Abstract: An information storage medium includes a drive zone having a plurality of physical clusters or ECC blocks. When new drive data is recorded in the drive zone, the new drive data is recorded in a physical cluster or ECC block next to the physical cluster or ECC block containing the most recently recorded drive data. In the method of recording drive data, the drive data is recorded in a physical cluster or ECC block of the drive zone. When the drive zone is updated with the new drive data, the new drive data is recorded in the physical cluster or ECC block adjacent to physical cluster or ECC block containing the most recently drive data. The drive data recording method is applicable to a new format of information storage medium.

Abstract: A method for storing a data block, involving storing the data block in a storage pool, obtaining a data block location, determining a checksum function for the data block, calculating a data block checksum using the checksum function for the data block, and storing a first indirect block in the storage pool, wherein the first indirect block comprises the data block location, the data block checksum, and a checksum function ID corresponding to the checksum function for the data block.

Abstract: Segregation of redundant control bits in an ECC permuted, systematic modulation code. Appropriately encoding of user information via combined modulation and RS (Reed-Solomon) encoding ensures segregation of scrambled user information, modulation redundancy bits, and RS redundancy bits in such a way that each of the components thereof can be segregated and stored within any desirable digital information memory storage device. By providing this segregated capability, when accessing a portion of a RS codeword from the memory, an entire RS codeword need not be read from the memory. In fact, only the particular field (or bits) needs to be accessed to perform correction thereon. This segregation provides for a reduction in the hardware complexity of translation between user information and a modulation codeword. Also, this segregation provides for the ability to perform correction of only one of the scrambled user information, the modulation redundancy bits, or the RS redundancy bits.

Abstract: A weighted defect estimating apparatus and a related method for determining a defect estimation value are disclosed. The weighted defect detecting apparatus includes: a defect detecting unit for generating a defect value when a defect in a predetermined region of an optical disc is detected; a weighting circuit, electrically connected to the defect detecting unit, to generate a weighted defect value according to the defect value and a weighting factor corresponding to a location of the defect on the optical disc; and a computing module, electrically connected to the weighting circuit, for computing the defect estimation value according to a plurality of weighted defect values corresponding to the predetermined region.

Abstract: A computer process establishes data frequencies for recording data in zones of a zone bit recording medium in a disc drive. At least three data points are identified for each zone correlating data frequencies and corresponding bit error rates, and a slope of a curve between each two data points is calculated. The slopes are averaged, and the data frequency is calculated based on the average slope. If a difference between the average and default slopes exceeds a first threshold value, or if a spread of the slopes exceeds a second threshold value, the data frequency is calculated based on the average slope and the default slope. In one embodiment, each of the three data points is generated by recording data in the zone at each of three selected data frequencies, reading the recorded data, and calculating bit error rates based on the recorded and read data.

Abstract: A computer system (10) and method are presented for performing ECC corrections on data contained in a mass data storage device (20). The computer system (10) has a host computer (12) having a CPU (14) and an associated mass data storage device (20). At least some ECC hardware is associated with the mass data storage device (25). A device driver (18) is associated with the host computer (12), which includes software instructions for execution by the CPU (14) for performing at least some ECC functions or instructions on data read from the mass data storage device (20).

Abstract: An optical recording medium record/playback apparatus manages defective areas in a rewritable optical recording medium. A linear replacement control (LRC) bit is added to a secondary defective list (SDL) entry to discriminate defective block information listed in the SDL entry, according to a linear replacement algorithm, from defective block information listed at the SDL entry, according to a skipping algorithm. This allows the apparatus to transmit correct information to a host. When a defective block requiring a new replacement block is found during recording or playing back data and the spare area is full, instead of carrying out the linear replacement, the LRC bit is set in the SDL entry, along with the location information of the defective block. This indicates that the SDL entry was made when the spare area was full. Thus, data is not written in, or read from, the defective block.

Abstract: Iterative code system for streaming hard disk drives (HDDs). A novel approach is presented by which any of a wide variety of error correcting codes can be applied within devices that include or interface to HDDs or other memory storage devices that provide streaming information. A means is provided by which at least two separate clock domains are employed such that the streaming information can be provided at a first rate according to a first clock domain, and the decoding processing of the streaming information can be provided at a second rate according to a second clock domain. Using this approach, a wide variety of error correcting codes can employed, including those whose decoding processing would not be possible if required to operate at the typically high rates at which streaming information is oftentimes provided from HDDs or other memory storage devices.

