M24256-B and M24128-B are two 256/128Kbit I2C bus EEPROMs with three chip enable lines, compatible with I2C extended addressing, support 400kHz protocol, single supply voltage 4.5V to 5.5V, can perform byte and page write (up to 64 bytes), support random and sequential read modes, self-timed programming cycle, automatic address incrementing, enhanced ESD/Latch-Up behavior, 100000 erase/write cycles (minimum), 40 years of data retention (minimum).