Abstract: Methods of encoding and decoding, as well as an encoding system and a digital communications system are provided for encoding data words into code words and decoding code words into data words. The data words are encoded according to a run-length-limited (RLL) code of “k” constraint, the encoding producing u-bit non-zero code words. The “k” constraint can be increased to a higher value by extending the u-bit non-zero code words to generate q-bit non-zero code words.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes an actuator assembly rotatably attached to the base and a device for moving the actuator assembly. The actuator assembly includes an arm carrying a transducer head in a transducing relationship with respect to the disc. The disc drive further includes a servo circuitry and a controller for controlling movement of the actuator assembly during a track follow and a track seek. Piezoelectric transducers are attached to the actuator assembly for non-intrusive measurement of stiction and friction forces developed between the transducer head and the disc during a disc drive spin-up.

Abstract: A system for testing a bus connector comprising an electronically controlled switch operatively coupled to be controlled by a microprocessor, the system having a first input operatively coupled to receive power from an internal power supply and a second input operatively coupled to receive power from a power supply connector, and an output operatively coupled to power an output display selectively from either power supplies.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc has an inner diameter and an outer diameter and a plurality of tracks. Information is written on the plurality of tracks. The plurality of tracks are written at a variable track pitch. The tracks positioned near the outer diameter are wider in pitch than the tracks positioned near the inner diameter. The plurality of tracks further include a first group of tracks written at a first track pitch, and a second group of tracks written at a second track pitch. The track pitch of each of the first group and the second group of tracks is selected such that the percentage of track misregistration for each group will be substantially the same. This method provides a means to increase storage capacity for a predetermined track misregistration budget.

Abstract: A disc drive with on-the-fly verification of an enabled condition of the write element, comprising a rotatable disc having a magnetic recording surface, and a data reading and writing assembly. The data reading and writing assembly comprises a read/write head comprising a write element and a read element, both adjacent the recording surface; a preamplifier comprising a write driver applying a series of write currents for writing data to the recording surface and a read amplifier for reading stored data from the recording surface; and an interconnect joining the write driver to the write element so as to generate time-varying magnetic fields selectively magnetizing the recording surface in response to the write currents, and joining the read amplifier to the read element so as to transduce magnetization vectors on the recording surface associated with stored data.

Abstract: An attenuating filter for the servo control processor of a disc drive data storage device. The filter is constructed by determining the peak resonance in the structure frequency response above a preselected magnitude and computing a digital notch filter to attenuate that peak resonance. The notch filter domain is then summed with the structure frequency response to derive a modified structure frequency response. The modified structure frequency response is substituted for the unfiltered structure frequency response and again the peak resonance in the modified structure frequency response above a preselected magnitude is determined and a notch filter is computed as necessary. This process of summing the structure frequency response with the latest computed notch filter domain to derive a modified structure frequency response continues until the peak resonance of the latest modified structure frequency response is less than the preselected magnitude.

Abstract: Radial correction factors are calculated for each ruler on a patterned media in a data storage system. A ruler is a position-sensing pattern that defines the radial position of a recording head. Rulers are patterned onto each disk before the disks are assembled into a storage system. The radial correction factors are then added to the measured position information during read and/or write operations of the data storage system. The radial correction factors correct for any radial misalignment created by disturbances in the data storage system. Circumferential correction factors are calculated for each patterned media in the data storage system. A corrected sector number is then determined by redefining the original sector numbers using the circumferential correction factors.

Abstract: A method for self-servo writing begins by calibrating at least one ruler formed on at least one storage disk. A ruler is a position-sensing pattern that defines the radial position of a recording head. The calibration process determines at least one correction factor for the at least one ruler on the disk. A servo system is then activated and the correction factors are used when writing the final servo pattern. During the process of writing the final servo patterns, the correction factors are modified to account for variations in any repeatable disturbances and for errors caused by any non-repeatable disturbances.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. A controller for a disc drive uses a system for mapping logical block addresses to actual location on a disc drive stores the number of skipped or defective sectors which occur prior to a target cylinder in a cylinder skip table. The system estimates a starting cylinder location for the selected logical block address. After estimating the cylinder location, a number of skipped defective sectors that have occurred prior to a cylinder start is determined. The starting location of the cylinder is slipped by this amount. A target track and associated head is also determined. Information in the track identification field is used to adjust the actual location on the track and to determine if a track seek to another track is needed.