Abstract: An error corrector with a high use efficiency of a memory includes a memory, a bus device, an input buffer and an error correction module. The memory stores data. The bus device controls a memory access. The input buffer receives and temporarily stores a coded blockcode data, and writes the coded blockcode data in the memory through the bus device. The error correction module reads the coded blockcode data in the memory through the bus device and decodes it in rows and columns to thereby obtain decoded data and check bytes. The error correction module writes the decoded data in the memory through the bus device and discards the check bytes.

Abstract: Disclosed is an error correcting system, which comprises: a demodulator, for receiving and demodulating data from the optical disc to generate input data; a data buffer, for storing the input data; an on the fly ECC decoder, for performing a PI error correction to the input data before the input data from the demodulator stored by the buffer; an ECC decoder, for performing an error correction on the input data in the data buffer to generate an error correction information and correcting the input data to transform it to corrected data; an non-linear EDC check device, for performing a non linear error detection on the input data to generate a first EDC result stored by the EDC memory; an EDC corrector, for adjusting the first EDC result according to the error correction information; wherein the ECC decoder first performs a PO error correction on the input data.

Abstract: An information storage medium includes a drive zone having a plurality of physical clusters or ECC blocks. When new drive data is recorded in the drive zone, the new drive data is recorded in a physical cluster or ECC block next to the physical cluster or ECC block containing the most recently recorded drive data. In the method of recording drive data, the drive data is recorded in a physical cluster or ECC block of the drive zone. When the drive zone is updated with the new drive data, the new drive data is recorded in the physical cluster or ECC block adjacent to physical cluster or ECC block containing the most recently drive data. The drive data recording method is applicable to a new format of information storage medium.

Abstract: First data representing user data and third data use the same error correction codes. The first data has a first error correction block structure and the third data has a second error correction block structure. That is to say, the first data and the third data have their respective error correction block structures proper for them. In particular, the recording density of the third data is made less dense than the recording density of the first data, and the number of correction codes in the first error-correction block is set at a multiple of m whereas the number of correction codes in the second error-correction block is set at n/m times the number of correction codes in the first error-correction block so that a data-piece count in the second error-correction block is also n/m times a data-piece count in the first error-correction block. As a result, it is possible to provide a good technique of recording shipping-time information onto a high-recording-density disc.

Abstract: A method for processing noise interference in a serial AT Attachment (SATA) interface. The method includes the steps of detecting whether there is an error in CRC (Cyclic Redundancy Check) checksum or whether an R_ERR primitive (reception error primitive) is received, detecting whether a FIS (Frame Information Structure) is a data type if there is any error and returning back to error state detecting step if there is no any error, detecting whether the FIS is a ATAPI packet command CDB (Command Descriptor Block) when the FIS is the data format, and writing a special tag to the CDB and returning back to the error detecting step.

Abstract: An optical disk playback apparatus for playing back or reproducing main data and its associated sub-code which are read from an optical recording medium comprises an interleave RAM for storing the main data. The optical disk playback apparatus performs a predefined synchronization protection on synchronization information included in the sub-code to generate a sub-code synchronization signal which is written into an empty area of the interleave RAM, and manages the addresses with a FIFO area in a manner similar to the main data, thereby causing the read sub-code synchronization signal to function in synchronization with the main data.

Abstract: A method for generating parity codes of a data sector having data information and main data. The main data is scrambled to generating outer-code parity. The main data is scrambled to generating inner-code parity. The outer-code parity generating is superior to the inner-code parity generating. The outer-code parity is generated by vertically scrambling the corresponding vertical data block.

Abstract: Embodiments of the invention provide methods and systems for improving the reliability of data stored on disk media. Logical redundancy is introduced into the data, and the data within a logical storage unit is divided into sectors that are spatially separated by interleaving them with sectors of other logical storage units. The logical redundancy and spatial separation reduce or minimize the effects of localized damage to the storage disk, such as the damage caused by a scratch or fingerprint. Thus, the data is stored on the disk in a layout that improves the likelihood that the data can be recovered despite the presence of an error that prevents one sector from being read correctly.

Abstract: A control unit transfers user data and an ECC that are read from a magnetic disk and stored in an FIFO to a data buffer. An erasure position movement control unit shifts an erasure start position from a predetermined initial value at predetermined intervals of erasure movement step, and an erasure position designating unit determines an erasure correcting position based upon the erasure start position and a predetermined erasure length. An ECC processing unit performs error correction by an ECC arithmetic processing in an erasure mode on the user data and the ECC in the data buffer.

