Abstract: In a method, read signals from each of a plurality of read transducers of a data head are buffered for each of a plurality of cross-track positions of the head relative to a data track. The buffered read signals are processed to establish a quality metric for each of the read signals and at least one combination read signal comprising at least two of the read signals. A data recovery cross-track position and a reader configuration comprising one or more of the read transducers are identified based on the quality metrics. A data read operation is then performed with the data head in the data recovery cross-track position using the read signals from the identified reader configuration.

Abstract: Embodiments of the present invention utilize a hard disk drive buffer to minimize seek delays during background replication of a first volume and fulfillment of application input/output requests. According to one aspect of the present invention, a requested first sector of data is read along with one or more additional sectors of data. Upon determining that one or more of the read sectors of data should be replicated, the sectors are read from the disk buffer and written to a second volume.

Abstract: A data processing circuit includes a subtraction circuit operable to subtract an ideal version of a data pattern from a sampled version of a data pattern to yield a difference signal, an error calculation circuit operable to calculate an error between the ideal version of the data pattern and the sampled version of the data pattern based on the difference signal, and a comparator circuit operable to compare the error with a threshold value and operable to assert a track refresh signal if the error is greater than the threshold value. The track refresh signal is operable to trigger a magnetic storage device to refresh data on a data track.

Abstract: A storage device includes a storage medium having a plurality of tracks of data. Reading apparatus for reading a current track of data that has been subject to previous encroachment to an extent from at least one adjacent track of data includes a write head that writes interfering data to the adjacent track of data while intentionally encroaching at least to that extent onto the current track of data, and circuitry that recovers data on the current track of data using the interfering data. A method for reading a current track of data, that has been subject to previous encroachment to an extent from at least one adjacent track of data, includes writing interfering data to the adjacent track of data while intentionally encroaching at least to that extent onto the current track of data, and recovering data on the current track of data using the interfering data.

Abstract: A storage device includes a storage medium having a plurality of tracks of data. Reading apparatus for reading a current track of data that has been subject to previous encroachment to an extent from at least one adjacent track of data includes a write head that writes interfering data to the adjacent track of data while intentionally encroaching at least to that extent onto the current track of data, and circuitry that recovers data on the current track of data using the interfering data. A method for reading a current track of data, that has been subject to previous encroachment to an extent from at least one adjacent track of data, includes writing interfering data to the adjacent track of data while intentionally encroaching at least to that extent onto the current track of data, and recovering data on the current track of data using the interfering data.

Abstract: Embodiments described herein include systems and methods for correcting for errors caused by disturbances to disk drives, such as disturbances due to shocks or vibrations incident on the drive. For example, systems and methods described herein advantageously correct for corruption to current data as well as previously written. Data may be rewritten in the current track that was being written to when the disturbance occurred, and may also be rewritten to one or more nearby previously written tracks, such as one or more adjacent tracks. According to some aspects, the direction of head deviation is used to select the appropriate corrective action.

Abstract: Systems and techniques to interpret signals on a noisy channel are described. A described technique includes storing a group of signals including a filtered digital signal and one or more previous signals, the filtered digital signal being based on an analog signal; interpreting the filtered digital signal as first discrete values; determining whether the first discrete values are adequately indicated based on a result of the interpreting; initiating a retry mode when the first discrete values are not adequately indicated; producing, in the retry mode, a new signal, the new signal being determined based on an average of at least a portion of the group of signals; interpreting, in the retry mode, the new signal as second discrete values; and determining whether the second discrete values are adequately indicated based on hard decisions indicated by the new signal and hard decisions indicated by the filtered digital signal.

Abstract: A hard disk drive (HDD) minimizes the effects of far track erasure (FTE) by counting the number of writes to the data tracks and incrementing counters based on the known effect of FTE on each track. The extent of the FTE effect is determined for each track within a range of tracks of the track being written, and based on the relative FTE effect for all the tracks in the range a count increment (CI) is determined for each track within the range. A counter is maintained for each track. For every writing to a track, a count for each track within a range of the track being written is increased by the CI value associated with the track number within the range. When the count value for a track reaches a predetermined threshold the data is read from that track and rewritten, preferably to the same track.

