This part is a kind of semiconductor called 27C256.

Function of this product has 256K (32K x 8) CMOS EPROM.

Manufacturers : Microchip Technology

Image and pinout :

Some of the text within the PDF file :

Obsolete Device 27C256 256K (32K x 8) CMOS EPROM FEATURES • High speed performance - 90 ns access time available • CMOS Technology for low power consumption - 20 mA Active current - 100 µA Standby current • Factory programming available • Auto-insertion-compatible plastic packages • Auto ID aids automated programming • Separate chip enable and output enable controls • High speed “express” programming algorithm • Organized 32K x 8: JEDEC standard pinouts - 28-pin Dual-in-line package - 32-pin PLCC Package - 28-pin SOIC package - Tape and reel • Data Retention > 200 years • Available for the following temperature ranges: - Commercial: 0°C to +70°C - Industrial: -40°C to +85°C - Automotive: -40°C to +125°C DESCRIPTION The Microchip Tech [ ... ]

27C256 PDF Datasheet Download