Chapter 1 BS Computer Science Notes (Introduction to Computer) 2021-22

Chapter 1 BS Computer Science Notes (Introduction to Computer) 2021-22



Definitions of Computer

  • An electronic machine that can store and process information. It is defined as stored program digital computing system.
  • A Computer is an electronic device of wires, transistors, circuits, instructions, and data can transmit, store and manipulate information.
  • A Computer is a machine that accepts data and processes that data (data may be numbers, letters or both or even sounds). Information is turned into electrical pulses so that it may be processed by sorting and deleting mathematical manipulation and other forms of data processing.
  • A computer accepts information using an input device. The information is processed by a central processing unit or stored in a storage unit i.e. Hard Disk and then processed.
Chapter 1 BS Computer Science Notes (Introduction to Computer) 2021-22

A Block Diagram of Computer System

The result is supplied by output devices. If the input and output units are connected to a manufacturing process, the computer can control the process and the system is called a computing system.

Data & Information


The word data is the Latin plural of Datum which means “to give” or “something gave” (the word data is usually used as a singular term). Data is a collection of facts, figures, numbers or ideas that can

be organized and processed. Data may or may not be meaningful and cannot be meaningful and cannot be used for the decision-making process.

“In short terms, the raw fact and figures are called data”.

Data are facts and figures which can be represented by values, numbers, strings or symbols and which carry meaning in a particular sense. The name of the person marks obtained by the student are Examples of Data.

Data may be Qualitative or Quantitative.

Qualitative Data:

The data usually non-numeric (Alphabetic) is called Qualitative data. This data states the characteristics of objects or things for example the words like good, average, excellent, heavy, red, green, hot, cold long, intelligent, dull etc. are examples of Qualitative data.

Quantitative Data:

The data which can be represented by numbers is called Quantitative data, for example, the marks obtained by the students in the examinations, total number of the students in a class, age of a student, phone number are all examples of Quantitative data.


When facts figures are numbers (data) are processed and converted into a meaningful form that can be used for decision making or any other useful activity, it is called information

“The Processed form of the data is called Information”.


“Meaningful form of data is called the information”.


“Manipulation of data into a useful form is called Information”.

The temperature, the atmospheric pressure, the wind speed etc. at a place represents data. These data items when combined together and analyse become more meaningful and predict the weather as Rainy Day, Strong Condition, or Dry Condition, which is information.

Differentiate Between Data and Information






Data is a collection of raw facts and figures.

Information is processed data.



Data is unarranged and unorganized.

Information is arranged and organized.



Data is not meaningful.

Information is meaningful.



Data is input.

Information is output.



Data is used less frequently.

Information is used frequently.



Data represents facts before processing.

The information represents results (obtained


after processing).



Data is not helpful in decision-making.

Information is helpful in decision-making.



Data is the raw material for information.

Information is the final product of data.



Data are unprocessed records

The information contains processed records



Data is in large amounts

Information is in small amounts



If data is lost, it is very difficult (or even

If information is lost, it is easily derived


impossible in some situations) to recollect.

from stored data, again.


Chapter 1 BS Computer Science Notes

History of Computer

The computer did not suddenly arrive on the scene rather we can say that their number and use is gradually Increased during the recent years. Initially, the computer was developed as an accounting machine. With the passage of time changes in this machine-made it most effective and it became a revolutionary invention of this century. Today we find billions of computers all around us converting all most all the fields of life. The research on computer technology is a process of hundreds of years and is still in progress.

See More: Notes of Computer Science Class 9th


“ABACUS” also known as “SOROBAN” was the first recognized calculating device, developed in “Babylonia” (Iraq) about 5000 years ago. So good was the abacus that can still be seen throughout the world as both, a toy and a teaching aid. This abacus marked the first step on the road to the computer.

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Napier’s Bone

In the early 1600s, John Napier, a Scottish mathematician and Politician, invented Logarithm and a device called Napier’s bones, constructed from strips (rod) of bone and wood. This device allowed quick and accurate multiplication and division of large numbers.

