This Unit introduces Senior One students to a Computer and how it works.


Computers are necessary in today’s society. We live in a fast-moving world where almost everything must come to us instantly.

Many times, we depend on the computer to help us complete tasks, and to solve problems.

The digital age has affected all of our lives and today’s society is no longer able to function without computer technology.

Therefore, we can say computers are vital in today’s society as they make life much easier for everyone.

Definition and characteristics of modern computers

What is a computer?

A computer is an electronic device that accepts user input (data), processes it under special instructions (programs), to produce the desired meaningful output (information).

Alternatively, a computer can be defined as a programmable machine that receives input, stores and manipulates data, and provides output in a useful format.



A computer is an electronic device which is used to store the data, as per given instructions it gives results quickly and accurately.
  • Data: Data is a raw material of information.
  • Information: Proper collection of the data is called information.

Characteristics of Computer

  • SPEED: In general, no human being can compete to solving the complex computation, faster than a computer.
  • ACCURACY: Since Computer is programmed, so whatever input we give it gives a result with accurately.
  • STORAGE: Computer can store mass storage of data with appropriate formate.
  • DILIGENCE: Computer can work for hours without any break and creating an error.
  • VERSATILITY: We can use the computer to perform a completely different type of work at the same time.
  • POWER OF REMEMBERING: It can remember data for us.
  • NO IQ : Computer does not work without instruction.
  • NO FEELING: Computer does not have emotions, knowledge, experience, feeling.

Computer and its components

Computer: Computer itself a combination of different type of separate electronic device. i.e. Computer only will be a computer if it has an INPUT DEVICE, PROCESS UNIT, and OUTPUT DEVICE.

  • Central Processing Unit (CPU): It is heart and mind of the computer without this unit computer unable to process.
  • Keyboard: This is an input device which is used to input the data into the computer.
  • Mouse: This is also an input device which is used to input the data into the computer.
  • Monitor: This is an output device which is used to show the result of the instructions.

There is a variety of monitor available in the market such as CRT Monitor, LCD Monitor, Touch Screen Monitor, TFT Monitor etc.

  • Switched Mode Power Supply (SMPS): This is an electronic device which is used to manage the power supply of the computer.

  • Hard Disk (HDD): This is used to store the data in a massive amount. There are so many types of HDD available in the market, i.e. SATA, PATA, External HDD, Internal HDD.
  • Printer: This is an output device which is used to show the result on the paper. There are plenty of printers available in the market like inkjet, Laser printer, dot matrix printer etc.

Universal Serial Bus (USB) : This is used to connect the external device to the computer.

  • Ethernet Cable: This is used to connect computer with another computer.
  • CD/DVD ROM: This is used to store the data.
  • Speaker: This is an output device which is used to listen to voice, songs, etc.
  • Microphone: This is an Input device which is used to record the sound.
  • Laptop: This is a complete computer which can be carried anywhere at any time.
  • Notebook: This is called a mini laptop which is generally lighter and smaller than a laptop.
  • Random Access Memory (RAM): This is called primary memory. This is also called the main memory of the computer. Whatever data is written in this memory, is lost after switching off the system.
  • Read Only Memory (ROM): This is called primary memory. Data is written in this memory by the vendor of the computer permanently.
  • Pen Drive: This is a very popular device nowadays for carrying data on move.
  • Blue Ray Disk: This is the same as CD/DVD but only different is it can store the multi time of data from CD/DVD and faster than CD/DVD.
  • Scanner: This is an input device which is used to scan the document for the soft copy.
  • LCD: It is known as Liquid Crystal Display. It is an output device as a monitor.
  • Motherboard: It is a combination of electronic circuits.
  • Sound Card: This is also a combination of electronic circuits which helps to give output in the form of sound.
  • Graphics Card: This is also a combination of electronic circuits which helps to give output the data into the monitor.

Computer Software

Software is a logical programme to handle/solve a complex problem.

  • System Software: This is a special type of software which is responsible for handle the whole computer system.
  • Application Software: This is a special type of software which is used to solve a particular problem.
  • Embedded Software: This type of software embedded with hardware to do a specific type of job.
  • Proprietary Software: In general, this type of software required to purchase to use that particular software for some time or single user as per conditioned by the vendor of that particular software.

Open Source Software : This type of software may be freely available and cannot be used in commercially. We can modify, and use it under the same license.

Computer Languages

  • Machine Level Language: This is low level programming language. Computer or any electronic device only understand this language. i.e. Binary number i.e 0 and 1.
  • Assembly Level Language: This is a low-level programming language which is converted into executable machine code by a utility programmer referred to as an assembler.
  • High-Level Language: High-level language is a programming language which is easily understandable/readable by a human.
  • Interpreter: This is a converter which converts a high-level language programme to low-level language programme line by line.
  • Compiler: This is also a converter which converts whole high-level language programme to low-level language programme at a time.

