Microcontroller

Micro -controller is the integrated circuit , which contains the following things:-
1.Processor

 2.Memory
3.Input-output peripherals .

In the micro-controller , For program memory we use the following :-
1.NOR FLASH
2. OTP ROM
3.Small amount of RAM

Micro-controllers are used in different control products such as
1.Automobile engine control system
2.Remote controls
3. Office systems
4.Appliances
5.Toys etc....

Now days micro-controllers are used in Home Automation systems & other Embedded  System.
A micro-controller is  self-contained system with a processor, Memory and Peripherals and can be used as Embedded system .Embedded systems are very sophisticated & minimal requirements for memory and program length, with no operating system, and low software complexity.

Program

 Micro-controller programs fit in the available on-chip program memory, Compilers and assemblers are used to convert high-level language and assembler language codes into a compact machine code for storage in the micro-controller's memory.
According to the requirement ,the program memory may be
1.Permanent,
2.Read-only memory
3. Field-alterable flash or Erasable read-only memory.

Micro-controllers included E PROM versions that have a "window" on the top of the device through which program memory can be erased by Ultraviolet light, ready for re-programming after a
programming ("burn") and test cycle.