Chapter 1 BS Computer Science Notes (Introduction to Computer) 2021-22

Computer Notes all Classes


One of the first mechanical calculators was developed about 1642 by 19 years old “Blaise Pascal”. Without the use of books, this French man developed a workable calculating machine called “Pascaline”. The construction of the device was straight forward a series of gears were used. Each gear has 10 teeth. The device had the ability to “carry “digits to the next gear.

(Introduction to Computer) 2021-22

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Leibnitz’s Machine

In 1694, Wilhelm Leibnitz completed his machine. Pascal’s machine could only add and subtract, but Leibnitz’s machine could also multiply, divide and find square roots.

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Jacquard’s Loom (1801)

Chapter 1 BS Computer Science Notes (Introduction to Computer) 2021-22

Joseph Jacquard, a French textile manufacturer developed a system that used the punched cards for controlling a weaving loom.

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Difference Engine & Analytical Engine

The man who perceived the computer was a British inventor “Charles Babbage” a 19th-century professor at Cambridge University, is considered to be the father of modern digital computer; Like Pascal and Leibnitz, Babbage also was a mathematician and he too, wanted to build a machine that could perform different calculation quickly.

Charles Babbage developed a steam-power calculator “Difference Engine”. In 1823, Babbage started to improve the Difference Engine. Actually, he wanted to develop a complete calculating machine “Analytical Engine”, but he failed, because the standard of Engineering technology was not so high at that time and therefore machine was never completed. But in fact, Babbage succeeded in establishing the basic principles on which modern computers are constructed.

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Charles Babbage analytical engine

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In 1937, Howard A. Aiken, at Howard University Washington began a project with the support of

IBM cooperation and completed in 1944. The machine was called the “Mark-I”. the Mark-I was about 8 feet high and 55 feet long and sounded like a room full of old ladies knitting away with the steel needles

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The history of computers and their development are described in the following five generations.

Generations of computer

First-generation (1940-1956): vacuum tubes

  • J.P Eckert and J. W. Mauchly invented the first successful electronic computer is called

ENIAC, ENIAC stands for “Electronic Numeric Integrated Calculator”.

  • It made use of vacuum tubes which are the only electronic component available during those days and require a large cooling system.
  • These computer were very costly and very big in size, weight was about 30 tones and consumed large amount of energy.
  • It could store only a small amount of information due to the presence of magnetic drums.
  • Very less work efficiency and limited programming capabilities.
  • Punch card were used to take inputs.
  • Not reliable and constant maintenance is required.
  • Example: ENIAC, EDVAC (Electronic discrete variable automatic computer), UNIVAC (Universal automatic computer), IBM (international business machine)-701and IBM-650.
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Vacuum tube

Second generation (1956-1963): transistors

  • Second generation computer were based on transistor instead of vacuum tubes.
  • Reducing the size of a computer as compared to first generation computers.
  • Less energy and not produce as much heat as the first generation.
  • Assembly language and punch cards were used for input.
  • Low cast than first generation computer.
  • Better speed, calculate data in microseconds.
  • A cooling system was required.
  • Examples: IBM 1620, IBM 7094, CDC 1604, CDC 3600, UNIVAC 1108.
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Third generation (1964-1971): integrated circuits

  • This generation computers were based on integrated circuits (ICs). IC was a single component containing number of transistors.
  • Computer were cheaper and small in size as compare to second generation computers, which was fast and reliable and also improves the performance.
  • Computer has big storage capacity.
  • Mouse and keyboard are used for input.
  • They used an operating system for better resource managements and used the concept of time sharing and multiple programming.
  • Reduce the computational time for microseconds to nanoseconds.
  • Examples IBM 360 series, Honeywell-6000 series, PDP (personal data processor), and IBM-370/168.
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Fourth generation (1972-2010): microprocessors

  • This generation is based on Microprocessor.
  • Microprocessor is used in a computer for any logical and arithmetic function to be performed in any program.
  • Graphical user interface (GUI) technology was exploited to offer more comfortable to users.
  • Small in size as compared to previous generation computers
  • Fastest in computation and size get reduced as compared to the previous generations of computer.
  • Heat generated is negligible.
  • Less maintenance is required.
  • All type of high-level language can be used in this type of computers.
  • Example STAR 1000, CRAY-X-MP (super computer), DEC 10, PDP 11, CRAY-1.
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Fifth Generation (2010- ): Artificial Intelligence

