Western Digital Corporation

Western Digital Technologies, Inc.

Rateze Remote Mgmt LLC

Western Digital (singapore) Pte. Ltd.

Richard William Hull

Vafa James Rakshani

Robert L Cloke

David Price Turner

Timothy G O'Shaughnessy

Kenneth W Ouyang

Michael R Spaur

Marc E Acosta

Sanjay S Mathur

David B Joan

Hoover K Jung

Nicholas James Witchey

Thomas Earl Ludwig

Charles William Frank

Charles Royston Patton, Iii

Mark A Adams

Carl Bonke

Mark F Vallis

Takashi Asami

Charles W Simmons

Alireza Atai-Azimi

Samuel K Baughman

Victor G Pierotti

David K Chung

Robert P Mento

Rochak Sharma

Adnan Khan

James H Wang

Joseph A Souza

Marshall D Lee

Min-Hui Wang

Ronald E Wilson

Leonard Teslenko

Donald E Tolsch

Mark Adams

Systems and methods ensure that datagrams retain integrity in light of the problems associated with the internetworking protocol's use of datagram identifiers drawn from a first pool of datagram identifiers. The methods involve controlling the use of datagram identifiers to ensure that only certain identifiers are allowable. A second pool of datagram identifiers is created that is different from the first pool. A datagram identifier is drawn from the second pool and assigned to a datagram in a manner that the datagram identifier is controlled from being reused during the lifetime of the datagram. In alternative embodiments the number of available datagram identifiers is either increased through optional header fields, or reduced through tracking allowed datagram identifiers. A first host notifies a second host of an allowed identifier. The second host uses the allowed identifier as a datagram identifier.

Datagram identifier management

A disk drive is disclosed comprising a microprocessor, a non-volatile serial semiconductor memory for storing code segments of a control program, a first semiconductor memory for storing code segments of a loader program, and a second semiconductor memory for receiving the code segments of the control program. When the disk drive is powered on, the microprocessor executes the loader program from the first semiconductor memory to load the control program from the non-volatile serial semiconductor memory into the second semiconductor memory. The microprocessor then executes the control program from the second semiconductor memory.

Disk drive employing a non-volatile serial semiconductor memory for storing a control program for a microprocessor

A disk drive has a channel circuit for demodulating data sectors and servo sectors stored on a rotating medium to provide data-sector data and servo-sector data. The channel circuit transmits the data-sector data and servo-sector data to a disk controller circuit in an order which is different than the order in which they are stored on a rotating medium to allow for demodulation latency while maintaining real-time updates of embedded servo information.

DISK DRIVE HAVING A CHANNEL CIRCUIT WHICH RECEIVES A READ SIGNAL REPRESENTING DATA IN A DATA SECTOR AND DATA IN A SERVO SECTOR IN A FIRST ORDER AND DEMODULATES THE READ SIGNAL TO PROVIDE DATA SECTOR DATA AND SERVO-SECTOR DATA IN A SECOND ORDER

A computer system is disclosed comprising a host connected to a disk drive, the disk drive comprising a disk having a disk surface. The disk drive further includes a controller and a channel integrated circuit chip. The controller includes a controller port. The channel integrated circuit chip includes an input for receiving a time-multiplexed analog read signal. The time-multiplexed analog read signal is processed to generate data symbols representing recovered servo data and recovered user data. The channel integrated circuit chip includes a channel port for transferring both the recovered servo data and the recovered user data. The disk drive further includes a communication bus connected between the channel port and the controller port. The channel port transfers both the recovered servo data and the recovered user data to the communication bus. The communication bus transfers both the recovered servo data and the recovered user data to the controller port.

