Spensley, Horn, Jubas & Lubitz
Method and apparatus for recording transducer positioning information
 In a magnetic disc storage system and a magnetic disc therefor, the disc having opposed surfaces, at least one of the surfaces being coated with a magnetic material, the disc being adapted to be mounted on a spindle for rotation relative to a magnetic transducer positioned for recording data on and retrieving data from the disc, a plurality of concentric annular tracks being defined on the surface of the disc, each of the tracks being divided into a plurality of sectors, each sector having associated therewith prerecorded servo data for identification thereof, the improvement wherein the servo data for each sector comprises a unit distance track identification code recorded three times in succession, the code changing between adjacent sectors of adjacent tracks, and a clock shift check code recorded immediately following the last recorded one of the track identification codes, the same clock shift check code being recorded for each sector of every track. 
DMA Systems Corporation
G
G11B
inventional
David A. Steven K. Martyn A.
Sutton Penniman Lewis