The low voltage X4C105 combines several functions into one device. The first is a 2-wire, 4Kbit serial EEPROM memory with write protection. A Write Protect (WP) pin provides hardware protection for the upper half of this memory against inadvertent writes. A one nibble NOVRAM is provided and occupies a single location. This allows access of 4-bits in a single 150ns cycle. This is useful for tracking system operation or process status. The NOVRAM memory is completely isolated from the serial memory section. A low voltage detect circuit activates a RESET pin when VCC drops below 3V. This signal also blocks new read or write operations and initiates a NOVRAM AUTOSTORE. The AUTOSTORE operation is powered by an external capacitor to ensure that the value in the NOVRAM is always maintained in the event of a power failure.