Computer system comprising a host connected to a disk drive employing read channel IC with common port for data and servo

A computer system is disclosed comprising a host connected to a disk drive, the disk drive comprising a disk surface having a plurality of tracks arranged in an embedded servo format including servo track segments for storing servo data and data track segments for storing user data. The disk drive includes a read element operative during a user-data read operation for reading data from the disk surface to produce a time-multiplexed analog read signal that during a revolution of the disk represents analog read servo data during each of a first set of time intervals and represents analog read user data during each of a second set of time intervals. The disk drive includes a sampled signal processing circuit that generates a servo state variable while processing the time-multiplexed read signal during the first servo time interval and a user data state variable while processing the time-multiplexed read signal during the first user data time interval. The disk drive includes a servo state variable trap register for storing the servo state variable at the end of the first servo time interval. The disk drive includes a data state variable trap register for storing the user data state variable at the end of the first user data time interval. The disk drive includes a control circuit for providing the stored servo state variable to the sampled signal processing circuit at the beginning of the second servo time interval. The control circuit provides the stored user data state variable to the sampled signal processing circuit at the beginning of the second user data time interval.

Computer system comprising a host connected to a disk drive employing state variable trap registers for providing stored servo and user data state variables to sampled-data channel

A disk drive includes a disk having a disk surface, the disk surface having a plurality of tracks arranged in an embedded servo format. The disk surface includes a plurality of radially-extending user-data regions and a plurality of radially-extending servo-data regions. Each user-data region has a plurality of data zones in each of which user data are stored in a plurality of track segments at a data channel frequency particular to that data zone. Each servo-data region has a plurality of servo zones in each of which servo data are stored in a plurality of track segments at a servo channel frequency particular to that servo zone, wherein in at least one of the tracks having servo data and user data, the servo channel frequency differs from the data channel frequency.

Disk drive including a recording surface employing servo zones recorded at a channel frequency different from data zones

A disk drive has a unified bus forming a signal path for transmitting register data, user data and servo sectors. The unified bus is connected between a channel circuit and a disk controller circuit. The channel circuit has an output stream engine which responds to and provides control signals to multiplex data on the unified bus at various times between demodulated user data, servo sector data and register data.

Disk drive with unified channel-disk controller bus for transmitting user data, servo data, and register data

A disk drive includes a disk having a disk surface. The disk surface has a plurality of tracks arranged in an embedded servo format including servo track segments for storing servo data and data track segments for storing user data. Data from the disk surface is read to produce a time-multiplexed analog read signal that during a revolution of the disk represents analog read servo data during each of a first set of time intervals and represents analog read user data during each of a second set of time intervals. The disk drive further includes a controller and a channel integrated circuit chip. The controller includes a controller port. The channel integrated circuit chip includes an input for receiving the time-multiplexed analog read signal. The time-multiplexed analog read signal is processed to generate data symbols representing recovered servo data and recovered user data. The channel integrated circuit chip includes a channel port for transferring both the recovered servo data and the recovered user data. The disk drive further includes a communication bus connected between the channel port and the controller port. The channel port transfers both the recovered servo data and the recovered user data to the communication bus. The communication bus transfers both the recovered servo data and the recovered user data to the controller port.

Disk drive employing read channel IC with common port for data and servo

A disk drive includes a disk having a disk surface, the disk surface having a plurality of tracks arranged in an embedded servo format. The disk surface includes a plurality of radially-extending user-data regions and a plurality of radially-extending servo-data regions. Each user-data region has a plurality of data zones in each of which user data are stored in a plurality of track segments at a data channel frequency particular to that data zone. Each servo-data region has a plurality of servo zones in each of which servo data are stored in a plurality of track segments at a servo channel frequency particular to that servo zone. The servo channel frequency differs from the data channel frequency for at least one track.

Disk drive including a recording surface employing servo zones with banded data zones

A disk drive includes a disk surface having a plurality of tracks arranged in an embedded servo format including servo track segments for storing servo data and data track segments for storing user data. The disk drive includes a read element operative during a user-data read operation for reading data from the disk surface to produce a time-multiplexed analog read signal that during a revolution of the disk represents analog read servo data during each of a first set of time intervals and represents analog read user data during each of a second set of time intervals. The disk drive includes a sampled signal processing circuit that generates a servo state variable while processing the time-multiplexed read signal during the first servo time interval and a user data state variable while processing the time-multiplexed read signal during the first user data time interval. The disk drive includes a servo state variable trap register for storing the servo state variable at the end of the first servo time interval. The disk drive includes a data state variable trap register for storing the user data state variable at the end of the first user data time interval. The disk drive includes a control circuit for providing the stored servo state variable to the sampled signal processing circuit at the beginning of the second servo time interval. The control circuit provides the stored user data state variable to the sampled signal processing circuit at the beginning of the second user data time interval.

