CONTROLLER FOR NONVOLATILE SEMICONDUCTOR MEMORY

摘要

According to one embodiment, a controller for a nonvolatile semiconductor memory that stores data expressed using n levels (n is a natural number not less than 3) page by page includes an extraction unit and a conversion unit. The extraction unit extracts a second data stream shorter than a first data stream from the first data stream that includes a plurality of data written to the nonvolatile semiconductor memory. The conversion unit converts the second data stream into a third data stream longer than the second data stream, when a difference between threshold voltages of the nonvolatile semiconductor memory corresponding to adjacent two data included in the second data stream is a first level difference. The third data stream has a second level difference smaller than the first level difference.

主权项

1. A controller for a nonvolatile semiconductor memory that stores data expressed using n levels (n is a natural number not less than 3) page by page, the controller comprising:
an extraction unit configured to extract a second data stream from a first data stream, the first data stream including a plurality of data written to the nonvolatile semiconductor memory, the first data stream having a first length shorter than a length of a page, and the second data stream being shorter than the first data stream; and a conversion unit configured to convert the second data stream into a third data stream longer than the second data stream, when a difference between threshold voltages of the nonvolatile semiconductor memory corresponding to adjacent two data included in the second data stream is a first level difference, the third data stream having a second level difference smaller than the first level difference.