Microprocessor and Microcontroller


Before going to study about microprocessor and microcontroller first lets study about the ICs.

A cell phone is a device made up of different circuits. Suppose if we want to connect ten transistors to design a part of circuit in a mobile if we consume so much space. Just for a one circuit of a cell phone just imagine the size of the mobile phone. The best solution for this is to reduce the size of all the circuits and fit them in a small angular device which we called as a chip. These chips are commonly known as ICs. These ICs are completely revolutionized in the electronics world.

Previously we use landlines then to pagers next invented mobile phones with antenna now a days we use compact size cell phones. All these are possible because of this ICs which are the size of finger nail.

IC fabrication

ICs are nothing but a logic gates and transistors connected together. The method by which ICs are manufactured is called as fabrication. Based on number of transistors and gates used ICs are categorized into four basic types, they are

  • Small scale integration (SSI)
  • Medium scale integration (MSI)
  • Large scale integration (LSI)
  • Very large scale integration (VLSI)
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Small scale integration

It consists of 1 to 12 transistors on chip. Examples of SSI are logic gates, flip-flops, op amps.

Medium scale integration

It consists of 13 to 99 transistors on chip. Few examples are counter, mux, adder circuits.

Large scale integration

It consists of 100 to 999 transistors on chip. Few examples are 8 bit microprocessor, ROM, RAM.

Very large scale integration

In this type of integration number of transistor or gates on a single chip is very large.

It consists of 1000 to 99999 transistors on chip. Few examples are 16 to 32 bit microprocessor, peripheral devices.

Before going to study lets study about the digital computer

What is digital computer?

A computer that performs calculations and logical operation with digits usually in the binary number system is called as digital computer.

Different blocks of digital computers as follows,

Central processing unit

It acts as heart of digital computer it makes all decision makings and all computations. It is also called as the microprocessor.

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Microprocessor is an electronic device it consists of arithmetic logic unit.


It is square wave length with fixed frequency which coordinates all the operations of CPU. When we say processor of 2 GHZ it determines the frequency of processor.


All the computation of CPU depends on different set of instructions tells CPU what to do and when to do it. The part of these programs are stored is called memory.

Input and output devices

An input and output device together is called a IO devices. In CPU communicates to outside world using IO devices. Few examples of input devices are keyboard, mouse, etc. and output devices are printer, monitor etc.


Microprocessor is an integrated circuit which performs all the functions of a CPU. It is abbreviated as “μp”. Μp consists of few blocks called ALU, register array, control unit.

Arithmetic Logic unit

ALU performs arithmetic operations, addition, subtraction, etc. logical operations like AND, OR, inverse, XOR, etc.

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Register array

Register array nothing but temporary memory location. Which stores a data to be processed and the proceed data. Number of registers varies from processor to processor.

Control unit

This unit produces all necessary timing and control signals for necessary operations. It controls exchange fa data between the μp and memory and IO devices. The different applications of μp are CPU, traffic lights, industrial applications like washing machines, mobile phones etc.



Microcontroller is a small computer on a single integrated circuit containing a processor core, memory, IO devices etc.

Microcontroller consists of following blocks

CPU, memory, I/O devices and peripheral devices

A peripheral device is an auxiliary device such as printer, modem, storage system, Hard disk and it works conjunction with computer.

Microcontrollers having few peripheral devices like A/D converter, timer, serial I/O devices etc.

Advantages of microcontroller

Inbuilt timer, I/O ports are available, separate memory to store program data, many pin on IC

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