There is some info on the keyboard circuit starting from page 14 in this translation:

https://dl.dropboxusercontent.com/u/55419307/Siemens%20PC-D/PCD%20translated.pdf

I'll take a look if there's more.


NCR DMV- DEC Rainbow- Siemens PCD- ITT 3030-Oly People- Acorn A5000- Olivetti M20