Introduction to Computer

By Suresh Chand

 Important Questions

A computer is an electronic device, which accept data and process it and gives us information with set of instructions called program. A computer is a programmable machine, multiuse machine. The word computer is derived from the latin word “computare”. The computer as a system which is a combination of hardware and software joined it has the ability to:

  1. Accept data
  2. input, store and execute instructions.
  3. perform mathematical and logical operation on data.
  4. output results.

Functions of computer:

There are various function of computer. The main functions are of five types. They are as follows:

1) Inputting:

The process which enter data inside computer system with the help of input devices is called inputting or In others words the process of entering data and instruction is called inputting.

2) Processing:

The process which performs different mathematical operations and logical operations (<,≤, ≥, ≠, >) is called processing.
The computer performs all processing by “calculating,” and “comparing” the data stored in its memory (RAM). It is done in two ways. They are as follows:

  1. Mathematical operation
    The computer can perform any mathematical operation on data by adding, subtracting, multiplying and dividing(+,-,*,/) one set with another.
  2. Logical operation
    The computer can analyze and evaluate data by matching it with sets of known data that are included in the program or called in from storage i.e. it compares two or more data either it is greater than, smaller than, greater or equal to, smaller or equal to and equals to((<, ≤,  ≥,  ≠,  >).
3. Outputting:

The process of giving information or results after processing and storing is called outputting. It is shown by output devices such as monitor. i.e. The process which display result to the user is called outputting.

4. Storing

The process which helps to store data and information is called storing. The computer is able to store (save) data and programs permanently and retrieve it when required. A system’s size is based on how much disk storage it has. The more disks, the more data are immediately available

5. Controlling

The CPU of a computer is responsible for controlling devices attached with computer. i.e. Controlling is the function of controlling all the input and output devices, application programmes and memory units.


The raw facts, measurements, or materials are called data which are collected from different areas to get information. These are also observations, old  records. Data is plural form of Datum. For example:

A                     40

50        B


C         80        D

In above fig.A,50,B,40……. Are data. when you simply look at figure, it does not give any meaning, so data are raw facts.


The proceeded data which are in meaningful form are called information. Data are regarded the most fundamental forms of information. Data are arranged  and processed to get information.

Section No of Students








When the data of fig 1 are arranged as in fig 2 it gives information since it shows that in section A, there are 50 students and in section B ,there are 40 students and so on.


The physical components which can be seen, touched, feel are called hardware which are resources of a computer .The hardware consist of following components.

Input Device:

These devices are used to input data and instruction into computer .eg:  keyboard, mouse etc.


These devices are used to store the data and instructions temporarily or permanently.

CPU(central processing unit):

It is a processing device ,which is used to perform different mathematical operations and execute instruction.

Output Devices:

Those devices are used to display result to the user. Monitor, printer etc.

Advantages of computer:

  1. The result given by computer100% accurate and it is reliable than other devices and human beings.
  2. Computer works in fast speed than human beings.
  3. Computer is versatile machine as it can do many types of jobs once at a time.
  4. Computer has higher storage space to store data and information.

Disadvantages: of computer

  1. Computer is expensive and poor people can not afford but day by day it is becoming cheaper.
  2. It is totally dependent on electricity and if there is no electricity computer cannot do anything and also the electric shock cause danger.
  3. Although it is reliable, sometimes the failures of devices and programs can produce unreliable result.

d).People are becoming too much dependent on computers.


Instructions are the commands which give the way or path to perform different operations inside computer with the help of different devices.


Collections of set of instructions are called programs. Which are used to run and perform different operations inside computer. Each collection of program parts called software.


Characteristics of computer

All computers have certain common characteristics irrespective their type and size. Computers are not just adding machines; they are capable of doing complex activities and operations. Computers are what they are because of following characteristics.

a) Speed:

Computers can calculate at very high speeds. As the power of computer increases, the speed also increases. The smallest unit of time in the human experience is realistically the second. We do not think of doing something in less than a second. But a computer performs operations at an incredible speed. It can process information within Pico second. The computers can process data at an extremely fast rate. i.e. in tune of million of instructions per seconds(MIPS). For example A microcomputer can execute a million of instruction per second. We will use the following terms to describe the processing capability of computer

Millisecond    :one thousand of second=1/1000

Microsecond  :One million of second=1/1000,000

Nanosecond   :One billionth of a second=1/100,000,000

Picoseconds   :One trillionth of a second=1/1000,000,000,000

b) Storage:

