Abstract: An audio frame loss recovery method and apparatus are disclosed. In one implementation, data from some but not all audio frames is included in a redundant frame. The audio frames whose data is not included in the redundant frame may include multiple audio frames but may not include more than two consecutive audio frames. Because not all audio frames are used in the redundant frame, the amount of information needed to be transmitted in the redundant frame is reduced. A lost audio frame during transmission may be recovered from either the redundant frame when the redundant frame incudes data of the lost frame, or from at least one neighboring frame of the lost frame derived from either the redundant frame or the successfully transmitted audio frames when the redundant frame does not include data of the lost frame.

Abstract: A system and method for adapting an audios stream for reducing latency. The method may include the steps of, and the system may function to, receive an audio stream having a packet buffer and an audio buffer, measure the audio buffer depth of the audio buffer, measure the presentation time margin of at the input to the packet buffer, and determine an adaptation level for latency based on the measured values.

Abstract: A method for manufacturing a magnetic recording medium includes the steps of (a) forming a perpendicular magnetic recording layer and (b) applying an ion beam to regions between tracks of the perpendicular magnetic recording layer so as to form separation regions for magnetically separating the tracks from each other. In the step (a), a continuous film layer composed of a multilayer film is formed, and CoB layers and Pd layers are laminated in the multilayer film. In the step (b), the CoB layers and the Pd layers are melted by the ion beam so as to form an alloy of metals contained in the CoB layers and the Pd layers to thereby form the separation regions.

Abstract: A data storage and retrieval system includes a head carriage unit having a working surface and multiple heads disposed at the working surface. The head carriage unit is adapted for rotational motion about an axis oriented substantially normal to the working surface. The system also includes a tape drive unit for moving a tape media past the working surface of the head carriage unit, the tape media having a width approximately equal to a width of the working surface of the head carriage unit. The multiple heads are configured to record multiple data tracks on or retrieve multiple data tracks from the tape media as the head carriage unit rotates while the tape media moves past the working surface of the head carriage unit.

Abstract: In an optical tape drive system, a movable planarizer subsystem includes a tape planarizer support structure for supporting an optical tape planarizer. The support structure is moveable between an operational position and a non-operational position. The movable planarizer subsystem also includes an actuator for moving the support structure and the optical tape planarizer between the operational position and the non-operational position. The operational position of the support structure positions the optical tape planarizer to permit reading/writing of information from/to an optical tape via an optical pickup unit (OPU), and the non-operational position of the support structure positions the optical tape planarizer to permit passage of a tape leader through the tape drive system without damage to the OPU.

Abstract: In one embodiment, an optical read/write apparatus includes first and second optical pickups 2a, 2b and a control section. The first optical pickup 2a includes a first lens 3a that condenses a light beam emitted from a first light source onto an optical storage medium, and a first lens actuator that can shift the first lens 3a in a track crossing section with respect to a middle position. The second optical pickup 2b includes a second lens 3b that condenses a light beam emitted from a second light source onto the optical storage medium, and a second lens actuator that can shift the second lens 3b in the track crossing section with respect to the middle position. The control section makes the lens actuators operate so that as the magnitude of shift of the first lens 3a increases, that of the second lens 3b decreases.

Abstract: A method, apparatus and a data storage device are provided for implementing data confidentiality and integrity of data stored in overlapping, shingled data tracks on a recordable surface of a storage device. A unique write counter is stored for each zone written to the recordable surface of the storage device. An encryption key is used together with the write counter information and a logical block address to encrypt each sector being written, and to decrypt all sectors being read. An individual sector is decrypted, obtaining the write counter information and reading the data sector. A message authentication code is stored for each zone. All sectors of the zone are read to perform integrity check on a sector.

Abstract: The optical storage medium comprises tracks with a mark/space data structure, wherein the tracks comprise alternately partitioned marks and not partitioned marks. The partitioned marks are partitioned in particular in tracking direction and are partitioned in two parts, advantageously in two equal parts. The partitions are arranged advantageously such that one track comprises not partitioned marks and a neighboring track comprises partitioned marks, for reducing the track pitch of the optical storage medium and for providing an increased data capacity. The optical storage medium is in a preferred embodiment an optical disc comprising a mask layer with a suitable material for providing a super resolution near field effect, and the data structure of the optical disc comprises two spirals which have either partitioned marks or not partitioned marks.

