Basics of Information Technology class 9th CBSE

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Computer Applications Class 9th CBSE Chapters

Index

  1. Basics of Information Technology
  2. Cyber Safety

Computer System

Computer runs on electricity. It takes input, process it and produce desired results. The results are known as outputs.

Characteristics of Computer system

Computers are capable of doing many important things in easy way for us. Its characteristics are speed, data storage, accuracy, versatility, diligence, reliability and  no iq.

Speed

  • The computer is a much faster device.
  • It can solve very complex problems faster than a person.
  • It gives results within a second.
  • Computer can solve multiple problems within very less time.

Data Storage

  • Can store a large amount of data for a long time period.
  • The data can be store in internal as well as external devices.
  • The internal device of data storage is Hard disk and external storage devices are Pen drive, External Hard disk, etc.

Accuracy

  • Computers can generate reliable results with high computational speed.
  • If the input is right then only the appropriate output will be generated.
  • The computer never gives inaccurate results; if results are inaccurate it means inputted data was erroneous.

Versatility

  • A computer is a versatile machine that can perform different types of jobs with the same accuracy rate.

Diligence

  • Computers never get tired.
  • As humans get tires when he works regularly but the computer can perform tasks over and over again, with the same outcome, and it does so without tiring.

No IQ

  • It performs a task that is exactly as directed by the user because it does not have its intelligence.
  • Reliable
  • Consistency refers that a computer is a reliable machine, as it always gives consistent results.

Components of computer system

CPU

CPU (Central Processing Unit) is a processing device in a computer. CPU is the brain of a computer.

It has a Microprocessor fixed inside it which processes data inputted by users using input devices. It is also known as processor and consist of three units namely

  • Control Unit ( CU )
  • Arithmetic logic Unit ( ALU )
  • Memory unit
Control Unit
  • Control Unit controls all the devices connected to the computer system so that interruption or unavoidable circumstances between device communications cannot happen.
  • CU not only controls device communication but also program executions.
  • CU mainly communicates between processor, memory and computer peripherals (input/output devices).
ALU
  • ALU stands for the Arithmetic and Logical Unit.
  • This is an important element of the computer system which is used to perform arithmetic and logical operations.
  • ALU is a part of a computer processor.
Memory Unit

The CPU’s memory unit includes registers, which store temporary data for processing. These registers are small, fast memory locations within the CPU. Registers hold data, instructions, and intermediate results, enabling the CPU to execute instructions efficiently.

Memory

  • Memory is a storage device of a computer system. This device is used to store data/ information.
  • As per user’s need and the advancements in the computer industry, the manufacturer’s developed advanced memory devices which can execute data speedily and can store large size data.
  • In computer, the nature of data storage is into two forms i.e. temporary and permanently.
  • Temporary storage is needed mostly at execution time.
  • While the permanent store is needed after the execution of the programs when the user wants to save results permanently for future reference.

Storage Devices

Storage devices hold data for computers. Its types are :

  • Hard Disk Drive (HDD) : traditional magnetic storage
  • Solid-State Drive (SSD): faster, flash-based storage
  • Pen Drive (USB): portable flash storage
  • SD Card: used in cameras and mobile devices
  • External HDD/SSD: for backup and extra storage
  • Optical Discs: CDs, DVDs for data storage and playback
  • RAM: Volatile memory storing data temporarily for fast access.
  • ROM: Non-volatile memory storing permanent data and firmware

I/O devices

I/O devices are hardware components that allow users to interact with computers

Input Device
  • The computer takes input through input devices.
  • It accepts data and instruction from the outside worlds.
  • It converts these data and instruction into computer understandable from a binary form.
  • It supplied the converted data and instruction to the computer system for further processing.
  • The most popular input devices are mouse, keyboard, joystick, microphone, camera, etc.
Output Device
  • These are the devices that show processed results or messages to the user.
  • The most popular output devices are Monitor and Printer.
  • The monitor shows computer instructions and output in the form of soft contents .
  • The printer prints the desired results on paper.
  • If the user wants to keep records then they prints it otherwise saves computerized contents in computer memory and uses these contents whenever they require.

