Abstract: An address generator for providing an address to one of a linear block encoder and a soft linear block code decoder comprises a counter to count c, a position of a bit within a codeword of user data and to count r the codeword, where r=floor(c/74), An inner deinterleaver deinterleaves count c counted by the counter and to output c?. A shift circuit shifts the deinterleaved count c? by the inner deinterleaver in accordance with count r counted by the counter and to output c?.

Abstract: An encoder includes an information holding section which stores flag bytes and an initial address, a data generation section which generates sets of first parity symbols from the initial address and the flag bytes, a parity generation section which generates and outputs sets of second parity symbols, for each column of data units included in the block, from the columns of data units included in the block and input user control data. The data generation section generates the addresses and the sets of first parity symbols, required to generate the columns of data units included in the block, based on the initial address and the flag bytes, selects necessary portions from the flag bytes and the addresses and the sets of first parity symbols generated, and outputs the portions to the parity generation section, as the columns of data units included in the block.

Abstract: Method, system and computer program product are provided for detecting and correcting dropped writes in a storage system. Data and a checksum are written to a storage device, such as a RAID array. The state of the data is classified as being in a “new data, unconfirmed” state. The state of written data is periodically checked, such as with a timer. If the data is in the “new data, unconfirmed” state, it is checked for a dropped write. If a dropped write has occurred, the state of the data is changed to a “single dropped write confirmed” state and the dropped write error is preferably corrected. If no dropped write is detected, the state is changed to a “confirmed good” state. If the data was updated through a read-modified-write prior to being checked for a dropped write event, its state is changed to an “unquantifiable” state.

Abstract: Methods are provided for detecting and correcting dropped writes in a storage system. Data and a checksum are written to a storage device, such as a RAID array. The state of the data is classified as being in a “new data, unconfirmed” state. The state of written data is periodically checked, such as with a timer. If the data is in the “new data, unconfirmed” state, it is checked for a dropped write. If a dropped write has occurred, the state of the data is changed to a “single dropped write confirmed” state and the dropped write error is preferably corrected. If no dropped write is detected, the state is changed to a “confirmed good” state. If the data was updated through a read-modified-write prior to being checked for a dropped write event, its state is changed to an “unquantifiable” state.

Abstract: The LDPC decoder includes a processor for updating messages exchanged iteratively between variable nodes and check nodes of a bipartite graph of the LDPC code. The decoder architecture is a partly parallel architecture clocked by a clock signal. The processor includes P processing units. First variable nodes and check nodes are mapped on the P processing units according to two orthogonal directions. The decoder includes P main memory banks assigned to the P processing units for storing all the messages iteratively exchanged between the first variable nodes and the check nodes. Each main memory bank includes at least two single port memory partitions and one buffer the decoder also includes a shuffling network and a shift memory.

Abstract: The search key and key fields of a CAM in a cache are encoded with a Hamming distance of at least two to increase the speed of the CAM by ensuring each mismatching match line is discharged by at least two transistors in parallel. Where the cache is physically tagged, the search key is a physical address. The page address portion of the physical address is encoded prior to being stored in a TLB. The page offset bits are encoded in parallel with the TLB access, and concatenated with the encoded TLB entry. If a page address addresses a large memory page size, a plurality of corresponding sub-page addresses may be generated, each addressing a smaller page size. These sub-page addresses may be encoded and stored in a micro TLB. The encoded key and key field are tolerant of single-bit soft errors.

Abstract: A parity adder obtains a second data by adding a parity for first data to be written to a memory to the first data. An access-key register holds an access key unique to a source of request. A first operating unit obtains a third data by calculating an XOR between the second data and the access key, the access key being set by the source of request for writing data to the memory. A second operating unit obtains a fourth data by calculating an XOR between the access key and the third data. A syndrome calculator calculates a syndrome from the third data, the access key being set by the source of request for reading data from the memory. A determining unit determines whether to output the third data as the first data, based on calculated syndrome.

Abstract: An access control apparatus includes a parity generator that generates a parity for original data to be written into a memory; and a parity adder that generates parity-added data by adding the parity to the original data; a first syndrome generator that generates a first syndrome of first mask data to mask the parity-added data. The first syndrome is a value associated beforehand with a first access code to be used when a writer accesses the memory. The apparatus also includes a first mask generator that generates the first mask data based on the first syndrome, the first access code, and a first memory address; a first XOR unit that obtains first post-operation data by calculating an XOR between the parity-added data and the first mask data; and a writing unit that writes the first post-operation data into the memory.

