Difference between a microprocessor and a microcontroller

Question :What is the difference between a microprocessor and a microcontroller?
Question From :

Rashmi R Nath
Post graduate Dept of computer Science
Farook college ,Calicut
E-mail: rashmivinodk@gmail.com

Answer:

Introduction to Microcontrollers

Microcontrollers are hidden inside a surprising number of products these days. If your microwave oven has an LED or LCD screen and a keypad, it contains a microcontroller. All modern automobiles contain at least one microcontroller, and can have as many as six or seven: The engine is controlled by a microcontroller, as are the anti-lock brakes, the cruise control and so on. Any device that has a remote control almost certainly contains a microcontroller: TVs, VCRs and high-end stereo systems all fall into this category. Nice SLR and digital cameras, cell phones, camcorders, answering machines, laser printers, telephones (the ones with caller ID, 20-number memory, etc.), pagers, and feature-laden refrigerators, dishwashers, washers and dryers (the ones with displays and keypads)... You get the idea. Basically, any product or device that interacts with its user has a microcontroller buried inside. First microcontroller was Intel 8048 released in 1976.

What is a Microcontroller?

Basically, a microcontroller is a device which integrates a number of the components of a microprocessor system onto a single microchip.

So a microcontroller combines onto the same microchip :
• The CPU core
• Memory (both ROM and RAM)
• Some parallel digital I/O

Most microcontrollers will also combine other devices such as:
• A Timer module to allow the microcontroller to perform tasks for certain time periods.
• A serial I/O port to allow data to flow between the microcontroller and other devices such as a PC or another microcontroller.
• An ADC to allow the microcontroller to accept analogue input data for processing.

Introduction to Microprocessor

A microprocessor incorporates most or all of the functions of a computer's central processing unit (CPU) on a single integrated circuit (IC, or microchip).^[1] The first microprocessors emerged in the early 1970s and were used for electronic calculators, using binary-coded decimal (BCD) arithmetic on 4-bit words. Other embedded uses of 4-bit and 8-bit microprocessors, such as terminals, printers, various kinds of automation etc., followed soon after. Affordable 8-bit microprocessors with 16-bit addressing also led to the first general-purpose microcomputers from the mid-1970s on.

During the 1960s, computer processors were often constructed out of small and medium-scale ICs containing from tens to a few hundred transistors. The integration of a whole CPU onto a single chip greatly reduced the cost of processing power. From these humble beginnings, continued increases in microprocessor capacity have rendered other forms of computers almost completely obsolete (see history of computing hardware), with one or more microprocessors used in everything from the smallest embedded systems and handheld devices to the largest mainframes and supercomputers.

Microcontroller versus Microprocessor

A microcontroller differs from a microprocessor in many ways. The first and most important difference is its functionality. In order that the microprocessor may be used, other components such as memory must be added to it. Even though the microprocessors are considered to be powerful computing machines, their weak point is that they are not adjusted to communicating to peripheral equipment.
Simply, In order to communicate with peripheral environment, the microprocessor must use specialized circuits added as external chips. In short microprocessors are the pure heart of the computers. This is how it was in the beginning and remains the same today.

On the other hand, the microcontroller is designed to be all of that in one. No other specialized external components are needed for its application because all necessary circuits which otherwise belong to peripherals are already built into it. It saves the time and space needed to design a device.

A microcontroller is a specialized form of microprocessor that is designed to be self-sufficient and cost-effective, where a microprocessor is typically designed to be general purpose (the kind used in a PC). Microcontrollers are frequently found in automobiles, office machines, toys, and appliances.
The microcontroller is the integration of a number of useful functions into a single IC package. These

functions are:
The ability to execute a stored set of instructions to carry out user defined tasks.
The ability to be able to access external memory chips to both read and write data from and to the memory.
Basically, a microcontroller is a device which integrates a number of the components of a microprocessor system onto a single microchip.
So a microcontroller combines onto the same microchip :
The CPU core (microprocessor)
Memory (both ROM and RAM)
Some parallel digital I/O
Also, a microcontroller is part of an embedded system, which is essentially the whole circuit board

 
Another points:

In Microprocessor more op-codes, few bit handling instructions. But in Microcontroller: fewer op-codes, more bit handling Instructions, and also it is defined as a device that includes micro processor, memory, & input / output signal lines on a single chip.

1.Microprocessors are general purpose digital computers. Micro controllers are special purpose digital computers.

2.Microprocessors contain CPU, memory addressing circuits and interrupt handling circuits. Micro controllers contain all these features as well as timers, parallel and serial i/o, and internal RAM and ROM.

3.Microprocessors have one or two types of bit handling instructions. Micro controllers will have many.

4.Microprocessors have many opcodes for moving data from external memory to the CPU. Micro controllers may have one or two.

• Microprocessors are intended to be general-purpose digital computers whereas microcontrollers are intended to be special-purpose digital controllers.
• Microprocessors contain a CPU, memory addressing circuits, and interrupt handling circuits. Microcontrollers have these features as well as timers, parallel and serial I/O, and internal RAM and ROM.

Applications:

• Engine management systems in automobiles. • Keyboard of a PC. • Electronic measurement instruments (such as digital millimetres, frequency synthesisers, and oscilloscopes) • Printers. • Mobile phones. • Televisions, radios, CD players, tape recording equipment. • Hearing aids. • Security alarm systems, fire alarm systems, and building services systems.

According to me the main difference between a typical microprocessor and a micro controller living there architectural specifications is the application area of both the devices. A typical microprocessor like Intel Core family or Pentium family processors or similar processors is in computers as a general purpose programmable device. In its life period it has to handle many different tasks and programs given to it.
On the other hand a micro controllers from 8051 family or PIC family or any other have found there applications in small embedded systems like some kind of robotic system or a traffic signal control system. Also these devices handle same task or same program during there complete life cycle.
(Best example is of traffic signal control system).
The other difference is that the micro controllers usually has to handle real time tasks while on the contrary the microprocessors in a computer system may not handle a real time task at all times.

 
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