Verified
A microcontroller is by definition is a computer upon a chip. This includes all the necessary parts (with the memory) all in one Integrated Chip. You just require applying the power (and possibly clock signal) to such device and this starts executing the program programmed to this. A microcontroller usually has the main CPU core, ROM or EPROM/EEPROM or FLASH, RAM and some essential functions (as timers and I/O controllers) all integrated in one chip. The original concept behind the microcontroller was to limit the abilities of the CPU itself, allowing a full computer (I/O, memory and interrupts) to fit upon the obtainable silicon real estate.