Abstract: Injecting pad bits during a read operation to improve format efficiency is disclosed. In some embodiments, a pad sequence associated with error correction is not stored in a sector on a disk. Instead, the pad sequence is merged at a read channel with data stored in a sector that is accessed by the read channel.

Abstract: Systems and methods for detecting a disk sync mark are provided. The systems and methods for detecting the disk sync mark rely on a detecting the disk sync mark on at least one timing interval. A window of data read bits from a particular disk sector are examined to determine whether they match the disk sync mark. The disk sync mark may be differentiated from expected versions of the disk sync mark using a calculated set of thresholds.

Abstract: The present invention is a disc drive storage unit incorporating novel apparatus, data structure and method for uniquely identifying data written during each write command operation of the disc drive storage unit. The disc drive storage unit attaches unique write identification data (sequence data, time data, or both) to host computer data written during each sector write operation. The unique write identification data is attached through independent action of the disc drive storage unit. The unique write identification data is attached to the host computer data in such a way that the unique write identification data is transparent to the host computer. The data structure relates the host computer data to the unique write identification data. The method documents the manner in which unique identification data is attached to, and detached from, the host computer data.

Abstract: An information recording apparatus for recording content information on an information recording medium includes a main information recording area on which main information to be reproduced is recorded, and a plurality of content information recording areas on which content information to be reproduced to indicate contents of the main information is recorded. The apparatus includes a recording device, a confirming device and a control device. The recording device records the content information on a part of the plurality of content information recording areas. The confirming device confirms a recording result of the content information thus recorded. The control device controls the recording device, only when the recording result is confirmed to be successful, so that content information that is identical with the content information recorded on the part of the content information recording areas can be recorded on the other part of the content information recording areas.

Abstract: In order to generate a sampling clock having a higher accuracy, a synchronous signal generating circuit is provided with a phase error detector, detecting a phase error of a read out signal digitized on the basis of FDTS algorithm, and a VCO, controlling an oscillation frequency on the basis of a phase error detected by the phase error detector, to generate a synchronous signal by the VCO. On the basis of the synchronous signal generated by the synchronous signal generating circuit, an ADC digitizes the read out signal. The digitized read out signal is then converted to binary data by a detection circuit.

Abstract: A method and an apparatus encodes and decodes blocks having a predetermined number of sectors of data bytes to detect and correct data bytes in error in each sector of a block. The method and the apparatus generates sector level check bytes for each sector in the block responsive to the data bytes in each sector according to a first level of an error correction code, and generates block level check bytes for a predetermined sector in the block responsive to the sector level check bytes of various sectors, including the predetermined sector, according to at least a second level of the error correction code.

Abstract: In order to generate a sampling clock having a higher accuracy, a synchronous signal generating circuit is provided with a phase error detector, detecting a phase error of a read out signal digitized on the basis of FDTS algorithm, and a VCO, controlling an oscillation frequency on the basis of a phase error detected by the phase error detector, to generate a synchronous signal by the VCO. On the basis of the synchronous signal generated by the synchronous signal generating circuit, an ADC digitizes the read out signal. The digitized read out signal is then converted to binary data by a detection circuit.

Abstract: A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. Other embodiments are also disclosed with the aim of ensuring that information recorded on a magnetic media can always be reproduced reliably, even in the case of high density recording.

Abstract: A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. Other embodiments are also disclosed with the aim of ensuring that information recorded on a magnetic media can always be reproduced reliably, even in the case of high density recording.

Abstract: A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. Other embodiments are also disclosed with the aim of ensuring that information recorded on a magnetic media can always be reproduced reliably, even in the case of high density recording.

Abstract: A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. Other embodiments are also disclosed with the aim of ensuring that information recorded on a magnetic media can always be reproduced reliably, even in the case of high density recording.