A computer can store large amount of data. i.e the storage capacity of computer is high. The data can be stored and retrieved according to the need of the user. In fact it takes very less time to retrieve desired information from a huge amount of data stored inside a computer memory. So the capability of storing and retrieving huge amount of data in fast and efficient manner is one of the important characteristics of computer.

c) Accuracy

In addition to being fast, computers are very accurate which means that the accuracy of computer is very high. The accuracy of a computer is consistently high and the degree of a accuracy of a computer depends upon its design. Every calculation is performed with the same accuracy.

d) Diligence:

A computer can perform repetitive task without being bored, tired and losing concentration. It can continuously work for several hours without human intervention after the data and programs are fed to it. They can handle complicated and complex tasks. Diligence means being constant and earnest in effort and application.


Computers are very versatile machines. They can perform activities ranging from simple calculations to complex operations. They can perform different tasks depending upon different programs fed to them. For each task to be performed there is one program associated with it.

f) Word length:

A digital computer operate on binary digits-0 and 1’s.It can understand information in terms of 0s and 1s.A binary digit is called a bit. A group of 8 bits is called a byte. Thus the number of bits that a computer can process at a time in parallel is called its word length .commonly used word length are 8,16,32 or 64 bits. Word length is the measure of the computing power of a computer .The longer word length ,the more powerful the computer is. When we talk about 32-bit computer, it means that its word length is 32 bits.

g) Automation:

The automation characteristics of a computer is that it finishes any task automatically. computers can be programmed  to perform a series of complex tasks involving multiple programs.

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Limitations of computer( What computer can not do?)

  1. No Intelligent: Computer are the machine which can not think. They do not show any intelligence of their own. It can not take its own their I.Q(Intelligence Quotient) is zero.
  2. No Intuition: Computer can not draw conclusion with out going through itself. i.e. they do not have intuition. Computer can only do a job, which can be expressed in a finite number of steps. The computer is useless without correct program.
  3. No Feeling: Computer has no emotions because they are machine.


Types of computer:

Computers are classified according to their application, work, size, capacity,  speed, brand  which are described as follows:

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Classification of computers Based on work:

  1. Digital computer
  2. Analog Computer
  3. Hybrid Computer

1. Digital Computer

A computer which uses binary digits 0s and 1s are called digital computer. They convert the data into binary digits (0s and 1s) and all operations are carried out on these digits at extremely fast rate. A digital computer basically knows how to count the digit and add the digits. Digital computers are much faster than analog computers and far more accurate. Digital computers have high storage or memory. They works upon discontinuous data. Digital computers are multipurpose and programmable and hence used for general purpose( can be used in many different application). Example: Digital Clock, personal computer (PC) etc.

2. Analog Computer

The computer which is  used  to measure physical magnitudes(such as-voltage , temperature, current and pressure) is called analog computer. Analog computers works with the natural or physical values. i.e. these computers works with continuous data. The accuracy of analog computer is low and there is very low or do not have storage or memory. Analog computer operates by measuring rather than counting. Analog computers are mostly used in scientific and engineering applications .E.g:- speedometer, voltmeter etc.

3. Hybrid computers:

A hybrid computer is a combination of both analog and digital computers. i. e  it can perform the functions of both a digital and analog computer. or example in an intensive care unit of hospital, analog devices measure the patients heart function, temperature, or other vital signs. These measures are then converted into numbers or digits and supplied to a digital component that monitors the patients vital signs. Hybrid computers are used in weather forecasting. E.g-Hybrid  watch.

Difference Between Analog and Digital Computer

Analog computer Digital computer
Analog computers works with the natural or physical values. Digital computer works with binary digits (0s and 1s).
These computer works with continuous data These computer works with discontinuous data.
Accuracy of analog computer is low. Accuracy of digital computer is high.
There is very low or do not have storage or memory in analog computer. Digital computers have high storage or memory.
Cost of analog computer is low. Digital computer is multipurpose and programmable and hence used for general purpose.
Analog computers can’t be re-programmed or if needed to be re-programmed then whole circuit system and hardware parts are to be replaced with new ones. These computers are totally flexible and can be re-programmed.
The wave of Analog signals are shown below:

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The wave of Digital signals are shown below:

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E.g: Thermometer, Barometer etc. E.g: PC, Digital camera, digital clock etc.

