The DS2250(T) soft microcontroller module is a fully 8051-compatible 8-bit CMOS microcontroller that offers "softness" in all aspects of its application. This is accomplished through the comprehensive use of nonvolatile technology to preserve all information in the absence of system VCC. The internal program/data memory space is implemented using 8, 32, or 64kB of nonvolatile CMOS SRAM. Furthermore, internal data registers and key configuration registers are also nonvolatile. An optional real-time clock gives permanently powered timekeeping. The clock keeps time to a hundredth of a second using an on-board crystal. All nonvolatile memory and resources are maintained for over 10 years at room temperature in the absence of power.