The 251 architecture is the next generation of the 8051 architecture that increases system performance by a factor of five using existing 8051 microcontroller code. By rewriting code using the 251 architecture instructions, designers can increase performance up to 15 times. The 251 architecture brings high performance, an increased memory mix and addressing, low power, low noise, efficient high level language support, enhanced instruction set, integrated features and functionality to the 8/16-bit embedded control market segment. Existing derivatives have various peripherals, memories, input / ouput (I/O) ports, and a BIU (Bus Interface Unit). Most importantly, new proliferations are binary code-compatible with existing 8051 components. Software investment is protected while providing an easy performance upgrade path.