Abstract: In the channel quality information (CQI) coding method of the present invention, first basis sequences for generating sub-codes of 32 bits are created, and second basis sequences for generating codewords of 20 bits are created using the first basis sequences, the second basis sequence maximizing system throughput such that five information bits are coded into CQI code using the second basis sequences. Also, since HSDPA system has been designed in order to increase the system throughput, the CQI coding method of the present invention, which shows the best system throughput in the simulation, can be the optimum CQI coding scheme for HS-DPCCH.

Abstract: A magnetic disk control apparatus includes an error determining unit and a correcting unit. When a correctable read error has occurred during read access to a disk drive, the error determining unit specifies an area on the disk drive where an error may occur due to the same cause as that of the correctable read error. The correcting unit corrects the area specified by the error determining unit by rewriting the area.

Abstract: The present invention is directed to a method and system for disk drive data recovery utilizing CRC information and RAID parity. CRC meta data is compared with either the CRC generated from the data read from the disk drive or the CRC generated from the data reconstructed from the parity drive. If the CRC metadata matches the CRC generated from the data read from the disk drive, the data from the disk drive is accepted as valid. Otherwise, another comparison is made between the CRC generated from data reconstructed from RAID parity and the CRC metadata. If there is a match, the reconstructed data is used as the valid data; otherwise, the data read from the disk drive is used as valid data.

Abstract: A dynamic threshold detector for a magnetic storage medium comprises a transition detector that receives the data comprising pairs of numbers based on data received from the magnetic storage medium, each of the pairs of numbers including a first number and a second number and that detects signs of the first and second numbers in the pairs. A threshold selector varies a magnitude of a threshold based on the detected signs.

Abstract: A method of reading data comprises receiving a request for a stripe of erasure coded data, sending read messages to at least a quorum of storage devices, and receiving at least the quorum of reply messages from the devices. The quorum of the reply messages includes at least a minimum number of stripe blocks needed to decode the data. The quorum meets a quorum condition of a number such that any two selections of the number of the stripe blocks intersect in the minimum number of the stripe blocks. A method of writing data comprises generating a timestamp, encoding the data, sending query messages including the timestamp to the storage devices, receiving query reply messages from each of at least the quorum of the devices, sending write messages to the devices, and receiving a write reply message from each of at least the quorum of the devices.

Abstract: A stable system is provided wherein the influence of disturbance or the like can be reduced. First error correcting code units and second error correcting code units are used, and thereby a wider range of random errors and burst errors are made correctable to avoid retry operation. Thus, stable data reproduction is carried out without degrading transfer rate. Further, the constitution of error correcting blocks is set so that when a head is moved to some track during seek operation, a sector having the second error correcting code recorded therein is the first sector to be read.

Abstract: File system is capable of performing long operations, such as deletions and truncations of long files, in a deterministic and atomic manner with regard to its recorded consistency points. The system includes both live filespace accessible to users, and user-inaccessible zombie filespace. In representative embodiments, the system includes a file deletion manager and a truncation manager capable of operating on files in the zombie filespace. Changes to the zombie filespace can be recorded in persistent memory. After a power failure or a similar event, the system can use the recorded changes to replay operations on the files in the zombie filespace, facilitating recovery. Zombie space can be sized dynamically, enabling the deletion manager to request enlargement of the zombie filespace. In some embodiments, files are transferred to the zombie filespace before links to the files' blocks in the live filespace are broken, and before performing operations on the files.

Abstract: A vestigial sideband (VSB) modulation transmission system and a method for encoding an input signal in the system are disclosed. According to the present invention, the VSB transmission system includes a convolutional encoder for encoding an input signal, a trellis-coded modulation (TCM) encoder for encoding the convolutionally encoded signal, and a signal mapper mapping the trellis-coded signal to generate a corresponding output signal. Different types of the convolutional encoders are explored, and the experimental results showing the performances of the VSB systems incorporating each type of encoders reveals that a reliable data transmission can be achieved even at a lower input signal to noise ratio when a convolutional encoder is used as an error-correcting encoder in a VSB system.

Abstract: When data is recorded onto a tape-shaped recording medium using N recording heads disposed on a rotary drum, of first and second series codes orthogonal to each other, the first series code is recorded by any one of the recording heads, and the second series code is recorded across N tracks formed by the N recording heads per revolution of the rotary drum. The redundancy rate of the second series code is set to 1/N or more. As a result, a recording apparatus and method can be provided, which can correct almost all errors at a ratio of one to N tracks even if one whole track of data is completely destroyed without increasing the redundancy rate.

