ABSTRACT
The generally accepted definition for a microprocessor is a device that comprises a central processing unit (CPU) with a large instruction set with the primary function of performing, processing, or computing functions at the highest achievable speed. The microprocessor could include a math co-processing unit but all other functions needed to operate (e.g., memory and I/O ports) are external to the device. Complex systems such as satellites implement microprocessors to meet performance requirements. On the other hand, microcontrollers comprise a CPU with a simpler instruction set along with on-chip functions such as non-volatile memory (e.g., flash or EEPROM), volatile memory (RAM), parallel I/O ports, and timers. Combining these functions into one device reduces component count to save size and cost, allowing microcontrollers to serve as embedded processors in a wide range of applications including toys, medical devices, and automotive controls where small volume is needed but not high performance. Military or space applications include small munitions such as projectile fuzes that have used 80C51-based microcontrollers or small space payload systems such as NASA’s Space Environments Testbed experiment payload which used an 80C196-based spaceflight-qualified microcontroller.