Classification of Digital Computer based on Size:

Now day’s computers are available in different sizes and with different capabilities. on the basis of storage capacity of speed of processing information computers are classified into:

1. Micro computers(PC):

The smallest general-purpose computers are called micro computers. Which consists of  a single small CPU(central processing units),normally called a microprocessor. Now a days microcomputers are being smaller and smaller but more powerful. Micro computers are known as PC(personal computer) or home computers. These computers are used in Business, engineering, schools, Bank, Entertainment  etc. for example: IBM PC(International Business machine),IBM XT(Extended Technology), laptop, notebooks, PDA(personal digital assistant) etc.

2. Minicomputer

Minicomputers are more powerful, high processing speed and having more storage capacity than micro computer. The cost of minicomputer is high than micro computer. These are multi-user( means more than one user can use the computer ) and multiprocessor( Having more than one processor in a single system). They have high processing’s speed, capabilities, large storage space than micro computers. E.g: VAX 50,IBM360.

3. Mainframe Computers:

Main frame computer large machines ,made of several units connected together. Mainframe computers are more powerful, high processing speed and having more storage capacity than minicomputer. Mainframe computers are generally used in big organizations and government departments for large-scale data processing. For example: IBM 3090,VAX 8842 etc.

4. Super computers

The largest computer in the world is called super computer. Which is more powerful ,  more expensive computers and they have extremely large storage capacities and processing speed is at least 10 times faster than other computers. so they  are big machines. Inside super computers, there are several smaller computers ,each of which can work on different parts of a work simultaneously. They can be handled and maintained by computer engineers only. super computers are used in weather forecasting, medicine and for creating computer graphics. Some of the super computers are CRAY,NEC super SXII,CYBER 205.

5. Workstation computer:

This is a powerful, single computer. A workstation is like a personal computer, but it has a more powerful microprocessor and a storage device for storing data. These are more expensive computer which are used by Engineers, scientist and other professionals who processed  a lot of data. People who use complex program use this types of computers. It has better quality display and others. The powerful workstations are called supermicro. For example: Workstations computer made by Sun, Applo, NeXT, IBM.

6. Portable Computers:

The computer which can be easily carried from one place to other place around is called portable computer. These are smaller computer and yet powerful. For example: laptops or Notebook PCs, PDA(personal Digital Assistant) etc.

7. Network Computers:

Network Computers are computers with minimal memory, disk storage and processor power designed to connect to a network, especially the internet. The idea behind network computers is that many users who are connected to a network do not need all the computer power they get from typical personal computer. Instead they can rely on the power of the network servers. These types of computer minimize the amount of disk storage, and processor.


Classification Based on Brand:

Computers are classified in terms of brand also. Many companies are involved in manufacturing of computer throughout the world .Many brands of computers are available in the market. On the basis of brand the following three categories are available:

  1. IBM PC
  2. IBM compatible
  3. APPLE/Macintosh

1. IBM PC(International Business Machine personal computer)

IBM is one the leading companies of the world in manufacturing computers, which established in 1924 in USA.In the beginning IBM  manufactured main frame computers followed by mini and micro computers. The computers manufactured by IBM are called as IBM computers or IBM brand computers. personal computer(PC) is the most important type of microcomputer, the microcomputers manufactured by IBM company are called as IBM PC.These computers are more reliable, durable and have better quality and the cost originally was very high but now a days the cost has gone down.

2. IBM Compatible

A computer that has the same functional characteristic and the principles of IBM computers are called as IBM compatibles. The basic architecture is similar to IBM PC excepting few technologies. All the software and programs, which run in IBM computers can equally run in IBM compatibles. IBM compatible computers are cheaper and their parts are easily available in the market. Therefore they are popular in the world. Most of the microcomputers used in Nepal are IBM compatibles.

3. Apple/Macintosh

The computer manufactured by Apple company with different architecture is called as Apple or Macintosh computer. This company was established in USA in 1970s.The Apple computers have their own software and hardware. Apple company manufactured new brand of computer popularly known as Macintosh. In Nepal most of the Desktop publishing houses use Apple/Macintosh because they are very easy to handle and the graphic print that we get is of better quality.



  1. Differentiate between microcomputer and supercomputer.
  2. Write short note:- Workstation computer, personal computer(PC)

Types of Computer on the basis of model:

1. XT (Extended Technology)

The computer which uses 8086 or 8088 microprocessor types are called XT computers. These types of computer have processing speed 4.77 MHz and they are comparatively slower in speed. They can not run advanced form of software programs.

