This document describes the M48Z129Y* and M48Z129V models of 5.0V or 3.3V 1Mbit (128 Kb x 8) ZEROPOWER® SRAM, which feature integrated ultra-low power SRAM, power-fail control circuit, and battery. It has conventional SRAM operation, unlimited write cycles, 10 years of data retention, microprocessor power-on reset, battery low pin for end-of-life warning, automatic power-fail chip deselect and write protection, and pin and function compatibility with JEDEC standard 128K x 8 SRAM.