US Patent 7242615 Non-volatile semiconductor memory device

A non-volatile semiconductor memory device includes: a memory cell array with electrically rewritable and non-volatile memory cells arranged therein; a data hold circuit configured to hold read data or write data of the memory cell array; a data bit detection circuit so connected to the data hold circuit as to detect a bit number of “0” or “1” in data held therein; and an internal control circuit, which serves for controlling data write, erase and read, and includes a data bit register for storing the bit number detected by the data bit detection circuit, the internal control circuit serving to output the bit number stored in said data bit register to external terminals in response to a command input.