This part is a kind of semiconductor called AT89C5121.

Function of this product has 8-bit Microcontroller.

Manufacturers : ATMEL Corporation

Image and pinout :

Some of the text within the PDF file :

Features • 80C51 Core – 12 or 6 Clocks per Instruction (X1 and X2 Modes) – 256 Bytes Scratchpad RAM – Dual Data Pointer – Two 16-bit Timer/Counters: T0 and T1 T83C5121 with 16 Kbytes Mask ROM T85C5121 with 16 Kbytes Code RAM T89C5121 with 16 Kbytes Code RAM and 16 Kbytes EEPROM On-chip Expanded RAM (XRAM): 256 Bytes Versatile Host Serial Interface – Full-duplex Enhanced UART (EUART) with Dedicated Baud Rate Generator (BRG): Most Standard Speeds up to 230K bits/s at 7.36 MHz – Output Enable Input – Multiple Logic Level Shifters Options (1.8V to V CC) – Automatic Level Shifter Option Multi-protocol Smart Card Interface – Certified with Dedicated Firmware According to ISO 7816, EMV2000, GIE-CB, GSM 11.12V and WHQL Standards – Asynchronous Protocols T = 0 and T = 1 with D [ ... ]

AT89C5121 PDF Datasheet Download