Abstract: A memory system according to an embodiment includes a semiconductor memory, and a memory controller. The semiconductor memory comprises memory cells and word lines. Each of the word lines is connected to the memory cells. The memory controller executes a patrol operation including a read operation of the semiconductor memory. The word lines are classified into one of first and second groups. The memory controller executes patrol operations in which the word lines are respectively selected in a first patrol period and, in a second patrol period subsequent to the first patrol period, executes a patrol operation in which the word line included in the first group is selected and omits a patrol operation in which the word line included in the second group is selected.

Abstract: According to an embodiment, a memory controller obtains first data in a first page using a first voltage, obtains a first shift amount based on a first and second number. The first and second numbers represent numbers of bits each of which has different values in a first and second manner between the first data and first expected data. The controller obtains second data in the second page using a second voltage and a second shift amount, and obtains a third shift amount based on a third and fourth number, the third and fourth numbers respectively represent numbers of bits each of which has different values in the first and second manner between the second data and second expected data.

Abstract: A memory system according to an embodiment includes a semiconductor memory, and a memory controller. The semiconductor memory comprises memory cells and word lines. Each of the word lines is connected to the memory cells. The memory controller executes a patrol operation including a read operation of the semiconductor memory. The word lines are classified into one of first and second groups. The memory controller executes patrol operations in which the word lines are respectively selected in a first patrol period and, in a second patrol period subsequent to the first patrol period, executes a patrol operation in which the word line included in the first group is selected and omits a patrol operation in which the word line included in the second group is selected.

Abstract: According to one embodiment, a shift register memory writes data having a first size corresponding to a capacity of a block to a plurality of layers of a plurality of data storing shift strings included in the block, in response to a first command sequence specifying a first write mode from a controller. In response to a second command sequence specifying a second write mode from the controller, the shift register memory writes data having a second size smaller than the capacity of the block to the plurality of layers of one or more first data storing shift strings of the plurality of data storing shift strings, without writing data to each of other data storing shift strings except the one or more first data storing shift strings.

Abstract: According to an embodiment, a memory controller obtains first data in a first page using a first voltage, obtains a first shift amount based on a first and second number. The first and second numbers represent numbers of bits each of which has different values in a first and second manner between the first data and first expected data. The controller obtains second data in the second page using a second voltage and a second shift amount, and obtains a third shift amount based on a third and fourth number, the third and fourth numbers respectively represent numbers of bits each of which has different values in the first and second manner between the second data and second expected data.

Abstract: A memory system includes a semiconductor storage device and a memory controller including a storage circuit that stores correction value for read voltages in association with the word line, and a control circuit that reads data from the memory cells, performs a correction operation on the read data to determine a number of error bits therein, determines the correction value for each read voltage based on the number of error bits and a ratio of a lower tail fail bit count and an upper tail fail bit count, and stores the correction values for the read voltages in the storage circuit. The lower tail fail bit count represents the number of memory cells in a first state having threshold voltages of an adjacent state, and the upper tail fail bit count represents the number of memory cells in the adjacent state having threshold voltages of the first state.

Abstract: According to one embodiment, a memory system includes a semiconductor memory device and a controller. The semiconductor memory device includes a first memory cell configured to store data. The controller is configured to output a first parameter and a first command. The first parameter relates to an erase voltage for a first erase operation with respect to the first memory cell. The first command instructs the first erase operation. The controller outputs the first command after outputting the first parameter to the semiconductor memory device.

Abstract: According to one embodiment, a memory system includes a semiconductor memory device and a controller. The semiconductor memory device includes a first memory cell configured to store data. The controller is configured to output a first parameter and a first command. The first parameter relates to an erase voltage for a first erase operation with respect to the first memory cell. The first command instructs the first erase operation. The controller outputs the first command after outputting the first parameter to the semiconductor memory device.

Abstract: According to an embodiment, a memory controller obtains first data in a first page using a first voltage, obtains a first shift amount based on a first and second number. The first and second numbers represent numbers of bits each of which has different values in a first and second manner between the first data and first expected data. The controller obtains second data in the second page using a second voltage and a second shift amount, and obtains a third shift amount based on a third and fourth number, the third and fourth numbers respectively represent numbers of bits each of which has different values in the first and second manner between the second data and second expected data.

Abstract: According to an embodiment, a memory controller obtains first data in a first page using a first voltage, obtains a first shift amount based on a first and second number. The first and second numbers represent numbers of bits each of which has different values in a first and second manner between the first data and first expected data. The controller obtains second data in the second page using a second voltage and a second shift amount, and obtains a third shift amount based on a third and fourth number, the third and fourth numbers respectively represent numbers of bits each of which has different values in the first and second manner between the second data and second expected data.

