This part is a kind of semiconductor called 27C512-120.

Function of this product has 512 Kbit 64Kb x8 UV EPROM and OTP EPROM.

Manufacturers : STMicroelectronics

Image and pinout :

Some of the text within the PDF file :

M27C512 512 Kbit (64Kb x8) UV EPROM and OTP EPROM 5V ± 10% SUPPLY VOLTAGE in READ OPERATION FAST ACCESS TIME: 45ns LOW POWER “CMOS” CONSUMPTION: – Active Current 30mA – Standby Current 100µA PROGRAMMING VOLTAGE: 12.75V ± 0.25V PROGRAMMING TIMES of AROUND 6sec. (PRESTO IIB ALGORITHM) ELECTRONIC SIGNATURE – Manufacturer Code: 20h – Device Code: 3Dh 28 28 1 1 FDIP28W (F) PDIP28 (B) DESCRIPTION The M27C512 is a 512 Kbit EPROM offered in the two ranges UV (ultra violet erase) and OTP (one time programmable). It is ideally suited for applications where fast turn-around and pattern experimentation are important requirements and is organized as 65,536 by 8 bits. The FDIP28W (window ceramic frit-seal package) has transparent lid which allows the user to expose the chip to ultr [ ... ]

27C512-120 PDF Datasheet Download