Abstract: A method according to one embodiment includes selecting an initial radius value (Rfull) for an outgoing reel, where Rfull is the initial radius of a tape on the outgoing reel; unwinding the tape from the outgoing reel; computing a radius value of the tape on the outgoing reel during the unwinding; adjusting the computed radius with an offset calculated from a direct measurement of velocity from the tape position; and outputting the adjusted computed radius. A method according to another embodiment includes selecting an initial radius value (R0) for an incoming reel, where R0 is the initial radius of the incoming reel; winding the tape onto the incoming reel; computing a radius value of the tape on the incoming reel during the winding; adjusting the computed radius with an offset calculated from a direct measurement of velocity from the tape position; and outputting the adjusted computed radius.

Abstract: A servo track has identical servo pattern frames including two pairs of parallel magnetic transitions, the transitions of each pair spaced apart an equal distance, the transitions of the first pair at an azimuth angle to the longitudinal axis of the tape, the transitions of the second pair at an opposite azimuth angle. A servo channel receives signals at first times corresponding to when a servo read head detects the first and second transitions of the first pair of parallel transitions of a servo pattern frame, and second times corresponding to when the servo read head detects the first and second transitions of the second pair of parallel transitions. The servo channel determines a relative lateral movement and velocity between the tape and the tape head based on the azimuth angle and the ratio of the difference of the first and the difference of the second times.

Abstract: A tape drive configured to accurately position a head actuator in the presence of physical disturbances is disclosed. The tape drive includes a track-follow controller to position a head actuator over data tracks on magnetic tape. The tape drive further includes a disturbance observer configured to estimate a vibration disturbance and output a compensation signal to assist the track-follow controller to accurately position the head actuator over the data tracks in the presence of vibration. When estimating the vibration disturbance, the disturbance observer takes into account vibration frequency characteristics, such as frequency characteristics derived from a vibration specification associated with the tape drive, or frequency characteristics derived from known vibration disturbances experienced by the tape drive. A corresponding method is also disclosed.

Abstract: A tape drive head includes a set of one or more servo readers designed for reading a servo pattern of a linear recording tape for positioning of the tape drive head, each of the servo readers of the set having: a sensor for sensing a magnetic field component of a servo pattern upon reading it; a first shield and a second shield, one on each side of the sensor, the shields configured to shield spurious components of magnetic fields occurring upon reading the linear recording tape, wherein: a gap between the first shield and the second shield is between 0.4 ?m and 1 ?m, and a minimal width of the sensor, the first shield and the second shield, in a direction perpendicular to the gap, is between 0.5 ?m and 4 ?m.

Abstract: Magnetic storage tape and techniques for erasing and writing to magnetic storage tape having a perpendicular squareness greater than 50 percent and a longitudinal squareness less than 50 percent are described. In general, the magnetic tape may be biased with a remanence magnetization, or magnetic orientation, in any direction. One or two head systems may use various magnetic field patterns to create the desired remanence magnetization. Servo marks may have a remanence magnetization in an opposite magnetic orientation than that of the remaining bias on the servo track, e.g., substantially perpendicular to the magnetic tape. In some examples, a write head may alternate the direction of the magnetic field to continuously bias and write servo patterns to the magnetic tape. In addition, a symmetrical servo mark may be created in the magnetic tape with a write head having a gap width approximately equal to the length of the servo mark.

Abstract: A tape drive system according to one embodiment includes a magnetic head having at least one servo sensor; a tape motion controller; a fine actuator; a skew actuator; a coarse actuator; and a control. The control is configured to perform various operations that help account for vibrations that effect track-following a servo track when operating a tape drive. Additional systems, methods and computer program products are also described.

Abstract: A servo system according to one embodiment includes at least one servo sensor for sensing a lateral position of a magnetic head with respect to at least one defined servo track of a longitudinal tape; a fine actuator configured to translate the magnetic head laterally with respect to the longitudinal tape; a coarse actuator configured to translate the fine actuator laterally with respect to the longitudinal tape; and a servo control. The servo control is configured to perform various operations that may be used to estimate a midpoint of lateral tape excursion of a flangeless tape path for calibrating a tape drive. Additional systems are also presented.