Abstract: System and method for decoding received information using batched processing of independent parameters. A preferred embodiment comprises a decoder (for example, decoder 210) with a memory (for example, memory 215) that may be partitioned into a plurality of parts, one of which being a parameter partition (for example, parameter partition 217). A digital signal processor (for example, DSP 205) programs the decoder 210 with various ways that it wishes received data to be decoded and the decoder 210 can operate independent of the DSP 205, storing the results of each decoding operation in a specified location. At specified instances, the decoder 210 interrupts the DSP 205 to allow the DSP 205 to retrieve the decoding results.

Abstract: Disclosed is an error correction system, comprising: a demodulator for receiving and demodulating raw data to generate an ECC block; an on the fly EDC check device for performing an EDC operation according to data of the ECC block from the demodulator to generate an EDC result; a data buffer for storing the ECC block and the EDC result; a syndrome generator for generating at least one syndrome according to a PI codeword and a PO codeword of the ECC block stored in the data buffer; an ECC decoder for performing an ECC operation according to the syndrome; and an EDC corrector for correcting the EDC result according to a result of the ECC operation received from the ECC decoder; wherein the syndrome comprises at least one of a PI syndrome and a PO syndrome.

Abstract: Method and apparatus for evaluating different digital data channel configurations. A digital data channel stores input data to a recordable medium and retrieves readback data from the medium. The input data are arranged into an input sequence of symbols of selected symbol length, and the readback data are arranged into an output sequence of symbols of the selected symbol length. Comparing the output sequence to the input sequence allows identification of the number of erroneous symbols for the selected symbol length. Different input and output sequences are generated using different symbol lengths from the same input and output data. In this way, error rate performance can be predicted for different error correction code (ECC) and run length limited (RLL) encoding scheme combinations. The steps are carried out by an emulation system preferably comprising a field programmable gate array (FPGA) which inhibits and emulates selected portions of the digital data channel.

Abstract: A method for decoding multiword information comprises steps (a) to (h). In step (a), a multiword information cluster including high protective words and low protective words is provided, wherein the multiword information, high protective words and low protective words can be ECC data, BIS data and LDC data, respectively. In step (b), the low protective words are partitioned into multiple groups. In step(c), the low protective words are de-interleaved, so as to generate a low protective word cluster including multiple segments corresponding to the multiple groups. In step (d), any error of the low protective words is detected, so as to generate segment erasure indicators with localities. In step (e), the low protective words and the segment erasure indicators are stored into a first memory, e.g., a DRAM. In step (f), the segment erasure indicators are stored into a second memory, e.g., a SRAM. In step (g), erasure bits of the low protective word are generated based on the segment erasure indicators.

Abstract: A method for decoding multiword information comprises multiple steps. In step (a), a multiword information cluster, e.g., ECC, including high protective codewords, e.g., BIS, and low protective codewords, e.g., LDC, is provided. In step (b), the high and low protective codewords are stored into a first memory, e.g., DRAM. In step (c), the high protective codewords are decoded to generate high protective word erasure indicators showing whether decoding errors occur. In step (d), the high protective word erasure indicators are stored into a second memory, e.g., SRAM. In step (e), the low protective codewords are decoded. In the meanwhile, an erasure bit for a low protective codeword is marked by finding high protective codewords close to the low protective codeword in the multiword information cluster and looking up the high protective word erasure indicators of the high protective codewords close to the low protective codeword.

Abstract: If a large minimum data unit for recorded data is used to record a small data amount of management information, the recording time is long, and furthermore when a WO (write once) is used as the recording medium, the number of recording operations which can be performed is restricted. To solve the above problems, the present invention can record data in a management area in units smaller than ordinary units for recorded data to suitably record information in a limited management area and thereby efficiently use the user data area. At that time, the present invention simplifies interleave processing usually applied to ordinary recorded data, and performs the simplified interleave processing on a data structure (for data of small size) of the present invention so as to ensure the signal processing compatibility between the ordinary data and data having the data structure according to the present invention.

Abstract: A communication system includes an encoder that receives user data and includes running digital sum encoding and turbo encoding. The running digital sum encoding is preserved in an encoder output to a channel. A decoder receives a channel output and comprises running digital sum decoding and turbo decoding to reproduce the user data in a decoder output.

