Method and apparatus for determining head positioning in a magnetic disk drive system using first and second gray codes

摘要

A method and apparatus for positioning a head over a track in an information recording medium to eliminate head positioning error. Data tracks are concentrically formed on a magnetic disk, and identification information for identifying each data track is recorded so as to correspond to each data track. The identification information consists of first and second gray codes, and the first gray code is of n-1 bits where n represents the number of bits of a track address and set for each block so that it has a value different among a plurality of blocks each consisting of a plurality of data tracks. The second gray code is of three bits, and set for each data track so that it represents a value which differs between data tracks contiguous in the radial direction of the disk and circulates for every three or more blocks continuous in the radial direction of the disk. Head positioning is determined based on reading the first and second gray codes by the head.