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The two most commonly used input devices are:

1. Keyboard
2. Mouse

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The three type of mouse are:

1. Mechanical mouse
2. Laser mouse
3. Wireless mouse

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Diagram of Computer System

As per the Von Neumann architecture of the computer system, the CPU consists of two main processing units called the Control Unit (CU) and Arithmetic Logic Unit (ALU).

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CPU contains various parts that make a computer work. It processes instructions, performs calculations and manages the flow of information through the computer system.

Information received from the input devices are processed in the CPU before showing the result on an output device such as monitor.

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Storage devices:

Storage devices are used for storing and transferring data. They are also known as storage media or secondary storage devices. Some of the storage media are hard disk, CD, DVD, pen drive etc.

• Hard disk is the main storage device. It is used to store large amounts of data.
• CD stands for Compact Disk. It is storage medium in the form of a circular plate.
• DVD stands for Digital Versatile Disk. It looks like a CD. It is capable of storing more data than a CD.

SOLUTION

Some commonly used input devices are as follows:

• Keyboard
• Mouse
• Light pen
• Joystick

Some commonly used output devices are as follows:

• Printer
• Monitor
• Projector

Keyboard: It is the most common input device. It has 104 keys.  It is used for typing letters, words, numbers and special symbols.

Projector: It is a visual display device. It displays the images or videos on the flat, large surface which is generated by a computer.

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Monitor: It is the most common output device. It is used to display the work done by computer to its users. Monitors are of two types: CRT monitor and LCD monitor.

Printer: It is a device that helps in taking printouts of text and images on a paper. Printers are of three types: Laser printer, Inkjet printer and Dot matrix printer

Projector: It is a display device that receives signals from a computer and displays the image or video on the screen. For example, it is used in class rooms, presentations, etc.

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Computer follows three easy steps. These are input, process and output.

Input: The data or instruction that enters into a computer with the help of input devices is known as input.

Process: Time taken by a computer to work on the given data following the given instructions is known as process.

Output: The final result that comes out in the form of information is known as output.

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1. Webcam: It is a camera that is used to do video chats and also take still images with the help of a computer.
2. Scanner: It is used to scan pictures into the computer.
3. Light pen: It is used to draw images and select the text and objects on screen.

SOLUTION

The devices that send data and instructions into a computer are known as input devices.

For example:

1. Scanner
2. Light pen
3. Joystick
4. Webcam
5. Touch screen

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Pen drive

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1. CD-ROM
2. Hard disk

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USB flash drive

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Icon

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Desktop

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Start

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Desktop gadgets

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Notification bar

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Desktop icons

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Desktop screen

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Notification bar is present at the lower right corner of the taskbar. It displays a clock and it contains a set of icons which show the status of programs running.

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Wallpapers are the pictures that appear as background on the desktop. We can set any image as wallpaper.

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Quick Launch bar shows the names of the active programs. It consists of some commonly used program icons which help us to open them on a single click.

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a) Calculator – It is used to do mathematical
             calculations.

b) MS Paint – It is used to draw and paint
              images.

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Search option helps us in finding a particular type of data stored in computer like images, videos, documents etc.

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The three desktop icons are:

1. Computer icon

2. Control Panel icon

3. Recycle Bin icon

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Steps to hide the desktop icons are as follows:
Step1: Right click on the blank area of the desktop. A menu appears.

Step2: Click on the View option. We would see that another small menu appears on the right side of the window.

Step3: Click on the Show desktop items option. We will see that the desktop items disappear.

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Steps to change the position of taskbar are as follows:

Step1: Left click on the blank area of a taskbar.

Step2: Keep pressing the left button and drag the taskbar to any corner of the desktop window.

Step3: Now, release the mouse button. The position of the taskbar will be changed.

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Run - It is used to open a program or a particular computer application.

Steps to open a program using Run command are as follows:

Step1: Click on Start button. A menu list appears.

Step2: Click on the Run option. A small dialog box opens.

Step3: Type the application name in the text area and click on OK button.

