Abstract: The present invention provides a novel method and apparatus for decoding digital information transmitted through the communication channel or recorded on a recording medium. The method and apparatus are preferably applied in the systems where data is encoded using regular LDPC codes with parity check matrices composed from circulants (a matrix is called a circulant if all its column or row are cyclic shifts each other).

Abstract: An actuator assembly including one or more actuator arms, wherein each of the actuator arms defines a clasp hole and a clamp-opening hole and a slot running between the clasp hole and clamp-opening hole, and optionally, a second slot running from the clasp hole to a distal end of the actuator arm, thereby creating two clasp fingers. A flex suspension assembly is included with a protrusion, such as a boss and a head on a distal end. The flex suspension assembly is coupled to the actuator arm by resiliently increasing the diameter of the clasp hole so as to allow the boss on the flex suspension assembly to be inserted into the clasp hole. With the boss is inserted, the clasp hole is allowed to revert to its original diameter, thereby clamping the boss in the clasp hole. A method for assembly is also provided.

Abstract: A method of manufacturing a patterned data/information storage and retrieval medium in the form of an annular disk having an outer diameter, a central opening defining an inner diameter, and opposed first and second major surfaces, the method including inserting a smaller diameter cylindrical shaft of a stamping/imprinting tool in the central opening and biasing the inner diameter of the disk into contact with the cylindrical shaft at a pre-selected location along the inner diameter of the disk during stamping/imprinting of a pre-selected pattern such as a servo pattern in at least one of the first and second major surfaces of the disk, the biasing creating a space between the inner diameter of the disk and the surface of the cylindrical shaft which has a maximum width at a location diametrically opposite the pre-selected location.

Abstract: An actuator assembly of a disc drive having an actuator arm rotatably mounted adjacent a data disc. The actuator arm includes a piezoelectric assembly configured to displace a data transducer relative to the data disc. The piezoelectric assembly may include a top-left piezoelectric element, a top-right piezoelectric element, a bottom-left piezoelectric element, and a bottom-right piezoelectric element. The actuator arm also includes an hourglass-shaped arm pivot configured to bias the data transducer to a rest position.

Abstract: A programmable controller and method for correcting operation of a read/write head in a disc drive having an embedded servo system in which the head is not reading correctly operates by applying a write current to the failed head only after the head is positioned over an area of a disc that does not have useful data thereon. Movement and position of the head that is not reading correctly is determined from a signal from an adjacent head. The adjacent head is used to read servo information. After the adjacent head has provided servo information and the controller repositions the adjacent head in a safe area, a write current is applied to the failed head to realign the head without the potential of adversely impacting data stored in adjacent tracks.

Abstract: A recording surface is segmented into a plurality of radial zones each containing a plurality of concentric tracks on which data may be recorded. The recording surface is initially formatted with a data frequency for each zone such that all of the zones have substantially the same data density. The data frequency is reduced for a first zone whose error rate is initially less than the predetermined error rate so that the first zone exhibits an error rate meeting the predetermined error rate. The data frequency for a second zone whose data transfer error factor initially exceeds the predetermined error rate is increased to restore any loss of storage capacity of the recording surface due to the reduced data frequency in the first zone. As a result, the data density in the first zone is substantially less than a nominal data density and the data density in a second zone is substantially greater than the nominal data density.

Abstract: A process of forming a two-piece pole for an inductive write head involves first forming a first pole piece having a width between opposite side surfaces defining a gap width of a transducing gap at an air bearing surface of the head. The process next involves forming a second pole piece having a first region remote from the air bearing surface and a second region extending from the first region toward the air bearing surface. The first region is wider than the width of the first pole piece. The second pole piece is formed so that at least a portion of the second region is contiguous a portion of the first pole piece and so that no sharp external corners exist between the first pole tip piece and the second pole piece within a pole tip region of the head.

Abstract: An isolator apparatus is described to attenuate or isolate vibration. The isolator apparatus includes a fluid isolator assembly including a flexible diaphragm and a pressure chamber having a flow passage opened to the pressure chamber to provide a fluid spring. A floating isolator body including an elastomeric damping element is floatably interfaced with the flexible diaphragm of the fluid isolator assembly to isolate vibration.

Abstract: Apparatus and method for emulating a virtual machine within the physical memory space of a programmable processor using virtual functions having a format independent of the hardware architecture of the processor. The virtual functions are executed using an execution engine emulated in the processor. A symbol table maps the virtual functions to native functions in the memory space, and a gate call interface block accesses the symbol table and initiates execution of the corresponding native function in response to each executed virtual function. Execution of the corresponding native function operates to evaluate the concurrent execution of at least one other native function. In this way for example, standardized platform virtual code can be generated for a number of different types of processors and used to evaluate the native operational routines of each processor.

Abstract: A data transducer having an air bearing surface is used to reduce thermal pole tip protrusion. The data transducer includes a write via and a top pole having one end adjacent the air bearing surface and an opposite end contacting the write via. The yoke extends from the write via in two directions towards the air bearing surface and is recessed from the air bearing surface. The yoke has a first end and a second end. The data transducer includes a shared pole adjacent the air bearing surface and co-planar to the yoke wherein a gap is located between the shared pole and the yoke. A shared pole extension extends between the shared pole and the first and second ends of the yoke.