Abstract: An apparatus comprising a storage array, a primary controller, a secondary controller and a solid state device. The storage array may be configured to be accessed by a plurality of controllers. A first of the plurality of the controllers may be configured as the primary controller configured to read and write to and from the storage array during a normal condition. A second of the plurality of the controllers may be configured as the secondary controller configured to read and write to and from the storage array during a fault condition. The solid state device may be configured to (i) store data and (ii) be accessed by the storage array and the secondary controller.

Abstract: A decoder for decoding low-density parity-check codes includes a first calculator that calculates ??rRml, for each parity check equation, at iteration i?1. A second calculator calculates ??rQ?m, for each parity check equation, at iteration i. ??rQ?m represents information from bit node I to equation node m, one for each connection. ??rRml represents information from equation node m to bit node I, one for each connection. The first calculator is responsive to the second calculator.

Abstract: A dual ported replicated data cache. The cache is configured for storing input data blocks. The cache includes an augmenter for producing an augmented data block with parity information from the input data block, a first memory array for storing the augmented data block, and a second memory array for storing the augmented data block.

Abstract: A memory address generation method and circuit architecture for time-multiplexed RS-based LDPC code decoder is presented. The method is developed for non quasi-cyclic RS-based LDPC code decoder implementation. A circuit for the memory address generation method achieves low area. High throughput time-multiplexed RS-based LDPC code decoder design models and circuit architectures are presented. The decoder models are specifically developed for 10BASE-T (10-Gigabit Ethernet Transceiver Over Copper) system. These time-multiplexed architectures enable higher throughput with lower area.

Abstract: A tag storing unit stores, in a plurality of entries, a plurality of tags corresponding to a plurality of addresses, a parity bit of each of the tags, and a reverse bit obtained by reversing the parity bit. A data storing unit stores a plurality of data corresponding to the tags in a plurality of entries. A comparing unit compares an address for search with a tag of each of the entries. A determining unit performs an OR-operation on contents stored in a plurality of entries when a multiple hit occurs from a comparison by the comparing unit, and determines a cause of the multiple hit based on a parity bit and a reverse bit obtained after the OR-operation.

Abstract: A computer system including: at least one host computer, a storage system for storing data used in the host computer, and a managing computer for managing storing the data in the storage system which are connected to each other with a network. The managing computer monitors the journal volume which is a storing destinations of the journal, in a case that the journal is stored in the journal volume in parallel, when it is detected that the storing destination of the journal changes from one of the groups into which the journal is just stored to another group, transmits an instruction to the storage system to change the storing destination of the journal to another group.

Abstract: A Random Access Error Detection and Correction unit (RAEDAC) that incorporates a bit-wise error detection and correction unit (BEDAC) in a memory system. In one embodiment, a word-wise error detection and correction unit (WEDAC) operates in coordination with a BEDAC that performs a bit-wise parity calculation. In another embodiment, a WEDAC operates in coordination with a full bit-wise BEDAC that calculates bit-wise check bits. The RAEDAC may be applied to create a multi-dimensional EDAC where, for example, the memory is partitioned into a stack of planes, and a stack-wise error detection and correction unit (SEDAC) is implemented.

Abstract: An apparatus to manage data stability, including a plurality of storage units and a control unit to determine when protected data is stored in a particular address row of at least one of the plurality of storage units, to select another storage unit of the plurality of storage units to store the protected data, and to store relevance data related to the protected data in the same address row of the selected storage unit. Methods of storing and recover data also included.

Abstract: A memory device for an error-correcting block code is provided, whereby each code word of the block code can have data bits and parity bits. The device also includes a memory for storing the data bits and the parity bits of each code word, and includes an error detection circuit, which is formed to detect an error of the data bits in a code word by evaluating exactly one subset of the stored parity bits of the code word. The subset being smaller than the total number of parity bits of the code word.

