Abstract: A disk drive is disclosed servo written from spiral tracks by generating a time-stamped sync mark detect signal processed by timing recovery firmware. A plurality of spiral tracks are written to the disk, wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. The head internal to the disk drive is used to read the spiral tracks, and a time-stamped sync mark detect signal is generated when one of the sync marks is detected. The time-stamped sync mark detect signal represents a time when the sync mark was detected relative to a servo write clock. A difference between the time-stamped sync mark detect signal and an expected time is computed in firmware to generate a coarse timing recovery measurement used to synchronize the servo write clock. The servo write clock and the head internal to the disk drive are used to write product servo sectors along a substantially circular target path.

Abstract: A disk drive is disclosed comprising a disk for storing initial host requested (IHR) data requested by a host computer during a start-up process of the host computer, a head actuated radially over the disk, and a non-volatile semiconductor memory (NVSM) for caching at least part of the IHR data. The disk drive transmits the cached IHR data from the NVSM to the host computer during the start-up process thereby avoiding the delay associated with initializing the mechanics of the disk drive as well as conserving battery power for mobile applications.

Abstract: A computer network is disclosed comprising a plurality of interconnected computer devices including a plurality of disk drives for storing network data, each disk drive comprising a head and a disk. The computer network comprises a plurality of interconnected nodes, and a reservation facility for reserving resources within the disk drives and the nodes to support a predetermined Quality-of-Service constraint with respect to data transmitted between the disk drives through the nodes of the computer network.

Abstract: A disk drive is disclosed comprising a pulse width modulated (PWM) signal generator for generating PWM control signals applied to the driver switches of a voice coil motor (VCM). The PWM control signals comprise a PWM cycle time, a Tforward time interval of the PWM cycle time wherein a positive control voltage is applied to the VCM, a Treverse time interval of the PWM cycle time wherein a negative control voltage is applied to the VCM, and a Tdead time interval of the PWM cycle time wherein a substantially zero control voltage is applied to the VCM. The Tdead time interval is adjusted to control a magnitude of an actual ripple current flowing through the VCM.

Abstract: A disk drive is disclosed comprising a cache buffer for caching data written to the disk and data read from the disk, the cache buffer comprising a plurality of cache segments linked together to form a plurality of cache links. At least one segment attribute is associated with each cache segment, including an allocation state, and at least one link attribute is associated with the segment attributes within each cache link. When a host command is received from a host computer, the link attributes are evaluated to allocate cache segments for a cache link associated with the host command.

Abstract: A disk drive is disclosed employing either back electromotive force (BEMF) spindle speed control mode or wedge spindle speed control mode. A BEMF detector monitors the BEMF voltage generated by the windings of the spindle motor to generate a BEMF speed error. The BEMF spindle speed control mode is used to spin up the disk to an operating speed, and the wedge spindle speed control to maintain the disk at the operating speed. While in the wedge spindle speed control mode, a BEMF detection window is disabled to reduce acoustic noise.

Abstract: A disk drive is disclosed comprising a first disk surface and a second disk surface, wherein a first head is actuated radially over the first disk surface and a second head is actuated radially over the second disk surface. Each disk surface comprises a plurality of tracks, wherein each track comprises a plurality of data sectors for storing user data and N embedded servo sectors for storing servo data. The N embedded servo sectors on the tracks on the first disk surface are recorded at a physical angular offset from the N embedded servo sectors on the tracks on the second disk surface. While accessing a track on the first disk surface through the first head, the servo data on the first disk surface is read through the first head and the servo data on the second disk surface is read through the second head, thereby increasing the servo sample rate.

Abstract: A disk drive is disclosed which generates a pole tip protrusion (PTP) measurement by performing a write operation to heat the transducer while measuring a fly height of the transducer. A first data sequence written to the disk is read without heating the transducer to generate a first signal measurement. A second data sequence is then written to the disk in order to heat the transducer, and the first data sequence is again read to generate a second signal measurement. The PTP measurement is then generated in response to the first and second signal measurements.

Abstract: A method of selecting a track density for a disk surface of a disk drive is disclosed. A first pattern is written along a circumferential path of the disk surface, wherein the first circumferential path comprise a first set of arcuate sections interleaved with a second set of arcuate sections. A second pattern is written radially offset from the circumferential path during time intervals corresponding to the first set of arcuate sections. The head is positioned substantially over the center of the first circumferential path and during time intervals corresponding to the second set of arcuate sections, the first pattern is read to generate a first read signal amplitude measurement A0, and during time intervals corresponding to the first set of arcuate sections, the first pattern is read to generate a second read signal amplitude measurement A1. A track density is selected in response to A0 and A1, wherein the track density is for use in writing embedded servo sectors to the disk surface.

Abstract: A disk drive with improved shrouding is disclosed. The disk drive comprises a disk, a spindle motor for rotating the disk, a head, an actuator arm for actuating the head radially over the disk, a base, and a cover attached to the base to form a head disk assembly chamber. The cover comprises an inner surface and an outer surface, and a shroud extending axially from the inner surface into the head disk assembly chamber substantially enveloping the periphery of the disk, including at least part of the periphery coextensive with the actuator arm, to provide radial shrouding of the disk.