Abstract: A method of enhancing the quality of data stored in a system includes receiving data from a first data enterer, accepting data received from the first data enterer into the system if the data are entered in a format compliant with a first set of rules, receiving first additional data from a second data enterer, the first additional data being related to the data received from the first data enterer, and accepting first additional data received from the second data enterer into the system if the data are entered in a format compliant with a second set of rules.

Abstract: A method of reproducing data by performing error correction on data read from a recording medium. The method includes reading a sync pattern, checking if the sync pattern has been read, recovering data following the sync pattern when the sync pattern has not been read, and performing the error correction on the recovered data. The data following the sync pattern is recovered in the error correction, which makes it easier to lengthen the time width of a detection window setting signal for detecting the sync pattern.

Abstract: A method for determining a maximum number of attempted retry operations when a read error occurs in an optical disk device. The method includes the steps of receiving an RF signal from a pickup of the optical disk device, detecting an envelope of the RF signal, asserting a defect signal when a level of the envelope is lower than a predetermined threshold, generating interrupt pulses during the assertion of the defect signal, and determining the maximum number of attempted retry operations using the interrupt pulses.

Abstract: A method and an apparatus for storing a superblock of data codewords. The method includes providing sectorwise error correction codes in the data codewords. The method also includes generating superblock error correction codes as functions of the data codewords. The method includes storing the data codewords and the superblock error correction codes in a plurality of sectors in a storage medium.

Abstract: An error correction block having an extended format compatible with a standardized format of a conventional error correction block, a method and apparatus for generating the error correction block, and a method of correcting an error using the error correction block. The method of generating an error correction block includes adding extra parity information for error correction to input data which is of a smaller size than main data of a standardized reference format, thereby generating an extra error correction block which is the same size as the main data, and generating an error correction block complying with the reference format using the extra error correction block as the main data.

Abstract: A signal processing method multiplexes/arranges digital data of a specific unit to form a predetermined unit, adds an error correction code to the predetermined unit to constitute an error correction coded block, replaces a part of the error correction coded block with specific data, and outputs the error correction coded block with the specific data being replaced to a transmission medium or a recording medium.

Abstract: Disk players for allocating pointers to the respective frames of CD data and storing the pointers in a memory, and methods of processing reproduced data of the disk player are provided. According to one aspect, a disk player includes a pointer controller, which allocates pointers to frames of recorded data read from a disk, wherein the allocation of the pointers starts from a first frame following frames having special sub-code synchronization signals and is performed in a predetermined order; a memory, which stores the frames and the allocated pointers; and a memory controller, which controls an operation of writing the data to memory. A pointer is allocated to every frame of the recorded data reproduced from the disk player, and the allocated pointers and the frame data are stored in the memory. The pointers are retrieved and the respective frame data stored in the memory are output. Therefore, the sound continuity can be maintained even in a vibration environment causing jitter.

Abstract: A method of calculating internal signals for use in a MAP algorithm is disclosed, comprising the steps of: obtaining first decoding signals by processing received systematic and received encoded symbols of each symbol sequence of a received signal; obtaining unnormalized second decoding signals for the current symbol sequence by processing the first decoding signals of the previous sequence and second decoding signals of the previous sequence; obtaining unnormalized third decoding signals for the current symbol sequence by processing the first decoding signals of the current sequence and third decoding signals of the next sequence; normalizing the unnormalized second and third decoding signals; and wherein at least one of said second decoding signals of the previous sequence and said third decoding signals of the next sequence are unnormalised.

Abstract: At the preceding stage of a first one of two APP decoders that constitute a turbo decoder, there is provided a logarithmic-likelihood computing circuit that creates and outputs logarithmic likelihoods L(y?i|yi) of a reproduced signal y?i which is soft information. The first APP decoder has an APP decoding function of receiving logarithmic likelihoods L(y?i|yi) of the reproduced signal yi as well as a priori information as to code data c?i, updating the code data c?i and producing outputs of a posteriori probabilities according to trellis diagram information that satisfy constraints concerning an RLL modulation. Turbo decoding becomes compatible with the RLL demodulation, and a turbo decoding with high error-correcting capability is usable in reproducing channel data ai recorded onto a recording medium, which allows a recording density of the recording medium to be increased.

