Digital Equipment Corporation

Maxtor Corporation

Seagate Technology Incorporated

Quantum Corporation

Michael D Leis

Ara Patapoutian

Lih-Jyh Weng

Mathew Power Vea

Richard M Ehrlich

Michael L Mallary

Kevin Dean Fisher

Robert C Rose

James A Henson

William R Akin, Jr

Elmer C Simmons

Michael J Muchnik

Bruce Douglas Buch

Joel N Harrison

Michael I Mallary

Russell W Brown

Peter A McEwen

Ba-Zhong Shen

Satish L Rege

Bruce A Leshay

Steven E Lambert

Charles M Riggle

Diana L Langer

Bernardo Rub

Robert Y Noguchi

Edward George Acciardi

Kimberly C Mann

Jonathan Haynes

Thomas C Stockebrand

Joseph M Rinaldis

Joshua Lindsay

Roy W Gustafson

Russell C Doane

Russell W Borwn

John DeRoo

Cecil Macgregor

A David Michael

Wilfred Y Benson

Gary S Engelson

Bruce J Lawrence

Robert A Rubke

A filter representing a complex impedance of a motor system based on a deviation between a first voltage driven by a command signal and a second voltage driven by the command signal can be dynamically adjusted. The motor system can be held in a steady state, eliminating back electromotive force, by providing zero mean current excitation.

Accurate and versatile back EMF sensor

An electronic device includes a flag circuit configured to generate a status flag indicating whether or not a power supply voltage to the electronic device has been cycled, and a controller configured to control an operation of the electronic device and to modify an operational characteristic of the electronic device in response to the status flag indicating that the power supply voltage to the electronic device has been cycled. Methods of operating an electronic device include generating a status flag indicating whether or not a power supply voltage to the electronic device has been cycled within about a defined time, and modifying an operational characteristic of the electronic device in response to the status flag indicating that the power supply voltage to the electronic device has been cycled within about the defined time.

Electronic device with temporary flag for fail safe and power cycling

A acoustic damping pad is provided. The acoustic damping pad includes a first surface and an opposing second surface that are defined by a periphery. A first set of perforations extend between the first surface and the second surface of the acoustic damping pad. Each adjacent perforation in the first set of perforations is uniformly spaced apart from each other across a first select surface area of the first surface and across a corresponding first select surface area of the opposing second surface to form a uniform pattern.

Acoustic damping pad that reduces deflection of a circuit board

A fly height controller measures electrical resistance of a heater element attached to a read/write head as an indication of head temperature and associated flying height relative to a data storage disk, and responds to the measured resistance of the heater element by varying a fly height adjustment signal applied to the heater element to change the temperature of the head and its resulting flying height.

Controlling head flying height based on head heater resistance

A disk drive includes a rotatable data storage disk, a transducer, an actuator, and a servo burst demodulator. The rotatable data storage disk includes a plurality of servo burst patterns thereon. The plurality of servo burst patterns are substantially radially aligned to each other, and radially adjacent ones of the servo burst patterns are configured to generate contributions to a read signal that are substantially orthogonal to each other. The transducer is configured to read the servo burst patterns on the disk to generate the read signal. The actuator is configured to position the transducer relative to the disk. The servo burst demodulator is configured to identify a separate contribution to the read signal from the radially adjacent servo burst patterns. The servo burst demodulator may be configured to generate transducer position information based on the identified separate contribution to the read signal from the radially adjacent servo burst patterns.

Disk drives with radially aligned servo burst patterns that generate orthogonal contributions to a read signal and related demodulators and methods

A disk drive includes a rotatable data storage disk, a transducer, an actuator, and a servo burst demodulator. The disk includes a servo burst pattern thereon within a single servo sector. The transducer is configured to generate a read signal from the servo burst pattern. The actuator is configured to position the transducer relative to the disk. The servo burst demodulator is configured to generate a position error signal from the contributions of the servo burst pattern to the read signal, and is configured to generate a fly height signal from the contributions of the servo burst pattern to the read signal. The position error signal is indicative of a radial location of the transducer relative to the disk. The fly height signal is indicative of a height of the transducer from the disk.

Disk drive that generates a position error signal and a fly height signal from a servo burst pattern

An apparatus and method for increasing the data storage capacity of a data storage devicehaving media surfaces. One or more of a linear density of data, a track density of data, or an error code level of data, is selected for a portionof a media surface. Data is recorded on the portionof the media surfaceat the selected linear density, track density, or error code level. Thereafter, the recorded data is read and an error rate of the recorded data is derived, directly or indirectly. The derived error rate is compared to an acceptable error rate, and if the derived error rate is greater than the acceptable error rate, the previous steps are repeated for another linear density, track density, or error code level, until the derived error rate is less than or equal to the acceptable error rate, to provide a recordable linear density, track density, or error code level of data for the media surface

Method and apparatus for selecting storage capacity of data storage media

A parity check matrix is generated for detecting predefined errors in a coded string of bits. A column of the matrix is generated by selecting values for elements in the column and processing a predefined error with the selected values in order to produce a syndrome. The selected values are assigned to the column of the parity check matrix if an element of the syndrome has a value indicative of the predefined error.

