The Microchip 11AAxxx/11LCxxx family of devices are Serial EEPROMs featuring Microchips proprietary UNI/O™ Serial Bus.
UNI/O™ Serial EEPROM devices require only one connection to a host Microcontroller as clock and data communications are combined into a single serial bit stream. The result is that UNI/O™ devices require one Microcontroller I/O instead of the 2 to 6 (depending on configuration) that I2C, Microwire and SPI bus EEPROM devices require. To the designer this opens up the possibility of employing a smaller host MCU with fewer I/Os, reducing the MCU cost and allowing for a more compact design.