Abstract: The present invention is a data buffering system for buffering information from an optical recording medium into a buffer memory. The information comprises a main data and a subcode. The system comprises a main target comparator, a correction target comparator and a transfer/buffer module. The main target comparator selects a start main data frame of the main data, and triggers a main data transferring procedure when detecting the start main data frame. The correction target comparator gets a correction main data frame by adding an additional value to the start main data frame, and trigger a subcode transferring procedure when detecting the correction main data frame. The transfer/buffer module transfers and buffers the subcode to the buffer memory and the main data according to the subcode transferring procedure and the main data transferring procedure, respectively.

Abstract: An information reproducing apparatus, in which a disk having correction data recorded thereon is placed, acquires region information indicative of a region corresponding to the correction data after load processing is performed by a ROM loader. Then, under the control of a CPU, the apparatus determines the correction data to be used for correcting a reproducing program based on the region information, reads the correction data from a lead out area or its outer region on the disk, temporarily retains the read correction data in a first RAM or a second RAM, and then stores the correction data to be resident in a nonvolatile first flash memory or a second flash memory, to correct the reproducing program based on the correction data. The information reproducing apparatus thereafter reproduces user data recorded on the disk according to the corrected reproducing program.

Abstract: Data requested from a disk drive by a host is read continuously from sectors in tracks on a rotating disk and is temporarily stored in buffer memory within the disk drive. Before releasing the sectors for host access, each sector is checked for errors, and if errors are identified, error correction is attempted in a correction engine, using a selected error correction facility. If the errors are not corrected using the first selected correction facility, the bad sector is held in the buffer memory until the correction engine is idle. The correction engine is idle, for example, when good sectors (which have no errors) are read and are immediately released for host access. This idle time in the correction engine is used to attempt error correction using one or more different correction facilities. If the errors are corrected using the correction engine's idle time, it is not necessary to re-read the sector.

Abstract: An error correction decoding method and apparatus are provided. The error correction decoding method involves (a) outputting data corresponding to input codewords by referring to a lookup table, which stores data of a predetermined size and corresponding codewords; (b) outputting predetermined error values if there are no matches for the input codewords in the lookup table; (c) forming an error correction block by arraying the data output in step (a) or the error values output in step (b); and (d) performing an error correction decoding process, without allowing codes constituting the error correction block to exchange erasure information with one another, by referring to locations of the error values in the error correction block and the number of errors in the error correction block.

Abstract: An information storage medium includes a drive zone having a plurality of physical clusters or ECC blocks. When new drive data is recorded in the drive zone, the new drive data is recorded in a physical cluster or ECC block next to the physical cluster or ECC block containing the most recently recorded drive data. In the method of recording drive data, the drive data is recorded in a physical cluster or ECC block of the drive zone. When the drive zone is updated with the new drive data, the new drive data is recorded in the physical cluster or ECC block adjacent to physical cluster or ECC block containing the most recently drive data. The drive data recording method is applicable to a new format of information storage medium.

Abstract: When data is read from a disk and stored in volatile memory, check bits are generated and stored in the memory using an algorithm such as cyclical redundancy check (CRC). The CRC algorithm operates on the basis of the bit length in which the data is organized, such as 8 bits. If the data has errors, an error correction code (ECC) algorithm is used to correct the data errors, but the ECC algorithm operates on the basis of symbols having a different bit length, such as 10 bits. To avoid having to re-read the data from the volatile memory to adjust the CRC value, the CRC algorithm is executed on selected mask data developed by the ECC algorithm, the CRC algorithm being executed on the basis of the second bit length to generate a CRC mask. The CRC mask corrects the stored CRC value.

Abstract: In a disk array system of RAID (level 5) improving the system performance by distributing data, duplicated fields are allocated in a parity group in order to reduce an overhead of data write. In the data write process, write data is tentatively and duplicately written in the duplicate fields. At this time, a write completion is reported to CPU. The parity is generated later at a proper timing and written in a SCSI drive. Generating a parity and writing data can be efficiently scheduled.

Abstract: Data is read from a recording medium and the reproduced data is deinterleaved and stored to a first memory while input/output to/from the first memory is arbitrated. It is determined whether a predetermined number of data units is stored to the first memory. Based on the result data, it is determined whether transfer of the data stored in first memory to a second memory is permitted. If data transfer is permitted, the reproduced data is transferred from the first memory to the second memory, during which time input/output to/from the second memory is arbitrated. The reproduced data stored to the second memory is then error corrected, and user data contained in the error corrected reproduction data is externally output from the second memory.