The MN63121 is a 1K-bit EEPROM supporting serial I/O and operating on a single power supply with a voltage between 1.8 and 5.5 V. It provides the following pins for easy interfacing to microprocessors or microcontrollers: chip select (CS), serial clock (SCK), data input (DI), data output (DO), reset (RESET), and busy (RDY/BUSY). It includes a built-in timer for use in automatically erasing and writing data during data update operations. The memory organization is 64 x 16 bits. The chip indicates the end of a write operation with either the RDY/ BUSY pin or the state of the DO pin after the status output mode has been set. Conversion of peripheral circuits to CMOS realizes great reductions in power consumption. Use of floating gate memory cells and a built-in error correction circuit ensures reliable operation for 105 write cycles.