Abstract: A glide head that can be used to certify disks of hard disk drives. The glide head includes a heater that can change the temperature of a slider surface of the head and vary the head flying height. The slider surface may induce the negative pressure so that the glide head more accurately simulates a head used in a production disk drive. A piezoelectric transducer may be coupled to the glide head so that contact between the head and a disk may be sensed and recorded in a disk certification routine.

Abstract: A head floating amount control unit control a head floating amount of each of a plurality of heads respectively having a heater, with respect to a recording medium, by detecting contact between each head and a corresponding recording medium by detecting a thermal asperity or a read error, and judging a heating amount of the heater at a time when the contact is detected as a state where the head floating amount is zero, and controlling the head floating amount of each head to an optimum head floating amount based on a relationship of the heating amount of the heater and an amount of thermal expansion of each head.

Abstract: Watermarks for patterned magnetic media. The watermarks are used to demonstrate the unauthorized replication of a patterned magnetic media. The watermarks include a dibit, a pattern in an open region, shifting of data, shifting of a sync mark and large length scale perturbations. Also described are methods to determine if a watermark appears on a patterned media.

Abstract: Embodiments of the invention provide a countermeasure against spike noise maintaining the data reliability of a magnetic recording layer. In one embodiment, the magnetic domain state right below and around the read head of the soft magnetic layer in the recording medium is locally and temporarily equalized using the write head, whereby, the effect of the spike noise caused by the magnetic domain boundaries (magnetic domain walls) of the soft magnetic layer on the read waveform is prevented. The read retry action of the magnetic hard disk drive is used as the trigger for the timing of the magnetic field application, thereby shortening the time for the magnetic field application.

Abstract: A disc drive including a transducer supported on the head suspension assembly to induce a transducer signal in response to head vibration. The transducer signal is level detected to output a level detected signal indicative of head vibration. A method for detecting head vibration via a transducer on a head suspension assembly. The transducer on the head suspension assembly operating between a detection mode and an actuator mode for selectively detecting vibration and actuating the head.

Abstract: The present disclosure is directed to systems and methods of compensating for thermal decay of a magnetic data storage medium. In a particular embodiment, the method includes reading a calibration track on a magnetic data storage medium to obtain a first measurement of a track characteristic. The method also includes overwriting the calibration track with a first specific data pattern and reading the calibration track to obtain a second measurement of the track characteristic. The method also includes determining whether a thermal decay rate of the calibration track is acceptable based on the first measurement and the second measurement.

Abstract: In one embodiment, a surface analyzer system comprises a radiation targeting assembly to target radiation onto a surface, a reflected radiation collecting assembly that collects radiation reflected from the surface, and a signal processing module. The signal processing module generates an image of magnetic characteristics of the magnetic disk, wherein the image comprises a plurality of servo sector arcs, locates a sample of points on a plurality of the servo sector arcs, fits a circle to the sample of points on each of the plurality of servo sector arcs, and determines at least one pivot-to-gap measurement from the radius of the circles.

Abstract: A method is used for optimizing a parameter of an processing unit. The method is for providing an initial input Fi=0 to be a value of the parameter, and detecting a corresponding initial output O(Fi=0), determining step value ?F, providing a first input F0??F and a second input F0+?F, detecting a first output O(F0??F) and a second output O(F0+?F), determining whether the first output O(F0??F) is greater than the second output O(F0+?F), determining a first seeking direction, providing other inputs Fi, Fi+1, Fi+2, . . . Fi+n?1, and then detecting corresponding other outputs O(Fi), O(Fi+1), O(Fi+2), . . . O(Fi+n?1), wherein n is a natural number, determining a stop point Fi, stopping seeking along the first seeking direction at the stop point, identifying an extremum output, and identifying an input to be the optimized value of the parameter. An information storage apparatus for optimizing a parameter is also disclosed.

Abstract: A video recording apparatus includes a tuner for receiving television broadcast waves, an intermediate frequency circuit for demodulating intermediate frequency (IF) signals outputted from the tuner into video signals, a video recorder for recording the video signals outputted from the intermediate frequency circuit on a recording medium, detecting means for detecting an IF AGC level or a level of noise contained in the video signals so as to detect radio field strength of an analog broadcast waves, and control means for setting of a recording mode defining a level of recording image quality at the video recorder. The control means output a mode setting signal to the video recorder in accordance with the radio field strength detected by the detecting means. The video recorder operates with the level of recording image quality dependent on the mode setting signal outputted from the control means. By such a configuration, recording can be performed in an appropriate mode, i.e.