  • This generation is based on artificial intelligence.
  • The aim of the fifth generation is to make a device which could respond to natural language input and are capable of learning and self-organization.
  • This generation is based on ULSI (Ultra Large Scale Integration) technology resulting in the production of microprocessor chips having ten million electronic component.
  • It is more reliable and work faster.
  • It is available in different sizes in and unique features.
  • It provided computers with more user-friendly interfaces with multimedia features.
  • Examples: Desktop, Laptop, Notebook, Ultra book, Chrome book.

Classification of Computers

Computers are available in different shapes, sizes and weights, and they are used for different purposes.

Computers can be classified according to the following:

  1. Classification by Purpose
  2. Classification by Capacity and size
  3. Classification by Nature / Type

Classification of the computer by purpose

They are designed to perform different types of tasks. Solving a problem or doing a particular job. Computers are different on the basis of their data processing abilities. They are classified according to purpose, data handling, and functionality. For this purpose, there are two types.

General-purpose computer

Special purpose computer

General-purpose computer:

By definition, a general-purpose computer can solve any problem. For example, they can be used to write letters and play games.

Special purpose computer:

Special purpose computers are designed to perform a specific task. Examples digital calculators, traffic signals, ATMs (automated teller machines). Digital watches.

Classification of Computers by Nature / Type

According to nature/type computers have the following three types.

Analog Computers.

Digital Computers.

Hybrid Computers.

Analog Computers

It accepts analogue input and provides analogue output information. An Analog computer is used to measure continuous values. It measures physical properties like voltage, pressure, speed, time and temperature. An analogue computer takes input in analogue form and gives output in analogue form. Its output is usually displayed on a meter or scale. Analog computer has low memory and fewer functions. Analog computer is mainly used in the field of engineering and medicine. Examples of Analog Computers includes are Thermometer, Speedometer and Analog clock.

Digital Computer

A digital computer works with digital data. Digital computer uses binary number system. A binary number system consists of only two digits 0 and 1. A digital computer represents data in digital signals. A 0 represents OFF and a 1 represents ON. The digital computer performs arithmetic and logical operations on data. It gives output in digital form. Digital computers are very fast. These computers can store results. They have large Memory (that is data storing capacity). Today most of the computers used in offices and homes are Digital computers. Examples: Personal Computer-(also called PC or Micro Computer), Digital Scoreboard, Digital watch

Hybrid Computer

This computer is a combination of both analog and digital computers in terms of speed and accuracy. Hybrid computers can measure physical and digital quantities. Examples of the hybrid computer are the machine measuring heartbeat in hospital, devices installed fuel pumps.

Classification by Capacity and Size

Computers are grouped according to their physical size, speed, storage capacity, cost, and the users at a time

There are many types of computers, some of which are given below:

Super Computer

Supercomputers are the most powerful and the most expensive computers design for scientific, engineering and business applications. These computers can process billions to trillions of instructions per second. The usages include worldwide weather forecasting, weapon research, stock analysis, automobile designing, special effects for movies and used for applications requiring complex mathematical calculations. Supercomputers process extremely high computing speed, higher capacity for storage, faster primary memory and secondary memory storage as compared to other types of computers.

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Mainframe Computer

Mainframe computers are the second most powerful and expensive computers than supercomputers. Mainframe computers are used mainly by large organizations for critical applications, typically bulk data processing such as Census Bauru industry and consumer statistics, enterpriser recourse planning and financial transaction processing. These computers have powerful processors and large memories to process large amounts of data at very high speed, such as billions of instructions per second. Mainly these are used by Airline companies, government departments, banks and insurance companies.

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Mini Computer

A midsized computer called minicomputers lies between workstations and mainframes. In the past decade, the difference between large minicomputers and small mainframes has blurred, however, as has the distinction between small minicomputers and workstations. But in general, a minicomputer is a multiprocessing system capable of supporting from 4 to about 200 users simultaneously.