Abstract: According to one embodiment, a shift register memory writes data having a first size corresponding to a capacity of a block to a plurality of layers of a plurality of data storing shift strings included in the block, in response to a first command sequence specifying a first write mode from a controller. In response to a second command sequence specifying a second write mode from the controller, the shift register memory writes data having a second size smaller than the capacity of the block to the plurality of layers of one or more first data storing shift strings of the plurality of data storing shift strings, without writing data to each of other data storing shift strings except the one or more first data storing shift strings.

Abstract: According to one embodiment, a memory system includes a nonvolatile memory and a memory controller. The memory controller is configured: to store, in a buffer, a data set read from a cell unit, and an expected data set generated by an error correction on the data set; to count a number of first and second memory cells corresponding to a first and a second combination of data in the data set and the expected data set, respectively, among the memory cells in the cell unit; to calculate a shift amount of a read voltage used in a read operation from the cell unit, based on the number of the first and second memory cells; and to apply the shift amount to a next read operation from the first cell unit.

Abstract: According to one embodiment, a memory system includes a semiconductor memory device and a controller. The semiconductor memory device includes a first memory cell configured to store data. The controller is configured to output a first parameter and a first command. The first parameter relates to an erase voltage for a first erase operation with respect to the first memory cell. The first command instructs the first erase operation. The controller outputs the first command after outputting the first parameter to the semiconductor memory device.

Abstract: A memory system according to an embodiment includes a semiconductor memory, and a memory controller. The semiconductor memory comprises memory cells and word lines. Each of the word lines is connected to the memory cells. The memory controller executes a patrol operation including a read operation of the semiconductor memory. The word lines are classified into one of first and second groups. The memory controller executes patrol operations in which the word lines are respectively selected in a first patrol period and, in a second patrol period subsequent to the first patrol period, executes a patrol operation in which the word line included in the first group is selected and omits a patrol operation in which the word line included in the second group is selected.

Abstract: According to one embodiment, a memory system includes a nonvolatile memory and a memory controller. The memory controller is configured: to store, in a buffer, a data set read from a cell unit, and an expected data set generated by an error correction on the data set; to count a number of first and second memory cells corresponding to a first and a second combination of data in the data set and the expected data set, respectively, among the memory cells in the cell unit; to calculate a shift amount of a read voltage used in a read operation from the cell unit, based on the number of the first and second memory cells; and to apply the shift amount to a next read operation from the first cell unit.

Abstract: A memory system includes a semiconductor storage device and a memory controller including a storage circuit that stores correction value for read voltages in association with the word line, and a control circuit that reads data from the memory cells, performs a correction operation on the read data to determine a number of error bits therein, determines the correction value for each read voltage based on the number of error bits and a ratio of a lower tail fail bit count and an upper tail fail bit count, and stores the correction values for the read voltages in the storage circuit. The lower tail fail bit count represents the number of memory cells in a first state having threshold voltages of an adjacent state, and the upper tail fail bit count represents the number of memory cells in the adjacent state having threshold voltages of the first state.

Abstract: A memory system according to an embodiment includes a semiconductor memory, and a memory controller. The semiconductor memory comprises memory cells and word lines. Each of the word lines is connected to the memory cells. The memory controller executes a patrol operation including a read operation of the semiconductor memory. The word lines are classified into one of first and second groups. The memory controller executes patrol operations in which the word lines are respectively selected in a first patrol period and, in a second patrol period subsequent to the first patrol period, executes a patrol operation in which the word line included in the first group is selected and omits a patrol operation in which the word line included in the second group is selected.

Abstract: A memory system includes a semiconductor storage device and a memory controller including a storage circuit that stores correction value for read voltages in association with the word line, and a control circuit that reads data from the memory cells, performs a correction operation on the read data to determine a number of error bits therein, determines the correction value for each read voltage based on the number of error bits and a ratio of a lower tail fail bit count and an upper tail fail bit count, and stores the correction values for the read voltages in the storage circuit. The lower tail fail bit count represents the number of memory cells in a first state having threshold voltages of an adjacent state, and the upper tail fail bit count represents the number of memory cells in the adjacent state having threshold voltages of the first state.

Abstract: According to an embodiment, a memory controller obtains first data in a first page using a first voltage, obtains a first shift amount based on a first and second number. The first and second numbers represent numbers of bits each of which has different values in a first and second manner between the first data and first expected data. The controller obtains second data in the second page using a second voltage and a second shift amount, and obtains a third shift amount based on a third and fourth number, the third and fourth numbers respectively represent numbers of bits each of which has different values in the first and second manner between the second data and second expected data.

Abstract: A memory system includes a semiconductor storage device and a memory controller including a storage circuit that stores correction value for read voltages in association with the word line, and a control circuit that reads data from the memory cells, performs a correction operation on the read data to determine a number of error bits therein, determines the correction value for each read voltage based on the number of error bits and a ratio of a lower tail fail bit count and an upper tail fail bit count, and stores the correction values for the read voltages in the storage circuit. The lower tail fail bit count represents the number of memory cells in a first state having threshold voltages of an adjacent state, and the upper tail fail bit count represents the number of memory cells in the adjacent state having threshold voltages of the first state.