Memory

Memory is also known as the storage medium of the computer system. This is a storage device that can store data/information. Memory is primarily categorized into two parts:

Primary Memory

This is also known as the main memory or temporary memory or volatile memory. This memory device stores data for a temporary period. Programs or instructions execute in Primary Memory.

Primary Memory further categorized into two parts – RAM (Random Access Memory) and ROM (Read Only Memory)

RAM (Random Access Memory) is volatile memory that stores data temporarily while a computer is running.

ROM (Read-Only Memory) is non-volatile memory that stores permanent data and instructions

Secondary Memory

Secondary memory is a memory that can store a large amount of data in it. Once, data is saved into secondary memory cannot delete until and unless the user’s permission. It is also known as a permanent memory.

Its examples are hard disk, ssd, pen drive , dvd etc.

Storage Devices

Storage devices are the computer hardware used to remember/store data. The different storage devices are:

Hard drive : An internal hard drive is the main storage device in a computer. An external hard drive is also known as removable hard drive. It is used to store portable data and backups.

CD-ROM disc : An optical storage device that is read-only or cannot be modified nor deleted.

DVD : These are recordable discs that can be written with data once or multiple times.

USB flash drive, jump drive or thumb drive : A small, portable storage device connected through the USB port.

Memory stick : A memory card that is removable.

Input/output devices

I/O devices are the pieces of hardware used by a human (or other system) to communicate with a computer.

Keyboard

  • It is the most commonly used input device.
  • It is used to enter data and instructions directly into the computer.
  • There are 104 buttons on the keyboard which are called keys.

Mouse

  • It is another input device which is commonly found connected with the computers.
  • It is basically a pointing device which works on the principle of Point and Click.
  • When the mouse is moved on the mouse pad, a light beam underneath reflect to give motion to the pointer on the screen.

Monitor

  • This is the most common output device connected with the computer to display the processed information.
  • It looks like a TV and is also know as VDU(Visual Display Unit).
  • Pictures are displayed by using a large number of very small dots on screen called pixels.
  • The number of pixels that a monitor can show on its screen is referred to as the resolution of the screen.

Printer

  • This is an important output device of the computer system.
  • It gives a printed output of the results that appears on the monitor screen.
  • Printed output is also called Hard Copy output because unlike monitor, this output can be preserved even if the computer is switched off.
  • Printers produce small to medium-sized documents and images.

Plotter

  • It is an output device which provides a high quality of printed output. It is generally used by engineers and architects.
  • Plotters create large, precise prints like architectural drawings or wall posters etc.

Scanner

A device that captures images or text from physical documents and converts them into digital format.

Web Camera (Webcam)

 A small camera connected to a computer, used for capturing video and images, often for video conferencing, online meetings, or streaming.

Types of software

System software

It is a software that provides platform to other software. Systems software includes the programs that are dedicated to managing the computer itself, such as the operating system, file management utilities, and disk operating system (or DOS). Some examples can be operating systems, device drivers etc.

Operating System

An operating system (OS) is a type of system software that manages computer’s hardware and software resources. It provides common services for computer programs. An OS acts a link between the software and the hardware.

Device drivers

Device drivers are software that help your computer communicate with hardware devices like printers, graphics cards, or sound cards

Application Software

These are designed to perform a specific task or a bunch of tasks. They can be user-designed (specific to the user’s needs) or readymade application software. Example: PowerPoint, Tally etc.

Mobile applications, or apps, are software designed for mobile devices, providing specific functionalities or services, like social media (Facebook), messaging (WhatsApp), or productivity (Microsoft Office) tools.

Computer Networking

A computer network is a system in which multiple computers are connected to each other to share information and resources.