Abstract: In an optical tape drive system, a movable planarizer subsystem includes a tape planarizer support structure for supporting an optical tape planarizer. The support structure is moveable between an operational position and a non-operational position. The movable planarizer subsystem also includes an actuator for moving the support structure and the optical tape planarizer between the operational position and the non-operational position. The operational position of the support structure positions the optical tape planarizer to permit reading/writing of information from/to an optical tape via an optical pickup unit (OPU), and the non-operational position of the support structure positions the optical tape planarizer to permit passage of a tape leader though the tape drive system without damage to the OPU.

Abstract: A conductive composition comprises a ? conjugated conductive polymer, a polyanion, and a hydroxy group-containing aromatic compound containing two or more hydroxy groups. An antistatic coating material comprises the conductive composition and a solvent. An antistatic coating is produced by applying the antistatic coating material. A capacitor comprises an anode composed of a porous valve metal body; a dielectric layer formed by oxidizing a surface of the anode; and a cathode formed on the dielectric layer, wherein the cathode has a solid electrolyte layer comprising the conductive composition.

Abstract: An optical disk device includes: an objective lens for focusing an optical beam on a recording layer of an optical disk; a converging lens for converging the reflected optical beam reflected on the recording layer; first and second light receiving units disposed at positions spaced ahead and behind at equal distances from the focal point of the reflected optical beam converged by the converging lens; and a focused recording layer discriminating unit for deciding, on the basis of the output signal of the first light receiving unit and the output signal of the second light receiving unit, the positional relation in a two-layer optical disk between a focused recording layer, on which the optical beam is focused, and a defocused recording layer, on which the optical beam is not focused, thereby to discriminate the focused recording layer on the basis of the decision result.

Abstract: It is to provide an optical disc recording apparatus and a recording power control method that are adapted to high-speed recording and can set an optimal erasing power with high accuracy. A test writing signal detector reproduces a test writing signal of a predetermined mark length or space length with varied power, and detects the number of error mark signals and an amplitude value of an envelope. A controller obtains a first threshold Pe0 of the erasing power based on the number of error mark signals in a region where laser power is low, and obtains a second threshold Pe1 of the erasing power based on the amplitude value in a region where the laser power is high. Then, the controller sets an optimal value of the erasing power from an average value of the first and second thresholds.

Abstract: A data transmission apparatus, comprising: a recording unit for recording data output settings for respective users preliminarily; a communication unit for transmitting to a recipient user target data with the output setting either for a sender user or the recipient user, which is recorded in said recording unit, according to an instruction by the sender user; and a display unit for previewing at least one of output settings for the sender user and the recipient user among those recorded in said recording unit, before transmitting said data.

Abstract: An apparatus for driving a tape-shaped optical recording medium, which comprises a supply reel (41) for supplying an optical tape (40), a take-up reel (42) for taking-up the optical tape (40), a friction capstan (43) for driving the optical tape (40) to run to the take-up reel (42) from the supply reel (41) and a running guide member (46) for guiding the optical tape (40) running between the supply reel (41) and the take-up reel (42). The running guide member (46) has a flat portion forming a guide face portion (70) for facing to the optical tape (40) is operative to cause the optical tape (40) to run along the flat portion. Thereby, an area on the guide face portion (70) of the running guide member (46) where an incident position on the optical tape (40) of a light beam is fixed invariably can be stably maintained to be relatively wide.

Abstract: A seek control method carries out a seek to a target position on a recording medium by moving a light beam spot which is irradiated on the recording medium. The recording medium has a first region in which information recording is made as variations in optical or magneto-optical properties and a second region in which information recording is made as variations in geometrical configuration, and the first and second regions are provided in different areas on a recording surface of the recording medium. The seek control method includes the step of carrying out a control so that a seek operation from a seek start position within the first region to a seek target position within the second region and a seek operation from a seek start position within the second region to a seek target position within the first region differ.

Abstract: Disclosed is an optical disk barcode forming method wherein, as information to be barcoded, position information for piracy prevention, which is a form of ID, is coded as a barcode and is recorded by laser trimming on a reflective film in a PCA area of an optical disk. When playing back the thus manufactured optical disk on a reproduction apparatus, the barcode data can be played back using the same optical pickup.

Abstract: The present invention relates to a layer jump control apparatus of a multilayer disk and a method thereof, when a layer jump request between record layers of the multilayer disk is inputted from outside, a sled, a tracking, and a focusing servo are converted into inactive state, a microcomputer sets an operation voltage of an inner focus lens of an optical pickup to allotted ports in order to transfer the focus lens vertically to the layer jump request direction. The present invention is capable of jumping accurately and rapidly on a request layer of the multilayer disk by jumping on a target layer of the multilayer disk accurately by converting the focusing servo into active state at the jump position of the focus lens on the basis of a FOK signal and a FZC signal detected in accordance with transferring operation, and adjusting vertical transferring speed of an optical pickup by considering minus offset of the optical pickup.