Disk drive employing state variable trap registers for providing stored servo and user data state variables to sampled-data channel

A disk drive controller having a microprocessor and a sampled signal head positioning system measures and stores the relative rotational offsets between heads arranged in a stacked relationship and respective servo wedges on different disk surfaces. The offsets are stored in a table and subsequently applied to a servo wedge detection circuit to ensure that a next sequential wedge is detected after a head switch.

Method and apparatus to compensate for servo wedge rotational offset

A disk drive having an embedded servo disk format preferably having a fixed-number of radial servo sample wedges per track, in which data blocks are located independently of the servo sample wedge locations of any particular track, and can be split around servo sample wedges. Thus, a fraction of a data block, or more than one data block, can be written between consecutive servo sample wedges, beginning almost anywhere in a data wedge. Each data sector has an associated identification (ID) field that includes at least one segment descriptor. Each segment descriptor describes the data segments into which a data block can be split. Provision is made for as many segment descriptors as there can be data segments for a data block. In general, a segment descriptor is a multi-bit digital signal that defines the absolute or relative location of split data segments (or, alternatively, the absolute or relative length of split data segments, from which the location can be determined). A disk system in accordance with the present invention can be independently optimized for flux changes per inch and tracks per inch, and the size of each data sector can be varied. The invention permits 'defect swallowing', by allowing a data sector to be split around small defects within a data wedge of a track, and 'wedge push down' defect management, in which a data segment can be started at a next servo sample wedge if a large defect occurs in the previous data wedge.

Disk drive employing dynamically reconfigured read channel to process a

A format for embedded servo track identification fields in rotating disk data storage units such as magnetic disk drives. The present invention uses the concept of tri-bits (i.e., three code bits per logical bit) to encode track identification information in servo wedges of embedded servo disk drive systems. More specifically, two particular sets (and their equivalents) of tri-bit codes have been discovered to have optimum characteristics for providing a phase coherent encoding of a Gray code that is simple to translate into straight binary code. The properties of such tri-bit encoding limit error propagation to a single bit, which allows for very reliable track identification during movement of a head transducer across tracks (i.e., 'seeks'). A full range of Gray scale codes is available since more than two consecutive logical '0's can be reliably decoded when encoded using such tri-bits. The properties of such tri-bit encoding also allow for relatively high servo channel rates, which results in a reduction in servo field length. Accordingly, a counter-intuitive result of increasing the length of the encoding symbols for track identification fields is to decrease the overall length of the servo field, thereby permitting an increase in areal density.

Tri-bit encoding for disk drive servo track ID information

An integrated servo system for a disk drive employing sector servo positioning information on concentric tracks of a recording medium utilizes a servo burst pattern with three sequentially occurring servo bursts. One burst is positioned to have a maximum amplitude plateau on a track centerline of alternate tracks, and the other two bursts have maximum plateau values at locations between the centerlines of adjacent tracks. The amplitudes of the bursts are sequentially detected by a peak detector and supplied to sample and hold circuitry for measuring their relative amplitudes. Discriminator circuitry utilizes a window to provide two samples of each transition in the servo pattern and compares the samples to detect different fields and events in the pattern.

Information detecting system

A comparator which is used to compare two analog voltages and provide a single ended output comprises three CMOS differential amplifiers. The use of three differential amplifiers provides improved matching of input capacitance, and a reduction in propagation delay over prior art use of a single differential amplifier. The comparator may be adopted for use in certain CMOS processes to extend the maximum operating voltage by limiting the internal node voltages otherwise subject to damage from impact ionization. An alternative embodiment is disclosed for comparing two analog voltages that are outside the power supply voltage range.

Growing community of inventors

Laguna Hills, CA, United States of America

Richard William Hull