Apparatus is disclosed for converting input step and direction commands from an external control source into stator winding drive current signals for a permanent magnet stepper motor. A translator circuit, having inputs coupled to the external control, generates sequential stator winding pulse enabling signals for transmission to a chopper-controlled power drive circuit. The chopper control features the sharing of a single chopper power switch by pairs of stator windings. The power drive circuit provides a winding current path to a reverse voltage supply upon initiation of winding current turn-off to enhance switching speed. A dual level current reference is generated in a current regulator circuit and compared with instantaneous stator winding currents to control the conduction states of the chopper power switches. Dual reference levels are established for idle versus accelerating or decelerating motor states, respectively. The translator circuit includes means for inhibiting chopper power switch conduction independently of the current regulator reference level comparison whenever the translator is switching drive current among stator windings, thereby decreasing power dissipation due to transients.