Abstract: A method of and apparatus for generating and protecting hard sector pulses using the read/write heads of the disk drive without using any external transducers is disclosed. Each track of the disk is pre-formatted with a pattern of a burst of data followed by a short erased gap repeated around the track once per sector. The data bursts are converted to digital pulses which are used to trigger a monostable as long as the read/write heads are positioned over data. The lack of an output signal from the monostable is used to detect the erased gaps. At the end of the erased gap, a sector marker pulse is generated. Various protection signals are also generated. The high capacity hard sectored computer disk drive system disclosed herein utilizes a hard disk which rotates at a speed of approximately 2750 r.p.m. The data received from the host computer for storage on the hard disk is converted to 2,7 RLL coding prior to being written onto the disk.

Abstract: A method and apparatus for controlling a stepper motor and a disk drive is described for minimization of stepper motor oscillations for a single step, minimizing the time taken for the stepper motor to move between tracks for multi-track seeks, and reduction of angular hysteresis due to the mechanical and magnetic properties of the stepper motor construction.This control is achieved using a microprocessor-based circuit adapted to drive the stepper motor in accordance with predetermined programs. Oscillations of the stepper motor are damped by controlling, using one program, the current applied to the stepper motor during the last step of its motion by switching this current on and off within small predetermined time intervals. The time taken to move between tracks is controlled by another program in which the non-linear torque speed characteristics of a particular stepper motor are matched by a non-linear pulse rate which is determined by data held in the memory of the microprocessor circuit.

Abstract: In a disk drive system which uses as stepper motor, overshooting of the desired final position is reduced by short-circuiting the windings of the stepper motor which normally remain open-circuit or are switched off. This short-circuiting provides a current path for any EMF induced in the unused windings. This effect is achieved by connecting a pair of transistors in parallel with each other and with each respective winding. The transistors are connected in opposite polarity to provide a short-circuit regardless of the polarity of the EMF across the windings. The transistors are connected to a microprocessor which is programmed such that the windings are selectively short circuited and the short circuits are applied at a predetermined time with regard to the step so that `damping` is optimized. The microprocessor may be programmed to switch the transistors on and off as desired giving flexible timing to suit different conditions. One or more stepper motor steps may be treated in this manner.