground
11 : Out 7
12 : Out 6
13 : Out 5
14 : Out 4
15 : Out 3
16 : Out 2
17 : Out 1
18 : Out 0
19 : Reset in
20 : +5V
Outputs are believed to be open-collector
22-950-3B
keyboard column decoder/driver.
1 : Col 8
More2 : Col 9
3 : Col 10
4 : Col 11
5 : Latch Clock
6 : Select 0 (LSB Input)
7 : Select 1
8 : Select 2
9 : Select 3
10 : Ground
11 : Sync Input
12 : Col 0
13 : Col 1
14 : Col 2
15 : Col 3
16 : Col 4
17 : Col 5
18 : Col 6
19 : Col 7
20 : +5V
Good luck.
dplass:
Thanks. The replacement chips are > $20 on eBay and I'm too cheap to go that route. I've seen that other thread too and tracked down the pinout from a Lisa keyboard schematic (http://www.kbdbabel.org/schematic/kbdbabel_doc_lisa.pdf).
I've determined that the X22-950 has 5 dead output pins, and so many keys aren't working (including both shifts, control, space, enter and most of the numeric keypad).
My current plan is to use an Arduino to listen on the control/select pins (pins 6-9, ABCD) and send an appropriately timed and duration pulse on the output pin that would have been energized by the X22-950. I've done a rough prototype and it seems to work. See my video at for more info.
dplass:
This plan has succeeded (see video, below) and I'm able to type all the previously dead keys on the bare board. I'm waiting on new F&F from Texelec so that's next.
One of the challenges I'm facing is how to deal with chords that are not supported by this keyboard, e.g., ctrl+shift+3. The board generates more or less pure ASCII and so there's no corresponding ASCII character for such a chord. I'm guessing I'll have to do something clever in the code to interpret certain sequences of keystrokes and return the interpreted keystroke/chord. (I'm already doing this somewhat, to map the Vector Graphic function keys and arrow keys to the proper keycodes.)
dplass:
--- Quote from: Klais on Wed, 05 October 2022, 22:31:36 ---
--- Quote from: dplass on Tue, 20 October 2020, 15:11:57 ---This plan has succeeded (see video, below) and I'm able to type all the previously dead keys on the bare board. I'm waiting on new F&F from Texelec so that's next.
One of the challenges I'm facing is how to deal with chords that are not supported by this keyboard, e.g., ctrl+shift+3. The board generates more or less pure ASCII and so there's no corresponding ASCII character for such a chord. I'm guessing I'll have to do something clever in the code to interpret certain sequences of keystrokes and return the interpreted keystroke/chord. (I'm already doing this somewhat, to map the Vector Graphic function keys and arrow keys to the proper keycodes.)
--- End quote ---
How stable does it work after that?
--- End quote ---
It worked, but it was really awkward to enter chorded keystrokes. I used a prefix key (F13 https://github.com/dplassgit/arduino/blob/trunk/keyboardv1/keyboardv1.ino#L117) to indicate "use alt for the next keystroke".
Also, after adjusting the foils TWICE, I still didn't have 100% of the keys working. When I gave up I think the C key and one or two others were still not working. This keyboard really solidified my hate for F&F keyboards, that's for sure.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version