Abstract: A data zone optimization method and architecture for optimizing the location of the data zone on a data storage disk is disclosed. The data zone is preferably biased toward the outer diameter of the disk, and is referenced to a data zone starting location established proximate a load/unload ramp apparatus. An optimum starting location for the data zone of an initially unformatted data storage disk is preferably determined by contacting the load/unload ramp with the transducer assembly, disengaging the transducer assembly from the ramp, and writing servo information indicative of the data zone starting location at a disk location proximate the ramp and transducer assembly contact point. Servo information indicative of the data zone is written at inner diameter disk location with respect to the optimum data zone starting location. The optimized data zone architecture may have a predetermined or variable data storage capacity.

Abstract: A method and apparatus for measuring absolute clearance between a magnetoresistive (MR) transducer and a moving medium utilizes a transduced signal that varies as a function of transducer-medium clearance. The medium may be devoid of, or include, magnetic information. The velocity of the medium is reduced relative to the MR transducer, and a rate of change of the signal is monitored. Using data associated with the rate of change of the signal during spindown, absolute clearance between the MR transducer and the medium is computed for a nominal medium-transducer velocity, such as a full operational velocity. Computing absolute transducer-medium clearance involves determining a transition velocity at which the rate of change of the signal exceeds a pre-established threshold. Computing absolute clearance may further involve associating the transition velocity with an absolute clearance value obtained using a clearance profile associated with the MR transducer.

Abstract: An apparatus and method for estimating one or more pole frequencies of an amplifier circuit, such as a readback signal amplifier circuit implemented in an arm electronics module of a data storage system, are disclosed. A bias signal that biases the read transducer is modulated at first and second modulation frequencies while a readback signal is obtained from a data storage medium using the read transducer. The readback signal is communicated to the amplifier, and an output signal of the amplifier circuit is measured at the respective first and second modulation frequencies. The amplifier pole frequency is determined by computing a square impedance measurement ratio using square magnitudes of the bias signal and the amplifier output signal respectively measured at the first and second modulation frequencies.

Abstract: In storing data on a storage device, for example, a disk drive, it is determined what type of data is to be stored, distinguishing between normal data and slow data, such as audio data or text messages. Slow data is data which can be used effectively when retrieved at a relatively low storage medium speed. Slow data is further assigned to be stored at a predetermined location on the storage medium selected to avoid reliability problems due to the slower medium speed. Storing and retrieving such data at a slower medium speed from the assigned location increases drive efficiency by conserving power without compromising storage device reliability.

Abstract: A method and apparatus for processing a readback signal obtained from a storage medium using a magnetoresistive (MR) element restores a thermal signal component of the signal. A readback signal obtained from the storage medium comprises a thermal component representing a thermal response of the MR element, and may further comprise a magnetic component representing servo or user data. The readback signal is filtered so as to degrade the thermal component of the signal, typically by amplification circuitry exhibiting a highpass filtering behavior. The highpass filtered readback signal is further filtered using a lowpass filter. The filtered signal is sampled, and a sliding window comprising a series of binary values is applied to groups of the signal samples to produce a plurality of signal sample values for each of the signal sample groups.

Abstract: The present invention is a method and apparatus for positioning a magnetoresistive (MR) head relative to a storage medium in a storage device. The storage medium is mounted in the storage device to allow relative movement between the MR head and the storage medium. The storage medium includes servo information provided to induce a thermal response in the MR head. A controller controls the relative movement between the MR head and the storage medium using the thermal response induced in the MR head.

Abstract: An apparatus and method for extending the service life of an MR element incorporated in a read/write head involves detecting periods of disk drive system inactivity and selectively switching between the heads for purposes of reading servo information during the inactive periods. Switching between heads may involve selecting each of the heads for reading servo information during one or more periods of disk drive system inactivity or selecting each of the heads in sequence during a respective period of system inactivity. Selecting between heads may also involve selecting a head having a minimum of usage, such as a head having an MR element with a minimum of cumulative operational time or energy dissipation relative to other MR elements provided in the disk drive system. Selecting between heads may further include selectively activating each of the heads for reading servo information for a predetermined duration of time during one or more periods of system idleness.

Abstract: A combined read and write VCO for data channels is disclosed. The combined read and write VCO for data channels shares a common loop capacitor while providing optimal read and write VCO loop responses, and allows the VCO to relock to the write timebase after a read very quickly while maintaining an accurate timebase. The combined read and write VCO includes an oscillator providing an output signal having a frequency that varies proportionately to an oscillator input signal and an adjustable voltage source, the adjustable voltage source having a first configuration for a write mode and a second configuration for a read mode, and the adjustable voltage source providing the oscillator input signal to the oscillator in response to receiving an input current signal. The adjustable voltage source includes a first and second capacitor coupled in series and a switch coupled across the second capacitor, the switch being open to provide the first configuration and closed to provide the second configuration.

Abstract: A method and apparatus for detecting changes in clearance between a read/write transducer and a data storage medium involves acquiring a readback signal from the data storage medium using the transducer, the readback signal comprising one or more isolated pulses, and detecting a change in spacing defined between the transducer and the data storage medium using a slope of an edge of one or more of the isolated pulses.

Abstract: An apparatus and method for estimating an amplitude of a readback signal obtained from a data storage medium and input to a gain modifying amplifier involves sensing an amplifier output signal in response to a readback signal applied to the amplifier. An amplifier control signal is produced which is representative of a difference between the amplifier output signal and a reference signal. A compensation signal associated with a temperature coefficient of amplifier gain is generated, and an estimate signal indicative of the amplitude of the readback signal is produced using the compensation signal. The estimate signal is representative of readback signal amplitude when the estimate signal has a magnitude equivalent to that of the difference signal and a polarity opposite that of the difference signal.

