Hi,
Did you see this?
https://www.old-computers.com/museum/computer.asp?st=1&c=799Terminal 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.
Or this?
https://deramp.com/vector_graphic.htmlThe 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)
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.)