The DE-9 plugs used for PC serial ports have the male end on the computer, female on the device. I'd suspect, of course, that it's backwards in this case to prevent someone connecting it because it's not compatible.
4 pins - that could be XT (perhaps AT), just with a different physical connector.
*facepalm*
Knew there was something odd about it.
Physical layout, sure. Protocol could be AT if the board was a late enough product and layout was simply maintained for whatever reason.
Unlikely, but without knowing for sure, anything is possible. With only 4 populated pins I'd say it's potentially very likely that it uses either the PC & XT protocol, the AT protocol, or the mostly-like-AT protocol the terminals used.
That example was made in 1987, the last year of the PC/XT Model F production, so they were still being made, or at least they had enough spare parts to make them.
Bare in mind that the controller was permanently attached to the keyboard PCB with a non-removable cable, so mixing and matching different controllers with different PCBs was not a trivial task.
Oddly enough, on that keyboard, they tried to normalize the location of Caps, Ctrl and Alt -
You can see that they obviously ran out of stock of the specially sized ]} you usually see on PC/XT Model Fs. =P
