The DS1230 256k Nonvolatile (NV) SRAMs are 262,144-bit, fully static, nonvolatile SRAMs organized as 32,768 words by 8 bits. Each NV SRAM has a self-contained lithium energy source and control circuitry which 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. DIP-package DS1230 devices can be used in place of existing 32k x 8 static RAMs directly conforming to the popular bytewide 28-pin DIP standard. The DIP devices also match the pinout of 28256 EEPROMs, allowing direct substitution while enhancing performance. DS1230 devices in the Low Profile Module package are specifically designed for surface-mount applications. There is no limit on the number of write cycles that can be executed and no additional support circuitry is required for microprocessor interfacing.