2. AT(Advanced Technology ) Computer:

The computer which uses 80286  microprocessor is called AT computers. These computers are faster than XT computers. The memory capacity is also higher than XT computers and can run advanced form of software programs. For example desktop pc, home pc etc.

3. PS/2 Computer

The PS/2 computers are called personal system computers, which are smaller than AT computer and having more storage capacity than XT computers.  These types of computer are known as portable computers so that they can easily carry from one place to another place. For example, laptop, notebook, mobile pc etc.


Personal computer (PC)

Personal computer (PC) is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals.

A personal computer may be a desktop computer, a laptop, tablet PC or a handheld PC (also called palmtop). The most common hardware components are CPU, RAM, Motherboard, keyboard and pointing device ,Hard Disk etc.

Software applications for personal computers include word processing, spreadsheets, databases, Web browsers and e-mail clients, games, and myriad personal productivity and special-purpose software. Modern personal computers often have high-speed or dial-up connections to the Internet, allowing access to the World Wide Web and a wide range of other resources.

A PC may be used at home, or may be found in an office. Personal computers can be connected to a local area network (LAN) either by a cable or wirelessly.

a) Workstation

A workstation is a high-end personal computer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems.

b) Desktop computer

Desktop PCs can fit on a desk was considered remarkably small than workstation PC. Today the phrase usually indicates a particular style of computer case. Desktop computers come in a variety of styles ranging from large vertical tower cases to small form factor models that can be tucked behind an LCD monitor. In this sense, the term ‘desktop’ refers specifically to a horizontally-oriented case, usually intended to have the display screen placed on top to save space on the desk top. Most modern desktop computers have separate screens and keyboards.

c) Single unit

Single unit PCs (also known as all-in-one PCs) is a subtype of desktop computers, which combine the monitor and case of the computer within a single unit. The monitor almost always utilizes a touch screen as an optional method of user input; however detached keyboards and mice are normally still included. The inner components of the PC are often located directly behind the monitor.

d) Laptop

A laptop computer or simply laptop, also called a notebook computer or sometimes a notebook, is a small personal computer designed for portability. Laptops contains high capacity batteries that can power the device for extensive periods of time, enhancing portability. Once the battery charge is depleted, it will have to be recharged through a power outlet. In the interest of saving power, weight and space, they usually share RAM with the video channel, slowing their performance compared to an equivalent desktop machine.

One main drawback of the laptop is that, due to the size and configuration of components, relatively little can be done to upgrade the overall computer from its original design. Some devices can be attached externally through ports (including via USB), however internal upgrades are not recommended or in some cases impossible, making the desktop PC more modular.

e) Notebook:

Notebooks are small portable computers in a “clamshell” design that are designed specifically for wireless communication and access to the Internet. They are generally much lighter and cheaper than subnotebooks, and have a smaller display, between 7″ and 9″, with a screen resolution between 800×600 and 1024×768 but newer models feature higher resolution at up to 1280×768.

f) Tablet PC

A tablet PC is a notebook or slate-shaped mobile computer, first introduced by Pen computing in the early 90s. Its touch screen or graphics tablet/screen hybrid technology allows the user to operate the computer with a stylus or digital pen, or a fingertip, instead of a keyboard or mouse. The form factor offers a more mobile way to interact with a computer. Tablet PCs are often used where normal notebooks.

g) Home theater PC

A home theater PC (HTPC) is a convergence device that combines the functions of a personal computer and a digital video recorder. It is connected to a television or a television-sized computer display and is often used as a digital photo, music, video player, TV receiver and digital video recorder. Home theater PCs are also referred to as media center systems or media servers. The general goal in a HTPC is usually to combine many or all components of a home theater setup into one box. They can be purchased pre-configured with the required hardware and software needed to add television programming to the PC, or can be cobbled together out of discrete components as is commonly done with MythTV, Windows Media Center, GB-PVR, SageTV, Famulent or LinuxMCE.

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History of computers

The history of computer development is often referred to in reference to the different generations of computing devices. Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices.

  1. History of computer starts from time when there were no any number systems discovered and no any device for calculation.
  2. First people counted on their fingers, then they cut the notched of sticks, counted stones and even tied knots in rope.

The development of computer is described in three parts:

I) Mechanical calculation era:

In this part we will discuss the development of mechanical calculating device.

