Abstract: A memory stores dummy data including a first data area having more “0” than “1” of a binary logic and a second data area having more “1” than “0” of the binary logic. An ECC processor detects a first error bit number related to the first data area and a second error bit number related to the second data area. A calculator calculates a relative difference of the first error bit number from the second error bit number. A comparator compares the relative difference with a predetermined value. A corrector corrects a read voltage on the basis of a result of comparison by the comparator.

Abstract: A memory stores dummy data including a first data area having more “0” than “1” of a binary logic and a second data area having more “1” than “0” of the binary logic. An ECC processor detects a first error bit number related to the first data area and a second error bit number related to the second data area. A calculator calculates a relative difference of the first error bit number from the second error bit number. A comparator compares the relative difference with a predetermined value. A corrector corrects a read voltage on the basis of a result of comparison by the comparator.

Abstract: A memory control method includes writing converted data which is produced by carrying out a code conversion on original data into a memory. An amount of 1s in the converted data is less than an amount of 1s in the original data. Further, the memory control method includes outputting reproduced data which is provided by carrying out an inverse transformation of the code conversion on the converted data which is read out from the memory, to a host system for processing the original data.

Abstract: Error-tolerant code conversion is carried out on original data including a large amount of binary data which is apt to be unintentionally rewritten, to produce converted data including a smaller amount of binary data which is apt to be unintentionally rewritten, and the converted data is written into a memory. While a host system is processing the original data, the memory reads out the converted data and the code inverse transformation part carries out inverse transformation of error-tolerant code conversion on the converted data, to output reproduced data which is identical to the original data, to the host system. As a result, it is possible to avoid or suppress the possibility that data is unintentionally rewritten due to repeated readout of the same data.