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Shutdown – It is a very important desktop option, which helps us to turn off the computer system.

Steps to shutdown a computer are as follows:

Step1: Click on the Start button. A menu list appears.

Step2: Click on the Shut down option to turn off the
computer system.

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Processing is a series of operations carried out to perform some task.

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Control Unit

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Arithmetic Logic Unit

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Speakers

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Process

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Central Processing Unit

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Operating system

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System

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Hardware

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Software

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a. Banks: Computer is used in banks for typing and printing documents, keeping record of employees, sending and receiving messages etc.

b. Homes: Computer is used at homes to do homework, watch videos, play games, listen to music etc.

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Process: The time taken by a computer to work on the given data is known as process.

Output: The final result that comes out in the form of information is known as output.

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The processing in computer is done by a processing unit known as CPU. It stands for Central Processing Unit. It is also known as the brain of computer. All the parts of a computer are connected to the CPU.

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The two types of software are:

1. Application Software
2. System Software

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Software represents a set of programs that tells the hardware what to do and how to do it. For example, MS Office, Windows XP, etc.

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Hardware represents the physical components of a computer that we can see and touch. For example, Keyboard, Mouse, Monitor, Printer, CPU and Webcam, etc.

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Characteristics of a computer are as follows:

1. A computer does not make mistakes.

2. A computer is fast and does large calculations in seconds.

3. A computer has large storage capacity.

4. A computer does not have emotions and feelings.

5. A computer cannot think.

SOLUTION

CPU is made up of three components. These are:

1. Arithmetic Logic Unit (ALU): All types of calculations are done by ALU. For example, addition, subtraction, division, multiplication etc.

2. Control Unit (CU): It is known as the manager of computer as it controls all the parts of computer.

3. Memory Unit (MU): It is used to store data and instructions given by the user. The memory unit then passes the data and instructions to Arithmetic and Logic Unit and Control Unit.

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System software controls and manages the overall activities of a computer system. It is a very important part of a computer. Also, it is used to run the application software.

For example:

1. Operating system: It is a software that helps us to operate the computer system.
2. Microsoft Windows: It is an operating system and the most popular software in the world.
3. Linux: It is also an operating system that helps in controlling and managing the computer system.

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Application software are those software that help in doing some specific work. They makes computer easy to use. For example:

1. MS Paint – It is used to paint and draw images.
2. Calculator – It is used to do mathematical calculations.
3. MS Office – It is used for making presentations, data in table form, etc.
4. Windows Media Player – It is used to play movies, videos and also listen to music.

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Software

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Printer

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Cathode Ray Tube

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Floppy disk

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Digital Video Disk

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ROM

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Secondary Memory

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Motherboard

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DVD (Digital Versatile Disk)

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Volatile memory

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Storage devices are used in the computers to store the data. Some of the secondary storage devices are hard disk, CD-ROM, DVD etc.

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We need secondary storage devices for the following reasons:

1. Computer memory is volatile. Secondary storage devices are non-volatile, i.e., they hold data even if the power is lost.
2. Secondary storage devices provide a large storage capacity.

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1. A hard disk works faster than a floppy disk.
2. The storage capacity of a hard disk is greater than a floppy disk. A hard disk can store about 160 GB data, while a floppy disk could store up to 1.44 MB of data.

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Commonly used storage devices are as follows:

1. CD-ROM

2. DVD

3. Hard disk

4. Pen drive

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A pen drive is shaped like a pen. It is a storage device which is used for storing and transferring files from one device to another.

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RAM can store the data and instructions only when the computer is turned on. If the power suddenly goes out, all the data stored on it is lost. So, it is also known as volatile memory.

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Hard disk is the main storage device. A hard disk works faster than a floppy disk. It can store a vast amount of information, including photos, videos, music, documents, programs and more. It is located inside a computer. The storage capacity is greater than a floppy disk and can store data about 160GB.

SOLUTION

Examples of secondary storage devices are:

• CD
• DVD
• Hard disk
• Floppy disk

CD-ROM stands for Compact Disk-Read Only Memory. It has a storage capacity of 700 MB. It is circular in shape that stores data in the computer.

