Writing of design choices for integrated keyboards reminded me that I have this board that I got as part of a package deal from tentator. So I dug it out from the bottom of the pile and hooked it up.The compact layout -- aside from the giant ISO Enter -- suggests a laptop and the Turbo key suggests maybe a 286. Other than this, and that it's for the Germanophone market, I don't have any specific ideas about origin or brand. There are no distinguishing marks on the PCB, aside from the printing error of 13 for 23 next to the header. It has amber Omron B3G-S switches, which is one of the reasons it was interesting. It's hard to do a completely fair comparison without a case. But to me these suggest an overdone version of orange or salmon Alps from AEKs. Louder, clickier, pingier. Which I could see having a certain appeal. The board itself has the switch matrix, diodes, and pull-up resistors. No logic components. No LEDs. Which means it doesn't care much about voltage, so I can use a 3.3V Teensy LC. (I know the IDC cable is kind of long; it's what I had in the drawer and I didn't feel like crimping a new one just for this.)
Turbo is a locking switch both of whose contacts are brought out on the header, making it completely independent of the matrix. Of course, I could make one an extra row and the other an extra column, with just the one possible connection. But that seemed like I waste (would go from bytes to shorts) and I wasn't sure what a good use for a locking key in that position was anyway. So, at present it doesn't do anything.