Abstract: A screw compressor includes a compressor housing which has a screw rotor chamber arranged therein. Two screw rotors are arranged in the screw rotor chamber. At least one control slider is arranged in a slider channel of the compressor housing and is adjacent to both screw rotors by means of slider compression wall surfaces. The control slider is moveable in a direction of displacement parallel to the screw rotor axes. There is a position determining device for the at least one control slider. The position determining device has a position indicator that is coupled to the at least one control slider. The position indicator cooperates with a detector that extends parallel to the direction of displacement of the at least one control slider and along which the position indicator is moveable. The detector element is coupled to an evaluation device that determines the positions of the position indicator along the detector.