This paper presents a switched mode model of a permanent magnet DC motor drive with a robust control scheme. The switched mode simulation model is developed for a using the Matlab/Simulink GUI environment. The model is based on the switching/pulsing sequence of the DC-DC chopper converter, which is used to supply controlled variable DC armature voltage to the motor. As the modulated DC voltage is applied to the motor, the energy stored in armature winding and rotating armature inertia is varied and need to be included in the model. In order to operate the motor at specified speed level with the required electrical torque for different load excursions, the DC-DC chopper converter is dynamically controlled by the General Predictive Speed Controller (GPC). The GPC is used as the main speed regulator due to its inherent ability to handle parameter variations and sudden excursions as an adaptive controller in nature. The performance of the GPC Scheme is validated by comparing the digital simulation results with those of obtained using the classical PI speed controller.