Micro Computer or Personal Computer

Microcomputers are more commonly known as personal computers (PCs). The microcomputer is generally the smallest and least expensive of the computer family. Originally these computers were designed only for individual users but nowadays they have become powerful tools for many businesses that, when network together, can serve more than one user.

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Desktop Computer:

Desktop computer is the most common type of microcomputer many people use desktop computers at work, home, schools.

Laptop Computer:

A portable computer complete with an integrated screen and keyboard. It is generally smaller in size than a desktop computer and larger than a notebook computer.

Laptop Computer/Digital Diary /Notebook /PDAs: a hand-sized computer.

Palmtops have no keyboard but the screen serves both as an input and output device. It is a terminal or desktop computer in a network.

Importance of Computer

Computers are now a fact of life. Computers have created a very effective information system to help

streamline the management of an organization. This makes it a much-needed tool for every business,

banking, government, entertainment, daily life, industry, education, and administration. It can be said

of all large organizations, whether the department government or private, use a computer for a variety

of their daily business and it is the fastest growing industry in the world today. Each organization

usually has one or more large computer systems and a number of microcomputers. The system is a

great computer for data processing tasks, while many small microcomputers to use for word processing.

Computers have become part of our life is essential. In general, the use of computers can be divided

into several groups. Both as a prediction for decision-makers on the planning, development, and

growth based on past data. It is also a link to link data around the world in a short time. For the fields

of use mentioned above, the programs needed to be developed, tested and implemented on a

computer. As the system -the system used to process the data or information, call our information


Advantages of Computers

There are few numbers of advantages of Computer, are discussed below Speed

A computer is a very fast device. While talking about the speed of computers, we do not talk in term of seconds or even milliseconds. Our unit of speed is Microsecond, the Nanoseconds. A powerful computer is capable of performing about 3 to 4 million simple arithmetic operations per second.


The computer gives 100% accurate results and makes no mistakes. Errors can occur in a computer, but these are mainly due to humans i.e. due to imprecise thinking by programmers or due to inaccurate data.

Reliability (Consistency)

A human becomes bored and quickly exhausted (tired) performing repetitive, tedious tasks, whereas a computer is a tireless machine. It does not take coffee breaks, or become depressed after a fight with its friend, wife or husband. It does not go on strike or become angry. If ten million calculations have to be performed, a computer will perform the ten-millionth calculations with exactly the same accuracy and speed as the first one.

Power of Remembering

A Computer can store a huge amount of data because of its secondary storage. Every piece of information can be retrieved as long as desired by the user and can be retrieved as and when required.

Communication Tool

The computer is the fastest medium of communication. Through the computer, your message or document or photograph can reach any part of the world using internet facilities. You can download any amount

of material through the computer. Through video conferencing, you can not only see each other but also talk with anybody living in any part of the world.

Limitations (Disadvantages) Of Computer

  1. Computers can make the mind lazy. Instead of reading a book, or researching something at the library you use just a few key-strokes on computer, you have your answer.
  2. It destroys your social life and interactions with humans if you do not maintain the balance.
  3. It spends too much time by playing online games or chatting or using Facebook over the computer instead of reading books, taking walks, and doing homework.
  4. By using computer too much, it can also lead to anti-social behaviour and depression.

Applications of Computer or Uses 0f Computer

Nowadays computers are used in almost every field of life. Here are some fields in which computer is used very commonly.


A computer has a high speed of calculation, accuracy, reliability, or flexibility which made it an integrated part in all business organizations. The computer is used in business organizations for:

  • Payroll calculations
  • Budgeting
  • Sales analysis
  • Financial estimation
  • Managing employee’s database Maintenance of stocks etc.


Today banking is almost totally dependent on computers. Banks provide the following facilities

Banks provide an online accounting facility, which includes current balance, deposits, interest charges, shares, and trustee records. ATM machines are making it even easier for customers to deal with banks.


