Magnetic data storage disk drive with data block sequencing by using ID fields after embedded servo sectors

Claim 1

A disk drive including a rotating data storage disk, a data transducer head producing Barkhausen noise when switching from a write mode to a read mode in a data channel connected thereto and a data sequencer means connected to the data channel, a servo controlled head positioner for positioning the data transducer among concentric data storage tracks defined as magnetic flux transition patterns on a surface of the disk, a plurality of embedded servo sectors recorded at a predetermined constant frequency across the radial extent of the disk surface and containing head positioning information recorded asynchronously with respect to user data and read by the data transducer head and recovered by a servo data recovery circuit, connected to the data channel, the concentric data storage tracks arranged as a plurality of radially offset circumferential data zones of contiguous tracks, each track of a said zone having a data transfer rate and storage capacity adapted to radial offset of the zone from a center of the disk, a data sector for blocks of the user data being formed between adjacent servo sectors and adapted to contain a plurality of variable length data segments of fixed length user data blocks, each data sector including one ID header, located immediately after each servo sector, the ID header including a plurality of count byte fields, each count byte field for providing to the data sequencer means a count of a variable number of bytes of each variable length user data block segment within the data sector, and a flag field for indicating whether a data block begins at a first user data block segment of a particular data sector next thereafter to be read by the data transducer head.