Abstract: Methods and systems in a data storage device selectively employ a seek time array and/or a seek time list to accurately predict a time required for a seek operation to move a transducer in the data storage device a given seek distance. The seek time list and/or seek time profiles are automatically compiled in the data storage device based on seek time entries located in a servo data table located in the data storage device.

Abstract: A high areal recording density, perpendicular magnetic recording medium, comprises: (a) a non-magnetic substrate having a surface with a layer stack formed thereon, the layer stack comprising, in overlying sequence from the substrate surface: (b) a soft ferromagnetic “keeper” or underlayer; (c) an anti-ferromagnetic coupling layer structure; and (d) a hard ferromagnetic perpendicular recording layer including a multilayer magnetic superlattice structure; wherein layers (b), (c), and (d) in stacked combination provide the medium with improved thermal stability and a high perpendicular coercivity which can exceed about 6,500 Oe.

Abstract: A data/information storage and retrieval medium, comprising: (a) a disk-shaped substrate including at least one surface with a layer stack thereon and including at least one magnetic or magneto-optical (“MO”) recording layer and an uppermost, protective overcoat layer comprising a carbon (C)-based material; and (b) a lubricant topcoat layer on the protective overcoat layer, the lubricant topcoat layer treated solely with UV radiation at a dosage sufficient to increase the glide yield, decrease the glide noise, and increase the number of CSS pass cycles of the medium before failure, relative to that of the same medium but with an untreated lubricant topcoat layer.

Abstract: A spin valve read element for use with, for example, magnetic recording media, includes a permanent magnet as one of the multilayers that make up the spin valve. The spin valve may also include a pinned ferromagnetic layer, an antiferromagnetic coupling inducing layer, a reference ferromagnetic layer, an electroconductive layer, and/or a free ferromagnetic layer. Epitaxy breaking layers may also be advantageously positioned within the spin valve. The multilayers of the spin valve may be constructed as a current perpendicular to the plane or a current parallel to the plane type spin valve.

Abstract: A disc drive data recovery system for recovering data from a magnetic disc having asperities provided. Readback data follows a nominal readback path and a thermal asperity cancellation readback path. A thermal asperity detector detects a thermal asperity in the readback signal and responsively selects the readback signal which follows the thermal asperity cancellation readback path.

Abstract: The temperature of an actuator voice coil in a disc drive is regulated so as to prevent outgassing. In a preferred embodiment, coil temperature is calculated at the beginning of each long seek. If the temperature is determined to be at or below a predetermined “safe” level, temperature rise is not limited and power may be applied to the coil without additional limitations. If, however, coil temperature is determined to be above the “safe” level, proportional control is used to scale back power generation so as to prevent the coil temperature from exceeding the coil's specified temperature limit.

Abstract: A data storage disc rotatably mounted on a spin or spindle motor fastened to a base plate. An actuator assembly is fastened or otherwise coupled to base plate adjacent to data storage disc. The actuator assembly positions a transducer or head over a data surface of the disc. A cover above the base plate encloses the disc, the spin motor, and the actuator assembly between the cover and the base plate. A pass-through connector is positioned above and coupled to the base plate for routing electrical leads from the transducer through a preamplifier mounted above the pass through the pass-through connector to a printed circuited board located below an underside of the base plate. The cover has a surface thermally coupled to the preamplifier to conduct heat from the preamplifier.

Abstract: A method for patterning a carbon-containing substrate utilizing a patterned layer of a resist material as a mask and then safely removing the mask from the substrate without adversely affecting the substrate, comprising sequential steps of: (a) providing a substrate including a surface comprising carbon; (b) forming a thin metal layer on the substrate surface; (c) forming a layer of a resist material on the thin metal layer; (d) patterning the layer of resist material; (e) patterning the substrate utilizing the patterned layer of resist material as a pattern-defining mask; and (f) removing the mask utilizing the thin metal layer as a wet strippable layer or a plasma etch/ash stop layer.

Abstract: A method of and apparatus for generating a reader-to-writer offset for a head positioned over a track on a disc in a disc drive having a plurality of tracks is disclosed. A reader and a writer are mounted on the head in a non-overlapping manner with a gap between the reader and the writer, which is known as the reader-to-writer offset. A disc drive controller is operably connected to the reader and the writer. The disc drive controller determines the reader-to-writer offset of the head for each track by computing the difference between a first head position x1 and a second head position x2. The first head position x1 is an optimal head position for writing information on the track and the second head position x2 is a midpoint of an off-track capability (OTC) of the head.

Abstract: A servo-patterned magnetic recording medium, comprising: a magnetic layer having a surface with substantially uniform topography, the magnetic layer including a data zone and a servo pattern, the servo pattern comprising: (a) a first patterned plurality of regions of first, higher values of magnetic coercivity Hc and magnetic remanence-thickness product Mrt; and (b) a second patterned plurality of ion-implanted regions of second, lower values of Hc. and Mrt; wherein the second, lower values of Hc and Mrt are sufficiently lower than the first, higher values of Hc and Mrt as to permit sensing for enabling accurate positioning of a read/write transducer head in the data zone but sufficiently high for providing the medium with thermal stability, high amplitude of magnetic transition, and high signal-to-noise ratio.