Abstract: A method and apparatus are disclosed for improving the maximum data rate of reduced-state Viterbi detectors with local feedback in magnetic recording systems. A read channel signal is processed in a magnetic recording device by precomputing branch metrics, intersymbol interference estimates or intersymbol interference-free signal estimates for speculative sequences of one or more channel symbols; selecting one of the precomputed values based on at least one decision from at least one corresponding state; and selecting a path having a best path metric for a given state.

Abstract: An apparatus and method for determining a head parameter value (e.g., head resistance) of a resistive head. A test head current is supplied to the head during a head parameter measurement interval using the same current sources that supply a bias current to the head during an operating (read operation) interval. The determined head parameter value is latched for use in setting the control loop gain for a control loop that controls the current sources during the operating interval.

Abstract: In one embodiment, irregular electronic disturbance signals in a partial-response read channel are detected by a disturbance detector using state metrics generated by maximum-likelihood sequence detector. For example, a thermal asperity (TA) detector detects the occurrence of TAs in the read channel of perpendicularly recorded magnetic media by using the state metrics generated by a Viterbi detector. Changes in state metrics (e.g., magnitudes of the branch metrics of the trellis diagram) used by the Viterbi detector are tracked. If the magnitude of the rise of the path metric increases above a set threshold, then a TA is detected. Alternatively, or additionally, the rate of change of the magnitude of the path metrics is tracked. If the rate of change within a set time window is above a specified threshold, then a TA is detected.

Abstract: Methods and structure for switching heads on a multiple recording surface disk drive that uses bi-directional radial writing toward a zipper zone at a middle diameter. When switching from a first head to a second head, features and aspects hereof assure that the second head will not be positioned in the zipper zone of the corresponding second surface and hence will not lose track following servo synchronization and control. In one aspect, added buffer or guard tracks having valid servo information but no data are added on either side of the zipper zone to assure that under the worst-case misalignment of surfaces the second head will not be positioned in its corresponding zipper zone when switching from the first head.

Abstract: In a magnetic recording medium including a servo pattern region having a servo pattern formed of a concave/convex pattern having convex portions and concave portions and a data recording region, the region having a data track pattern, the convex portions are formed in an address pattern region of the servo pattern region such that the maximum opening lengths, which are located in the respective same radius regions of the respective opening lengths along the rotating direction of a substrate of the concave portions constituting the concave/convex pattern are set to first lengths that are double the minimum opening lengths along the rotating direction of the concave portions in the respective same radius regions. With this arrangement, the magnetic recording medium can securely read a magnetic signal and has a servo pattern having excellent surface smoothness.

Abstract: A self servo writing disk controller detects a plurality of spiral sync marks and a plurality of spiral bursts corresponding to one of a plurality of servo spirals from a read signal from the read/write head. A timing reference signal is generated based on timing of at least one of the plurality of the spiral sync marks. A position error signal is generated based on timing of at least one of the plurality of spiral sync marks and a magnitude of at least one of a plurality of spiral bursts. The timing reference signal and the position error signal are used by the disk drive for timing and positioning in self writing initial servo wedges to the disk.

Abstract: Embodiments of the present invention provide a mixed-mode amplifier for amplifying signals in data storage devices such as disk drives. In one embodiments, a circuit for amplifying data signals comprises a magnetoresistive sensor having a bias voltage applied thereto; a signal amplifier which amplifies a signal detected by the magnetoresistive sensor having the bias voltage applied thereto; a feedback control block which is coupled to an output of the signal amplifier and outputs a feedback current used to vary a loop gain of the circuit; a bias setting circuit which outputs a bias setting current; and a transimpedance amplifier which receives the bias setting current from the bias setting block and the feedback current from the feedback control block and generates the bias voltage applied to the magnetoresistive sensor.

Abstract: Provided is a highly reliable disk array device.

Abstract: Apparatus, systems, and methods implementing techniques for converting a signal. In an apparatus form, an input circuit receives a differential input signal and produces a single-ended intermediate signal. An amplifier circuit receives the intermediate signal and produces an amplified signal, and a feedback path couples the amplified signal to the intermediate signal. An inverter circuit receives the amplified signal and produces an output signal.

Abstract: An apparatus, system, and method are disclosed for fabricating a patterned media imprint master. A substrate and a deposition mask may be fixably attached by an intervening spacing element, such that the substrate and deposition mask act as a unified element during a deposition process. A deposition mask may include a plurality of apertures generated by a conventional lithographic process. Material may be deposited onto the substrate through the deposition mask from more than one deposition source oriented at a unique deposition angle. A resulting substrate deposition pattern thus exhibits a density greater than a deposition mask aperture density while avoiding deposition pattern distortion.

