The DS1249W 2048kb nonvolatile (NV) SRAMs are 2,097,152-bit, fully static, NV SRAMs organized as 262,144 words by 8 bits. Each NV SRAM has a self-contained lithium energy source and control circuitry that constantly monitors VCC for an out-of-tolerance condition. When such a condition occurs, the lithium energy source is automatically switched on and write protection is unconditionally enabled to prevent data corruption. There is no limit on the number of write cycles that can be executed, and no additional support circuitry is required for microprocessor interfacing.