Write circuitry for semiconductor RAM with extended service life due to avoid excessive writing, containing flash memory

摘要

Data is written into a flash memory of the semiconductor RAM and verified so that only incorrect data or unsuitable to be written-in are rewritten. The write circuitry comprises an EX-NOR circuit, which compares write with verified data and generates write data according to the comparison. Preferably the EX-NOR circuit comprises numerous EX-NOR circuits, with their number identical to that of write data. Typically the write data are stored in a data buffer, while data read-out for verification are stored in a read-out buffer.