Abstract: A system and method for providing an adapter for re-use of legacy DIMMS in a fully buffered memory environment. The system includes a memory adapter card having two rows of contacts along a leading edge of a length of the card. The rows of contacts are adapted to be inserted into a socket that is connected to a daisy chain high-speed memory bus via a packetized multi-transfer interface. The memory adapter card also includes a socket installed on the trailing edge of the card. In addition, the memory adapter card includes a hub device for converting the packetized multi-transfer interface into a parallel interface having timings and interface levels that are operable with a memory module having a parallel interface that is inserted into the socket. In addition, the hub device converts the packetized multi-transfer interface into a parallel interface having timings and interface levels that are operable with a memory module having a parallel interface that is inserted into the socket.

Abstract: A triple parity (TP) technique reduces overhead of computing diagonal and anti-diagonal parity for a storage array adapted to enable efficient recovery from the concurrent failure of three storage devices in the array. The diagonal parity is computed along diagonal parity sets that collectively span all data disks and a row parity disk of the array. The parity for all of the diagonal parity sets except one is stored on the diagonal parity disk. Similarly, the anti-diagonal parity is computed along anti-diagonal parity sets that collectively span all data disks and a row parity disk of the array. The parity for all of the anti-diagonal parity sets except one is stored on the anti-diagonal parity disk. The TP technique provides a uniform stripe depth and an optimal amount of parity information.

Abstract: The resistance against recording defects of a write-once optical disk is enhanced allowing realtime recording and playback of data streams with a single speed disk drive. A data stream is recorded in data blocks on the optical disk. An error correction block for one or more data blocks is generated and written on the same optical disk during recording. A spare data area is kept blank on the storage medium and used for storing a defect data block reconstructed by using the error correction block.

Abstract: Verifying a file in a system with duplicate segment elimination is disclosed. A data file is segmented into a plurality of distinct data segments, and a checksum is computed for each of the plurality of distinct data segments. A constructed data file checksum is constructed from the checksums of each of the plurality of distinct data segments, and, it is determined if a checksum of the data file is the same as the constructed data file checksum.

Abstract: An apparatus, system, and method are disclosed for detecting and replacing failed data storage. A read module reads data from an array of memory devices. The array includes two or more memory devices and one or more extra memory devices storing parity information from the memory devices. An ECC module determines, using an error correcting code (“ECC”), if one or more errors exist in tested data and if the errors are correctable using the ECC. The tested data includes data read by the read module. An isolation module selects a memory device in response to the ECC module determining that errors exists in the data read by the read module and that the errors are uncorrectable using the ECC. The isolation module also replaces data read from the selected memory device with replacement data and available data wherein the tested data includes the available data combined with the replacement data.

Abstract: Techniques are described for use by an implantable medical device equipped to use trim values, which allow the device to continue to use trim values despite certain memory errors such as parity errors. Briefly, optimal trim values are stored within RAM. Nominal trim values are stored within ROM. Device functions are then performed using the trim values stored within RAM. If an error is detected indicative of possible corruption of RAM, then the trim values from ROM are loaded into RAM to enable continued operation of the device using the nominal trim values despite the error. In a preferred implementation, the optimized trim values are initially stored at two separate locations within RAM. A procedure is described herein for allowing the device to continue to use the optimized trim values following a device reset if no parity error is detected. If a parity error occurred, the device instead uses the nominal trim values from ROM.

Abstract: A method and system for indicating an executable as Trojan Horse, based on the CRC values of the routines of an executable. The method comprising a preliminary stage in which the CRC values of the routines of known Trojan Horses are gathered in a database, and a stage in which indicating an executable as Trojan Horse is carried out by the correspondence of the CRC values of the routines of said executable to the CRC values of the known Trojan Horses, as gathered in said database. The system comprising means for calculating the CRC values of routines; means for identifying the borders of the routines of an executable; a database system, for storing the CRC values of routines of known Trojan Horses; and means for determining the correspondence between two groups of CRC values, thereby enabling detection of the correspondence of an executable to at least one known Trojan Horse.

Abstract: A method for writing data to a storage pool includes receiving a write operation to write a logical block of data to the storage pool, determining a number (n?1) of physical blocks required to store the logical block of data, generating a parity block using the logical block of data, allocating n physical blocks in the storage pool, writing the parity block in the first of n allocated physical block, and writing the logical block of data across the remaining n?1 allocated physical blocks, where n is less than a number of disks in the storage pool, and where each of the n allocated physical blocks is located on a different disk in the storage pool.

