This part is a kind of semiconductor called AT89S51.

Function of this product has 8-bit Microcontroller.

Manufacturers : ATMEL Corporation

Image and pinout :

Some of the text within the PDF file :

Features • Compatible with MCS®-51 Products • 4K Bytes of In-System Programmable (ISP) Flash Memory – Endurance: 10,000 Write/Erase Cycles • 4.0V to 5.5V Operating Range • Fully Static Operation: 0 Hz to 33 MHz • Three-level Program Memory Lock • 128 x 8-bit Internal RAM • 32 Programmable I/O Lines • Two 16-bit Timer/Counters • Six Interrupt Sources • Full Duplex UART Serial Channel • Low-power Idle and Power-down Modes • Interrupt Recovery from Power-down Mode • Watchdog Timer • Dual Data Pointer • Power-off Flag • Fast Programming Time • Flexible ISP Programming (Byte and Page Mode) • Green (Pb/Halide-free) Packaging Option 1. Description The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K bytes of In-System Programmable [ ... ]

AT89S51 PDF Datasheet Download