Microcomputer having EEPROM.

摘要

A microcomputer includes a central processing unit (CPU) and an electrically erasable and programmable nonvolatile memory (EEPROM) fabricated on a single semiconductor chip. When CPU issues a data write request to EEPROM, a data write control circuit is initiated to perform a data write-processing in which data in an address of EEPROM selected by CPU is first erased and thereafter data from CPU is written into that selected address. There is further provided an over-write detection circuit for detecting that CPU issues another data write request to EEPROM while the data write control circuit is performing the data write-processing and for producing an over-write detection signal to CPU.