An apparatus for use in drilling a borehole , the apparatus comprising: (a) an upper assembly comprising an upper end which is connectable with a drilling string ; (b) a lower assembly comprising a rotary drilling motor including a drill bit which is positioned at the lower end of the lower assembly , such that the lower assembly is subjected to a reactive torque during drilling as a result of the operation of the drilling motor; (c) an orientable rotatable connection between the upper assembly and the lower assembly ; characterized in that the apparatus further comprises: (d) a reactive torque control device associated with the orientable rotatable connection , wherein the reactive torque control device is actuatable to selectively allow rotation of the lower assembly relative to the upper assembly or prevent rotation of the lower assembly relative to the upper assembly ; (e) an orientation sensing device for providing a sensed actual orientation of the lower assembly ; (f) a feedback control system associated with the reactive torque control device and the orientation sensing device , for actuating the reactive torque control device in response to the sensed actual orientation of the lower assembly in order to achieve a target orientation of the lower assembly , wherein the feedback control system is comprised of components, and wherein the components of the feedback control system are associated with either the upper assembly or the lower assembly ; and (g) at least one parameter sensing device , for sensing a parameter other than the actual orientation of the lower assembly and for providing a sensed parameter value relating to the parameter. (a) an upper assembly comprising an upper end which is connectable with a drilling string ; (b) a lower assembly comprising a rotary drilling motor including a drill bit which is positioned at the lower end of the lower assembly , such that the lower assembly is subjected to a reactive torque during drilling as a result of the operation of the drilling motor; (c) an orientable rotatable connection between the upper assembly and the lower assembly ; characterized in that the apparatus further comprises: (d) a reactive torque control device associated with the orientable rotatable connection , wherein the reactive torque control device is actuatable to selectively allow rotation of the lower assembly relative to the upper assembly or prevent rotation of the lower assembly relative to the upper assembly ; (e) an orientation sensing device for providing a sensed actual orientation of the lower assembly ; (f) a feedback control system associated with the reactive torque control device and the orientation sensing device , for actuating the reactive torque control device in response to the sensed actual orientation of the lower assembly in order to achieve a target orientation of the lower assembly , wherein the feedback control system is comprised of components, and wherein the components of the feedback control system are associated with either the upper assembly or the lower assembly ; and (g) at least one parameter sensing device , for sensing a parameter other than the actual orientation of the lower assembly and for providing a sensed parameter value relating to the parameter. <EOS>