I have been looking for info about ASCII keyboards and I tried to understand how they works.
At the keyboard connector you can find lines PA0 to PA6 (7 bits to encode ASCII code). When you push a key, an encoder circuit put ASCII code in paralel way through these lines, working at high level. I imagine PA6 is the bit at the left side of ascii byte.
That's what I understood... Is it right? I have a ZX Spectrum +2 matrix black keyboard, and it seems very nice and "retro" to use with replica, and I imagine it would be easy to program a PLD to encode characters from the matrix.