Abstract: A portable recording and/or reproducing apparatus for receiving and recording and/or reproducing data and management data to and/or from a recording medium having a data area in which data are stored and a management data area in which the management data for managing these data are stored has a selecting circuit, a reproducing circuit, and a control circuit. The selecting circuit selects, in accordance with a user operation, group management data to be stored in the recording medium. The group management data are stored in the management data area and manage, as a data group, plural data stored in the data area. The reproducing circuit reads the selected group management data and the data group managed thereby. The control circuit controls the reproducing circuit to reproduce the plurality of data managed by the selected management data.

Abstract: An optical tape transport system including an optical head, tape transport structure and a focus stabilizer element including the stabilizer element including a cylindrical surface section supports the full width of the tape; the stabilizer element being disposed on the opposite side of the tape from the optical head; the optical axis of the optical head being perpendicular to the stabilizer surface at the point of intersection between the optical axis and the stabilizer surface; the tape being supported at the stabilizer surface by an air film; and the air film thickness at the point of intersection being in the range 1-50 &mgr;m while the tape is transported for reading or writing.

Abstract: A recording and/or reproducing apparatus for recording and/or reproducing data to and/or from a recording medium having a data area in which data are stored and a management data area in which management data for managing these data are stored. The apparatus according to the invention has a selecting circuit, a reading circuit, and a transfer circuit. The selecting circuit selects, in accordance with a user operation, group management data to be stored in the recording medium. The group management data are stored in the management data area and manage, as a data group, plural data stored in the data area. The reading circuit reads the selected group management data and the data group managed thereby. The transfer circuit transfers the read group management data and the read data group managed thereby to an external device.

Abstract: Optical recording articles, such as tapes, and methods of making and using such articles are disclosed.

Abstract: A method for writing compressed audio data to a compact disc media is provided. The method includes selecting songs to be written in a session and reserving a first track. After the first is reserved, the method proceeds to writing a first temporary data structure and audio data to a second track following the first track. After the second track is closed, part of first temporary data structure (e.g., the recompiled INFO.CD3 part) is written to the reserved first track and the session is closed. Another method includes beginning a session writing the compressed audio data to the compact disc media. A track that includes a file system and an audio data section is then written. The writing of the track further includes writing an INFO.CD3 file, writing an ISO file system, and writing a FILEINFO.LC file following the ISO file system. Once the audio data section is written, the method proceeds to closing the track and closing the session.

Abstract: A recording medium has first and second areas on which first and second information signals are recorded respectively. The first information signal has a size Ya. The second information signal has a size Yb. A head operates for reproducing the first and second information signals from the first and second areas of the recording medium and transmitting the reproduced first and second information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving between the first and second areas of the recording medium. A buffer memory operates for receiving the first and second information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the first and second information signals, and for outputting the first and second information signals at first and second transfer rates Ra and Rb respectively. The first and second transfer rates Ra and Rb are lower than the predetermined constant transfer rate Rp.

Abstract: A turntable record has a track with at least one scale of notes and/or series of chords of a predetermined musical key, the scale being diatonic, pentatonic, whole tone or one of the modes.

Abstract: A method and apparatus for determining the distance between transitions from a first logical state to a second logical state stored on a medium (i.e., a document). This determination is used to precisely characterize the information pattern in order to authenticate the information and the medium on which the information is stored. The invention uses a reader having a leading and trailing read apparatus which allow information to be read simultaneously from two or more locations spaced a known distance apart. The distance between the centerlines of each read apparatus is preferably an odd integer multiple of one half the distance between logical clock transitions. The distance between a first transition at the leading read apparatus and a next transition at the trailing read apparatus is used as a reference (i.e., the “Reference Value”). The Reference Value is compared with the distance between the first transition and the next transition on the medium (i.e., the “Jitter Value”).

Abstract: An optical pickup apparatus includes a light source for emitting a light flux; and a converging optical system having a first, second, and third divided surface, which are divided in the order named from the vicinity of an optical axis of the converging optical system, for converging the light flux emitted from the light source, wherein a beam spot passing through the first and third divided surfaces is formed onto a first optical information recording medium having a transparent substrate whose thickness is t1, and a beam spot passing through the first and second surfaces is formed onto a second optical information recording medium having a transparent substrate whose thickness is t2 that is more than t1. The optical pickup apparatus further includes an image sensor for receiving a light flux reflected from the first and/or second optical information recording-medium.