Abstract: An information medium having digital signals recorded therein includes a disk having first and second recording surfaces. The digital signals are in the form of a data frame including a lead-in block and n data blocks. The lead-in block has a same format as the n data blocks. n block addresses are assigned to the n data blocks. Information identifying an area on the disk in which the n data blocks is recorded is assigned to the n data blocks. m data blocks (0<m<n) are recorded on the first recording surface, and remaining (n−m) data blocks are recorded on the second recording surface. The lead-in block is recorded at the head of the data frame, and includes information identifying an area on the disk in which the lead-in block is recorded, a number of recording surfaces, the block address of one of the m data blocks recorded last on the first recording surface, and the block address of a last one of the n data blocks in the data frame.

Abstract: In a data recording system utilizing multiple channels and data blocks wherein the data blocks are read subsequent to being written so as to check for errors, the data blocks are rewritten according to a method to provide for rewriting only the defective data blocks. The blocks may be rewritten on other than their original channels. Channels for rewriting are determined by selecting a channel with a highest current block number so that data is rewritten in a channel which has been able to write and verify the most of its original blocks. Error checking is continued in a channel even after finding of an error in that channel. Data blocks of the frames may be skewed between the channels at a beginning of the frame. A ring counter output is applied to break a deadlock where a block is continously rewritten on a failing channel.

Abstract: A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. According to yet another embodiment, the temperature in the disk drive is measured by a thermometer 18, and if the temperature is higher than a reference value, information is automatically copied at shorter intervals than when the temperature is less than the reference value.

Abstract: A method of recording digital signals on a disk having at least a first recording surface and a second recording surface. The digital signals are in the form of a data frame including a lead-in block and n data blocks. The lead-in block has a same format as the n data blocks. The method includes the steps of assigning n block addresses to respective ones of the n data blocks, assigning, to each of the n data blocks, information identifying an area on the disk in which a respective one of the n data blocks is to be recorded, recording m data block (0<m<n) of the n data blocks on the first recording surface of the disk, recording remaining (n-m) data blocks of the n data blocks on the second recording surface of the disk, and recording the lead-in block at the head of the data frame.

Abstract: An audio playback apparatus for an input data stream (d0) delivered by an audio data source (1) in a standardized data format (F1) is disclosed comprising an input decoder (2) for forming a first data stream (d1), which contains the audio information and is separated by means of an output decoder (5) into its audio signal components (L, R). In addition to the first data stream (d1), the input decoder (2) generates a second data stream (d2) which corresponds to the data contained in the data field (D1) of the standardized data format (F1), and which is fed to an additional decoder (3) that detects a second data format (F2) possibly contained in the second data stream (d2) and passes the audio information of the second data format (F2) as a third data stream (d3) to the output decoder (5).

Abstract: A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. According to yet another embodiment, the temperature in the disk drive is measured by a thermometer 18, and if the temperature is higher than a reference value, information is automatically copied at shorter intervals than when the temperature is less than the reference value.

Abstract: Method and apparatus are provided for re-recording of a frame on magnetic tape (22) when a first recording of the frame is determined to be defective. A frame whose first recording is defective is re-recorded at a spare or reserved location on the tape. The reserved location is dedicated to re-recording of frames, and otherwise cannot have data stored therein. The tape contains a defect map frame (326) which is used to pair physical locations of defective frames with the reserved location whereat the frame is re-recorded. In one embodiment, the reserved location whereat a frame is re-recorded is a reserved physical frame on the same track in which the defective frame is recorded. In another embodiment, the reserved location is on a reserved portion of a track (TG39R) which is not the original track (TG39) upon which the frame is recorded. For embodiments having multi-channel or multi-track frames, the reserved location employs a corresponding plurality of tracks.

Abstract: An input signal from an audio system is divided into a plurality of frequency bands, and the signal in each frequency band is attenuated by an attenuator. The output signals of the attenuators are added. A level of the signal in each frequency band is detected by a level detector. A memory is provided for feeding an attenuation dependent on a level detected by the level detector. A controller is provided for controlling a signal attenuation of the attenuator by an attenuation fed from the memory in accordance with a detected level.

