Abstract: A servo system for compensating for environmental forces acting on, for example, a disk drive. A circuit is provided for causing an electrical current to flow in the voice coil controlling a read/write head; the head is caused to seek a predetermined track; and a device adjusts the current delivered to the voice coil so that the force generated thereby at least approximately balances environmental forces acting upon the voice coil so that the read/write head does not move by more than a predetermined amount from said predetermined track.

Abstract: A low-wear floppy disk drive system includes an anti-wear controller which randomly selects successive disk tracks to which it directs the disk read/write head whenever the disk drive is idle, so as to more evenly distribute head contact wear across lesser used portions of the disk, and thus increase disk life. The anti-wear controller does not intercede until after the disk drive has been idle for a minimum idle time (e.g. 15 seconds). After a maximum number (e.g., 6) of such idle periods--after the head has been moved a maximum number of times to randomly selected tracks--the anti-wear controller stops the disk rotation, thus stopping head contact wear on the disk altogether. The system excludes the most frequently used disk tracks--i.e., those tracks storing the disk file allocation tables--from the random selection. The system further excludes the innermost tracks on the disk--where the media is less compliant and disk wear more rapid--from the random selection.

Abstract: A velocity servo system for a disk drive, the servo system being responsive to digital signals and generating a control signal for moving a read head of the disk drive from a current track position to a commanded track position. The servo system includes a circuit for reading current track address information and servo bursts recorded on a disk in said disk drive and for generating threshold signals when said read servo bursts are of a predetermined amplitude. An appropriately programmed data processing system provides a decoder responsive to the current track address read by the reading means and to the threshold signals for generating a current half track address, a first comparator which compares the current half track address with the commanded track position to generate half tracks-to-go digital data in response thereto; and generates commanded acceleration data in response to the half tracks-to-go data and to successive half track addresses.