Abstract: An optical pickup apparatus includes a light source for emitting a light flux; and a converging optical system having a first, second, and third divided surface, which are divided in the order named from the vicinity of an optical axis of the converging optical system, for converging the light flux emitted from the light source, wherein a beam spot passing through the first and third divided surfaces is formed onto a first optical information recording medium having a transparent substrate whose thickness is t1, and a beam spot passing through the first and second surfaces is formed onto a second optical information recording medium having a transparent substrate whose thickness is t2 that is more than t1. The optical pickup apparatus further includes an image sensor for receiving a light flux reflected from the first and/or second optical information recording medium.

Abstract: A recording medium to which this invention is applied includes a first recording area 3 where a digital audio signal sampled at a predetermined sampling frequency and quantized by a predetermined number of bits is recorded, a first management area 2 where information for carrying out management of the digital audio signal recorded in the first recording area 3 is recorded, a second recording area 6 where a digital audio signal corresponding to the digital audio signal recorded in the first recording area 3 is recorded, and a second management area 5 where information for carrying out management of the digital audio signal recorded in the second recording area 6 is recorded, wherein discrimination data indicating that plural recording areas exist is recorded in the first management area 2.Thus, this recording medium has compatibility with the conventional CD player, and can be reproduced in the state of high sound quality by a higher rank reproducing equipment.

Abstract: Storing data on a data processing system is done upon generation of a data file by displaying a user interface allowing user selection of storage criteria for the data file. Responsive to user selection of storage criteria for a file determining a physical format type for the file from a plurality of available physical format types. Then the file is stored on a direct access storage device as at least a first record conforming with the determined physical format type.

Abstract: A recording medium to which this invention is applied includes a first recording area 3 where a digital audio signal sampled at a predetermined sampling frequency and quantized by a predetermined number of bits is recorded, a first management area 2 where information for carrying out management of the digital audio signal recorded in the first recording area 3 is recorded, a second recording area 6 where a digital audio signal corresponding to the digital audio signal recorded in the first recording area 3 is recorded, and a second management area 5 where information for carrying out management of the digital audio signal recorded in the second recording area 6 is recorded, wherein discrimination data indicating that plural recording areas exist is recorded in the first management area 2.Thus, this recording medium has compatibility with the conventional CD player, and can be reproduced in the state of high sound quality by a higher rank reproducing equipment.

Abstract: An apparatus and method for recording and reproducing data with respect to closely spaced magnetically recording areas or tracks of a magnetic recording member such as a card, tape or magnetic disc wherein scanning, tracking and reproduction functions are controlled by electro-optically scanning markers or indicia which are predeterminately recorded with respect to the magnetic recordings of the record member. Signals generated when such electro-optically scannable markers are detected are employed to control either or both the functions of selectively tracking and locating a magnetic transducer with respect to a select recording area or track of the magnetic record member and selectively controlling magnetic reproduction of information from the select recording area by either controlling the driving of the magnetic transducer mount or the operation of the transducer as it scans a select portion of the recording area or track along which it scans.

Abstract: A method and system for mitigating and compensating for loss of digital audio data transmitted as a stream of packets to a client (30). A server (10) compresses digital audio data corresponding to a digitized analog audio signal. The compressed data are divided into N frames of data per packet. The server interleaves the frames, producing interleave packets of up to order N. The interleave operation minimizes the effect of any lost packet when the interleave packets are received, deinterleaved, and converted to an analog signal that is played on a speaker at the client. Lost frames are replaced using the data from frames that are received. As a further aspect, the frames can be scrambled at the server by applying a permutation function F that depends upon the packet number (PN) and a Key value. At the client, an inverse permutation function F.sup.-1 is applied to unscramble the frames.

Abstract: A multi-layered optical disk reading method which makes possible to reproduce encoded data from each data layer by focusing laser beam precisely onto a data layer of the multi-layered optical disk. After a multi-layered optical disk is loaded, a central processing unit (CPU) receives an operator's signal to access certain data layer. Then the CPU refers to stored data in the CPU's memory for a diffraction angle to focus laser beam onto a certain data layer. The CPU retrieves an operational coded signal, and transmits the signal to a liquid crystal diffraction device to modulate the liquid crystal diffraction device to deflect and focus the laser beam onto the certain data layer. After the liquid crystal diffraction device is modulated by the operational signal from the CPU, the CPU also operates a routing circuit to transmit read-out signal from a detector which receives reflected laser beam from the certain data layer, to a selected decoding circuit in a data processor.