Abstract: A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. According to yet another embodiment, the temperature in the disk drive is measured by a thermometer 18, and if the temperature is higher than a reference value, information is automatically copied at shorter intervals than when the temperature is less than the reference value.

Abstract: A method and apparatus for verifying that data written on magnetic disk media can be successfully recovered in subsequent read operations and ensuring that the data to be written is held by a buffer until a read-verify operation indicates that the buffer space storing the data may be relinquished for new operations.

Abstract: A video printer for printing a magnetic pattern of a master tape on a slave tape comprises a read head for reading a control signal printed on the slave tape, a phase shift circuit for shifting a phase of the control signal read by the read head, and a write head disposed downstream of the read head with respect to a running direction of the second tape and for rewriting on the second tape the control signal with the phase shifted by the phase shift circuit.

Abstract: A method and apparatus of reproducing and recording data stored in a plurality of tracks of a memory. A recording and reproducing head reproduces data from at least one of a plurality of tracks of a disk-shaped recording medium. The reproduced data is stored in a memory and rewritten. Data is read out of the memory and controllably supplied to a recording operation of the recording and reproducing head so that data of every track read out from the memory is recorded on the disk-shaped recording medium. In a preferred embodiment, the reproduced data is stored, rewritten read out from the memory in response to an index signal representing a starting portion of a track and then recorded on a magnetic floppy disk.

Abstract: The present invention pertains to a data recording control method of a magnetic tape in which tape a data, constructed by combining a plurality of packets into physical blocks, is recorded, the method being such that: the entire physical block of data is read from a magnetic tape and store in a buffer, when a command for reading a data corresponding to a packet in the physical block is output from a host unit; a new physical block is created by reorganizing the data in the buffer and the data to be recorded, when a write command and the data to be recorded are output from the host unit at any position in the physical block on the magnetic tape; and the data thus reorganized into a physical block is recorded on the magnetic tape.

Abstract: A magnetooptical recording method for recording data using a bit having upward-magnetization and a bit having downward-magnetization on a recording layer of a magnetooptical recording medium comprises the steps of using, as the medium, a multilayered magnetic recording medium consisting of a first layer having a perpendicular magnetic anisotropy acting as a recording layer, and a second layer having a perpendicular magnetic anisotropy acting as a reference layer; moving the medium; applying an initial field so that, before recording, the direction of magnetization of the recording layer is left unchanged, and that of the reference layer is aligned either upward or downward; radiating a laser beam onto the medium; pulse modulating an intensity of the laser beam in accordance with binary data to be recorded; when the laser beam is radiated, applying a bias field to the irradiated portion; and when the intensity of the pulse-modulated laser beam is at high level, forming one of the bit having upward-magnetizatio

Abstract: An arrangement for reading a digital audio signal from a master medium (7) and storing it in a digital storage medium (10, 90, 90') at a first bit rate in a first step, and for repeatedly reading the digital audio signal from the storage medium and recording the digital audio signal on a recording medium (20') at a second bit rate in a second step. The digital storage medium is adapted to store a digital information signal which is a representation of a first music program (M1) and a digital information signal which is a representation of a second music program (M2). The arrangement (FIG. 1b) is further adapted to repeatedly read the digital information signal representing the first music program from the digital storage medium while reading the digital information signal representing the second music program into the digital storage medium in the second step.

Abstract: A recording position compensation circuit for use in the digital information recording-reproduction apparatus of the present disclosure has a microprocessor for generating an offset signal indicating a deviation between standard signal processing time, which is required for a process wherein digital medium information already recorded on the recording medium is reproduced through the advanced reproduction head and re-recorded on the recording medium through the recording head, and inter-head travelling time required for the recording medium to travel a distance from the advanced reproduction head to the recording head. A first counter generates a reference symbol pointer indicating a reference of a sequence whereby digital information stored in the memory is read out so that a part of the digital information is rewritten. A second counter generates a compensated symbol pointer having a phase difference corresponding to the deviation with respect to the reference symbol pointer.

