A method includes: retrieving a first word comprising a plurality of data bits and a plurality of parity bits that correspond to the first word, wherein the plurality of data bits form N−1 groups and the plurality of parity bits form a first group different from the N−1 groups, and N is a positive integer greater than 2; receiving a request to update respective data bits of a first one of the N−1 groups; and providing a second word comprising updated data bits that form a second one of the N−1 groups and a plurality of updated parity bits that correspond to the second word, wherein the plurality of updated parity bits form a second group that has a same group index as the first one of the N−1 groups.

A semiconductor memory device includes a memory cell array, an error correction code (ECC) engine, a refresh control circuit, a scrubbing control circuit and a control logic circuit. The refresh control circuit generates refresh row addresses for refreshing a memory region on memory cell rows in response to a first command received from a memory controller. The scrubbing control circuit counts the refresh row addresses and generates a scrubbing address for performing a scrubbing operation on a first memory cell row of the memory cell rows whenever the scrubbing control circuit counts N refresh row addresses of the refresh row addresses. The ECC engine reads first data corresponding to a first codeword, from at least one sub-page in the first memory cell row, corrects at least one error bit in the first codeword and writes back the corrected first codeword in a corresponding memory location.

Methods, systems, and media for decoding data are described. A sequence of read-level voltages for decoding operations may be determined based on a trend of decoding success indicators, including a first decoding success indicator and a second decoding success indicator. The first decoding success indicator is obtained from a more recent successful decoding operation. The first one of the sequence may be set to a read-level voltage of the first decoding success indicator. If the read-level voltage of the first decoding success indicator is less than a read-level voltage of the second decoding success indicator, then the trend is decreasing, and the second one of the sequence may be set to a read-level voltage less than that of the first one of the sequence. After executing one or more decoding operations, the decoding success indicators may be updated based on the read-level voltage of the current successful decoding operation.

Methods, systems, and media for decoding data are described. A sequence of read-level voltages for decoding operations may be determined based on a trend of decoding success indicators, including a first decoding success indicator and a second decoding success indicator. The first decoding success indicator is obtained from a more recent successful decoding operation. The first one of the sequence may be set to a read-level voltage of the first decoding success indicator. If the read-level voltage of the first decoding success indicator is less than a read-level voltage of the second decoding success indicator, then the trend is decreasing, and the second one of the sequence may be set to a read-level voltage less than that of the first one of the sequence. After executing one or more decoding operations, the decoding success indicators may be updated based on the read-level voltage of the current successful decoding operation.

A semiconductor memory device includes a memory cell array, an error correction code (ECC) circuit, a fault address register and a control logic circuit. The memory cell array includes a plurality of memory cell rows. The scrubbing control circuit generates scrubbing addresses for performing a scrubbing operation on a first memory cell row based on refresh row addresses for refreshing the memory cell rows. The control logic circuit controls the ECC circuit such that the ECC circuit performs an error detection and correction operation on a plurality of sub-pages in the first memory cell row to count a number of error occurrences during a first interval and determines a sub operation in a second interval in the scrubbing operation based on the number of error occurrences in the first memory cell row.

A semiconductor memory device includes a memory cell array, an error correction code (ECC) circuit, a fault address register and a control logic circuit. The memory cell array includes a plurality of memory cell rows. The scrubbing control circuit generates scrubbing addresses for performing a scrubbing operation on a first memory cell row based on refresh row addresses for refreshing the memory cell rows. The control logic circuit controls the ECC circuit such that the ECC circuit performs an error detection and correction operation on a plurality of sub-pages in the first memory cell row to count a number of error occurrences during a first interval and determines a sub operation in a second interval in the scrubbing operation based on the number of error occurrences in the first memory cell row.

According to one embodiment, a memory system includes: a controller configured to execute an error correction process on first data read from a first area at a first address of a memory device and determine a read level used for reading data at the first address according to a result of the correction process. The controller executes the correction process on first frame data of the first data. When the correction process on the first frame data has failed, the controller executes the correction process on second frame data of the first data. When the correction process on the second frame data has succeeded, the controller determines the read level based on a result of comparison between the second frame data and a result of the correction process on the second frame data.

According to one embodiment, a memory system includes: a controller configured to execute an error correction process on first data read from a first area at a first address of a memory device and determine a read level used for reading data at the first address according to a result of the correction process. The controller executes the correction process on first frame data of the first data. When the correction process on the first frame data has failed, the controller executes the correction process on second frame data of the first data. When the correction process on the second frame data has succeeded, the controller determines the read level based on a result of comparison between the second frame data and a result of the correction process on the second frame data.

Methods and apparatus for configurable ECC (error correction code) mode in DRAM. Selected memory cells in the bank arrays of a DRAM device (e.g., die) are used to store ECC bits. A DRAM device (e.g., die) is configured to operate in a first mode in which an on-die ECC engine employs selected bits in the arrays of memory cells in the DRAM banks as ECC bits to perform ECC operations and to operate in a second mode under which the ECC bits are not employed for ECC operations by the ECC engine and made available for external use by a host. In the second mode, the repurposed ECC bits may comprise RAS bits used for RAS (Reliability, Serviceability, and Availability) operations and/or metabits comprising metadata used for other operations by the host.

Methods and apparatus for configurable ECC (error correction code) mode in DRAM. Selected memory cells in the bank arrays of a DRAM device (e.g., die) are used to store ECC bits. A DRAM device (e.g., die) is configured to operate in a first mode in which an on-die ECC engine employs selected bits in the arrays of memory cells in the DRAM banks as ECC bits to perform ECC operations and to operate in a second mode under which the ECC bits are not employed for ECC operations by the ECC engine and made available for external use by a host. In the second mode, the repurposed ECC bits may comprise RAS bits used for RAS (Reliability, Serviceability, and Availability) operations and/or metabits comprising metadata used for other operations by the host.