Abstract: An objective lens for reproducing/recording information from/onto discs having different thicknesses and an optical pickup device adopting the same. The objective lens device includes an objective lens provided along a light path facing a plane of a disc and having a predetermined effective diameter, and a light controller provided along the light path for controlling the light of an incident light beam between near and far axes of the objective lens, wherein the central portion of the objective lens corresponding to the near-axis region of the incident light beam has the optimum curvature and aspherical coefficient for both thick and thin discs. Therefore, the objective lens device is simplified and inexpensive. Also, the objective lens device can be used for discs of different thicknesses in a single disc drive, by reducing the spherical aberration effect.

Abstract: A storage control system with auxiliary storages includes a system information generator which determines an optimum process data length and gap value to minimize switching between cylinders or tracks in reading/writing of data based on device information obtained from a specified auxiliary storage. Based on the determined optimum process data length and gap value, a data area generator secures a data area on the specified auxiliary storage. The system information generator determines the process data length and the gap value so that the process data length is less than the size of a track in the specified auxiliary storage and satisfies either of the following conditions: (a) Size of a track can be divided by the process data length; or (b) Sum of the process data length and the gap value is a value obtainable by multiplying the track size by an integer.

Abstract: An information recording-reproduction method wherein: upon reproducing, recorded information corresponding to a predetermined number of sectors from the leading sector of each of a plurality of information tracks on an optical disk is preliminarily stored on a buffer memory, and during a period in which the optical pickup is shifted to another information track, the recording information, stored in the buffer memory, is reproduced; and upon recording, during a period in which the optical pickup is shifted to another information track, recording information is temporarily stored in the buffer memory, and after completion of the recording, the recording information is recorded on the optical disk. In this method, information tracks, which are formed on the optical disk discontinuously with one .another, are regarded as if they were continuous tracks, and the apparent recording and reproducing operation is carried out continuously.

Abstract: A buffer serves as a sub-memory with respect to a hard disk and performs a data recording/reproducing operation. With this arrangement, even if the access rate of data in the hard disk is not so high, data transfer between the hard disk and an audio I/O, a MIDI I/O, and image I/O can be performed, and audio, MIDI, and video data can be simultaneously and selectively recorded/reproduced.

Abstract: An apparatus for reproducing digital information from a recording medium having a plurality of parallel tracks and digital information recorded thereon as n-channel (n being an integer greater than or equal to 2) digital signals. The n-channel digital signals are reproduced by n-reproducing heads. The digital information contained in the reproduced signals is stored in a storage device. Discriminating data is obtained for determining which of the n-channel digital signals reproduced correspond to the reproducing heads. The timing of an access device, accessing the storage device for performing a predetermined processing of the digital signals stored in the storage device relative to the reproducing timing of the digital information reproduced by the n reproducing heads, is controlled in accordance with the discrimination data.

Abstract: An optical disk apparatus includes an optical storage medium, an optical head, a head drive section, and a recording data processor. The optical storage medium is rotated at a constant angular velocity. The optical storage medium has a storage area constituted by track areas ranging from the 0th area on the innermost periphery to the nth area on the outermost periphery of the storage area. The track areas are set by dividing the storage area into (n+1) equal areas (n is an integer satisfying n (.gtoreq.1) in the radial direction. The optical head optically records and reproduces recording data on and from the optical storage medium with a constant wave length. The head drive section drives/controls the optical head. The recording data processor generates recording data such that the data amount is increased by .DELTA.

Abstract: A recording film of a recording medium has tracks with a track pitch of 1.6 .mu.m. Each track has a land and a groove, and the width of each of the land and groove is about 0.8 .mu.m. The groove and land differ relatively in height by a degree corresponding to (2n-1)/4 (n: a natural number) times the wavelength of the irradiated beam. At the time of reproduction, reflected diffraction beam components reflected from the land and groove are provided with a phase difference .pi.. Thus, a peak of the diffraction beam is concentrated within the range of the NA of an objective lens, with high intensity. As a result, the presence/absence of pits located at a distance less than a diffraction limit, which have not been detected in the prior art, can be detected.

Abstract: A buffer serves as a sub-memory with respect to a hard disk and performs a data recording/reproducing operation. With this arrangement, even if the access rate of data in the hard disk is not so high, data transfer between the hard disk and an audio I/O, a MIDI I/O, and image I/O can be performed, and audio, MIDI, and video data can be simultaneously and selectively recorded/reproduced.

