I have disassembled Parts of something (I think it was an old TV or RC controller). There I found an IC with this printed on top of it: "Futaba Japan FP2108T 9175K". I am not good enough that i can understand the circuit/datasheet so I want to ask you out of curiosity what it does. Its enough for me to get a rough Idea, of what its purpose is.
Futaba is a known brand of consumer radio control equipment.
The schematic using the IC you linked to seems to indicate that it is a complete Radio control encoder and modulator. It will 'measure' the joy-stick positions with potentiometers and provide some other features and then generate a baseband or encoded servo control sequence. If I had to guess from the schematic style (age) I would say a generic 2 (perhaps even 3-6) channel analogue PWM system.