Zeropower SRAM 16K, 48Z02, DIP24 - 

The M48Z02-150PC1 is a 16kb Non-volatile Static RAM which is pin and function compatible with the DS1220. The M48Z02 button cell has sufficient capacity and storage life to maintain data functionality for an accumulated time period of at least 10 years in the absence of power over commercial operating temperature range. The M48Z02 is a non-volatile pin and function equivalent to any JEDEC standard 2K x 8 SRAM. It also easily fits into many ROM, EPROM and EEPROM sockets providing the non-volatility of PROMs without any requirement for special write timing or limitations on the number of write that can be performed.