Abstract: A concurrent recording and reproducing optical disc has a magneto-optical medium film coated on a ROM disc having rows of pits. The magneto-optical film is arranged by a predetermined interval between the two adjacent rows of the pit rows. The predetermined interval is determined by a dark Airy disc circle band of a beam spot obtained by focusing a light beam on the concurrent recording and reproducing optical disc. Preferably, two light beams are focused on the optical disc to provide first and second beam spots. The first beam spot is focused on one of the pit rows, and the second beam spot is focused on an area between two selected pit rows.

Abstract: A disc recording device for recording left channel signals and right channel signals having a super audio-frequency signal range up to 40 kHz on a left master disc and a right master disc respectively comprises a left disc recording control portion, a right disc recording control portion, and a common control portion. An another disc recording device for recording the left channel signals and the right channel signals having sounds of super audio-frequency signal range up to 40 kHz onto one face and other face of a master disc respectively comprises a disc inverse face playback control portion, a disc front face playback control portion, and a common control portion. A signal frame as a channel bit used in the above mentioned devices has 316 bits per one left channel signal and one right channel signal, respectively.

Abstract: There are disclosed improved optical information storage cards or tape which include on a substrate thereof a plurality of offset and interlacing data rings.

Abstract: A system for recording data onto optical tape by means of a laser. The optical tape may be disposed on reels and transported along a tape path between supply and takeup hubs. A laser or laser array is used to write data on the tape in a plurality of parallel tracks as it is driven along the tape path. The tape features a flexible web backing, a reflective metallic layer deposited over the backing and an optical storage layer on top of the metallic layer with a planar crust of irregular, nonfilamentary and oblong black silver particles within the top one-half micron of the storage layer and substantially clear gelatin below the crust. The tape may have prepatterned indica, such as servo track guides or timing marks. Laser recording modifies the black silver particles of the crust to expose the reflective underlayer through the clear gelatin. The laser at low power together with a light detector may be used to read the data, an optical reflective contrast ratio of at least 1.

Abstract: An optical information recording disk and optical information recording disk apparatus which increase the recording capacity of data recorded on the disk, and are capable of fast recording and reproduction. Logical tracks are arranged by sequentially merging physical tracks starting at the inner portion of the disk and physical tracks starting at the outer portion, and the number of sectors on corresponding tracks recorded at a constant linear density is invariably constant on the basis of the relation of arithmetical series. Consequently, the inventive system, despite of the MCAV system of constant disk speed, achieves track access and fast data transfer comparable with the conventional CAV system.

Abstract: A digital information signal recording apparatus has a first mode in which a digital information signal of one channel is recorded on a recording medium at a given bit rate and a second mode in which digital information signals of n channels (n: an integer which is at least 2) are simultaneously recorded on the recording medium at a bit rate which is 1/n of the given bit rate.

Abstract: In the optical memory device of this invention, an annular information recording area is formed on one surface of a disc-shaped subplate which is rotatable about a center hole. Information is recorded on, or read from, the circular or spiral track of the information recording area, the track being centered on the center hole. On the same surface of the subplate is formed a position signal area of the same material as that of the information recording area, but at a different position from the information recording area. As the device is rotated, the time when the position signal area passes a given point may be detected and used as a reference, so that the location within the track of recording or reproducing information can be determined.

Abstract: A dual mode disk controller is disclosed for use between a host processor and its storage medium for controlling data transfer to and from the storage medium. The data is formatted on the medium in two distinct formats, one capable of bulk fast transfers useful in a swapping operation, and the other capable of periodic slower transfers as is acceptable for file retrieval. The disk controller is designed having a small fast buffer memory for accepting information from the storage medium. File transfer data is transferred immediately without host CPU intervention, to a larger cache memory. The host CPU accesses the fast buffer memory periodically to retrieve swap transfer data while only accessing the larger cache memory when it needs to retrieve the file formatted information.

Abstract: In the present invention, there is provided an abnormality detector circuit for comparing a scanning width signal with an upper limit setting signal and a lower limit setting signal and detecting that a scanning width indicated by the scanning width control signal becomes larger than an upper limit scanning width indicated by the upper limit setting signal or becomes smaller than a lower limit scanning width indicated by the lower limit setting signal, whereby when a signal level of an electrical input signal indicative of an information to be recorded exceeds a proper range, this can be positively discriminated by an operator.