Abstract: According to one embodiment, a method includes sensing a first servo sensor while a longitudinal tape is moved in a first direction; determining position error between the magnetic head and a desired position related to the at least one defined servo track; providing signals to operate a fine actuator to translate the magnetic head laterally in a manner to reduce the determined position error; calculating a first average position of the magnetic head for at least one first run-out cycle while the longitudinal tape is moved in the first direction; calculating a first offset of the magnetic head while the longitudinal tape is moved in the first direction; operating a coarse actuator to position the coarse actuator substantially at a target position using the first offset and the first average position.

Abstract: An output is generated in response to an indication associated with movement of a moveable part in a storage device. The output is for reducing a noise component associated with the movement of the moveable part.

Abstract: A method, system, apparatus, and computer readable medium storing instructions for recording data tracks and a method and system for reading data tracks. For recording data tracks, virtual boundary of a first data track recorded on the storage medium is determined. The recording element is positioned based on the determined virtual boundary of the first track and a second data track is recorded by the positioned recording element. For reading data tracks, a first virtual boundary of a first data track and a second virtual boundary of the first data track are determined and a reading element is positioned at a center of the first data track based on the determined virtual boundaries. In the system of reading recorded data tracks, a number of forward reading elements and backward reading elements are provided. The forward reading elements have different pitches.

Abstract: A method of aligning read elements and write elements with a storage media in a data storage device includes determining a position of a data track associated with the storage media, shifting one of a first and second head module relative to the storage media. The first head module includes at least one of a read element and a write element and the second head module includes at least one of a read element and a write element operatively associated with the at least one of the read element and write element of the first head module. The first head module is selectively shiftable relative to the second head module. The method further includes aligning one of the at least one read element and write element of the one of the first and second head module that is shifted with the data track on the storage media.

Abstract: In one general embodiment, a system includes a module having multiple transducers; and a sizing mechanism for actively applying a force to at least one lateral side of the module for selectively compressing the module, thereby adjusting a pitch between the transducers, wherein the lateral side of the module intersects an axis of the module oriented parallel to the direction of the force. Additional systems and methods are also presented.

Abstract: A digital control system, and in particular a tape drive system having a track-following servomechanism with a predictor (also referred to herein as a predictor filter), is described. In certain embodiments, the servomechanism includes an actuator, a servo channel, and a predictor coupled to the servo channel. The predictor receives from the servo channel a lateral position estimate signal and determines a modified lateral position estimate signal that reduces a difference, introduced by a tape velocity-dependent delay, e.g., introduced by the servo channel, between the modified lateral position estimate signal and an actual lateral position. The modified lateral position estimate may be used to modify a control signal sent to the actuator.

Abstract: A servo signal in which a magnetic pattern composed of a first portion magnetized in one direction that is one of two opposite thickness directions and a second portion magnetized in a direction opposite to the one direction is repeatedly arranged in a longitudinal direction of the tape at predetermined intervals is read out and a waveform of the servo signal is acquired from the readout servo signal. In the acquired waveform of the servo signal, a unit waveform having a pair of peaks of opposite polarities corresponding to the magnetic pattern appears periodically. A crest or trough portion of the waveform containing one of the peaks located rearwardly in the tape transport direction in a time of writing the servo signal is selected from the unit waveform contained in the acquired waveform of the servo signal. Tracking control or servo signal verification is performed based on the selected portion.

Abstract: A transducer head apparatus (140) is disclosed for concurrently transferring data relative to a plurality of tracks on a data carrier. The head apparatus comprises a body (310) extending longitudinally, the body supporting a plurality of longitudinally spaced transducer elements (240, 241, 242, 250, 251, 252, 260, 261, 255, 256, 257, 265, 266, 267), and adjuster apparatus (330) operable to adjust the relative longitudinal dispositions of at least some of the transducer elements.

Abstract: A reader apparatus is disclosed to read data magnetically stored on a storage medium. The apparatus has a sense structure to change resistance in response to a proximity of a stored magnetic field, and a variable magnetic field biasing arrangement to vary an active response length of the sense structure.

Abstract: A magnetic data storage system according to one embodiment includes a magnetic head; and guides on opposite sides of the magnetic head for directing a magnetic medium over the magnetic head. The magnetic head includes: outer portions each having a tape bearing surface and an array of transducers selected from a group consisting of readers and writers; and a central portion positioned between the outer portions, the central portion having a tape bearing surface and an array of transducers selected from a group consisting of readers and writers. An inner edge of each of the tape bearing surfaces of the outer portions is adapted for skiving air from the magnetic medium when the magnetic medium travels in a direction from the central portion towards the respective outer portion.