Abstract: A method and apparatus for exactly compensating for a track zero position when copying a reference servo pattern in a disc drive adopting a reference servo track copying method. The method of compensating for a track zero position in a reference servo track copy system for copying a reference servo pattern in a head disc assembly into which a reference disc, on which the reference servo pattern is recorded, produced offline and at least one blank disc are assembled, includes: searching for a collision position of an actuator arm against a stopper for limiting the displacement of the actuator arm on the reference servo pattern; calculating an optimal track zero position based on the searched collision position; and copying the reference servo pattern on all disc surfaces from the calculated optimal track zero position.

Abstract: A method of forming servo data, and a self-servo write method using the same, the method including partial response maximum likelihood (PRML)-coding servo data into m bits in n-bit units; multiplying each bit of the PRML-coded result by an o multiple; and converting a bitsream obtained in the multiplying to ((m/n)?p) bits in m/n-bit units.

Abstract: A method and an apparatus for copying data of a disc drive are provided. The method includes: determining whether the first disc drive has a predetermined jumper pin connection by identifying which of a plurality of jumper pins in a jumper block of the first disc drive are connected, the jumper block being used to determine an operation mode of the first disc drive; transmitting a copy command from the first disc drive to the second disc drive if the first disc drive has the predetermined jumper pin connection; and copying data recorded in the first disc drive to the second disc drive in response to the copy command. Accordingly, it is possible to copy data recorded in a first hard disc drive (HDD) to a second HDD without the aid of an additional host.

Abstract: The present invention relates to a reproducing apparatus which, in a case where a burst error has occurred, corrects an error preceding a synchronization pattern detected thereafter to have less errors. A bit slip judging section 81 in a bit slip correcting section 53 calculates a bit slip correction amount and a bit slip correction position on the basis of phase error signals detected by a phase error detecting section 51, synchronization pattern signals detected by a synchronization detecting section 52, reproduced clocks and detected data. A FIFO control section 82 controls a FIFO buffer 83 on the basis of the bit slip correction amount and the bit slip correction position, to perform bit slip correction. As a result, in the case where a burst error has occurred, an error preceding a synchronization pattern detected thereafter is corrected, whereby an error reduction can be implemented. The present invention is applicable to a reproducing apparatus.

Abstract: A novel means for performing dibit extraction is presented. Any one of an unequalized signal dibit, equalized signal dibit, or noise dibit can be extracted. Instead of using the correlation properties of a PN (Pseudo-Noise) sequence to approximate a PN deconvolution sequence, the use of the actual deconvolution sequence (i.e., PN sequence that includes values of +k and 0, where k is oftentimes 1) is employed so that no approximations are needed. The resulting estimate of the channel is therefore very accurate.

Abstract: A media storage device which reads and writes data from and to a storage medium using a head prevents in advance data loss due to thermal relaxation of data recorded on the storage medium. Management information is created, in units of received write commands, for holding the recording areas on the storage medium of the write data and signal quality information; the management data is stored in a management table, and signal quality is measured, updated, and used in re-recording judgements, in write command units. Thermal relaxation state management can be performed in write command units; thermal relaxation processing is simple, and moreover degradation of recorded data due to thermal relaxation can be detected accurately, and data loss can be prevented.

Abstract: A system reads data from a magnetic storage media. A read head reads data from the magnetic storage media and produce an analog signal. A variable gain amplifier amplifies the analog signal. An offset adjust module substantially centers the amplified analog signal to a midscale. A Magneto Resistive Asymmetry (MRA) collection module MRA corrects the amplified analog signal. A Continuous Time Filter (CTF) compensation module processes the amplified analog signal. An Analog to Digital Converter (ADC) samples the amplified analog signal based upon a control signal to produce a digital signal. A Disk Lock Clock (DLC) system produces the control signal to the ADC. The control signal is representative of a frequency offset caused by at least one servo wedge rate error. A Finite Impulse Response (FIR) filter module filters the digital signal. A sequence detector processes the digital signal and detects a bit sequence from the digital signal.

Abstract: An apparatus and method for determining a resistance of a magneto-resistive head. A current drawn by the head, in response to a fixed bias voltage across the head, is converted to a zero temperature coefficient current such that when supplied to a resistor connected to an input terminal of a comparator the effects of variations in the resistance value are avoided. An output signal of the comparator indicates the resistance of the magneto-resistive head.

Abstract: A media storage device reads and writes data from and to a storage medium using a head and prevents in advance data loss due to thermal relaxation of data recorded on the storage medium. Table stores information which is related to a read error detected by a channel circuit in record units. The channel circuit measures information which is related to a read error and updates the information in the table. Further, data degradation is judged by this information which is related to the read error. Degradation of recorded data due to thermal relaxation can be detected accurately, and data loss can be prevented.

Abstract: One embodiment of a tape drive apparatus has a non-volatile memory for storing an identifier. Data that is written by the tape drive apparatus to a loaded tape media is tagged using the identifier. This facilitates to identify the tape drive apparatus that has written the data onto the tape media such as for the purpose of failure analysis. Other devices and methods are included.