Abstract: A disk drive is disclosed comprising a disk and a head actuated radially over the disk. A pattern detector detects a predetermined pattern in write data to be written to the disk, and in response, adjusts a write current overshoot in a write current applied to the head.

Abstract: A production line spindle control circuit is disclosed for use in manufacturing a disk drive. The production line spindle control circuit generates sinusoidal driving currents applied to a spindle motor of the disk drive, and processes a back EMF signal generated by the spindle motor in order to control a commutation sequence as well as the angular velocity of the spindle motor. The production line spindle control circuit is attached to the spindle motor during a manufacturing procedure, such as servo writing, and detached from the spindle motor after the manufacturing procedure.

Abstract: A disk drive is disclosed comprising a velocity extraction circuit for extracting a velocity of an actuator arm from a back EMF voltage across a voice coil of a voice coil motor when embedded servo information is unavailable. The velocity extraction circuit comprises a dual slope integrator for integrating a voltage representing a current flowing through the voice coil and the voltage across the voice coil. The sum of the integrations cancels the resistance of the voice coil from the back EMF measurement. In one embodiment, the dual slop integrator also integrates the reverse polarity of the voltage representing the current flowing through the voice coil and the reverse polarity of the voltage across the voice coil in order to cancel the inductance (L·di/dt) of the voice coil from the back EMF measurement.

Abstract: A method and apparatus are disclosed for transmitting advertising information comprising a plurality of banner ads to a mobile terminal over a first connection during a synchronization session and storing the advertising information in a local memory of the mobile terminal. A web page is transmitted to the mobile terminal over a second connection, wherein the web page comprises web page content including a banner ad display area for displaying a banner ad. During a first time interval, a first one of the banner ads is retrieved from the local memory and the web page content is displayed on the screen of the mobile terminal together with the first one of the banner ads in the banner ad display area. During a second time interval, a second one of the banner ads is retrieved from the local memory and the web page content is displayed on the screen of the mobile terminal together with the second one of the banner ads in the banner ad display area.

Abstract: A disk drive is disclosed employing a spindle motor comprising a hub ratchet arm disengaged through angular velocity. In one embodiment the ratchet arm is connected to the hub and engages a spindle shaft or a stator, and in an alternative embodiment the ratchet arm is connected to the spindle shaft or the stator and engages the hub. In one embodiment the ratchet arm disengages through centrifugal force, and in an alternative embodiment the ratchet arm disengages through an air bearing or windage.

Abstract: A disk drive is disclosed comprising a disk, a spindle motor for rotating the disk, an actuator arm, and a head coupled to the actuator arm. While powered down the head is latched in a parked position. During a start-up process, the spindle motor is controlled to rotate the disk toward an operating speed and the head is unlatched prior to the disk reaching the operating speed. If the disk drive is in a first spin-up mode (e.g., a normal spin-up mode) the head is unlatched relative to a first target speed, and if the disk drive is in a second spin-up mode (e.g., a re-sync spin-up mode) the head is unlatched relative to a second target speed greater than the first target speed.

Abstract: A disk drive is disclosed comprising a disk, a head, an actuator arm for actuating the head radially over the disk during a seek operation, and a voice coil motor (VCM) for rotating the actuator arm about a pivot, the VCM comprising a coil comprising a VCM resistance R. A back EMF voltage detector measures a back EMF voltage across the coil, and a current detector detects a current I flowing through the coil. An IR voltage detector, responsive to the current I detected by the current detector, detects an IR voltage proportional to the current I times the VCM resistance R. A voltage compensator substantially cancels the IR voltage from the measured back EMF voltage to generate a compensated back EMF voltage. A control voltage generator, responsive the compensated back EMF voltage, generates a control voltage applied to the coil to generate the current I flowing through the coil. A memory stores a first compensated back EMF voltage generated at a first time period of the seek operation.

Abstract: A disk drive comprising a programmable inverting voltage regulator (PIVR) for generating an inverted voltage supply applied to a preamp is disclosed. The PIVR is programmably configured relative to the disk drive's mode of operation, including a read mode and a write mode.

Abstract: A disk drive is disclosed comprising a head, a spindle motor having a hub, the hub comprising a cylindrical shaft, the shaft defining a generally cylindrically-shaped outer surface, the outer surface defining a latching member extending around at least part of the circumference of the shaft. A disk is positioned on the spindle motor and an actuator moves the head radially over the disk. A disk clamp clamps the disk to the spindle motor. The disk clamp comprises a ring-shaped body comprising an outer ring-shaped surface abutting the disk, and an inner neck spaced-apart from the outer ring-shaped surface, the inner neck comprising a plurality of independently flexing teeth for contacting the latching member.

Abstract: A disk drive is disclosed comprising a disk, a spindle motor for rotating the disk, and a head actuated radially over the disk. A disk clamp clamps the disk to a hub of the spindle motor, wherein the disk clamp comprises a notch at a predetermined location along an outer diameter of the disk clamp. The disk is aligned non-concentric with the hub such that a center of the disk is aligned offset from a center of the hub toward the notch. The notch substantially counteracts an imbalance due to the non-concentric alignment of the disk with respect to the hub.