Nonvolatile memory system, semiconductor memory, and writing method
A nonvolatile semiconductor memory recovers variation in the threshold of a memory cell due to disturbance related to a word line. The nonvolatile memory continuously performs many writing operations without carrying out single-sector erasing after each writing operation, performing the additional writing operations quicker than the usual writing operation, and lightening the burden imposed on software for use in additional writing. The data stored in a designated sector is read out before being saved in a register, and the selected sector is subjected to single-sector erasing when a predetermined command is given. Then write expected value data is formed from the saved data and data to be additionally written, completing the writing operation.
1. A method of programming for a nonvolatile memory, which comprises a plurality of word lines, each of which is coupled with memory cells, and is adapted to perform an erase operation and a program operation,
wherein in the erase operation, all of the memory cells coupled to a selected word line shift into an erase state,
wherein in the program operation, a first part of said memory cells coupled to the selected word line are in a corresponding state in accordance with first data before performing the program operation and a second part of said memory cells coupled the selected word line are in the erase state, wherein the method comprises the steps of:
receiving second data, quantity of which is 512 byte, to be programmed to the second part of memory cells coupled to the selected word line,
merging the first data already programmed in the first part of the memory cells and the second data to be programmed in the second part of the memory cells, and
programming the second data to the second part of memory cells coupled to the selected word line, the first part of memory cells coupled the selected word line remaining in the corresponding state in accordance with the first data before performing the program operation by programming a merged data to the memory cells coupled with the selected word line.
2. A method of programming for the nonvolatile memory according to claim 1 ,
wherein the first data already programmed to the first part of memory cells before the program operation is used as management information.
3. A method of programming for the nonvolatile memory according to claim 2 ,
wherein the memory cells coupled to the selected word line are capable of being programmed with data more than 512 byte.
4. A method of programming for the nonvolatile memory according to claim 1 ,
wherein each of the memory cells coupled to the selected word line has a threshold voltage within one of an erase state voltage range and a program state voltage range.