Abstract: In a perpendicular magnetic recording system, the data that is being written by the write channel is fed back into the read channel. The read channel processes the data and decides if the written sequence is likely to have very poor DC characteristics. If that is the case, the write channel changes a scrambler seed and rewrites the data using the new scrambler seed. The data may also be inspected for patterns that might cause large baseline wander before being written to disk, i.e., in the write channel. A data sequence may be repeatedly scrambled and encoded until an acceptable level of estimated DC-wander has been achieved. The data sequence may then be written to disk.

Abstract: A method and system for determining contact potential voltages between a slider body and a hard disk of a hard disk drive. In embodiments of the present invention, at least one continuous negative direct current (DC) voltage is applied between a slider body and a hard disk of a hard disk drive. Then, at least one continuous positive direct current (DC) voltage is applied between the slider body and the hard disk. A contact potential voltage between the slider body and the hard disk is then determined in response to the applying of the direct current voltages.

Abstract: Embodiments of the invention prevent demagnetization or degaussing of recorded magnetizations, even if a stray field is applied. In one embodiment, an output of a read head including a magneto-resistive effect element is inputted to a stray field detector through a DC amplifier and a DC filter. The stray field detector monitors dc components of the output from the read head, and escapes a head from above a magnetic recording medium.

Abstract: Acceptability of a disk is determined by passing a detection signal from a head through a low-pass filter to obtain a detection signal component corresponding to side runout of the disk due to rotation of the disk and by comparing the maximum level of the signal with a predetermined reference value. Thus, it is possible to extract unacceptable disk which causes erroneous write and/or read or clash due to surface undulation of disk, even when the disk has no protrusion having bad influence upon the disk.

Abstract: A data detection circuit includes a transient detector that senses transient events in data. A first data detector path applies a first equalization target to generate a first bit stream from the data. A second data detector path applies a second equalization target to generate a second bit stream from the data. A baseline correction circuit generates a baseline correction signal using the first bit stream when the transient detector does not sense the transient events and the second bit stream when the transient detector senses the transient events. The first equalization target is a non-DC free equalization target and the second equalization target is a DC-free equalization target. When transients are detected during a sector, the detection circuit continues using the DC-free equalization target until the sector ends.

Abstract: A preamplifier for correcting for thermal asperity transients in disk drives using magneto resistive read heads. The preamplifier has an input gain stage receiving a signal from the read head and an output buffer outputting a reader output to a read channel that is filtered of thermal asperity transients by a high pass filter positioned between the input gain stage and the output buffer. The high pass filter is voltage controlled based on an input control signal from a filter controller. The filter controller uses a low pass filter functioning as a peak detector to detect peaks in either the input or output voltage of the high pass filter. The low pass filter output is applied to a non-linear function generator generating the control signal for the high pass filter based on an increasing function of the absolute value of the low pass filter output.

Abstract: Embodiments in accordance with the present invention provide a perpendicular magnetic recording medium which is easy to record, offers superior thermal stability of recording magnetization, and allows high-density recording. In one embodiment, a perpendicular magnetic layer with controlled magnetic properties is used as a magnetic storage layer of a perpendicular magnetic recording medium, the magnetic properties having been controlled such that an indicator ?hsw [%] of the dispersion of magnetization switching fields in the perpendicular magnetic layer and an indicator Dn [nm] of the intensity of exchange interactions, in film surface directions, in the perpendicular magnetic layer satisfy inequalities ?hsw/27+Dn/90<1, and Dn>20. The indicators can be measured using a magnetometer.

Abstract: Embodiments of the invention enable the flying of a slider to be lowered and increase recording density with a simple configuration in a magnetic disk apparatus. In one embodiment, a magnetic disk apparatus comprises a magnetic disk including tracks for recording data; a magnetic head slider disposed with a magnetic head that flies over the rotating magnetic disk and records data to, or plays back data from, the magnetic disk; and a control device that controls the operation of the apparatus. Slider flying height data that vary inside the tracks are prerecorded in the tracks of the magnetic disk. The control device controls the operation of the magnetic head slider with respect to the magnetic disk on the basis of the slider flying height data recorded in the tracks.