Insurance companies are keeping all records up-to-date with the help of computers. The insurance companies, finance houses and stockbroking firms are widely using computers for their concerns.

  • Insurance companies are maintaining a database of all clients with information showing
  • procedure to continue with policies
  • starting date of the policies
  • next due instalment of a policy
  • maturity date
  • interests due
  • survival benefits
  • bonus


The computer has provided a lot of facilities in the education system.

  1. The computer provides a tool in the education system known as CBE (Computer Based Education).
  2. CBE involves control, delivery, and evaluation of learning.
  3. The computer education is immediately increasing the graph of number of computer students.
  1. There are number of methods in which educational institutions can use computer to educate the students.
  2. It is used to prepare a database about performance of a student and analysis is carried out on this basis.


In marketing, uses of computers are Advertising – With computers, advertising professionals create art and graphics, write and revise copy, and print and publish ads with the goal of selling more products.

At-Home Shopping

Home shopping has been made possible through the use of computerized collections that provide access to product information and permit direct entry of orders to be filled by the customers.

Health Care

Computers have become an important part of hospitals, labs, and dispensaries. The computers are being used in hospitals to keep the record of patients and medicines. It is also used in scanning and diagnosing different diseases. ECG (Electro cardio graphy heart test), EEG (electro encephala gram brain test), Ultrasounds and CT Scans (computed tomography) etc. are also done by computerized machines.

Some major fields of health care in which computers are used are:

  1. Diagnostic System – Computers are used to collect data and identify cause of illness.
  2. Lab-diagnostic System – All tests can be done and reports are prepared by computer.
  3. Patient Monitoring System – These are used to check patient’s signs for abnormality such as in Cardiac Arrest (sudden loss of blood flow), ECG etc.
  4. Pharma Information System – Computer checks Drug-Labels, Expiry dates, harmful drug’s side effects etc.

Engineering Design

Computers are widely used for engineering purposes.

One of the major areas is CAD (Computer-aided design) that provides the creation and modification of images.

Some fields are:

  • Structural Engineering – Requires stress (hard) and strain (twisted) analysis for design of Ships, Buildings, Budgets, and Airplanes etc.
  • Industrial Engineering – Computers deal with design, implementation and improvement of integrated systems of people, materials and equipment’s.
  • Architectural Engineering – Computers help in planning towns, designing buildings, determining a range of buildings on a site using both 2D and 3D drawings.


Computers are largely used in defence. Modern tanks, missiles, weapons etc. The Military also employs computerized control systems.

Some military areas where a computer has been used are:

  • Missile Control
  • Military Communication
  • Military Operation and Planning and Smart Weapons


Communication means to convey a message, an idea, a picture or speech that is received and understood clearly and correctly by the person for whom it is meant for.

Some main areas in this category are:

  • E-mail
  • Chatting and Video-conferencing


Computers play an important role in government. Some major fields in this category are: Budgets

  • Sales tax department
  • Income tax department
  • Male/Female ratio
  • Computerization of voters lists
  • Computerization of driving licensing system
  • Weather forecasting (information, judgment)
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Basic Computer Operations/ Function

To understand the computer basic concepts one must know about the 4 functions or Operations of the computer.

Input Operation

The computer receives information from users. A user enters information using input devices like a keyboard, mouse or any other devices like a webcam, punch card, magnetic tapes, joystick or magnetic disk etc. The Input unit accepts information using input devices then it converts the given data to a readable form and this data moves to Central Processing Unit (CPU).

Storage Operation

The given information is stored in a computer using the different storage devices i.e. central processing unit and auxiliary memory. The auxiliary memory is also known as secondary or external storage have hard devices for example Floppy, Hard Disk, Compact Disk (CD) and Flash Drive (USB). These different storage devices have both advantages and disadvantages. Auxiliary storage speeds up information and stores it long term and permanent.

Processing Operation

It is considered the basic computing operation. It executes the instructions, control storage data and inputs or outputs devices attached to the computer.

Output Operation

word image 18 Last but not least the output unit represents results from the operations of the central processing unit CPU. The result may be in hard or soft form i.e. visual display unit, printers, and headphones.

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