This part is a kind of semiconductor called 80C51.

Function of this product has 80C51 8-bit microcontroller family 4K/128 OTP/ROM/ROMless low voltage 2.7V.5.5V/ low power/ high speed 33 MHz.

Manufacturers : NXP

Image and pinout :

Some of the text within the PDF file :

INTEGRATED CIRCUITS 80C51/87C51/80C31 80C51 8-bit microcontroller family 4K/128 OTP/ROM/ROMless low voltage (2.7V–5.5V), low power, high speed (33 MHz) Product specification Supersedes data of 1999 Apr 01 IC28 Data Handbook 2000 Jan 20 Philips Semiconductors Philips Semiconductors Product specification 80C51 8-bit microcontroller family 4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V), low power, high speed (33 MHz) 80C51/87C51/80C31 DESCRIPTION The Philips 8XC51/31 is a high-performance static 80C51 design fabricated with Philips high-density CMOS technology with operation from 2.7V to 5.5V. The 8XC51/31 contains a 4k × 8 ROM, a 128 × 8 RAM, 32 I/O lines, three 16-bit counter/timers, a six-source, four-priority level nested interrupt structure, a serial I/O port for either mul [ ... ]

80C51 PDF Datasheet Download