View ds2502 u datasheet:

DS2502/5/6-UNW UniqueWareTM Add-Only Memory www.dalsemi.com SPECIAL FEATURES PIN ASSIGNMENT 1024 bits, 16 kbits or 64 kbits Electrically TO-92/PR-35 Programmable Read Only Memory (EPROM) 1 8 communicates with the economy of one signal plus ground 2 7 Unique, factory-lasered and tested 64-bit 3 6 registration number (8-bit family code, 36-bit 4 5 serialization, 12-bit UniqueWare identifier 5E7H, 8-bit CRC-tester) assures absolute 8-Pin SOIC traceability because no two parts are alike. See Mech. Built-in multidrop controller ensures Drawings Section compatibility with other MicroLAN products EPROM partitioned into 256-bit pages for randomly accessing packetized data records Each memory page can be permanently write- TSOC PACKAGE protected to prevent tampering