Abstract: A method for determining whether a spike in a read back signal from a read head positioned over a perpendicular recording disk having a magnetically soft underlayer (SUL) is caused by a defect in the SUL or by a thermal asperity (TA). A first read back signal with the spike is obtained in the absence of a local magnetic field near the read head. Then, a permanent magnet or electromagnet is used to induce a small local magnetic field by the read head, and a second signal is obtained. If the signals are substantially similar, a thermal asperity is indicated. Otherwise a defect in the 13 magnetically soft underlayer of the disk is indicated.

Abstract: A recording-medium inspection apparatus checks whether a protrusion provided on a recording medium to be inspected has a height larger than a predetermined height by detecting a contact between the protrusion and a head slider by a sensor while the head slider is flying above the rotating recording medium. The inspection apparatus includes an output-value obtaining means for obtaining an output value from the sensor when the head slider comes into contact with a protrusion having the predetermined height and provided on a reference recording medium, a flying-height adjusting means for adjusting a flying height of the head slider by changing a voltage applied between the head slider and the reference recording medium on the basis of the obtained output value, and a checking means for checking whether the recording medium is good or defective while the head slider is placed at the adjusted flying height.

Abstract: Embodiments of the invention prevent or alleviate head damage ascribable to the TA-causing sections (projections) of disks (TA is thermal asperity). With respect to a TA-causing section that has been detected during initial defect registration, X±A tracks in a radial direction and Y±B sectors (or Y±B bytes of space) in a circumferential direction, with the TA-causing section as a center, are registered collectively during primary registration. Following this, secondary registration is conducted to register a region ranging from±several tens of tracks to several hundreds of tracks present in a radial direction, and all sectors (or all bytes of space) present in a circumferential direction, with a track of the detected TA-causing section as a center. Furthermore, a cylinder of a region equivalent to the same radial positions as those of the secondary registration is registered (as tertiary registration) for all disks, except for the disk where the TA-causing section was detected.

Abstract: A pattern dependent write equalization method is disclosed. The method includes identifying a trait of a data pattern in a stream of write data. A characteristic of a write equalization signal is then defined according to the identified trait for the data pattern.

Abstract: A method for testing electromagnetic characteristics of magnetic media while maintaining consistent performance of a read/write head and recording channel is disclosed. The disclosed method is performed such that reduced statistical sampling is achieved. The method includes recording a first set of baseline measurements utilizing a first magnetic media with the read/write head and recording channel. The first magnetic media is then removed from an assembly containing the read/write head and recording channel and is replaced with a second magnetic media. Measurements are made utilizing the second magnetic media with the read/write head and recording channel, wherein the measurements are comparable with the baseline measurements and wherein consistent performance of the read/write head and the recording channel is maintained so as to reduce the size of statistical samples needed.

Abstract: A nonlinearity measuring method capable of measuring NLTS with a higher precision while taking the state of magnetization inversion of a preceding bit string into consideration. A constitution includes a first measuring section measuring a first predetermined higher harmonic component from a regenerated signal of the reference signal magnetically recorded on a medium, a second measuring section measuring a second predetermined higher harmonic component from regenerated signals with respect to plural kinds of signals to be measured magnetically recorded on the medium, and a calculating section calculating NLTS from the first component and the second component corresponding to each of the signals, wherein each of plural kinds of signals to be measured includes a magnetization inversion pattern string P1 preceding the objective bit to be measured of NLTS; thereby NLTS depending on the string P1 can be quantitatively measured easily.

Abstract: An electrical potential difference between a slider body and a hard disk of a hard disk drive is eliminated based on the flying-height spacing of the slider body between the slider body and the hard disk. A predetermined bias voltage is applied between the slider body and the hard disk that includes a DC component and an AC component and that is based on the detected flying-height spacing of the slider body. The flying-height spacing can be detected based a minimum slider-to-disk clearance change from a design flying height of the slider at a frequency of the AC component as the DC component of the predetermined bias voltage is varied. Alternatively, the flying-height spacing can be detected based on a minimum electrodynamic response of the slider to a first harmonic of the AC frequency of the AC component as the DC component is varied.