Abstract: The storage apparatus is provided with a host interface adapter unit, a storage interface adapter unit, a cache memory unit storing data temporarily, a switch unit connecting the host interface adapter unit, the storage interface adapter unit, and the cache memory unit, a compressed data circuit unit producing compressed data based upon writing data into the physical storing device, and a compressed data saving unit saving compressed data produced in the compressed data circuit unit, where the compressed data circuit unit compressed reading data at a reading time of the data from the physical storing device, and compares the compressed data with compressed data corresponding to reading data saved in the compressed data saving unit with each other, and detects data rigging.

Abstract: Techniques are described for detecting corruption of buffer pointers passed between a local processor and a remote processor on a network device. For example, the first processor, which may be a memory controller, receives and stores packets within memory. A second processor, such as a host processor for the network device, is coupled to the first processor by a bus. The first processor communicates a memory pointer associated with an a given packet to the second processor for processing of the packet, and maintains a backup copy of the memory pointer. Upon receiving the memory pointer back from the second processor, the first processor compares at least a portion of the memory pointer received from the second processor with an equivalent portion of the copy of the memory pointer to determine whether the received memory pointer has been corrupted.

Abstract: Example embodiments may provide a memory device and memory data reading method. The memory device according to example embodiments may include a multi-bit cell array, an error detector which may read a first data page from a memory page in the multi-bit cell array and may detect an error-bit of the first data page, and an estimator which may identify a multi-bit cell where the error-bit is stored and may estimate data stored in the identified multi-bit cell among data of a second data page. Therefore, the memory device and memory data reading method may have an effect of reducing an error when reading data stored in the multi-bit cell and monitoring a state of the multi-bit cell without additional overhead.

Abstract: An approach is provided for bit labeling of a signal constellation. A transmitter generates encoded signals using, according to one embodiment, a structured parity check matrix of a Low Density Parity Check (LDPC) code. The transmitter includes an encoder for transforming an input message into a codeword represented by a plurality of set of bits. The transmitter includes logic for mapping non-sequentially (e.g., interleaving) one set of bits into a higher order constellation (Quadrature Phase Shift Keying (QPSK), 8-PSK, 16-APSK (Amplitude Phase Shift Keying), 32-APSK, etc.), wherein a symbol of the higher order constellation corresponding to the one set of bits is output based on the mapping.

Abstract: An external expanding apparatus or “docking station” operable with a portable computer device of a type having a display unit having a display screen on an inner surface thereof and a hard shell backing surface opposite thereof and pivotally mounted on a substantially rigid casing having a pair of locating holes adjacent to opposite corners of a substantially planar bottom surface thereof, and an input/output (I/O) connector positioned on a back plane thereof with a pair of positioning apertures provided on opposite sides thereof.

Abstract: A cyclic redundancy check (CRC) system for a storage controller comprises a memory that stores first sector data and a corresponding CRC non-zero seed value. A buffer control module includes a CRC module, calculates a CRC value of the first sector data with the CRC module, and combines the CRC value with the CRC non-zero seed value.

Abstract: A memory system includes a main memory, a sub-memory, a controller, first and second data readers and a comparator. The main memory stores data and the sub-memory stores data extracted from the data stored in the main memory for detection of an attack. The controller controls operations of the memory system through interfacing with a host. The first data reader is configured to read first data from the main memory based on address information from the controller. The second data reader is configured to store information relating to second data stored in the sub-memory and to read the second data from the sub-memory based on address information from the controller which is the same as the address information received by the first data reader. The comparator compares the first data read by the first data reader with the second data read by the second data reader to detect the attack.

Abstract: A computer system configured to enhance data protection. A computer system includes one or more clients, such as processing subsystems and a memory subsystem interconnected via a network. Transactions within the system may involve the separation of data and a corresponding address in both space and time. At various points in the system, operations may be performed which seek to reunite a data and corresponding address, such as a store operation. In order to further ensure the correspondence of data and an address which is to be used in an operation, clients are configured to generate and utilize an additional symbol. The symbol is generated at least in part on an address which corresponds to data. The symbol is then associated with the data and serves to represent the corresponding address. The symbol may then be utilized by various clients within the system to check an address which is proposed to be used in an operation with the data.