Abstract: A method is disclosed for detecting defects in a recordable medium such as a hard disc drive based on error energy. The method may include the steps of writing test data to the medium and reading back the test data. The method may also include the steps of computing an error energy based on the square of the difference between the read back data and an ideal version of the test data and comparing the error energy with an energy threshold. The method generates a defect signal when the error energy exceeds the energy threshold. The method may also be used to identify the media defect according to its error energy profile. An apparatus for detecting defects in a recordable medium is also disclosed.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes a defect management system for managing defective sectors located on the disc surface of a disc within the disc drive. The defect management system includes a controller, and a memory associated with said controller. The controller skips at least a first defective sector and a second defective sector. The first defective sector may be contiguous with the second defective sector or at least one writable sector is located between the first defective sector and the second defective sector. The controller also controls the head to write at least the last two sectors of the plurality of sectors to be written to at least two contiguous sectors located in a pool of spare sectors.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes an actuator assembly rotatably attached to the base and a device for moving the actuator assembly. The actuator assembly includes an arm carrying a write head in a transducing relationship with respect to the disc. The write head further includes a preamp current driver circuit. A data pulse circuit is operatively coupled to the preamp current driver circuit to provide a write current impulse based on an input data pattern. The preamp current driver circuit further includes a plurality transistors to receive the write current impulse and provide a sequence of write current impulses of opposite polarity to the write head for effecting magnetic recording on the disc of the disc drive based on the input data pattern.

Abstract: An apparatus and method are disclosed for improving data recovery operations in a disc drive employing a redundant sync data block format. The disc drive includes a rotatable disc and a controllably positionable head which is used to store user data in a plurality of data blocks on tracks of the disc. Each data block includes a user data field to store user data, a first sync field and a redundant, second sync field, the sync fields storing first and second sync words, respectively, which establish symbol boundaries used by a read channel of the disc drive. User data are recovered from a selected data block by initiating a delay of selected duration during which a first portion of the selected data block passes proximate the head, allowing the second, remaining portion of the selected data block to be read at the completion of the delay.

Abstract: Presently, almost all commercially available data storage systems use saturation recording and binary signaling schemes. Earlier data channels for storage systems utilized various forms of bit by bit peak detection. More recently, various forms of PRML (partial response maximum likelihood) or DFE (decision feedback equalization) have appeared in products. These improvements are still limited by the fact that the storage data channel is a saturation channel, and as such, has a significantly reduced information handling capacity compared to a linear data channel. Recording media defects are currently mapped out at the factory and skipped under normal device usage, while remaining errors are corrected by error correction code. However, at higher aerial densities, defects in the media tend to become a greater problem. The above-incorporated applications teach a linearization technique for linearizing magnetic recording channels without suffering signal to noise loss and not suffering bandwidth loss.

Abstract: An apparatus and method for writing data to a magnetizable recording medium in the form of spaced-apart magnetic flux transitions forming magnetization vectors having alternating magnetic orientations and selected lengths. A write element adjacent the medium includes a leading edge and a trailing edge forming a write gap which, when the write element is activated by an electric current, provides a write field for selectively magnetizing the magnetizable medium. A write driver circuit is responsive to a data input stream in providing a write current activating the write element, the write current comprising a pulse current in a phased relationship with a continuous current.

Abstract: The present invention uses temperature readings obtained aperiodically, on demand. Rather than merely obtaining temperature readings on each expiration of a fixed timer, operating parameters are updated in response to a fault detected in the data path. Data handling systems of the present invention each include at least one data path having a thermal range within which it operates best. Applicant notes that some “key” operating parameters typically have a substantial effect on this thermal range. Temperature sensors positioned near the transducers provide a temperature reading to control circuits, which update “key” operating parameter values in response to indications of faults in a primary data path. This reduces the need for more frequent temperature monitoring and calculation-intensive recalibration.

Abstract: A method for data detection includes signal transition detection of an input signal. When a falling edge is detected, a rising edge in a negative signal is generated. When a rising edge is detected, a rising edge in a positive signal is generated. Data is latched from the bus for the rising edge of the positive/negative edge signal. A falling edge in the positive/negative edge signal is generated after a period of time. The steps are repeated for each detected signal transition. A data detection apparatus includes a QAEDN to generate a rising edge on the negative signal for detected falling edges. A memory unit latches data from the bus for rising edges of the negative signal. A QAEDP generates a rising edge on a positive edge signal in response to detected rising edges. A memory unit latches data from the bus for rising edges of the positive signal.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes an actuator assembly rotatably attached to said base and a device for moving the actuator assembly. The disc drive also includes at least one sensor for sensing disturbances to the disc drive. The disc drive has a system microprocessor in electrical communication with the sensor. In the event a read error is detected, a plurality of sets of corrective procedures are stored in the random access memory of the microprocessor. The system microprocessor executes the sets of corrective procedures in an order in response to the sensed disturbances input to the system microprocessor.

Abstract: The invention relates to apparatus and method that provide an improved media codeword and which can distinguish an uncorrectable data error from a wrong block address error and permit the address to be recovered from readback data. In accordance with one embodiment of the invention, method for generating parity is provided in which a sequences representing address and data are received. The address sequence is multiplied by a set of multiplier symbols to generate a first sequence of product symbols. A first portion is added to the data sequence prior to generating a first parity sequence and second portion is added directly to the first parity sequence to generate the final parity sequence. A corresponding method of generating syndromes from readback data is provided. System and apparatus incorporating the inventive method are also provided.

Abstract: A dual channel readback recovery circuit includes a high resolution channel and a low resolution channel and a data latch. A logical filter in one or both channels rejects signals that are followed by other signals if they are spaced apart less than the rejection time interval allowed by the code used. Polarity qualifying logic rejects signals in the channels that are not matched in polarity.