Abstract: A magnetic tape driving apparatus, which does not cause damage to either a magnetic head or a magnetic tape when making transition of the magnetic tape from a stopped state to a running state, when making transition of the magnetic tape from a running state to a stopped state, or when reversing the transportation direction of the magnetic tape, is provided. In a state where any one of a magnetic head and a magnetic tape moves and the other rests (i.e., a state where static friction may occur), such as at the time of starting transportation of the magnetic tape, at the time of stopping the tape in a running state, and at the time of reversing the transportation direction of the magnetic tape, a head displacing portion vibrates the magnetic head under the control by a displacement control portion, and thus no static friction occurs between the magnetic head and the magnetic tape.

Abstract: In one embodiment, a linear magnetic recording tape includes at least one servo band having a servo pattern readable by a servo reader of a magnetic head for positioning thereof, wherein the servo pattern is adapted to substantially fill a width b of the servo band, the servo band width h is less than or equal to about 1.2 B/N, N is an integer greater than or equal to 2, and b corresponds to a distance between data read/write transducers of the magnetic head in a direction transverse to a longitudinal length of the tape. In another embodiment, a method includes providing the linear magnetic recording tape, formatting the tape, and positioning the magnetic head within a first lateral tape region. Other linear magnetic tapes, systems, and methods are described according to other embodiments.

Abstract: Where a tape is subject to lateral shift excursions from one side of a head to another, a coarse actuator is positioned laterally to enable a fine actuator to follow lateral motion of a longitudinal tape having at least one longitudinal defined servo track. A position error signal loop is configured to sense servo sensor(s) and to determine position error between the head and a desired position related to the defined servo track(s). A servo control senses the lateral shift excursion of the defined servo track(s); determines a maximum positive peak and a maximum negative peak of the lateral shift excursion; and positions the coarse actuator substantially at a midpoint of the maximum positive peak and the maximum negative peak of lateral shift excursion of the defined servo track(s). Thus, the fine actuator follows the lateral shift excursion, while the coarse actuator remains at the midpoint.

Abstract: The method employs a servo system for positioning a head laterally to follow lateral motion of a longitudinal tape having longitudinal defined servo track(s), the servo system comprising a servo element configured to sense lateral position of the head with respect to an acquired servo track, a fine actuator configured to translate the head laterally with respect to the longitudinal tape, and a position error signal loop to operate the fine actuator to translate the head laterally to reduce position error. If the servo element is positioned away from the defined servo track(s), a continuous position error offset signal is applied to the fine actuator in a direction towards the defined servo track(s), whereby the fine actuator translates the head in accordance with the continuous position error offset signal; and, in response to the servo system acquiring the defined servo track(s), the continuous position error offset signal is discontinued.

Abstract: Embodiments of the present invention are directed to the design and implementation of backward-compatible magnetic tape drives (102) that are read/write compatible with a current magnetic-tape format (1820) as well as one or more previous magnetic-tape formats (1802 and 1804). Embodiments of the present invention include read/write tape-head configurations (1902, 1904, 1906, 1908-1923, 1930, 1932, 1934, 2102) and corresponding magnetic-tape-drive-component features (518) that allow a magnetic-tape drive to read and write magnetic tapes formatted according to different formats.

Abstract: A servo detection system for detecting servo tracks of a longitudinal tape. In a read/write head, two servo read heads are spaced laterally on a first head module, and a servo read head is on a second head module spaced longitudinally from the first module. A method comprises initially sensing a tape servo track with one servo read head of the first module and the servo read head of the second module to determine skew misalignment of the servo track. A zero reference value is stored representing the determined skew misalignment. The detection system switches from the one servo read head of each module, to the two servo read heads of the first module, and employs the stored value to position the read/write head in the zero skew position. The two servo read heads are then employed to read two servo tracks to identify the data band and to control skew.

Abstract: To locate an access head element of a head assembly for a tape storage device, a storage tape having a data track that contains servo information is provided. The data track further contains data. The servo information that is in the data track is used to determine a position of the access head element.