Abstract: To calibrate the VGA of a read head, test signals from a DAC are input to the VGA and the output of the VGA is observed, with the gain of the VGA being adjusted as appropriate. So that the DAC need not be made with tight tolerances, a DC signal can be fed into the DAC prior to VGA calibration, and an auxiliary ADC is used to receive the output of the DAC and to determine, for a given DC input, what the signal produced by the DAC actually is. In this way, during subsequent VGA calibration the test signal from the DAC is known not by virtue of the DAC having a tight manufacturing tolerance but by virtue of the actual measurements of its outputs for given register inputs.

Abstract: A system and method for determining head-disk contact (HDC) in a magnetic recording disk drive uses the signal from the magnetoresistive (MR) read head. The analog MR signal is digitized and input to a digital signal processor with circuitry and/or software for integrating the signal amplitude over a low-frequency range. The calculated value from the integration when the slider is out-of-contact with the disk is a reference value. The same integration is then performed during operation of the disk drive and the measured value is compared to the reference value. If the measured value exceeds the reference value by some predetermined amount, this is an indication of the onset of HDC or that HDC has occurred.

Abstract: The thermal decay of data written to a magnetic mass storage medium is determined by measuring and analyzing the time-domain equalized-signal-to-noise ratio (ESNR) and equalized signal-to-total-distortion noise ratio (ESTDR) of written data. In some embodiments, a test track and a reference track are initialized from data. Subsequently, the reference track is re-initialized from the test data, and the time-domain ESNR and/or ESTDR measurements are made of the test track and the reference track, at predetermined time intervals. Later, the time-domain ESNR and ESTDR measurements are analyzed to determine the thermal decay of the data written. In another embodiment of the present invention, the ESNR and/or ESTDR measurements includes reading the data through a non-return-to-zero bus in phases, in which the phases are selected in sequence.

Abstract: A method and apparatus for compensating for head-to-disk contact-induced disturbances in a hard disk drive is disclosed. The method includes determining topographical variations across a surface of a disk during the manufacturing or operation of the hard disk drive. Error signal variations that occur as a result of head-to-disk contact-induced disturbances resulting from the topographical variations are recorded. Current to a voice coil motor in the hard disk drive is varied to correct for the contact-induced disturbances before they occur.

Abstract: The present invention is a method or apparatus configured for analyzing a data storage device containing a transducer head positionable adjacent a data storage media surface. First, a defect is detected in a region of the surface. Two or more readback signals are obtained, each received during a respective pass of the transducer head adjacent the defective region. The signals are then combined to define a category for the defective region, either automatically or by visual examination of an image. Preferably, all of the read signals are received from the transducer head while the data storage device remains sealed in a substantially opaque chamber. That way, the media defects of an entire population of data storage devices can be analyzed quickly, disassembling the drives for direct visual analysis only on a selective basis.

Abstract: A disk drive includes a disk for storing information, a head with a transducer that writes data to and reads data from the disk, and an AC power source. The head is suspended adjacent to the disk and a flying height gap exists at the head/disk interface. The AC power source generates an AC exciter signal across the flying height gap that discharges electrostatic charge at the head/disk interface. The head/disk capacitance can be measured based on the AC exciter signal to sense the flying height. The AC exciter signal can also alter an attraction force between the head and the disk and thus control flying height. The AC exciter signal can also be based on a flying height signal representative of the head/disk capacitance and thus the flying height.

Abstract: A system and method for processing track identifier errors to mitigate head instability in data storage devices is disclosed. The system and method includes computing a track id differential between an expected track id and a received track id, encoding the expected track id and the received track id, initiating a first action if the track id differential exceeds a pre-determined threshold and the encoded expected track id varies from the encoded received track id by a pre-configured number of bits, and initiating a second action if the track id differential does not exceed the pre-determined threshold or the encoded expected track id does not vary from the encoded received track id by a pre-configured number of bits.

Abstract: A recording apparatus of a tape-shaped magnetic recording medium includes a transfer unit, a recording head, a signal-processing unit and a control unit. The transfer unit transfers a tape-shaped magnetic recording medium having an anisotropic property oblique with respect to the thickness direction in a forward or reversed direction. The recording head is positioned in such a way that a recording track is formed on the traveling tape-shaped magnetic recording medium, which is transferred by the transfer unit, in a direction parallel to the transfer direction of the tape-shaped magnetic recording medium. Connected to the recording head, the signal-processing unit receives a signal to be recorded onto the tape-shaped magnetic recording medium. The signal-processing unit then carries out signal processing required for an operation to write the signal to be recorded onto the tape-shaped magnetic recording medium.

