According to one embodiment, a memory system includes a nonvolatile semiconductor memory device, a voltage generation unit and a control unit. The nonvolatile semiconductor memory device includes a memory cell array having a plurality of blocks each including a plurality of memory cells, and a voltage generation unit configured to change a read level of the memory cell. The control unit controls write, read, and erase of the nonvolatile semiconductor memory device. The control unit changes the read level between a start of use of the nonvolatile semiconductor memory device and a timing after an elapse of a time.

A semiconductor storage device includes memory cells, select transistors, memory strings, first and second blocks, word lines, and select gate lines. In the memory string, the current paths of plural memory cells are connected in series. When data are written in a first block, after a select gate line connected to the gate of a select transistor of one of the memory strings in the first block is selected, the data are sequentially written in the memory cells in the memory string connected to the selected select gate line. When data are written in the second block, after a word line connected to the control gates of memory cells of different memory strings in the second block is selected, the data are sequentially written in the memory cells of the different memory strings in the second block which have their control gates connected to the selected word line.

A memory system according to an embodiment includes a nonvolatile memory and a memory controller. The nonvolatile memory includes a plurality of memory cells. The memory controller is configured to control the nonvolatile memory. In read operation for the memory cells, the memory controller is configured to: perform tracking including a plurality of reads in which a read voltage is shifted; determine a hard bit read voltage based on results of the tracking; calculate a soft bit read voltage based on the determined hard bit read voltage; perform soft bit read using the calculated soft bit read voltage; and perform a soft bit decoding process using a result of the soft bit read and a log-likelihood ratio table associated with the calculated soft bit read voltage.

A storage system includes: a control processor, configured to: read user data with a read threshold, determine which threshold adjustment range has been activated by reading a 1 and 0 counter, select an adjusted read threshold, based on the threshold adjustment range, to reread the user data in a physical block using the adjusted read threshold to correct the user data; and reading the user data in the physical block using the adjusted read threshold selected from the threshold adjustment range.

A write operation performed on a first memory unit of a memory device is detected, wherein the first memory unit comprises one or more memory cells. Responsive to detecting the write operation, a value of a counter associated with the first memory unit is incremented. It is determined whether the value of the counter satisfies a threshold criterion, wherein the threshold criterion is based on a random or pseudo-random number within a defined range. Responsive to determining that the value of the counter satisfies the threshold criterion, a refresh operation is performed on a second memory unit.

A media management operation can be performed at a memory sub-system at a current frequency. An operating characteristic associated with the memory sub-system can be identified. The operating characteristic can reflect at least one of a write count, a bit error rate, or a read-retry trigger rate. A determination can be made as to whether the identified operating characteristic satisfies an operating characteristic criterion. In response to determining that the operating characteristic satisfies the characteristic criterion, the media management operation can be performed at a different frequency relative to the current frequency.

A memory device includes a memory structure including at least one non-volatile memory cell capable of storing multi-bit data, and a control device configured to perform a program verification after a first program pulse is applied to the at least one non-volatile memory cell, determine a program mode for the at least one non-volatile memory cell based on a result of the program verification, and change a level of a pass voltage, applied to another non-volatile memory cell coupled to the at least one non-volatile memory cell, from a first level to a second level which is higher than the first level, or a setup time for changing a potential of a bit line coupled to the at least one non-volatile memory cell, according to the program mode.

A nonvolatile memory device includes at least one memory block and a control circuit. The at least one memory block includes a plurality of cell strings, each including a string selection transistor, a plurality of memory cells and a ground selection transistor. The control circuit controls a program operation by precharging channels of the plurality of cell strings to a first voltage during a bit-line set-up period of a program loop, applying a program voltage to a selected word-line of the plurality of cell strings during a program execution period of the program loop and after recovering voltages of the selected word-line and unselected word-lines of the plurality of cell strings to a negative voltage smaller than a ground voltage, recovering the voltages of the selected word-line and the unselected word-lines to a second voltage greater than the ground voltage during a recovery period of the program loop.

According to one embodiment, a cache memory system includes a cache memory and a cache controller. The cache memory can store first data to be read or written by a processor. The cache controller is configured to execute a refresh. The refresh includes reading the first data stored in the cache memory and writing the read first data to the cache memory. When executing the refresh, the cache controller is configured to exchange the first data stored in a first area of the cache memory for second data stored in a second area of the cache memory.

Described are systems and methods for estimating the resistance-capacitance time constant of an electrical circuit (e.g., of a wordline of a memory device). An example system comprises: a memory device comprising a plurality of memory cells electrically coupled to a plurality of wordlines; a resistance-capacitance (RC) measurement circuit to measure a voltage at a specified wordline of the plurality of wordlines; and a processing device coupled to the memory device. The processing device is configured to: apply an initial voltage to a selected wordline of the plurality of wordlines; discharge the selected wordline for a discharge period of time; float the selected wordline until a voltage at the selected wordline is stabilized; determine, by the RC measurement circuit, a stabilized voltage at the selected wordline; and estimate, based on the stabilized voltage, an RC time constant of the wordline.