Abstract: A tape recording device, method, and computer program product are provided for performing operations of position movement, reading, and writing on a tape medium, and receiving a series of commands from an upper-layer device. The tape recording device includes a buffer for temporarily storing data related to the reading and an additional writing, a tape for recording the data stored in the buffer, a reading and writing head for reading data from the tape into the buffer and writing the data onto the tape, control means for reading data from a designated position of the tape and storing the data in the buffer, and for writing the data stored in the buffer onto the tape from a written data end position in response to an additional writing command, and a non-volatile memory for storing data stored in the buffer in response to an additional writing command.

Abstract: A recording system controller according to one embodiment includes a controller capable of selecting a level of a current or voltage applied to a first writer during the creation of a magnetic transition based on a current in at least one nearby writer. A recording system controller according to another embodiment includes a controller capable of selecting a timing of a current change applied to a first writer based on a current in at least one nearby writer for compensating for an effect of crosstalk from the at least one nearby writer. A method according to yet another embodiment includes selecting a level of a current or voltage applied to a first writer or selecting a timing of a current change applied to the first writer based on a current in at least one nearby writer for compensating for an effect of crosstalk from the at least one nearby writer.

Abstract: A storage medium on which servo patterns are encoded to provide lateral and longitudinal position (LPOS) information is provided. Each of the servo patterns includes a servo frame, including first through fourth bursts, which are each independently modulated with multi-level pulse position modulation (PPM) to encode at least one independent bit per burst.

Abstract: A guide for guiding a magnetic data storage tape has a curved support portion for supporting a major tape surface and at least one flange adjoining the support portion. At least in a region of transition between the support portion and the at least one flange, the guide has an under coating of a diamond like carbon material, tungsten carbide, or similarly wear resistant material, and a surface coating having lower surface tension than the under coating. A tape guide apparatus and a method of making a tape guide are also disclosed.

Abstract: A method, system and computer-usable medium are disclosed for performing data write and data read operations on a tape storage medium. A dual head/tape actuator assembly, comprising two head/tape actuator assemblies, is implemented to perform data write and data read operations on a tape medium. Each of the head/tape actuator assemblies comprises a set of data writer elements and a set of data reader elements. During data write operations, the data writer elements on one head/tape actuator assembly are used to write data to a tape medium and the data reader elements on the other head/tape actuator assembly are used to read the data from the tape medium. During read operations, half of the data readers on one head/tape actuator assembly are used to read data from half of the written data tracks on the tape medium and half of the data readers on the other head/tape actuator assembly are used to read the other half of the written tracks.

Abstract: A digital control system, and in particular a tape drive system having a track-following servomechanism with a predictor (also referred to herein as a predictor filter), is described. In certain embodiments, the servomechanism includes an actuator, a servo channel, and a predictor coupled to the servo channel. The predictor receives from the servo channel a lateral position estimate signal and determines a modified lateral position estimate signal that reduces a difference, introduced by a tape velocity-dependent delay, e.g., introduced by the servo channel, between the modified lateral position estimate signal and an actual lateral position. The modified lateral position estimate may be used to modify a control signal sent to the actuator.

Abstract: A weighted combining scheme exploits information from two servo channels operating in parallel. A timing-based servo module comprises two synchronous servo channels coupled respectively to receive two digital servo signals read from a data tape. Both channels have outputs for an unweighted parameter estimate and for a measure of the channel reliability. A weight computation module provides first and second weight signals using the measures of channel reliability from the servo channels. An offset computation module provides first and second offset terms which are summed with the unweighted parameter estimates. Multiplying nodes receive the unweighted parameter estimates and the weight signals and outputs offset weighted parameter estimates. A summing node receives the offset weighted parameter estimates and outputs a combined offset weighted parameter estimate to a servomechanism.

Abstract: The present disclosure relates to apparatus and methods for recording heads with tape guides, including embedded tape guides. In one embodiment a magnetic recording head includes a contour modified to include a tape guide. The tape guide may include compliant or non-compliant edge guides. In another embodiment, a magnetic recording head includes a contour configured to impart a lateral force on the surface of tape streaming over the head. The head may include air-bleed slots, air skiving edges, non-symmetrical head surfaces, specific contour topographies, negative pressure elements, or any combination thereof. The streaming tape may be held referenced against the a tape guide by the lateral force. In a further embodiment, the present disclosure relates to magnetic tape wherein the written-in lateral tape motion is substantially eliminated.