Abstract: A data-recording/reproducing apparatus and method, that determine a reproduction position with high degree of reliability for data recorded on an information-recording medium even after the data is edited. From a process to edit an AV stream file, a DV data recording/reproducing apparatus splits a DVF-sequence into sequences including consecutive frames. When data is deleted in sector units in the edit process, pieces of data included in deleted frames are left at the beginning and end of each of the sequences. The DV data recording/reproducing apparatus records data representing the length of the data left at the head and the end of the sequences, data representing a frame number assigned to a frame located at the head of the sequences, and data representing the number of frames included in the sequences, on a disc used as the information-recording medium, for example an optical disc.

Abstract: Systems and methods of storing error correction data are provided. A method may include storing data at a first memory having a first non-volatile memory type. The method may also include determining error correction data related to the stored data. The method may further include storing the error correction data at a second memory having a second non-volatile memory type. The first non-volatile memory may have a slower random access capability than the second non-volatile memory.

Abstract: A method for improving the reliability of host data stored on Fiber Channel attached storage subsystems by performing end-to-end data integrity checks. When a read or write operation is initiated, an initial checksum for data in the read/write operation is generated and associated with the data, wherein the association exists through a plurality of layers of software and attached storage subsystems. The initial checksum is passed with the data in the read/write path. When a layer of software in the read/write path receives the initial checksum and data, the layer performs an integrity check of the data, which includes generating another checksum and comparing it to the initial checksum. If the checksums do not match, the read/write operation fails and the error is logged. If the checksums match, the integrity check is repeated through each layer in the read/write path to enable detecting data corruption at the point of source.

Abstract: A decoder for decoding low-density parity-check codes comprises a first calculator to calculate LLrRml, for each parity check equation, at iteration i?1. A detector detects LLrRml, at iteration i, in response to the first calculator. A second calculator calculates LLrQLm, for each parity check equation, at iteration i in response to the detector. LLrQLm represents information from bit node l to equation node m, one for each connection. LLrRml represents information from equation node m to bit node l, one for each connection. The first calculator is responsive to the second calculator.

Abstract: Apparatus and methods for autonomously identifying and mitigating soft-errors affecting integrated circuit memory storage devices are provided. A soft-error mitigation process is invoked upon finding that an integrated circuit memory device is affected by a parity error. In a staged approach, unused memory regions of the integrated circuit memory device are reinitialized; if a redundant deployment prevails, the subsystem corresponding to the affected integrated circuit memory device is reset; memory regions having copies of contents thereof stored at remote locations are rewritten with obtained copies of the contents; and memory regions storing contents which are generated at run-time are reinitialized. Directed parity error scans are employed at each stage. If the parity error persists, one of the apparatus, and the subsystem corresponding to the affected silicon memory device is reset during a maintenance window.

Abstract: The embodiments of the invention provide a method, apparatus, etc. for a cache arrangement for improving RAID I/O operations. More specifically, a method begins by partitioning a data object into a plurality of data blocks and creating one or more parity data blocks from the data object. Next, the data blocks and the parity data blocks are stored within storage nodes. Following this, the method caches data blocks within a partitioned cache, wherein the partitioned cache includes a plurality of cache partitions. The cache partitions are located within the storage nodes, wherein each cache partition is smaller than the data object. Moreover, the caching within the partitioned cache only caches data blocks in parity storage nodes, wherein the parity storage nodes comprise a parity storage field. Thus, caching within the partitioned cache avoids caching data blocks within storage nodes lacking the parity storage field.

Abstract: Disclosed are an error-detecting encoding apparatus for creating parity bits by error-detecting encoding processing, appending the parity bits to an input data string and encoding the data string, and an error-detecting decoding apparatus for detecting error using these parity bits. Data segmenting means segments an input data string, which is to undergo error-detecting encoding, into a plurality of sub-data strings, dividing means divides the segmented sub-data strings by a polynomial, which is for generating an error-detecting code, and calculates remainders, converting means applies conversion processing, which conforms to a segmentation position of the sub-data strings, to the remainders on a per-remainder basis, and combining means combines converted values, which have been obtained by the conversion processing, and outputs parity bits. An encoder appends this parity to a data string, and a decoder detects error using this parity.

