Abstract: An improved method and apparatus for encoding data prior to storage on a disk or other magnetic media is disclosed which features comparison of input data patterns with stored data patterns in a programmable logic array or other logical mapping structure and outputting of uniquely encoded patterns of flux transitions to be written to said magnetic media based upon the results of the comparison. The apparatus additionally comprises means for serializing the data to be written and deserializing data upon reading from the media.

Abstract: An improved format sequencer for use in conjunction with a disk drive is disclosed which features read-only memory means for outputting appropriate control signals to the various functional elements of the disk drive upon detection that a number of bytes equal to the number of bytes to be in a given segment of a disk track have passed by a read/write head in a given period of time. The length of each segment in bytes is stored in the read-only memory means together with appropriate control signals to be output thereby in correspondence with a particular segment being juxtaposed to the read/write head. In this way, the format of each sector of each track is controlled by the read-only memory means.