Abstract: Embodiments include methods, apparatus, and systems for servo write head gap width correction. One method includes measuring a pulse mismatch for servo stripes on magnetic tape written with a servo write head having servo head gaps with different physical sizes, and separately energizing the servo head gaps to correct the pulse mismatch so servo stripes written on the magnetic tape are within a predefined tolerance.

Abstract: A control apparatus connectable to a memory unit for storing data, for controlling a first tape writing unit including a plurality of first tapes and a second tape writing unit including a plurality of second tapes so that the first and second writing units write same data stored in the memory unit to one of the first tapes and one of the second tapes, respectively, has an obtaining unit for obtaining a progress value indicating a progress of writing data into the one of the second tapes upon completely writing the data into one of the first tapes and a controller for controlling the first and the second tape writing units so that the first and the second writing unit change the writing tapes to another of the first tapes and another of second tapes when the progress value being not more than a predetermined value.

Abstract: A method is presented to rotate a read/write head rotatable along a first axis and comprising a first assembly having a first servo element and a second servo element. The method moves a sequential information storage medium adjacent to the read/write head along a second axis, wherein the second axis is substantially orthogonal to the first axis, and determines the rotation angle for the read/write head with respect to the sequential information storage medium using the first servo element and the second servo element. The method then positions the read/write head with respect to the second axis based upon the rotation angle.

Abstract: A method to adjust the positions of a write element and read element disposed on a read/write head comprising a first assembly independently moveable along a first axis and comprising a first servo element, a second servo element, and the write element disposed between the first servo element and the second servo element and a second assembly independently moveable along the first axis and comprising a third servo element, a fourth servo element, and the read element disposed between the third servo element and the fourth servo element. The method moves a sequential information storage medium adjacent to the read/write head along a second axis, wherein the second axis is substantially orthogonal to the first axis, and determines a dynamic skew for the sequential information storage medium with respect to the read/write head using the first servo element and the second servo element. The method then positions the first assembly with respect to the second assembly to correct for that dynamic skew angle.

Abstract: A servo writing method is provided for use with unoriented magnetic tape media. A biasing zone is formed, such as between a pair of permanent block or disk magnets, with a strong DC magnetic field that is substantially free of perpendicular components. The method includes feeding the tape through the magnetic biasing zone to form a longitudinal magnetic bias in the magnetic layer of the tape media. The method includes using a write head to write a servo pattern on the tape media after the forming of the longitudinal magnetic bias in the tape media, and the servo pattern produces an output that is substantially symmetric with high amplitudes. In one embodiment, the biasing zone is formed or defined as the gap between first and second magnetic assemblies oriented with a single direction of magnetization, such as in the same direction as the tape travel through the biasing zone.

Abstract: A data storage device includes a first head module independently moveably mounted relative to the storage device. The first head module includes at least one of a read element and a write element. In addition, the data storage device includes a second head module independently moveably mounted relative to the storage device. The second head module includes at least one of a read element and a write element operatively associated with the at least one of a read element and write element of the first head module. The second head module is selectively shiftable relative to the first head module in order to align the at least one of the read element and the write element of the first head module and the at least one of the read element and the write element of the second head module to one another.

Abstract: A device for guiding a magnetic tape in a data storage drive including a cylindrical body rotatable about a longitudinal axis. The cylindrical body having opposing ends and defining a surface area for mating with a magnetic tape. A curved section at opposite ends of the cylindrical body is contiguous with the surface area of the cylindrical body. A plurality of vents in the cylindrical body allow air flow therethrough between the surface area and the tape. The amount of air flow between the cylindrical body and the tape produces varying frictional forces on the tape such that the tape is biased to a nominal position on the cylindrical body by air pressure on the tape resulting from the air flow interaction with the curved sections.

Abstract: A sequential data storage medium, such as for example and without limitation a magnetic tape, comprising a plurality of servo patterns encoded in a non-data region, wherein each of said servo patterns comprises a first subframe comprising 10 pulses, a second subframe comprising 8 pulses, and a third subframe comprising (N) pulses, wherein (N) is greater than or equal to 0. The first subframe and the second subframe do not encode any linear position (“LPOS”) data. The third subframe encodes up to (N) LPOS bits.

Abstract: A sequential information storage medium, comprising a plurality of servo patterns encoded lengthwise thereon, wherein each servo pattern encodes at least one LPOS bit and comprises a width less than 187 microns.