  • In computer networking computers, Share resources from one computer to another.
  • We Create files and store them in one computer, access those files from the other computer(s) connected over the network.
  • We can Connect a printer, scanner, or a fax machine to one computer within the network and let other computers of the network use the machines available over the network.

Types of networks

LAN(Local Area Network)

  • Local Area Network is a group of computers connected to each other in a small area such as building, office.
  • LAN is used for connecting two or more personal computers through a communication medium such as twisted pair, coaxial cable, etc.
  • It is less costly as it is built with inexpensive hardware such as hubs, network adapters, and ethernet cables.
  • The data is transferred at an extremely faster rate in Local Area Network.Local Area Network provides higher security.

PAN(Personal Area Network)

  • Personal Area Network is a network arranged within an individual person, typically within a range of 10 meters.
  • Personal Area Network is used for connecting the computer devices of personal use is known as Personal Area Network.

MAN(Metropolitan Area Network)

  • A metropolitan area network is a network that covers a larger geographic area by interconnecting a different LAN to form a larger network.
  • Government agencies use MAN to connect to the citizens and private industries.
  • In MAN, various LANs are connected to each other through a telephone exchange line.
  • The most widely used protocols in MAN are RS-232, Frame Relay, ATM, ISDN, OC-3, ADSL, etc.
  • It has a higher range than Local Area Network(LAN).

WAN(Wide Area Network)

  • A Wide Area Network is a network that extends over a large geographical area such as states or countries.
  • A Wide Area Network is quite bigger network than the LAN.
  • A Wide Area Network is not limited to a single location, but it spans over a large geographical area through a telephone line, fibre optic cable or satellite links.
  • The internet is one of the biggest WAN in the world.
  • A Wide Area Network is widely used in the field of Business, government, and education.

Wireless Communication

  • That incorporates All procedures and forms Of connecting and communicating Between two or more devices Using a wireless signal Through wireless communication technologies and devices.
  • Wireless communication involves the transmission of information over a distance without the help of wires, cables or any other forms of electrical conductors.

Wi-Fi

  • It is a low-cost wireless communication technology.
  • A WiFi setup consists of a wireless router which serves a communication hub, linking portable device with an internet connection.
  • This network facilitates connection of many devices depending on the router configuration.
  • These networks are limited in range due to the low power transmission, allowing the user to connect only in the close proximity.

Bluetooth technology

  • It allows you to connect a variety of different electronic devices wirelessly to a system for the transfer and sharing of data and this is the main function of Bluetooth.
  • Cell phones are connected to hands-free earpieces, wireless keyboard, mouse and mike to laptops with the help of Bluetooth as it transmits information from one device to other device.
  • Bluetooth technology has many functions, and it is used most commonly in wireless communications’ market.

Cloud Computer

Cloud computing is a model where data and programs are stored and accessed online. It allows users to access apps and data from anywhere, on any device.This model provides scalability, flexibility, and cost savings. Businesses can scale up or down as needed, without huge upfront costs.

Cloud computing reduces the need for local storage and software maintenance. Updates and security are managed by the cloud provider. It enables collaboration and remote work, making it a popular choice for individuals and businesses.

  • Public cloud: These are the services offered over public internet, shared infrastructure (e.g., AWS, Google Cloud) for computing needs of public.
  • Private cloud: These are dedicated infrastructure for single organization, more control and security.

Multimedia

  • Multimedia means that computer information can be represented digitally.
  • We can also define it like Computer-controlled integration of Text, graphics, drawings, still and moving images (Video), animation, audio, and any other media where every type of information can be represented, stored, transmitted and processed digitally.
  • Images are visual representations or digital pictures used for communication, art, or information, displayed on screens or printed on paper.
  • Audio refers to sound or music files that contain recorded or live sound which is played through speakers, headphones, or other audio output devices usually.
  • Video is the combination of moving visuals and sound, used for entertainment, education, or communication, displayed on screens like TVs, computers, or mobiles.
  • Animation is a motion from series of images, used in films, games, ads, or online content, bringing cartoon characters, objects, or stories to life digitally.