Abstract: A dual channel helical scan recording system (30) includes a rotating dum (36) having sets of heads (W1, W2) (R1, R2) mounted on its peripheral surface (56). A set of write heads (W1, W2) is situated on an opposite side of the drum (36) from a set of read heads (R1, R2). The write heads (W1, W2) simultaneously write two adjaent tracks (T1, T2), which are read for verification 180 detrees later by corresponding read heads (R1, R2). The heads (W1, W2, R1, R2) are strategically mounted on the drum (36) with respect to angular and axial placement, and have selected head widths and azimuthal angles. Should a block of data (317) written to tape (32) be determined, during readback, to be bad block, that bad block is subsequently rewritten on the tape (32) in the course of writing good blocks and amongst other good blocks. The rewritten block is recorded at a row position on the tape which is sufficiently displaced from the row position of a previous writing to avoid media defects occuring on the tape.

Abstract: An improved method of managing media defects in disk drives keeps an operating list of the tracks in the disk drive, and for each track enters on the list the number of good sectors (i.e., those free of defects) in that track. Thus the information on the operating list is sufficient for the disk drive microprocessor to avoid use of the defective sectors, each of which is labelled in its header as being defective. This method is compatible with SCSI and other common disk drive interfaces.

Abstract: A system for managing data errors and media defects on magnetically and optically encoded disks. The invention is a disk controller utilizing a cylinder-based defect management system that reduces the amount of physical media space needed for bad block data replacement blocks. A unique attribute is calculated for and stored with each data block on each track that permits the controller to rapidly determine if a desired data block is in the current track. Spare blocks within a cylinder may be allocated to any track within that cylinder, permitting the system to more efficiently handle larger media or data errors than prior art devices that are limited to a particular number of spare blocks per track. When a bad data block occurs, the data from that block and all subsequent blocks is "slipped" to succeeding data blocks, thereby preserving the contiguity of the logical data structure and minimizing disk access time.

Abstract: An information recording and reproducing apparatus for recording and reproducing information on and from a disk type information recording medium, wherein the information recording medium is used in which normal sectors (s1, Sn) each having an address formatted on an address area 12 in a sector ID field 9 and an alternative sector R1 having an address not yet recorded thereon are included on a same track. When a defective sector S3 is detected, first, the address of the defective sector is disabled to be reproduced by recording a delete signal 109 on the address area 12 of the defective sector S3, and at the same time, the address of the defective sector is recorded on an address area 13 in the unused alternative sector R1 located on the same track as the defective sector S3, and then, the data to be recorded on the defective sector is recorded within the alternative sector R1.

Abstract: The binary coded data signal is divided into data blocks in the video translation system in accordance with the invention. n copies are made of each data block. Televison synchronization signals are added to the original data block and to the n copies thereof, the assembly thus forming a video data block. This video data block is transferred to a video processing device, for example, a video recorder in which it is recorded. When the video data block is recovered, the corresponding data block is recovered from the n+1 data blocks present.

Abstract: Dejitterizer apparatus is disclosed which uses a counter to track the number of bits stored in a 64-bit FIFO buffer. The counter is incremented on a falling edge of pulses of a timing pulse signal, nominally 6.176 Mhz, that coincides with a pulse of a jittered, nominally 1.554 Mhz, clock pulse signal derived from a jittered T1 signal applied to the input of the apparatus. The counter is decremented on the rising edge of pulses of a local clock pulse signal which is derived from the timing pulse signal. The bits are stored in the buffer in response to pulses of the jittered clock pulse signal. Output from the buffer in response to timing pulses derived from the local clock pulse signal is enabled when the counter indicates that the buffer is one-half full. The frequency of the local clock pulse signal is a function of the average frequency of the jittered clock pulse signal over more than sixteen jittered clock periods.