Number System

  • Binary Number System: It has only base 2 i.e 0 and 1
  • Octal Number System  : Base of octal is 8 i.e. 0, 1, 2, 3, 4, 5, 6, 7
  • Decimal Number System : Base of Decimal is 10 i.e. 0 1 2 3 4 5 6 7 8 9
  • Hexadecimal Number System: Base of this number system is 16 i.e. 0 1 2 3 4 5 6 7 8 9 A B C D E F

Operating System

  • Windows: This is a Proprietary Operating system and vendor is Microsoft. i.e. Windows 2007, Windows Vista, Windows 2008 etc.
  • Linux: This is an open source Operating System such as ubuntu, Fedora, Debian, Mandriva, centOS etc.

Linux (Ubuntu ) Desktop Elements

File Management in Linux (Ubuntu)

Computer Security

  • Virus and worms: These are the computer programme which malfunction the computer system. A virus requires a carrier while worms do this by itself. The worm does not require any carrier.
  • Spoofing: Through this, deceiving the computer users and making the fool.
  • Intrusion or Hacking: If a computer is used and controlled by unauthorised users then it is called hacking and who does this is called hacker. The main purpose of hacking to steal private data or alter the actual data.

Denial of Services: The main aim of this attack is to bring down the targeted network and make it to deny the service for legitimate users.

Sniffing: Data can be seen and watched when it travels one computer to other computer. Generation of the Computer Charlse Babbase is known as the father of the computer he has invented first analytical computer in the year 1822

  • First Generation (1940 – 1955). Example: Electronic Numerical Integrator and Computer (ENIAC), EDVAC
  • Second Generation (1956 – 1965) : IBM 1401
  • Third Generation (1966 – 1975) : IBM System/360
  • Fourth Generation (1976 – 1985) : Macintosh 128k
  • Fifth Generation (1986 -to date): Supercomputer

The characteristics of computers that have made them so powerful and universally useful are speed, accuracy, diligence, versatility and storage capacity. Let us discuss them briefly.

  • Speed

Computers work at an incredible speed. A powerful computer is capable of performing about 3-4 million simple instructions per second.

  • Accuracy

In addition to being fast, computers are also accurate. Errors that may occur can almost always be attributed to human error (inaccurate data, poorly designed system or faulty instructions/programs written by the programmer)

  • Diligence

Unlike human beings, computers are highly consistent. They do not suffer from human traits of boredom and tiredness resulting in lack of concentration. Computers, therefore, are better than human beings in performing voluminous and repetitive jobs.

  • Versatility

Computers are versatile machines and are capable of performing any task as long as it can be broken down into a series of logical steps. The presence of computers can be seen in almost every sphere – Railway/Air reservation, Banks, Hotels, Weather forecasting and many more.

  • Storage Capacity

Today’s computers can store large volumes of data. A piece of information once recorded (or stored) in the computer, can never be forgotten and can be retrieved almost instantaneously.


  • To promote creative knowledge for problem solving.
  • Computing requires and develops capabilities in solving deep, multidimensional problems requiring imagination and sensitivity to a variety of fields.
  • To acquire skills in the use of IT for enhanced productivity and development.
  • This is because the dimensions of computing are part of the necessary skills set for an educated person in the 21st century.
  • With computer studies, a student gets to acquire the following skills:
  • Technology Skills: Nearly all students will be faced with the need for technology skills when they go to university or enter the workforce.
  • Keyboarding Classes: Students learn at a young age how to use
    computers to generate reports, type essays and research homework
  • Career Preparation: Computer skills learned in school will benefit
    students during higher education courses and their careers. Students as young as 12 learn how to create Electronic Spreadsheets, Power Point presentations, Databases and Website Design.
  • Online Access: By learning how to use computers, students even in
    low-income areas have access to the world at large.
  • Adult Learning: Students who are introduced to computer courses at an early age adapt quickly to advances in technology, and typically do not fear additional training and new concepts as adult learners.
  • To promote critical and analytical thinking for proactive (hands-on) solutions.
  • Computing drives innovation in the sciences such as vaccine research, environmental protection, business, entertainment and education. Through computer studies, one can make a positive difference in the world.
  • To create awareness in a learner about the developments and emerging issues concerning computing and society.
  • Computing is one of those highly evolving fields where it is
    almost impossible to predict what will happen in the future.
  • To get jobs. Computing offers many types of highly rewarding
    careers. Computer studies provides a foundation that serves as a competitive advantage in a career, in whatever field one chooses. Examples of such jobs include: Typists, Computer operators, Computer technicians, System analysts, Computer programmers, Software engineers, Computer engineers, Database administrators,
    website masters, Graphic designers, IT Teachers, etc.




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