View ds2506 datasheet:

DS2506 64-kbit Add-Only Memory www.dalsemi.com FEATURES PIN ASSIGNMENT 65536 bits Electrically Programmable Read PR-35 Only Memory (EPROM) communicates with NC 1 8 NC the economy of one signal plus ground DALLAS DS2506 NC 2 7 NC Unique, factory-lasered and tested 64-bit registration number (8-bit family code + DATA 3 6 NC 48-bit serial number + 8-bit CRC tester) GND 4 5 NC assures absolute traceability because no two parts are alike 8-PIN SOIC Built-in multidrop controller ensures (208 mil) compatibility with other MicroLAN products EPROM partitioned into two hundred fifty six 256-bit pages for randomly accessing packetized data records Each memory page can be permanently write- protected to prevent tampering Device is an “add only” memory where addi