Introduction to Microprocessor

In this course, we will study the microprocessor, its generations, its features, and the basic terms used. So let us start.

What is a microprocessor?

A Microprocessor is a computer architecture that plays the main role, without the microprocessor we are not able to perform any action on your computer system. It is a programmable device that takes in input, performs some arithmetic and logical operations over it and produces the desired output. In simple words, a Microprocessor is a digital device on a chip that can fetch instruction from memory, decode and execute them and give results.


Basics of Microprocessor

In a Microprocessor, we take a bunch of instructions that are in machine language and execute them, which tells the processor what actions it has to do. There are three basic things that the microprocessor performs while executing the instruction:

  1. Some basic operations like addition, subtraction, multiplication, division, and some logical operations using its Arithmetic and Logical Unit (ALU) are performed. The new generation of Microprocessors also performs operations on floating-point numbers also.
  2. Data in a Microprocessor can move from one location to another.
  3. It has a Program Counter (PC) register that stores the address of the next instruction based on the value of the PC, Microprocessor jumps from one location to another and makes the decision.

What are the generations of a microprocessor?

We can categorize the microprocessor according to the generations or according to the size of the microprocessor:

First Generation (4 - bit μ)

The first generation of microprocessors was introduced back in the year 1971-1972 by Intel Corporation. The first generation of the microprocessor was named Intel 4004 since it was a 4-bit processor.

It was a processor on a single chip. It was able to perform simple arithmetic and logical operations such as addition, subtraction, Boolean OR and Boolean AND.

It was composed of a control unit which was capable of performing control functions like fetching an instruction from storage memory, decoding it, and then generating control pulses to execute it.

Second Generation (8 - bit μ)

The second-generation microprocessors were introduced back in 1973 again by Intel. It was a first 8 - bit microprocessor that could perform arithmetic and logic operations on 8-bit words. Its name was Intel 8008, and there was another improved version namedIntel 8088.

Third Generation (16 - bit μ)

The third generation microprocessors were introduced back in 1978 and were represented by Intel's 8086, Zilog Z800 and 80286, which were 16 - bit processors and have a performance like minicomputers.

Fourth Generation (32 - bit μ)

There were many different companies who introduced the 32-bit microprocessors, but the most popular one among them is the Intel 80386.

Fifth Generation (64 - bit μ)

From 1995 to now we are in the fifth generation. After 80856, Intel came out with a new processor named the Pentium processor which was followed by Pentium Pro CPU, allowing multiple CPUs to run in a single system which helps to achieve multiprocessing.
There are many other improved 64-bit processors such as Celeron, Dual, Quad, Octa-Core processors

What are the features of a microprocessor?

Low Cost

Due to the presence of integrated circuit technology microprocessors (μ) are available at very low cost. It will reduce the cost of a computer system.

High Speed

Due to the technology involved in it, the microprocessor can work at a very high speed. It can execute millions of instructions per second.

Small Size

A microprocessor is fabricated in a very less footprint due to a very large scale and ultra large scale integration technology. And thus the size of the computer system is reduced.


We can use the same chip for several applications, therefore, microprocessors are versatile.

Low Power Consumption

We use metal oxide semiconductor technology in the microprocessors which consume less power.

Less Heat Generation

Microprocessors use semiconductor technology which will not emit much heat as compared to vacuum tube devices.


As the microprocessors use semiconductor technology, therefore, the failure rate is very low. Hence it is very reliable.


Because of the small size and low power consumption microprocessors are portable.

What are the basic terms used in a microprocessor?

Instruction Set

The group of commands that the microprocessor can understand is called an Instruction set. It is an interface between hardware and software.


It is a set of conductors that are intended to transmit the data, address or control information to different elements in a microprocessor. There are three types of buses, i.e., data bus, address bus, and control bus.

IPC (Instructions Per Cycle)

It is to calculate how many instructions a CPU can execute in a single clock.

Clock Speed

It is the total number of operations that a processor can perform per second. It can be expressed in megahertz (MHz) or gigahertz (GHz). It is also called the Clock Rate.


It is the number of bits that are processed in a single instruction.

Word Length

The total number of bits that a processor can process at a time is called the word length of the processor. 8-bit Microprocessor has the capability to process 8 -bit data at a time. The word length ranges from 4 bits to 64 bits and it depends upon the type of the microcomputer.

Data Types

The microprocessor supports multiple data type formats like binary, ASCII, signed and unsigned numbers.