LSI INCORPORATED NON-VOLATILE MEMORY

PURPOSE:To protect security of only the desired data by providing a security means which makes the access to a block from the external impossible when an address signal accesses this block corresponding to a security bit of a non- volatile memory. CONSTITUTION:Security bits b0-b7 corresponding to several blocks in 1:1 are provided for an EPROM 2 divided into these blocks. A decoder 4 is provided which decodes the address signal from the external and outputs a signal, which permits or inhibits the access to the address of the EPROM corresponding to a security bit, if the address signal accesses the address designated by this security bit. The address access to the EPROM is controlled to perform the write to the EPROM and the access inhibition for each block. Thus, security of only desired data out of data written in a non-volatile memory like an EPROM incorporated in an LSI is protected.