DVD looks like a CD. It stands for Digital Video Disk. It has large data storage capacity. Drives in a computer are used to store and retrieve data on a CD or DVD respectively.

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ROM is the memory that stores the data permanently. It stands for Read Only Memory. Data stored on the ROM can only be read, which means that we cannot write on the ROM. The data stored on ROM does not get wiped out when the computer is turned off.
ROM is most commonly used in devices such as calculators, laser printers, etc.

SOLUTION

Primary Memory: Primary memory is the part of the computer which stores information temporarily. It is handled by the CPU; generally known as “memory”.
RAM and ROM are the two types of primary memory.

Secondary Memory: The place where information can be saved is called secondary memory. It is also known as external memory. It stores the results and the data for future use; generally known as “storage”.

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RT 30

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Left

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Clear the graphics screen

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Input

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Storage

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A microphone is an input device, used to input sound into a computer. We can also use it to record different types of sounds.

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CRT monitors are heavy and large in size. They are used to display result of processing to the user.

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Hard disk is the main storage device of a computer. It is attached inside the CPU box. All the work done is by default stored on the hard disk.

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A printer is an output device that is used to print the information stored on a computer system. The printout of a printer can be coloured or black and white depending on the type of printer used.

Some commonly used printers are:

• Laser printer
• Inkjet printer and
• Dot-matrix printer

SOLUTION

• Mechanical Mouse - A mechanical mouse contains a rubber or a metal ball inside it. The movement of the cursor depends on the movement of the ball.
• Optical Mouse - An optical mouse does not contain any ball inside it. It uses a light emitting device to detect its movement.
• Wireless Mouse - A wireless or cordless mouse does not require a wire to work. It transmits the data by using a wireless technology, such as radio waves or infrared light waves.

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Text Tool

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Slideshow

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Alt+S

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Paint tool

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Thumbnail

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New command is used to make a new drawing on Tux Paint.

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Shape tool is used to draw filled shapes and unfilled shapes. We can draw shapes like triangle, rectangle, oval, polygon etc.

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Tux Paint is a drawing program which is used to draw and colour pictures.

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The steps to open an existing drawing are as follows:

Step 1: Click on Open button.

Step 2: A list of saved drawings are displayed on the thumbnail.

Step 3: Double click on the drawing to open it.

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The steps to draw a rectangle are as follows:
Step 1: Click on the Shape tool from the toolbox.

Step 2: Select and click on the Rectangle tool from the selector.

Step 3: Click on blue colour from the color box.

Step 4: Move the pointer to the drawing area. While keeping the left mouse button pressed, drag the mouse to draw the shape.

Step 5: Release the mouse. The shape will be drawn.

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Control keys

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Return key

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Space bar

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Arrow key

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Function

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Backspace is used to erase text to the left (backwards) of the cursor.

Delete key is used to delete text to the right of the cursor.

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Caps Lock key is used to write the text in capital letters. It can be turned ON/OFF. When the Caps Lock is ON, we can write capital letters on the screen. When the Caps Lock key is off, we can type small letters.

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A keyboard has two enter keys: one above the right hand Shift key and the other on the lower right of the numeric keypad.

SOLUTION

1. Arrow keys: Arrow key is used for moving cursor on the computer screen. It is located at the right hand side of the keyboard.
2. Number keys: These keys are used to type numbers on the computer. A keyboard has two sets of number keys.
3. Enter key: Enter key is used to move cursor to the next line. There are two enter keys present on the keyboard: one is located on the lower right of the numeric keypad and the other on the right side of the alphanumeric part of the keyboard, between backspace and the right hand Shift key.

SOLUTION

The special keys are used to do special jobs. It performs special functions with the help of some other keys. Some of the special keys are:

• Escape key is used to stop the actions. This key is usually marked ‘Esc’.
• Caps Lock key is used to write the text in capital letter.
• Spacebar is used to move the cursor one space forward between letters, words and sentences.