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Determining keyboard protocol for dumb terminal

Can't be synchronous unless there's a common bit clock for both host and keyboard. I don't see that in your pinout. PS/2, XT keyboards have a clock that's shared with the host (hence, the extra clock signal line).
 
Can't be synchronous unless there's a common bit clock for both host and keyboard. I don't see that in your pinout. PS/2, XT keyboards have a clock that's shared with the host (hence, the extra clock signal line).
Hi Chuck,

Soooo the port pinout I posted is for the host, which is async TX/RX as far as I can tell.

The keyboard that came with the terminal is not the correct keyboard despite being made by the same company.

It just came with the wrong keyboard. It arrived fried from being plugged in. I repaired it and it was suggested I analyze the keyboard to see if the scancodes might be similar to the scancodes expected by the host since they are made by the same company.

The keyboard has a CLOCK (blue) and DATA (yellow) line.

So I've figured out the protocol for the keyboard, not entirely for the host yet.
 

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XT protocol is stupid-simple. 9 bit shift register in the PC, bits clocked out from the keyboard. When the 9th bit in the SR goes high, it signals a completed character and is read via one port of the 8255 PPI. SR is then cleared, ready for the next character.
 
I recently acquired a Liberty Aspect keyboard. Anything I could do to help?
 

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