This part is a kind of semiconductor called AT28C256.

Function of this product has 256K (32K x 8) Paged Parallel EEPROM.

Manufacturers : ATMEL Corporation

Image and pinout :

Some of the text within the PDF file :

Features • Fast Read Access Time – 150 ns • Automatic Page Write Operation – Internal Address and Data Latches for 64 Bytes – Internal Control Timer • Fast Write Cycle Times – Page Write Cycle Time: 3 ms or 10 ms Maximum – 1 to 64-byte Page Write Operation • Low Power Dissipation – 50 mA Active Current – 200 µA CMOS Standby Current • Hardware and Software Data Protection • DATA Polling for End of Write Detection • High Reliability CMOS Technology – Endurance: 104 or 105 Cycles – Data Retention: 10 Years • Single 5V ± 10% Supply • CMOS and TTL Compatible Inputs and Outputs • JEDEC Approved Byte-wide Pinout • Full Military and Industrial Temperature Ranges • Green (Pb/Halide-free) Packaging Option 256K (32K x 8) Paged Parallel EEPROM AT28C256 1. [ ... ]

AT28C256 PDF Datasheet Download