Abstract: An apparatus for providing data dependent detection in a data read channel is disclosed. Parameters in a read channel are dynamically adjusted according to data dependent noise. For example, a comparison in an add-compare-select (ACS) unit of a Viterbi decoder may be adjusted or offset terms in error event filters may be biased to choose a Viterbi sequence with more transitions or to compensate for polarity dependent noise.

Abstract: Disclosed are techniques related to cluster-based defect detection testing for disk drives. A disk drive comprises a disk, a moveable head to scan the tracks of the disk, and a defect detection circuit to detect defects on the disk scanned by the moveable head. The disk drive includes a microprocessor for controlling operations in the disk drive including cluster-based defect detection. The microprocessor under the control of a cluster detection program defines a scan window. The scan window corresponds to an area of the disk scanned by the moveable head. The microprocessor under the control of the cluster detection program further defines a cluster threshold corresponding to a minimum number of defects required to occur within the scan window and identifies a defect cluster if a cluster threshold of defects occurs within the scan window. By identifying defect clusters on the disk these defect clusters can be margined.

Abstract: A drive and method of identifying write velocity during reading are provided. When a track is being read, the data signal is processed prior to determining the data stream to identify the velocity with which the track data were written. The read channel is adjusted based on the identified velocity to compensate for write channel transfer function variation.

Abstract: Method and apparatus for characterizing the flight characteristics of a read/write head. A disc is accelerated to a selected rotational velocity sufficient to aerodynamically support the head. The head is positioned over a portion of the disc non-accessible to customer data and a magnetoresistive element of the read/write is biased using a suitable voltage or current. A media noise landing signature obtained as the element transduces white noise from the surface identifies the head as a low-flying head.

Abstract: Embodiments of the present invention relate to systems, methods, and computer readable media for calibrating storage devices such as hard drives. A testing system is connected to a group of storage devices that are being prepared for release and eventual sale. Alternately, a storage device may be connected to an end-user system for which it is in use. The storage devices are tested for head instability. A lower frequency test pattern is performed, which induces a stronger magnetic field. A measurement of servo gain control is taken while reading from a disk and compared to a baseline for servo gain control. If the variance is larger than a predetermined amount, then the read/write head is determined to be unstable.

Abstract: A method for determining a type of a head in a hard disc drive, the head being a normal head, a weak head, or an ATE (Adjacent Track Erasure) head, and a method for adjusting a write parameter using the head type determining method. The head type determining method includes writing data via the head under multiple tracks per inch (TPI) conditions, in which TPIs are equal to a reference TPI, and wider and narrower than the reference TPI by a respective first and second predetermined ratios, and reproducing the written data, to detect a bit error rate under each TPI condition, and comparing the bit error rate under each condition to the bit error rate of the reference TPI, to determine a type of a head.

Abstract: A method optimizing a recording current in consideration of operating temperatures of a hard disk drive and a method of setting a recording density in consideration of tracks per inch (TPI) or adjacent track erasure (ATE) characteristics. The method of optimizing the recording current measures a rate of errors under a test condition corresponding to the operating temperature of a hard disk drive, while changing a recording parameter, selects a recording parameter value corresponding to a smallest rate of errors, and optimizes the recording current for the hard disk drive under operating environmental conditions using the selected recording parameter value.

Abstract: Disk drive preconditioning allows the head-disk interface to be burnished or worn so that head-disk interference is reduced or eliminated before servo track writing. The head is positioned closer to the disk than the normal fly height during a preconditioning sweep and then returns to the normal fly height during servo track writing.

Abstract: An embodiment of the present invention includes receiving a disk having a servo pattern and automatically identifying the center of the servo pattern. The present invention also automatically identifies the center of the physical disk and then automatically identifying the variance between the servo center and physical disk center.

Abstract: A disk drive and method for estimating a sinusoidal error in a wedge time period is disclosed. An estimated WTP is calculated according to: EST_WTP=RTP+â*cos(2?k/N)+{circumflex over (b)}*sin(2?k/N) wherein RTP is a reference time period corresponding to a nominal WTP, k is an index representing a servo wedge, and {â,{circumflex over (b)}} are adjustable coefficients. A wedge time error e(k) is estimated as the difference between the estimated WTP and a detected actual WTP. The coefficients {â,{circumflex over (b)}} for generating the estimated WTP are adjusted according to: â(k+1)=â(k)?G*e(k)*cos(2?k/N) {circumflex over (b)}(k+1)={circumflex over (b)}(k)?G*e(k)*sin(2?k/N) wherein G is a predetermined gain.

