A disk drive apparatus is disclosed for primary use with portable, laptop or other information storage systems. The disk drive apparatus includes one or more about 2.5 inch hard disks. A rotary actuator is utilized and includes an arm assembly having a cam follower member for use in dynamically loading/unloading read/write head(s). The cam follower member moves along a ramp, which forms a cam surface, for loading/unloading. The spin motor assembly of the disk drive apparatus includes a rotor having a clamp ring that enables a more powerful spin motor to be incorporated, as well as facilitating and enhancing the connection of the hard disks to the spin motor. The disk drive apparatus also includes servo electronics responsive to a back emf generated signal for use in the servo operation, which use has the potential to increase the servo bandwidth. The accuracy of the servo operation is also enhanced by the use of a flexible circuit that prevents unwanted torque from being applied to the actuator during operation. The disk drive electronics also includes hardware and software for reducing power consumption.