Output Devices

Any device that is capable of representing informationin a computer is called output device.There are three important output devices connected to the system unit.
 §      Monitor §      Printer
 §      Speakers



Monitor
A monitor resembles a television screen, only with a much higher resolution for better display quality. It is used to display information from the computer. The monitor display text grephics. It typically comes with its own separate power button to turn it on or off.
Printer
A printer is used to transfer data from a computer onto paper. There are colour printers well as grayscale printers available on the market. The fdifferent types of printers are dot matrix printers, inkjet printers and laser printers.
Speakers
Speakers are used to play sound. They may be built in or externally connected to your system. Speakers allow you listen to music and hear sound effects spoken text using your computer. Suppose you want to give a lesson to a group a visually impaired students, you can multimedia presentation. To make the lesson more accessible to these students, you can structure the lesson around an audio componet, thus allowing the students to participate in the lesson using sound rather than relying on the screen presentation.

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INPUT DEVICES

In the input-process-output cycle, input for the process should be provided through a device. Devices  used to provide data and instructions  to the computer are called input devices.Some important computer input devices are listed below.·       Mouse
·       Keyboard
·       Scanner
·       Miccrphone
·       Web camera
 Mouse

A mouse is used to point to and select options displayed on the monitor. It is usually connected to the system unit ny means of a long wire.although wireless mouse devices are also increasingly available. A mouse may have two or three buttons. The left button is the most frequently used button. Newer mouse devices called scroll mouse or wheel mouse come with a wheel between theleft and right buttons. This wheel enables you to smoothly scroll through screens of information. Optical mouse is another advanced pointing device that ises a light emitting component instead of the mouse ball. It detects movement my sensing changes in the light reflected by the light-emitting component. Nowadays, wireless mouse devices are also available.

             When you move theon a flat surface,you will see an arrow moving on the screen correspondingly. This arrow is known as the mouse printerIt is good practice to use a mouse pad instead of just any flat surface. A mouse a small mat with a plastic surface and a rubber or plastic-based cushion on which you can move the mouse. It provides greater traction than smooth surfaces and this makes it easier to move the mouse pointer with greater precision. The mouse ball is likely to glide and not roll on smooth glass or wooden surfaces.KeyboardThe keyboard is used for typing text into the computer.lt is also known as the standard input device. A computer keyboard is similar to that of a typewriter,but it has additional keys as well. The most commonly available computer keyboard has 104 keys.There are different types of keys on the keyboard. The keys are categorized as:§      Alphanumeric keys, including letters and numbers.
§      Punctuation keys, such as the colon (J), the semicolon (;), the question mark (?), single quotes (‘) and double quotes (“)
§      Special Keys, such are, control keys and Function keys  (F1 to F12). There keys have different functions depending on where they are used. For example, the enter key starts a new paragraph in aword processor, but in the command line, it executes a command.
 Function keys are special  keys that are used to perform specific functions. They are labeled as F1 F2 F3 and so on, up to F12. The functionality of the keys differs from software. The function of F1 key in most software is to provide kelp with the software.    Software refers to computer instructions or data that can be stored electronically.ScannerA scanner is used to make an exact copy of a picture or a photograph, For example, if you are a creating a report on an event at your school,you can use scanner to scan photographs or logos and insert them into the report.MicrophoneA microphone is a device used to record sound.Microphones convert sound waves into audio signals.Web CameraA Web Camera is a device capable of converting visuals into digital form. When connected to a computer, iy functions as the eye of the computer. You can use it to take a phototgraph of yourself and store it in the computer or for video conferencing.  

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PARTS OF A PC

A computer has various parts and each part performs a specific function. In this chapter, you will learn about some of the important parts of computers and their functions. Some important parts of the computer are shown in Figure. A computer system  unit,often simply called a box, consists of various internet such as motherboard,video card and sound card. Typical external  componets attached to a computer include monitor,keyboard,mouse and printer.Connecting the PCThe followinh points will help you to understand how these parts are connected to each other through cables.§    The system  unit is connected to power supply.
§    The monitor is connected to the system unit and to the power supply. Some monitors draw power directly from the system unit.
§    The keyboraed is connected to the system unit.
§    The mouse is connectedto the system unit.
§    The printer is connected  to the system unit and to the power supply.
§    Other hardware devices, such as scanners and speakers are connected to the system unit and to the power supply.
The Input-Process-Output CycleAny activity, whether simple or comple, follows the basic principle of input-process. For example, consider the simpletask of making tea. The task requires tes leaves, water, sugar and milk as the input. The process includes boiling water,brewing tea leaves, straining and adding milk and sugar. The hot cup of tea that results at the end of the process is the output. Computer also work on the input-process-output principle. Input refers to the data and instructions given to the computer. Process refers towhat the computer does with the data. Output refers to the result of the process. For example, you want the computer to do a simple calculation; the multiplication of tow number 46 and 29. you must first provide the input and specify the process. Here, number 45 and 29 are the input and multiplication is the process. The computer performs the multiplication process on the given inputs. This process results in 1105 as the ouput. INPUT   PROCESS   OUTPUT         

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