Abstract: According to an embodiment, a semiconductor memory, on receiving a first command, applies a voltage within a first range and a voltage within a second range to a word line and reads a first bit from a memory cell, and, on receiving a second command, applies a voltage within a third range to the word line and reads a second bit from the memory cell. The controller issues the first command a plurality of times and changes the voltages to be applied to the word line within the first range and the second range in accordance with the plurality of first commands, specifies a first and second voltage within the first and the second range, respectively, and estimates a third voltage within the third range. The voltage applied to read the second bit is the estimated third voltage.

Abstract: According to one embodiment, a nonvolatile memory includes: a memory cell array including memory cells; and a controller configured to execute a first refresh process on receiving a first command. The first refresh process includes reprogramming at least one second memory cell among first memory cells to which data has been programmed in a first group. In executing the first refresh process, the controller is configured to: select the second memory cell by verifying with a first voltage using a first amount in a case where the second memory cell has been programmed using the first voltage; and select the second memory cell by verifying with a second voltage using a second amount in a case where the second memory cell has been programmed using the second voltage.

Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory includes first to fourth word lines and first to fourth memory cells. The controller is configured to issue first and second instructions. The controller is further configured to execute a first operation to obtain a first read voltage based on a threshold distribution of the first memory cell, and a second operation to read data from the second memory cell.

Abstract: According to one embodiment, a memory system includes a semiconductor memory device and a controller. The device includes a plurality of memory cells capable of storing at least first to third data and a word line coupled to the plurality of memory cells. The first data is determined by a first read operation including a first read level. The second data is determined by a second read operation including a second read level. The third data is determined by a third read operation including a third read level. The controller controls the semiconductor memory device to perform a forth read operation including the first and second read levels in a search operation for first to third read voltages corresponding to the first to third read levels, respectively.

Abstract: According to an embodiment, a semiconductor memory, on receiving a first command, applies a voltage within a first range and a voltage within a second range to a word line and reads a first bit from a memory cell, and, on receiving a second command, applies a voltage within a third range to the word line and reads a second bit from the memory cell. The controller issues the first command a plurality of times and changes the voltages to be applied to the word line within the first range and the second range in accordance with the plurality of first commands, specifies a first and second voltage within the first and the second range, respectively, and estimates a third voltage within the third range. The voltage applied to read the second bit is the estimated third voltage.

Abstract: A memory system includes a memory chip and a memory controller. The memory chip has a first plane and a second plane. A threshold voltage corresponding to multiple bit data is set for each of the memory cells. The memory controller causes the memory chip to execute a first read process on the first plane and the second plane in parallel by using a plurality of first read voltages different from each other for the first plane and the second plane. The first read process being a process of reading a data group of one bit among the multiple bits by using the first read voltages. The memory controller subsequently adjusts the voltage levels of the first read voltages on the basis of the data group read from the memory cells of the first plane and the data group read from the memory cells of the second plane.

Abstract: In general, according to an embodiment, a memory system includes a memory device including a memory cell; and a controller. The controller is configured to: receive first data from the memory cell in a first data reading; receive second data from the memory cell in a second data reading that is different from the first data reading; convert a first value that is based on the first data and the second data, to a second value in accordance with a first relationship; and convert the first value to a third value in accordance with a second relationship that is different from the first relationship.

Abstract: According to one embodiment, a memory system includes a semiconductor memory device and a controller. The device includes a plurality of memory cells capable of storing at least first to third data and a word line coupled to the plurality of memory cells. The first data is determined by a first read operation including a first read level. The second data is determined by a second read operation including a second read level. The third data is determined by a third read operation including a third read level. The controller controls the semiconductor memory device to perform a forth read operation including the first and second read levels in a search operation for first to third read voltages corresponding to the first to third read levels, respectively.

Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory includes first to fourth word lines and first to fourth memory cells. The controller is configured to issue first and second instructions. The controller is further configured to execute a first operation to obtain a first read voltage based on a threshold distribution of the first memory cell, and a second operation to read data from the second memory cell.

Abstract: According to an embodiment, a semiconductor memory, on receiving a first command, applies a voltage within a first range and a voltage within a second range to a word line and reads a first bit from a memory cell, and, on receiving a second command, applies a voltage within a third range to the word line and reads a second bit from the memory cell. The controller issues the first command a plurality of times and changes the voltages to be applied to the word line within the first range and the second range in accordance with the plurality of first commands, specifies a first and second voltage within the first and the second range, respectively, and estimates a third voltage within the third range. The voltage applied to read the second bit is the estimated third voltage.

Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory includes: first memory cells, first word lines, a first row decoder, and a driver circuit. The first row decoder includes first transistors capable of coupling the first word lines to first signal lines, and a first block decoder supplying a first block selection signal to the first transistors. When the controller issues a data read command, the first block decoder asserts the first block selection signal to allow the first transistors to transfer a first voltage to a selected first word line, and a second voltage to unselected other first word lines. After data is read, the first block decoder continues asserting the first block selection signal, and the driver circuit transfers a third voltage.

Abstract: According to one embodiment, a nonvolatile memory includes: a memory cell array including memory cells; and a controller configured to execute a first refresh process on receiving a first command. The first refresh process includes reprogramming at least one second memory cell among first memory cells to which data has been programmed in a first group. In executing the first refresh process, the controller is configured to: select the second memory cell by verifying with a first voltage using a first amount in a case where the second memory cell has been programmed using the first voltage; and select the second memory cell by verifying with a second voltage using a second amount in a case where the second memory cell has been programmed using the second voltage.

Abstract: According to an embodiment, a control circuitry performing: a first operation of reading data out of a memory cell with a first voltage applied to a word line while changing the first voltage by a first shift amount within a first range, and a second operation of reading data out of the memory cell with a second voltage applied to the word line while changing the second voltage by a second shift amount within a second range, wherein the second shift amount is smaller than the first shift amount, and wherein the control circuitry performs the second operation to apply the second voltage to the word line subsequently to application of the first voltage to the word line in the first operation.

Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory includes: first memory cells, first word lines, a first row decoder, and a driver circuit. The first row decoder includes first transistors capable of coupling the first word lines to first signal lines, and a first block decoder supplying a first block selection signal to the first transistors. When the controller issues a data read command, the first block decoder asserts the first block selection signal to allow the first transistors to transfer a first voltage to a selected first word line, and a second voltage to unselected other first word lines. After data is read, the first block decoder continues asserting the first block selection signal, and the driver circuit transfers a third voltage.

Abstract: According to an embodiment, a control circuitry performing: a first operation of reading data out of a memory cell with a first voltage applied to a word line while changing the first voltage by a first shift amount within a first range, and a second operation of reading data out of the memory cell with a second voltage applied to the word line while changing the second voltage by a second shift amount within a second range, wherein the second shift amount is smaller than the first shift amount, and wherein the control circuitry performs the second operation to apply the second voltage to the word line subsequently to application of the first voltage to the word line in the first operation.

Abstract: According to one embodiment, a nonvolatile memory includes: a memory cell array including memory cells; and a controller configured to execute a first refresh process on receiving a first command. The first refresh process includes reprogramming at least one second memory cell among first memory cells to which data has been programmed in a first group. In executing the first refresh process, the controller is configured to: select the second memory cell by verifying with a first voltage using a first amount in a case where the second memory cell has been programmed using the first voltage; and select the second memory cell by verifying with a second voltage using a second amount in a case where the second memory cell has been programmed using the second voltage.

Abstract: According to one embodiment, a controller is configured to write four-bit data in each of memory cells, and read first data item from the memory cells through application of a first voltage to a word line. The controller is configured to read second data items by repeating a first operation of reading data including data of respective first bits of the memory cells through application of two voltages to the word line at different timings while changing the two voltages in each first operation from the two voltages in another first operation. The controller is configured to mask part of each of the second data items using the first data.

Abstract: According to one embodiment, a controller is configured to write four-bit data in each of memory cells, and read first data item from the memory cells through application of a first voltage to a word line. The controller is configured to read second data items by repeating a first operation of reading data including data of respective first bits of the memory cells through application of two voltages to the word line at different timings while changing the two voltages in each first operation from the two voltages in another first operation. The controller is configured to mask part of each of the second data items using the first data.

Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The memory system is capable of executing a first operation and a second operation. In the first operation, the controller issues a first command sequence, the semiconductor memory applies a first voltage to a first word line and applies a second voltage to a second word line to read data from the first memory, and the read data is transmitted to the controller from the semiconductor memory. In the second operation, the controller issues a second command sequence, the semiconductor memory applies a third voltage to the first word line and applies a fourth voltage to the second word line, and data held in the memory cell array is left untransmitted to the controller.

Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The memory system is capable of executing a first operation and a second operation. In the first operation, the controller issues a first command sequence, the semiconductor memory applies a first voltage to a first word line and applies a second voltage to a second word line to read data from the first memory, and the read data is transmitted to the controller from the semiconductor memory. In the second operation, the controller issues a second command sequence, the semiconductor memory applies a third voltage to the first word line and applies a fourth voltage to the second word line, and data held in the memory cell array is left untransmitted to the controller.