Detecting errors in coded bit strings

A network storage device having a network controller card and a data storage device is described herein the card and storage device are either enclosed in a small from factor unit or assembled together to fit within a standard hard disk drive bay in a computer. The combination of a controller card and storage device is designed to transfer files from and to a network using standard network file protocols. As the network storage device does not process the files, much of the computational overhead of a network server can be eliminated, resulting in a simpler device capable of faster file exchange.

Mass storage device with network interface

Several ways of avoiding collisions between a transducer and asperities on the surface of a moving data storage medium are described. In general, information that indicates locations of the asperities on the surface is provided, and relative movement between the transducer and the surface is altered in response to the information. Approaches for altering the relative movement include preventing the transducer from idling over a track that contains an asperity or over a nearby track, and moving the transducer over an asperity-containing track before a read/write operation or away from the track after the read/write operation to avoid colliding with the asperity. In another technique, the transducer is temporarily moved away from the track as the asperity approaches during a data exchange, and is then returned to the track after the asperity passes. In yet another approach, the trajectory of the transducer during a seek operation between tracks is changed to avoid an asperity on an intermediate track or a destination track.

Avoiding asperities on a storage medium

A magnetic disk drive data storage disk defines recording tracks divided into data sectors by narrow servo spokes. A data sector lying between servo spokes is recorded with user data encoded in accordance with a code having a predetermined distance and user data code rate. Each servo spoke of the recording area has at least one servo information field encoded in a wide bi-phase code pattern. The disk drive further includes a synchronous sampling data detection channel having a data transducer head positioned by a servo-controlled actuator over the recording track, a preamplifier for receiving electrical analog signals magnetically induced by the data transducer head from flux transitions present in at least the servo information field, a digital sampler for synchronously sampling the electrical analog signals to produce digital samples, and wide bi-phase decoding circuitry coupled to receive digital samples from the synchronous sampling data detection channel for decoding the wide bi-phase code pattern.

Synchronous detection of wide bi-phase coded servo information for disk drive

Disclosed is a method and apparatus for increasing the reliability of a disk drive. A block of information is read from a storage medium to provide a first sample, which is stored. The method determines whether an uncorrectable error occurred during the reading, and when the error is determined to have occurred, the block of information is reread from the storage medium to provide an averaged sample, and the average sample is decoded. Further disclosed is a storage unit, which includes a reader for reading a block of information from a storage medium to provide a first sample and for storing said first sample. An error determining mechanism determines whether an uncorrectable error occurred during the reading and issues a command to the reader to re-read the block of information to provide a second sample when the uncorrectable error is determined. A processor receives and averages the first sample and the second sample and produces an averaged sample. A decoder decodes the average sample.

Method and apparatus for using block reread

Synchronous detection of wide bi-phase coded servo information for disk

A Reed-Solomon error-correction coding (ECC) scheme selectively supports two different-length codes to optimize the trade-off between error performance and the amount of disk space required to store protection symbols. The encoder contains two sets of alpha multipliers; part of one set is multiplexed with the other depending on which code is being used. Also, a shift register within the encoder is selectively lengthened or shortened depending on the code. The code pair is selected so that the generator polynomial of the shorter code is a complete divisor of the generator polynomial of the longer code. Thus, one code is a sub-code of the other. Accordingly, the ECC system is able to use the same syndrome calculator for each code. The error-correction decoder uses those syndromes that correspond to the roots of the generator polynomial of the code being used.

ECC system supporting different-length Reed-Solomon codes whose

An encoding system uses a modified 8/9 rate modulation code to encode 8-bit data symbols into 9-bit cells in a conventional manner in accordance with the modified code and 9-bit ECC symbols into 10-bit cells by (i) encoding 8 bits of the symbol into a 9-bit cell in accordance with the modified code, and (ii) inserting into the 9-bit cell the remaining, that is, the non-encoded, bit of the ECC symbol. The system reproduces the 8-bit data symbols by decoding the 9-bit cells in a conventional manner in accordance with the modified code, and the 9-bit ECC symbols by (i) removing from the associated 10-bit cell the bit inserted during encoding, (ii) decoding the remaining 9 bits to reproduce 8 bits of the symbol, and (iii) inserting into the 8 bits the bit that was earlier removed. In an exemplary embodiment, the 8 least significant bits of the ECC symbol are encoded using the modified 8/9 rate code. The 9 bits produced by the code are used essentially as the first 'c' bits and last '10-c' bits of a 10-bit cell. The most significant bit of the ECC symbol is included in the cell as the c+1.sup.st bit. The mapping of 8 bits to 9-bit cells is such that the inclusion of this c+1.sup.st bit does not violate the code's run length limitations, either within the cell or within a modulation code word, which is a concatenation of the cells. The system can similarly encode, using a modified n/m rate code, n-bit and (n+i)-bit symbols, where (n+i)&lt;m, to produce, respectively, m-bit cells and (m+i)-bit cells.

Method and apparatus for encoding data with variable block lengths

Growing community of inventors

Framingham, MA, United States of America

Michael D Leis