Abstract: A transducer head on a disk drive apparatus is offset about an expected center of a data track as indicated by servo information not included in the data track. If data does not have a predetermined level of readability, the head is known to be shifted with respect to the track. The data is then incrementally read and rewritten in a track centered about its expected center as indicated by the servo information. The amount of data incrementally rewritten at one time is a function of the disk characteristics and the amount of resources available to temporarily store the data. If more than one track appears shifted with respect to the head, the order of rewriting the tracks is selected to minimize risk of overlapping the tracks during the writing.

Abstract: An apparatus for re-recording a new digital signal in a track on a magnetic record medium which has a previously recorded digital signal in the track, the digital signal being arranged in data blocks each containing a sync signal, a data signal, an error correction code signal, and an error detection code signal, comprises a reproducing circuit which reproduces each digital signal recorded on the magnetic record medium, a code generating circuit which supplies a discriminating code signal for each of the data blocks, and a recording circuit which re-records the new digital signal and the respective discriminating code signals in the track on the magnetic record medium.

Abstract: Each face of a magnetic disc memory is divided into sectors of a circle and into concentric tracks on which are recorded or from which are recovered binary data transferred between a central processing unit and the disc memory. Each sector of each track includes an address. One or more sectors on each track is a salvage sector, i.e., a sector where data are stored if a sector on the track is faulty. Faulty sectors on a track are detected and the order in which the faulty sectors are detected is indicated. In response to the detected faulty sectors and the indication of the order in which the faulty sectors are detected, as well as in response to addressing means for sectors of the memory, a number of replacement sectors equal to the number of detected faulty sectors is assigned at the end of a track address by the addressing means.

Abstract: A digital data transmission system comprises a transmitter and a receiver, said transmitter comprising storage means for temporarily storing a data bit string forming a coded digital video signal, means for supplying a read request signal for reading out said data bit string from said storage means, means for forming one frame out of time slots alloted to a frame synchronization bit, a predetermined number of data bit of said data bit string and a dummy flag bit which indicates whether or not a dummy bit exists in said one frame, means for detecting whether or not a fixed bit pattern is formed in said one frame, means for providing said dummy bit to a predetermined one of said time slots in response to the result of said detection, means for inserting a dummy flag bit indicative of whether or not the dummy bit has been inserted to a time slot for said dummy flag bit, means for supplying a data bit which have dropped out by addition of said dummy bit to said frame forming means so that said dropped data bit is

Abstract: Loss of a magnetic track on a rotating drum memory is compensated for by a erially connected shift register. Since replacement of an entire magnetic drum is a costly venture, it usually is not warranted when only one or two or several tracks have become corroded or otherwise scored. The shift register is provided with an appropriate amount of stages to handle the data otherwise stored on a damaged magnetic drum track. Provision is made in the inventive concept herein disclosed for providing index and clock signals in event of the failure of the index and clocking tracks in the memory drum.

Abstract: A method and means for filtering and intensifying signal components of a desired predetermined period of repetition wherein a plurality of recording heads in tandem arrangement are provided, adjacent recording heads being equally spaced from each other. A magnetic tape is drawn past the recording heads at a constant velocity. The recurring signal component of desired period of repetition is delivered to the recording heads simultaneously and in such a way that the portion of the magnetic tape upon which each individual recording of the desired signal component is made by each recording head reaches the next recording head simultaneously with the next such signal component. As a result the amplitude of the desired signal component is increased on the magnetic tape and the amplitude of all other periods of repetition is relatively reduced. The summated signal can be reproduced by means of a playback head and an appropriate readout means.

Abstract: Novel equipment utilizing a single head, single gap on a single track in an audio magnetic recorder to permit control of a large variety of audio-visual devices for the pre-programming of a multi-media presentation in educational, entertainment and other fields. Particular structure, including an audio magnetic tape drive mechanism, which permits, by means of a single head with a single gap on a single track, index signal recording, data signal recording, data signal updating and data signal playback is provided to perform multiple discrete and proportional control functions. The same magnetic tape may carry on a separate track or tracks audio information which is correlated with the functions controlled by the data recorded on the device control track.