There’s an OpenSource-hardware system, mainly for controlling Microsoft Flightsimulator. The whole system is modular and an easily be expanded. After some research, I decided to use this system also for my simulator:

In the middle is the MasterCard, the main part of the system: it gives 72 digital inputs (for buttons and switches), 45 outputs for LEDs and an expansion-bus to connect smaller controllercards.
On the picture there’s already one Display-II card connected, to control 16 7-segment-displays. Up to 4 Display-II-cards can be connected to one MasterCard.
Top left is the USB-Expansion Card: the IOCards were intened to be connected to the parallel port – with this card up to 4 MasterCards can be used on 1 USB-port.
The 2 small card left under the MasterCard are 2 USB-Servoboard, each able to control 6 servomotors and directly connected to the USB-port.

Controlling the hardware is done with IOCard’s SIOC software. To bring data from Falcon to SIOC I wrote my own program: FAST (FAlconSioc-Transfer). More info will be available here (as own menu item)