This was a prototype I2C EEPROM for Siemens Halbleiter (their semiconductor division). This group eventually became Infineon security chips.

This die went into money cards used in German phone booths (Deutsche Bundespost). Evidently this was also used in some odometers. While the chip itself doesn't have any security features, this NVM provided the foundation for later secure systems.

NMOS depletion

Designed and manufactured by Siemens Munich. Layout drawn on mylar sheets for digitization using GE CALMA layout tool.

Package

Die