Abstract: An approach is provided for a method of encoding structure Low Density Parity Check (LDPC) codes. Memory storing information representing a structured parity check Matrix of Low Density Parity Check (LDPC) codes is accessed during the encoding process. The information is organized in tabular form, wherein each row represents occurrences of one Values within a first column of a group of columns of the parity check matrix. The rows correspond to groups of columns of the parity check matrix, wherein subsequent columns within each of the groups are derived according to a predetermined operation. An LDPC coded signal is output based on the stored information representing the parity check matrix.

Abstract: A detection and recovery mechanism is herein disclosed for soft errors corrupting TLB data. The mechanism works with a hardware page walker (HPW) and instruction steering control mechanisms in a processor to provide soft error recovery in the TLB arrays and latches. Through use of the disclosed detection and recovery mechanism, efficient and robust protection from silent data corruption is provided without requiring more expensive built-in redundancy.

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: The parity of this invention includes two arrays of parities surrounding the memory. One array is generated in parallel. The other array is generated in serial. The two dimensional parity is used to protect, locate and correct errors automatically. The second parity is provided for only a subset of the address range of the memory. The memory controller does not compare the second parities unless there is a soft error in the first parity. The second parities are calculated upon command and not upon each memory write as the first parity.

Abstract: A high reliability dual inline memory module with a fault tolerant address and command bus for use in a server. The memory module is a card approximately 151.35 mm or 5.97 inches long provided with about a plurality of contacts of which some are redundant, a plurality of DRAMs, a phase lock loop, a 2 or 32K bit serial EE PROM and a 28 bit and a 1 to 2 register having error correction code (ECC), parity checking, a multi-byte fault reporting circuitry for reading via an independent bus, and real time error lines for determining and reporting both correctable errors and uncorrectable error conditions coupled to the server's memory interface chip and memory controller or processor such that the memory controller sends address and command information to the register via address/command lines together with check bits for error correction purposes to the ECC/Parity register.

Abstract: A mobile communication terminal with a NAND flash memory is described. The terminal includes a memory for storing address information indicative of a start address of a specific area including boot data to be read from the NAND flash memory; and a sub-controller for determining whether a predetermined block including the boot data of the NAND flash memory is a bad block incapable of being booted, requesting transmission of the address information from a main controller when the predetermined block is determined to be the bad block, and reading the boot data from the predetermined block of the NAND flash memory corresponding to the address information transmitted from the main controller. The main controller detects the address information stored in the memory upon receiving the transmission request of the address information from the sub-controller, and transmits the detected address information to the sub-controller.

Abstract: A method and circuit is provided for detecting and correcting errors in an array of content addressable memory (CAM) cells. The array includes wordlines, searchlines, bitlines, and matchlines for reading from, writing to, and searching CAM cells in the array.

Abstract: One embodiment of the present invention provides a demultiplexer implemented as a nanowire crossbar or a hybrid nanowire/microscale-signal-line crossbar with resistor-like nanowire junctions. The demultiplexer of one embodiment provides demultiplexing of signals input on k microscale address lines to 2k or fewer nanowires, employing supplemental, internal address lines to map 2k nanowire addresses to a larger, internal, n-bit address space, where n>k. A second demultiplexer embodiment of the present invention provides demultiplexing of signals input on n microscale address lines to 2k nanowires, with n>k, using 2k, well-distributed, n-bit external addresses to access the 2k nanowires.

Abstract: Determining an error-correcting code (ECC) for a cache entry based at least on the data stored in the cache entry and the memory address at which the data is permanently stored is disclosed. A cache entry for a desired memory address is retrieved. The cache entry includes data and a stored ECC based on the data and a memory address. An ECC is determined based at least on the data of the cache entry and the desired memory address. If the ECC at least based on the cache entry data and the desired memory address equals the stored ECC, then the cache entry caches the desired memory address without error.

Abstract: An error correcting apparatus includes a storing means for storing product code with n2 rows and n1 columns, an error correcting unit 5 that performs error correction for four code sequences simultaneously in parallel, and a bus control unit 2 for reading codes on four rows from the buffer memory 1 and transferring the codes to the error correcting unit 5. The bus control unit 2 reads and transfers four consecutive codes on each of four rows in order before shifting the reading position by four codes in the row direction.