When you start learning about Microprocessors (in most cases you will begin with Intel 8085) and Microcontrollers (usually you will begin with Intel 8051 from the MCS 51 micro controller family), the first question that pops up is “hey… what’s the difference in between”? In this article, I am explaining the basic differences and similarities between a microprocessor and microcontroller. In fact, you can call this article a simple comparison of both micro computing devices. This comparison will be same (at the basic level) for any microprocessor and controller.  So let’s begin.

At the basic level, a microprocessor and micro controller exist for performing some operations – they are – fetching instructions from the memory and executing this instruction (arithmetic or logic operations) and the result of these executions are used to serve to output devices. Are you clear? Both devices are capable of continuously fetching instructions from memory and keep on executing these instructions as long as the power is not turned off. Instructions are electronic instructions represented by a group of bits. These instructions are always fetched from their storage area, which is named as memory.  Now, let’s take a closer look at block diagrams of a microprocessor-based system and a microcontroller-based system.

Microprocessor-based system

microprocessor system - schematic arrangement

Take a closer look at the block diagram and you will see a microprocessor that has many support devices like Read-only memory, Read-Write memory, Serial interface, Timer, Input/Output ports, etc. All these support devices are interfaced to the microprocessor via a system bus. So one point is clear now, all support devices in a microprocessor-based system are external.  The system bus is composed of an address bus, data bus, and control bus.

Okay, now let’s take a look at the microcontroller.

Microcontroller system

microcontroller schematic arrangement

The above block diagram shows a microcontroller system in general. What’s the primary difference you see? All the support devices like Read-only memory, Read-Write memory, Timer, Serial interface, I/O ports are internal. There is no need for interfacing these support devices and this saves a lot of time for the individual who creates the system. Did you get the basic understanding? A microcontroller is nothing but a microprocessor system with all support devices integrated inside a single chip. There is no need for any external interfacing in a microcontroller unless you desire to create something beyond the limit, like interfacing an external memory or DAC/ADC unit, etc. To make this microcontroller function, you need to give a DC power supply, a reset circuit and a quartz crystal (system clock) from an external source.

Okay, so we have an idea about the basic difference between a microprocessor and a microcontroller. Now, let’s compare some features of both systems.

So you wanna read more about a specific microprocessor and microcontroller? Here is:-

Intel 8085 (microprocessor) and Intel 8051 (microcontroller)


As you already know, support devices are external in a microprocessor-based system where as support devices are internal for a microcontroller. Micro controllers offer software protection where a microprocessor base system fails to offer a protection system. This is made possible in microcontrollers by locking the on-chip program memory which makes it impossible to read using an external circuit. Okay! So that are basic differences, now you can come up with some more. As we need to interface support devices externally in a microprocessor-based system, the time required to build the circuit will be more, the size will be more and power consumption will be more in a microprocessor-based system compared to the microcontroller.



  1. Pavan kumar Puppala

    i am very interested in microprocessing so please guide me to learn more

  2. can any one give the list of all processor form starting of 8085 to till now available in market


  3. Very helpful , logical and easy to understand.

  4. ankitasambhare

    What’s the difference between RISC & CISC???? Thanks for the above info, would be better if differences were arranged in tabular form rather than big paragraphs…

  5. sandeepsingh

    Thank u a lot.it helps me a lot.as a rural backgrund.

  6. well,this article is really helpful. thank you for sharing.

  7. Sir,what is on chip program memory and serial interface? Can u explain in detail….

  8. riya sharma

    today is my papr nd it is so useful 4 me :):) thnk u so much sir 🙂

  9. venkatesh


    It is a good theory with proper explanation.


    Hope u keep on posting such explanations about the
    electronic circuits and components too.

  10. what is the difference between microprocessor and microcontroller based on software?

    • jojo

      @Tuhin – They both differ mainly on hardware. I think there’s not much of a difference in the way “software” is handled for both!

  11. dear sir, could you pls suggest some ideas on embedded system project.. pls reply soon..

  12. devendra thakur

    i want even a deep explanation………….

  13. dear sir can u explain about the timing diagrams of the microprocessor

  14. kavi priya

    good eve sir,i want to know the traffic light controller program based on 8051.thank u sir

  15. udaya kumar

    dec 10,2011 at 5.45pm

    sir, i am having a project on implementation of modifying single phase preventer with meu-p 8051 micro controller.sir can you please help me with the circuit diagram and programming for 8051.please help me as soon as possible.

  16. umesh yadav

    sir i need detail of the programing detail of the MC908JL16CPE micro controler

  17. umesh yadav

    sir i wanted to know all detais of the fir alarm system and abut circuit dagram detail and latest fire alarm system

  18. shweta k.

    Sir,I am having a project on interfacing a temperature sensor with mue-p 8085 if able also with mue-c 8051,along with two seven segment displays,which will sense the temperature and display it on the seven segment display.Sir,can you please help me with the pcb design circuitary and programming for both?Sir,Please help me as soon as possible.

    • jojo

      Hello shweta, please wait one or two weeks, we will come up with articles on 8051 interfacing very soon. We are working to develop complete tutorial for 8051.

  19. sameer gupta

    Sir,please publish an article on microcontroller programming.For this I am searching in many websites but not clear.
    I want to program a chip through my laptop(windows7).What are the hardwares,softwares,cables & ports required to program a microcontroller?

  20. Sir, I am seeing your mails everyday. It is very useful to me.Thanking many more

    • i need major feature between microprocessor and microcontroller

  21. Sir, Please tell me what is the major difference between the ICs of the CD 4011B and GD 4011B.

  22. Dear Sir, I am seeing your mails everyday. It is very useful to me. I am watching your topics everyone in your website at free of cost. Thanking many more.