Microcontrollers and Processors

Microcontrollers and processors are semiconductor devices that contain a central processing unit (CPU) and other supporting circuitry. They are used in computers and similar products where computation is required (for example, a cellphone). They are found today in a vast array of products—anything from microwave ovens to satellites and are usually in a circuit referred to as the digital board, main board, controller or motherboard.
A microcontroller is a special type of CPU oriented chip that is usually intended to embedded applications driven by cost, power consumption and size. They tend to have integrated memory for running their application code, and embedded peripherals like serial ports, timers, and PWM digital outputs. Many microcontrollers incorporate non-volatile storage (EEPROM and Flash) to store their code even when unpowered. They typically have lower performance processing capability, lower CPU instruction cycle clock rates, and have are 8, 16 or 32-bit instruction sets. Microcontrollers tend to be targeted towards a specific market, having on-board peripheral functions that suit the requirements of that type of product.
A processor is most often referred to as a microprocessor. This is distinguished from a microcontroller in that it focuses on performance rather than application. They will tend to have fewer peripherals than a microcontroller and tend to have internal functionality that provides acceleration to the software algorithms that may run on that type of microprocessor. This may include internal memory cache, complex data and instruction busing, complex internal instruction units (pipelines), arithmetic instruction units (ALUs) and supervisor circuits. Modern microprocessors can contain hardware accelerators for particular algorithms (for example H.264 video codecs) or graphics processing. They may even handle special instruction sets and interfaces for multiprocessor architectures. Instruction sets can be 32, 64 or even very long word instruction sets in the hundreds of bits wide.
Thanks to cellphones and tablets, todays processors blur the line between microcontrollers and microprocessors. Many very low power processors now have high levels of peripheral integration and can even come in multiprocessor configurations. As technology advances, and there is a greater need for smaller more highly integrated systems this trend will increase. However, there will always be a market for dedicated processing chips in products where performance is crucial and it makes architectural sense to have a system existing on multiple devices for example managing heat dissipation or application flexibility.