Abstract: A very high capacity, closed-loop Winchester disk drive system particularly suited to meet the demands of a portable computer system is disclosed. The micro-Winchester disk is a Winchester disk of 95 mm in diameter. The disk drive system of the present invention, by virtue of its small size and vibration isolation, is ideally suited for use in portable computer systems. The micro-Winchester disk drive system was developed to store data at a density in excess of 1000 tracks per inch utilizing a closed-loop rotary voice coil positioning mechanism. This disk drive system provides fast access data storage for use with small business computers, terminals and microprocessor-based systems, portable or otherwise, and many other areas where compact, rugged, and lightweight hard disk storage is required. The disk drive system of the present invention normally utilizes between two and four hard disks, such as Winchester disks, with one disk containing a dedicated servo surface.

Abstract: In a disc data store, wherein a read/write head is radially positionable by a feedback servomechanism to interact with a selectable one out of a plurality of radially equispaced data storage tracks on a rotary disc, the positioning errors resultant from phase errors between the plural signals available as the output of an optical grating head position transducer are eliminated by replacing one of the data storage tracks with a servo track by arranging that the period of the recursive, triangular wave position indicating signals from the transducer is equal to twice the radial spacing between tracks on the disc, by selecting as the exclusively-used position indicating signal that one of the plurality of transducer signals which brings the head to the center of the servo track with least offset, and, while employing that selected signal or its generated inverse as the feedback signal to the servomechanism applying that least offset as a correction when positioning the head over data storage tracks.