Abstract: A disc drive data storage system is disclosed that includes a disc storage medium having a disc surface. The system also includes an armature and a slider coupled to the armature. The slider supports a transducer head that communicates with the disc storage medium. The slider flies above the disc surface and positions the transducer head proximate the disc surface. Data representing a topography map of the disc surface is stored in a memory. A controller controls the fly height of the slider above the disc surface as a function of the topography map of the disc surface.

Abstract: A method is presented for glide testing a disk which tests the glide head fly-height by inducing a collision between the glide head and a disk under test. The glide test system is initially calibrated using calibration disks. The method of the invention periodically tests the calibration without interrupting the production testing by lowering the rotation rate until the glide head collides with the rotating disk surface. The rotation rate at which the collision occurs is then compared with the value expected based on knowledge of disk samples and the initial calibration. Parameters for acceptable high and low values are established to detect changes in the glide test system performance to trigger automatic or manual recalibration.

Abstract: A method for determining whether a data storage device read/write head is a low-flying read/write head or a non low-flying read/write head. A disc attached to a spindle motor is accelerated to an operating rotational velocity, the head is positioned over a portion of the disc non-accessible to customer data and a data pattern of selected frequency is written. A magnetoresistive element of the is biased and the data pattern is read while the disc is decelerated to a predetermined rotational velocity threshold. Occurrence of a read signal landing signature comprising readback signal amplitude modulation prior to reaching the predetermined rotational velocity threshold identifies the head as a low-flying head. Contrawise, non-occurrence of the read signal landing signature prior to reaching the predetermined rotational velocity threshold signifies the head as a non low-flying head.

Abstract: An apparatus for providing head amplitude characterization is disclosed. A DAC is used to apply known signals to a variable gain amplifier in the front end of a read channel. The signal is processed through the read channel and at the output of an ADC, the signal is read and used to determine the input channel amplitude. Knowing the amplitude of the two input signals, the ADC code spread and the two VGA gain codes, an equation is generated for determining the amplitude of a head.

Abstract: An apparatus for providing head amplitude characterization using gain loops is disclosed. A variable gain amplifier (VGA) receiving input signals and generates a VGA output signal. A digital-to-analog converter (DAC) circuit provides a desired input signal to the VGA and a gain control loop drives the VGA to gain lock the VGA to the provided desired input signal. An analog-to-digital converter (ADC) provides a digital output representing an ADC code spread in response to the VGA output. A controller drives the DAC to provide the desired input signal to the VGA and generates control signals for controlling the ADC, the controller further determines read head channel amplitude based upon the signal provided to the DAC, the ADC code spread received from the ADC and gain code provided by the gain control loops.

Abstract: A slider having leading and trailing edges is configured to fly on an airbearing above a data storage disk rotating from the leading edge to the trailing edge. Read and write heads are mounted on the slider proximate the trailing edge. An auxiliary thermal sensor is mounted on the slider, but preferably nearer the leading edge. Forward placement of the sensor allows it to sense mechanical defects before they reach the heads, thereby permitting a write inhibit operation, for example. The sensor may also be used to detect airbearing modulation. Appropriate action may be taken when unacceptable airbearing modulation is detected, such as notifying the user and/or scrubbing the slider. The sensor is preferably wider than the heads. This allows, for example, an in-situ glide test to be performed faster using the sensor. An arm electronics module is preferably configured to permit concurrent operation of the sensor and heads.

Abstract: A correction mechanism for use in a data storage system that allows data to be read even if the recorded data has been phase shifted.

Abstract: A recording/reproducing apparatus capable of switching over among a plurality of heads with high precision, wherein the apparatus is provided with: a recording/reproducing unit for recording/reproducing signals onto/from a recording medium with a plurality of heads; a generating unit for generating control data for controlling the recording/reproducing unit; and a transmitting unit for transmitting control data generated by the generating unit to the recording/reproducing unit, wherein priority is given in transmission to data for controlling the switching of the plurality of heads over other data.