Real-Time Clock (RTC) with internal 64 bit ROM
SOIC6-150mil +---\/---+ GND | 1 6| X2 1-WIRE | 2 5| X1 Vdd | 3 4| Vbat +--------+
SOIC6 Set reader to FREQ, put black probe to GND, red probe to 5 and to 6 to measure CPU clock
DS2415P Datasheet