Abstract: A pulse generating unit responds to a series of instruction pulses to generate a series of driving pulses which includes alternately occurring first driving pulses and second driving pulses. The pulse generating unit generates the first driving pulses directly in response to the series of instruction pulses. The pulse generating unit measures a predetermined delay time using a series of reference clock pulses since the unit received the first pulse of the series of instruction pulses. The pulse generating unit generates the second driving pulses after the thus measured predetermined delay time has elapsed. A motor requires an initial exciting period between a first one of the first driving pulses and a first one of the second driving pulses of the series of driving pulses, and requires a steady-state exciting period between each two adjacent pulses of the series of driving pulses. The predetermined delay time is longer than the initial exciting period.

Abstract: A floppy disk drive controller has a control part which performs a plurality of kinds of controls by means of outputting control information appropriate to each kind of control, and a memory part in which information which selects a predetermined kind of control from among the plurality of kinds of controls is pre-stored, the control part outputting the control information corresponding to the predetermined kind of control which is selected based on the information from the memory part.

Abstract: In order to drive the stepper motor of a floppy disk drive with practically constant current in the face of fluctuations in supply voltage fed from a host system, a power control pulse generator circuit is provided which produces a series of power control pulses having a duty ratio dependent upon fluctuating supply voltage. The power control pulses are used for interrupting the excitation of the stepper motor windings during track seek operation. The power control pulses are generated by first repeatedly counting clock pulses from the host system to a predetermined number to provide periodically varying digital data, then translating the digital data into a triangular wave having an amplitude dependent upon the supply voltage, and then comparing the triangular wave with a reference voltage.