This part is a kind of semiconductor called HT66F03T3.

Function of this product has (HT66F03T3 / HT68F03T3) 8-Bit Flash MCU.

Manufacturers : Holtek Semiconductor

Image and pinout :

Some of the text within the PDF file :

HT66F03T3/HT68F03T3 8-Bit Flash MCU with RF Transmitter Features MCU Features · MCU operating voltage with RF Transmitter: fSYS= 8MHz: 2.2V~3.6V fSYS= 12MHz: 2.7V~3.6V Up to 0.33ms instruction cycle with 12MHz system clock Power Down and Wake-up functions to reduce power consumption Five oscillators: - External High Speed Xtal - External 32.768kHz Xtal - External RC - Internal High Speed - no external components - Internal 32kHz - no external components Multi-mode operation: NORMAL, SLOW, IDLE and SLEEP Fully integrated internal 4MHz, 8MHz and 12MHz Oscillator All instructions executed in one or two instruction cycles Table read instructions 63 powerful instructions Up to 4 subroutine nesting levels Bit manipulation instruction Flash Program Memory: 1K´14 RAM Data Memory: 64´8 EEPROM M [ ... ]

HT66F03T3 PDF Datasheet Download