Abstract: The present disclosure relates to the minimization of servo format transition bit length of magnetic recording media. More particularly, the present disclosure relates to bi-polar and trailing edge recording when formatting the servo track of magnetic recording media. In one embodiment, magnetic media having a timing-based pattern is written using a bi-polar energized recording head. In some embodiments, the magnetic media may be AC or DC erased. The recording head may include a plurality of independent recording channels, each of which may be magnetically energized individually. The bi-polar energized state of the recording head may be controlled to vary the bit length and bit sequence within the timing-based pattern. In further embodiments, the magnetic media may include both uni-polar and bi-polar transitions.

Abstract: A magnetic head according to one embodiment includes a substrate having a tape bearing surface; a plurality of elements coupled to the substrate and positioned towards the first tape bearing surface, the elements being selected from a group consisting of readers, writers, and combinations thereof; and an outrigger held in a fixed position relative to the substrate, the outrigger having a tape bearing surface; wherein the outrigger tape bearing surface and the substrate tape bearing surface lie along planes, the planes being offset from one another.

Abstract: A system and method for determining the value of a longitudinal position (“LPOS”) bit of a storage medium. A system comprises a selector that selects a value for a longitudinal position (“LPOS”) bit from a plurality of possible values derived from LPOS information read from a storage medium. A quality determiner that determines a quality value for each of a plurality of LPOS values derived from the LPOS information. The selection of the value for the LPOS bit is based, at least in part, on the quality values.

Abstract: A device and method are disclosed for processing data recorded on a tape medium. The device comprises a first control part controls a read head to read specific data recorded in a first area among data recorded in a first format on the tape medium. The device further comprises a second control part that controls a write head to write the specific data in a second area different from the first area of the tape medium and to write the specific data in a second format in a third area different from the second area of the tape medium. Moreover, the device may comprise a recording part for recording specific information that specifies a read position of other data among data recorded in the first format on the tape medium.

Abstract: An apparatus and method for reading out data recoded on a tape with a read head is provided. A command processing unit receives a request for reading out old data behind EOD of new data. A channel input/output unit receives, data read out with a read head and a buffer managing unit receives this data. A header information determining unit determines whether this data includes header information of the old data. If it is determined that this data includes the header information of the old data, a data set determining unit determines whether a data set is extractable from this data. If it is determined that data set is not extractable, a move signal output unit outputs a signal for moving the read head in a direction of the new data.

Abstract: The invention relates to a method for moving to a predetermined position of a carrier tape 2 moving continuously in a displacement direction, wherein a displacement head 4 is moved to the predetermined position, wherein the displacement head 4 is moved to the predetermined position in the displacement direction at a speed which corresponds essentially to the displacement speed of the carrier tape 2; wherein a procedure is carried out at the predetermined position on the moving carrier tape 2 by means of the displacement head 4.

Abstract: Servo control methods and apparatus for a tape drive. A read/write head reads and writes data on magnetic tape with at least one servo track providing transverse position information. At least two servo readers arranged for reading a servo track associated with the read/write head operate concurrently to generate servo read signals. A position estimator processes each servo read signal to generate a series of position values corresponding to respective time instants indicative of their transverse positions. A servo controller calculates a skew value indicative of tape skew relative to the read/write head and a tension variation value indicative of variation of tape tension. The servo controller is adapted to account for cross-coupling between tape skew and tension variation.

Abstract: The information recording apparatus of the present invention includes N servo heads. Servo signals outputted respectively from the servo heads are delayed by a delay circuit such that the peaks of the waveforms of the servo signals coincide with each other. The delayed servo signals are added up by an adder. Thus, the output level of the servo signal can be increased by N times and the S/N ratio of the servo signal can be also increased by ?N times. As a result, the precision of PES improves and the amount of off-track can be reduced. Therefore, even if a magnetic layer in magnetic tape has a small thickness, it is possible to prevent the decline of the output level of the servo signal and the S/N ratio.

Abstract: In a controller of a tape drive, when a command processing unit receives a Write FM0 command, a channel input/output unit writes the data in the buffer and a speculative FM onto the tape, and a CM input/output unit records speculative FM presence information in a cartridge memory. When the command processing unit receives Write FM1 command next, the CM input/output unit erases the speculative FM presence information from the cartridge memory. When the command processing unit receives a command other than Write FM1 command next, the channel input/output unit overwrites a speculative FM.