Abstract: A memory system includes a memory device having a memory cell array, and a controller. The memory cell array includes a plurality of first units and at least one second unit. The second unit includes the plurality of first units. The controller counts a first number of times of read operation for each of the plurality of first units, and, in response to the first number of times for one first unit among the plurality of first units reaching a first value, updates a second number of times for the second unit that includes the one first unit. In response to the second number of times reaching a second value, the controller determines whether to rewrite data stored in at least one of the first units included in the second unit.

Abstract: According to one embodiment, a memory system includes a non-volatile semiconductor memory that includes a memory cell and a controller having a memory storing a write parameter used in a write operation to the memory cell. The controller instructs the non-volatile semiconductor memory to perform the write operation to the memory cell using the write parameter, receives, from the non-volatile semiconductor memory, a result of checking of the write parameter which is obtained in the write operation and updates the write parameter stored in the memory on the basis of the result of checking of the write parameter.

Abstract: A memory system includes a nonvolatile memory, a buffer, and a controller. The buffer can temporarily store a plurality of data bits to be written to the nonvolatile memory. The controller can write the plurality of data bits, read from the buffer, to the nonvolatile memory; write a plurality of intermediate parity bits to the buffer, but not to the nonvolatile memory, wherein each of the plurality of intermediate parity bits is associated with an error correction process on each of the plurality of data bits; and write, to the nonvolatile memory, an accumulated parity bit that is an integration of the plurality of intermediate parity bits.

Abstract: According to one embodiment, a memory system includes a non-volatile memory including first and second block groups, and a controller that performs a first write operation for the first block group and the first or a second write operation for the second block group. A first or second number of bits is written into a memory cell in the first or the second write operation. The second number of bits is larger than the first number of bits. The controller allocates a block to a buffer as a write destination block in the first write operation based on a degree of wear-out of at least one block, and writes data from an external device into the buffer in the first write operation.

Abstract: According to one embodiment, a memory system includes a nonvolatile semiconductor memory, and a controller. The semiconductor memory includes a memory cell, and a write circuit configured to write data to the memory cell by applying a program voltage to the memory cell and comparing a threshold voltage of the memory cell with a first reference voltage corresponding to the write data. The write circuit is configured to execute a first programming operation to obtain a value of a write parameter by comparing the threshold voltage with a second reference voltage different from the first reference voltage.

Abstract: According to one embodiment, a memory system includes a nonvolatile memory and a controller electrically connected to the nonvolatile memory. The controller selects a write mode from a first mode in which data having N bits is written per one memory cell and a second mode in which data having M bits is written per one memory cell. N is equal to or larger than one. M is larger than N. The controller writes data into the nonvolatile memory in the selected write mode. The controller selects either the first mode or the second mode at least based on a total number of logical addresses mapped in a physical address space of the nonvolatile memory.

Abstract: A memory system includes a non-volatile memory and a controller that includes a toggle encoder configured to encode first data having a first bit length and a first number of toggles, into second data having a second bit length longer than the first bit length and a second number of toggles smaller than the first number of toggles, and transmit the second data to the non-volatile memory. The memory system may further include a toggle decoder configured to decode third data received from the non-volatile memory into fourth data, the third data having the second bit length and the second number of toggles and the fourth data having the first bit length and the first number of toggles.

Abstract: According to one embodiment, a memory system includes a nonvolatile memory and a controller electrically connected to the nonvolatile memory. The controller selects a write mode from a first mode in which data having N bits is written per one memory cell and a second mode in which data having M bits is written per one memory cell. N is equal to or larger than one. M is larger than N. The controller writes data into the nonvolatile memory in the selected write mode. The controller selects either the first mode or the second mode at least based on a total number of logical addresses mapped in a physical address space of the nonvolatile memory.

Abstract: According to one embodiment, a memory system includes a nonvolatile semiconductor memory, and a controller. The semiconductor memory includes a memory cell, and a write circuit configured to write data to the memory cell by applying a program voltage to the memory cell and comparing a threshold voltage of the memory cell with a first reference voltage corresponding to the write data. The write circuit is configured to execute a first programming operation to obtain a value of a write parameter by comparing the threshold voltage with a second reference voltage different from the first reference voltage.

Abstract: A memory system includes a non-volatile memory chip that includes a memory cell array, and a memory controller. The memory controller is configured to perform a read operation on the non-volatile memory chip by instructing the non-volatile memory chip to perform a sensing operation to read data stored in the memory cell array, estimating a time when the read data becomes ready to be transferred from the non-volatile memory chip to the memory controller, and instructing the non-volatile memory chip, after the estimated time, to perform a transfer operation to transfer the read data to the memory controller.

Abstract: According to one embodiment, a memory system includes a nonvolatile memory and a memory controller that controls operation of the nonvolatile memory. The nonvolatile memory is configured to receive, from the memory controller, a first command for execution of at least one of an erase operation and a program operation; in response to receiving a second command from the memory controller during execution of a first operation requested by the first command, execute a second operation for suspending the first operation before the first operation reaches a given section; and in response to receiving a third command from the memory controller during the execution of the first operation, suspend the first operation after the given section.

Abstract: A memory system includes a nonvolatile memory including a plurality of blocks, in each of which a plurality of memory cells is arranged between bit lines and a source line, and a memory controller configured to control an operation of the nonvolatile memory. The memory controller is configured to issue a warming command to the nonvolatile memory when a temperature of the nonvolatile memory is lower than a first temperature, and the nonvolatile memory, in response to the warming command, causes current to flow through at least one bit line connected to memory cells of a first block.

Abstract: According to one embodiment, a memory system includes a non-volatile semiconductor memory that includes a memory cell and a controller having a memory storing a write parameter used in a write operation to the memory cell. The controller instructs the non-volatile semiconductor memory to perform the write operation to the memory cell using the write parameter, receives, from the non-volatile semiconductor memory, a result of checking of the write parameter which is obtained in the write operation and updates the write parameter stored in the memory on the basis of the result of checking of the write parameter.

Abstract: According to one embodiment, a memory system includes a nonvolatile memory and a controller electrically connected to the nonvolatile memory. The controller selects a write mode from a first mode in which data having N bits is written per one memory cell and a second mode in which data having M bits is written per one memory cell. N is equal to or larger than one. M is larger than N. The controller writes data into the nonvolatile memory in the selected write mode. The controller selects either the first mode or the second mode at least based on a total number of logical addresses mapped in a physical address space of the nonvolatile memory.

Abstract: According to one embodiment, a memory system includes a nonvolatile semiconductor memory, and a controller. The semiconductor memory includes a memory cell, and a write circuit configured to write data to the memory cell by applying a program voltage to the memory cell and comparing a threshold voltage of the memory cell with a first reference voltage corresponding to the write data. The write circuit is configured to execute a first programming operation to obtain a value of a write parameter by comparing the threshold voltage with a second reference voltage different from the first reference voltage.