Maxtor Corporation

Seagate Technology Incorporated

Digital Equipment Corporation

Richard E Olsen

Bruce Douglas Buch

Michael L Mallary

Mourad Benakli

Roger J Kassab

Jason Wolfson

Ahmet Kaya

Dwight C Baker

Methods of generating a write current in response to a write command include generating a reverse preshoot write current having a polarity opposite to a polarity for generating a magnetic transition corresponding to the write command, and then generating a write current to effect the magnetic transition corresponding to the write command. The write current may be used for writing data to a storage disk of a disk drive that includes a write head configured to apply a magnetic field to the storage disk responsive to write currents. A preamplifier circuit includes a write current generator configured to receive a write current command and configured to generate, responsive to the write current command, a reverse preshoot current having a first polarity that is opposite a second polarity for generating a magnetic transition corresponding to the write command.

Reverse write current preshoot

A technique for de-gaussing the pole tips and yoke of a write transducer in a perpendicular magnetic recording system is provided. An oscillator in the read channel is configured to produce an adjustable signal pattern output to the preamplifier when a write operation ends for a given time and at a predetermined frequency, such that as the preamplifier write current decays, it decays with transitions (polarity reversals). This results in a decaying AC field being applied to the write transducer at the end of a media write operation, effectively de-gaussing it and reducing the effects of remanent magnetization remaining in the poles and yoke of the magnetic recording head after a write current is turned off. This defeats a potential pole tip lockup or yoke lockup circumstance in the magnetic recording media which can result in an inability to write further data or a possible erasure of valid data on the hard disk with which the write head is associated.

Channel postamble extension to de-gauss pole tips

A disk drive includes a rotatable data storage disk, and head, a controller, and a preamplifier. The head is configured to write data to and read data from the disk. The controller is configured to generate a write current command. The preamplifier includes a plurality of write current parameters, and is configured to select among the plurality of write current parameters based on the write current command from the controller, and to generate a write current having a shape that varies based on which of the write current parameters are selected. The write current is provided to the head to write a plurality of data bits on the disk.

Disk drive partially autonomous preamplifier for write current parameters

A central processor unit (CPU) is capable of being connected in data processing systems having diverse logical operating characteristics. The CPU contains an operating mode register that has stages that identify various logical operating conditions in the data processing system, and modify the operation of the central processor unit in accordance therewith.

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Framingham, MA, United States of America

Richard E Olsen