  1. Abacus:
    1. It was the earliest counting device. It was believed to be discovered in china about 3000 BC. But it actually evolved in different culture at about the same time.
    2. It used beads to represent digits and wire to hold places.
    3. It was used only to add and subtract.
    4. It has two parts heaven and earth.
  2. Napier’s Bone:
    1. Invented by English mathematician John Napier in 1614 AD. (Napier was the founder of modern logarithms).
    2. This mechanical device was used for multiplication and division.
    3. It consists of nine pieces of rectangular cards; each divided horizontally into nine
    4. Square.
    5. Each square is divided diagonally from the right hand corner to bottom left hand corner. In each card multiplication tables from 1 to 9 was written. He places ten above diagonal and unit below the diagonal of square.
  3. Slide Rule:
    1. This device was developed by an English mathematician William Ought Red in 1920.
    2. It was based on the principle of logarithms
    3. It was made up of three parts:
      1. The body (ruler)  .
      2. The slide with scale marked on it.
      3. The transparent cursor marked with sharp lines as indicator.
    4. It was very easy to use; the results of the calculation were obtained by just moving the slide along the body.
  4. Pascaline (Pascal’s calculator):
    1. French mathematician, Blaise Pascal, developed Pascaline in 1642.
    2. It was the first mechanical calculator, and limited to performing only addition and subtraction. And calculation was possible up to 8 digits.
    3. It used a mechanical gear to add and subtract. And had simple monitor to see the results.
    4. Multiplication was performed by repeated addition and division by repeated subtraction.
  5. Stepped Recknor:
    1. In 1971, a German mathematician Gothfried Von Leibnitz modified the Pascaline machine and invented the calculating machine called stepped Recknor.
    2. It could perform addition, subtraction, multiplication, division and could find out square root also. 1 Logarithm: one of a series of arithmetic exponents tabulated to simplify computation by making it possible to use addition and subtraction instead of multiplication and division.
  6. Jacquard’s loom:
    1. In 1802 AD, Frenchman Joseph Marie Jacquard, a textile manufacturer discovered a mechanism for automated weaving of clothes. [I.e. he developed a loom that could be programmed, used large card with holes punched in them to activate rod that raised and lowered threads in a weaving machine.]
    2. It was based on principle of present and absent of some holes, in which principle punch cards were developed afterwards.
    3. So he is called the father of punch cards concepts.
  7. Difference and analytical engine:
    1. In 1822 AD, a British mathematician Charles Babbage develop mechanical device called Difference engine. It was designed specially to compute polynomials (expression of more than two algebraic terms).
    2. In 1833, Babbage designed analytical engine which was general purpose computer that solve any arithmetic problems.
    3. Not only these calculators, he invented working principle of computer, on which modern computers are also based. So, he is called the ‘father of the computer’.
  8. Lady Augusta Ada:
    1. She was the disciple of Charles Babbage. She carried forward the works of Babbage.
    2. She made the first program to be used in Babbage Machine. So she is called the ‘first programmer’.
    3. To honor her work, a programming language called ‘Ada Prog’ was named after her and used in US defense department for long time.
  9. Gorge Boole:
    1. Gorge Boole an English mathematician discovers a mathematical logic called “Boolean Algebra” in 19th century.
    2. Boole reduced the logic to two valued binary notation in which two digits 0s and 1s can be used to represent any form of data.
    3. The mathematical system of 0s and 1s provided theoretical foundation for switching electronic devices in modern digital computers.
  10. Dr. Herman Hollerith: Dr. Herman Hollerith was a census statistician, who was remembered in the history of computer for following contributions:
    1. He invented a machine called Tabulating machine (Tabulator) in 1886 AD which could process on punch cards and performs census calculation faster than ever before.
    2. He was the first person to use punch card practically.
    3. He was the founder of IBM (international Business machine), which he founded in 1923 AD.

II) Age of electromechanical computers:

  1. Mark‐I:
    1. In 1937 Prof.  Howard Aiken developed an electromechanical computer called Mark‐I.
    2. It was also called automatic sequence controlled calculator (ASCC).
    3. It was very large computer of dimension 51ft*8ft*3ft.
    4. It consumed a lot of electricity and generates lot of heat.
    5. It used 18,000 vacuum tubes as memory device.
    6. In 1944 AD, Aiken modified Mark‐I and invented Mark‐II which used 19,000 vacuum tubes. (note: Mark‐I is also called first computer) 
  2. ABC (Atanasoff Berry computer):
    1. It was also called first electronic digital computer.
    2. It was invented by Dr. John V. Atanasoff and Clifford Berry in 1942 AD.
    3. It used 18,000 vacuum tubes and other 45 valves for internal logic and capacitor for storage of electrical charges.
    4. It used punch card as secondary storage.

