This part is a kind of semiconductor called 27C4100.

Function of this product has 4M-BIT [512K x 8/256K x 16] CMOS EPROM.

Manufacturers : Macronix International

Image and pinout :

Some of the text within the PDF file :

MX27C4100/27C4096 4M-BIT [512K x 8/256K x 16] CMOS EPROM FEATURES • 256K x 16 organization(MX27C4096, JEDEC pin • • • • out) 512K x 8 or 256K x 16 organization(MX27C4100, ROM pin out compatible) +12.5V programming voltage Fast access time: 100/120/150 ns Totally static operation • • • • Completely TTL compatible Operating current: 60mA Standby current: 100uA Package type: - 40 pin plastic DIP - 44 pin PLCC - 40 pin SOP GENERAL DESCRIPTION The MX27C4100/4096 is a 5V only, 4M-bit, One Time Programmable Read Only Memory. It is organized as 256K words by 16 bits per word(MX27C4096), 512K x 8 or 256K x 16(MX27C4100), operates from a single + 5 volt supply, has a static standby mode, and features fast single address location programming. All programming signals are TTL leve [ ... ]

27C4100 PDF Datasheet Download