Abstract: A method and apparatus for estimating the value of a slider airbearing resonance frequency involves obtaining a readback signal from a data storage medium over a plurality of complete airbearing periods and estimating the value of an airbearing resonance frequency using the readback signal. In one embodiment, a discrete signal segment comprising a plurality of frequency transform components is produced using the readback signal information, and the value of the airbearing resonance frequency is estimated using spectral leakage in the discrete signal segment. A ratio of the magnitudes of a first DFT component to a second DFT component is computed at each of a plurality of sampling rates. Each of these sampling rates is defined by a number of samples per average airbearing cycle multiplied by a frequency falling within a range of expected airbearing frequencies associated with a given implementation.

Abstract: A method for measuring an amplitude of a readback signal obtained from a data storage medium involves transmitting the readback signal to a gain modifying amplifier, such as a variable gain amplifier (VGA), preferably provided in the read channel. A voltage signal associated with a loop gain of the amplification circuitry is sensed and compared with a number of control voltage signals, each of the control voltage signals being associated with a corresponding digital word value. The digital word value associated with a control voltage signal that is equal to the sensed voltage signal represents the relative amplitude of the readback signal. Gain characterization circuitry may further be combined with readback signal amplitude measuring circuitry, preferably in-situ a read channel, to obtain the absolute amplitude of a readback signal.

Abstract: A method and apparatus for calibrating a thermal response of a magnetoresistive element is provided. In accordance with one embodiment of the invention, a thermal spacing signal is read using an MR element spaced apart from a surface of a moving storage medium. From the thermal spacing signal a signal value and calibration value are produced. Using the signal value and the calibration value a calibrated signal value is produced. The calibrated signal value may, for example, be compared against a pre-determined threshold to detect surface defects on the storage medium.

Abstract: An apparatus and method for distributing a clock signal within circuitry disposed on a number of separate system cards includes a first system card that generates a reference clock signal representative of a fixed delay of a system clock signal. A number of variable clock signals are produced using the system clock signal. Each of a number of system cards separate from the first system card receive one of the variable clock signals. A delay associated with the reference clock signal is typically longer than a delay associated with each of the variable clock signals. The phase of each of the variable clock signals is adjusted to a substantially in-phase relationship with respect to the reference clock signal in response to a phase difference between the reference clock signal an output signal received from each of the separate system cards.

Abstract: A method and apparatus for automating the convergence of tap weights in an equalizer for a data channel is disclosed. The automated equalization method is contained within the channel and obtains a temporary copy of each of a plurality of current tap weights from a current tap weight memory, determines a direction for modifying the temporary copy of each of the plurality of current tap weights, constrains the modifications to the temporary copy of each of the plurality of current tap weights to produce adjusted tap weights and at the end of a read operation, stores the adjusted tap weights to the current tap weight memory for use during a next read operation.

Abstract: A multimedia direct access storage device and a method for transferring source program signals representative of a compressed digital multimedia program to and from the direct access storage device are disclosed. A multimedia program is transmitted from a multimedia server as a custom ordered series of discrete program segments and received by the multimedia direct access storage device, which buffers the compressed program segments for subsequent presentation on a local display monitor. The multimedia direct access storage device is preferably incorporated as a component of a local set-top control system for buffering a predetermined number of compressed program segments received from the multimedia server, some of which may be non-sequentially ordered and others of which may be sequentially ordered. A novel formatting methodology provides for the sequential presentation of the program segments asynchronously distributed on one or more data storage disks disposed in the direct access storage device.

Abstract: A boundary configuration (Common Input/output CIO) for Generalized Scan Designs (GSD) in a single clock chip design includes at least one generalized scan design internal latch; a boundary scan clock input to the internal latch; an input/output cell connected to the internal latch; and at least one control line between the internal latch and the input/output cell. The CIO GSD is arranged and configured to operate in various modes including a function mode, a RUNBIST/INTEST/LBIST mode, an EXTEST/WIRETEST mode, a SAMPLE/PRELOAD mode, etc. In a different version, a MUX controller is connected to the internal latch. The MUX controller selects data from one of at least two control lines and sending the selected data to at least one internal logic unit of the chip for a test operation.

Abstract: A system and method for conducting a repeatable logic test on at least one functional unit of an IC chip includes steps of selecting at least one functional unit of at least several functional units, propagating test data through a part or all functional units of the time domain; and capturing test data of the selected functional unit. The functional units are either selected or held inactive such that only the selected functional unit is allowed to capture the test results for determining a critical timing path within the selected functional unit and only the functional unit. By selecting different combination of the functional unit(s), a number of the critical timing paths are readily determined in the chip.

Abstract: The present invention is a method and apparatus for positioning a dual element magnetoresistive (MR) head relative to a storage medium in a storage device. The MR head has first and second MR elements. The storage medium is mounted in the storage device to allow relative movement between the MR head and the storage medium. The storage medium includes servo information provided to induce first and second thermal responses in the MR elements. A controller is coupled to the MR head and controls the relative movement between the MR head and the storage medium using the first and second thermal responses in the MR elements.

Abstract: A test device is formed on a chip which allows the susceptibility to failure of functional circuitry formed on the chip to be tested. The test device allows aggressive design of chips which include sensitive circuitry, such as precharged dynamic logic, by testing whether deviations from the design specification introduced during manufacturing of the chip are sufficient to cause failure of the functional circuitry.