III)Age of electronic computers:

  1. ENIAC (Electronic Numerical Integrator and calculator):
    1. It was developed by Dr John W. Mauchly and J. Presper Eckert in 1946.
    2. It was developed for U.S army to compute new trajectory table for use in world war‐II. But it was too late to made use of in the war.
    3. It was built from 17,468 vacuum tubes
    4. It could perform 5000 addition and 300 multiplications per second.
    5. It was extremely large and occupied a space of 1500 sq. feet.
    6. It was the first and last computer to use decimal number system.
    7. It was used still 1955 in US army.
    8. ENIAC has some disadvantages such as:
      1. It generates a lot of heat
      2. Small storage capacity
  2. John Von Neumann:
    1. He developed the principle of stored program in 1945 AD. So he is called the father of stored program.
    2. Before his principle, the program required for computer were integrated and written permanently in machine, so modification of program was not possible.
    3. But after stored program concept, we stored programs inside computer in some storage media.
  3. EDSAC (Electronic delay Storage Automatic Computer):
    1. It was invented by Maurice Wilkes in 1949.
    2. It also used vacuum tubes.
    3. It was the first stored program computer.
  4. EDVAC (Electronic Discrete Variable Automatic computer):
    1. It was developed by J.P. Eckert and John Mauchly in 1952. Although started before, it was completed after EDSAC.
    2. It also used vacuum tubes and some internal storage.
  5. UNIVAC (Universal automatic computer):
      1. It was also developed by john Mauchly and J.P. Eckert in 1961 AD.
      2. It was the first computer manufactured for commercial use and is a general purpose digital computer.
      3. Before this all the computer were used for either defense or census.

The Generations of computers

The term computer generation is often used in relation to the hardware of computers. Each phase of computer development is known as a separate generation of computers.

1)The first Generation computers(1945-55)

The first generation computers were very slow ,very large size and consumed a lot of power and produced large amount of heat. All these computer uses vacuum tube circuitry and programming was a difficult task

Storage devices: magnetic drum(2kb memory)

Input Methods: punched cards, output devices: punched cards, printed reports

Application: scientific purposes.

The first generations computers are as follows.

ENIAC(Electronic Numerical Integrator And Calculator),UNIVAC(Universal Automatic computer),EDVAC(Electronic Discrete variable Automatic Computer) etc.

2) Second Generations computers(1956-65)

The second generation computers began with the advent of semiconductor transistor by Bell laboratories .Transistor were highly reliable compared to tubes. They occupied less space and required only 1/10 of the power required by tubes and were ten times cheaper than using tubes. These computers used transistor, were faster, more reliable, relatively smaller, consumed less power.

These computer uses magnetic disk as storage devices. These computer uses high level programming languages such as FORTRAN, COBOL, Algol and snobol etc. At that time with advent of CPU and magnetic disk, operating systems came into begin which is Batch operating systems. For example: IBM 700,1401,ATLAS etc. are examples of second generations computers. These computers are used for Business and engineering purposes.

3) Third generations computers(1966-75)

The third generation computers replaced transistor with “Integrated Circuits” known popularly as chips. These computers using integrated circuits proved to be highly reliable, relatively inexpensive and faster. These computers have CPU, large storage space. These computer uses high level programming languages . The third generations computers are IBM 360-370ICL-1900,NCR 395,CRAY-1 etc. These computers were used in educations, Research, small businesses as well as scientific and engineering purposes.

4) Fourth Generations Computers(1976-90)

These computers uses the concept of very large scale Integrated(VLSI) circuits. At that time the advent of microprocessor was introduced which is a single small CPU  attached inside computer system. Data are entered through keyboard, and displayed using monitor. These computer uses high level programming languages such as C,C++,JAVA PROLOG etc.

This generation computer has high processing speed, large storage capacity and much more powerful operating system. E.g: IBM, PC, PENTIUM I, PENTIUM II and PENTIUM III  etc.

5) Fifth Generation (Present and Beyond)

Fifth generations computers are only in the minds of advance research scientists and being tested out in the laboratories. These computers will be under Artificial Intelligence (AI), They will be able to take commands in a audio visual way and carry out instructions. Many of the operations which requires low human intelligence will be performed by these computers.

Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.

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