Connect servo motor to 8255
To drive a servo you send it pulses every 20ms or so, and the pulse width determines the servo angle. 1ms pulse makes it go all the way to one end, and 2ms pulse makes it go the other end. 1.5 ms pulse should set it to the middle position. The pulse lengths are not that exact, each model will vary but those are good starting points.

Basically, in Proteus, you should be able to connect that servo directly to 8255 PPI.