Abstract: The invention relates to a disk drive servo apparatus, and method for implementing the same, that maintains a transducer on a substantially non-perturbed path despite the fact that the tracks were written in a perturbed manner by a servo track writer. The invention utilizes a non-causal filter to determine servo track writer repetitive run-out (STW_RRO) values for each sector of each track at the drive level. The STW_RRO values are stored, preferably in their respective servo sectors on the surface of the disk, for use during track following operations. During read and write operations, the STW_RRO values are retrieved from storage and are used to generate position error signals necessary to maintain the transducer on the desired path.

Abstract: The invention relates to a disk drive servo apparatus, and method for implementing the same, that maintains a transducer on a substantially non-perturbed path despite the fact that the tracks were written in a perturbed manner by a servo track writer. The invention utilizes a non-causal filter to determine servo track writer repetitive run-out (STW.sub.-- RRO) values for each sector of each track at the drive level. The STW.sub.-- RRO values are stored, preferably in their respective servo sectors on the surface of the disk, for use during track following operations. During read and write operations, the STW.sub.-- RRO values are retrieved from storage and are used to generate position error signals necessary to maintain the transducer on the desired path.

Abstract: An improvement in a system for encoding a data field on a disk with write gate data. The system has an encoder and a data receiving controller for directing write gate data in the form of 0 and 1 bits to the encoder. The encoder, in response to the write gate data, produces a primary code in the form of 0 and 1 bits and directing the primary code to the disk. The primary code has certain predetermined criteria with the encoder producing a secondary coding rate as an exception when the write gate data does not result in the predetermined criteria. The improvement comprises a mechanism for ensuring that the last predetermined number of bits in the data field are free from the exception.