Hardware

(Computer hardware refers to the physical component of a computer that can be seen and touched by the user)

By the use of these hardware devices, it made very easy for the computer for processing its data, store and retrieve. Hardware is one of the basic and necessary parts of a computer system

Input devices

An input device can be defined as an electro mechanical device that allows the user to feed data into the computer for analysis and storage and to give commands to the computer. The data is entered into the main memory through the input devices. They accept instructions from the user and convert the accepted instructions into the machine language.

Some of the commonly used input devices are keyboard, mouse, trackball, joystick, light pen, touch screen, barcode reader, OMR, OCR, MICR, smart card reader, biometric sensor, scanner, Mic, web cam, PC card etc. which are described below

Keyboard

• The keyboard is the most frequent and widely used input device for entering data into a computer. Although there are some additional keys for performing other operations, the keyboard layout is similar to that of a typical typewriter.
• Generally, keyboards come in two sizes :  84 keys or 101/102 keys, but currently keyboards with 104 keys or 108 keys are also available for Windows and the Internet.

Types of Keys on Keyboard :

• Alphanumeric Keys include the alphabet keys (A, B, C, …, Z) and number keys (0, 1, 2, 3, …, 9).
• Numeric Keys are located at the right hand side of the keyboard. They consist of digits and mathematical operators.
• Function Keys are the programmable keys, i.e. the programs can assign some specific actions. They are numbered from F1 to F12.
• Special Keys : Enter, Shift, Caps Lock, Num Lock , Tab, etc., and Print Screen

Mouse

• The most common pointing device is the mouse. The mouse is used to move a little cursor across the screen while clicking and dragging.
• A mouse is an input device that lets you move the mouse on a flat surface to control the coordinates and movement of the on-screen cursor/pointer..

There are three types of mouse as follows

There are four actions of mouse as follows :

• Click or Left Click :  It selects an item on the screen.
• Double Click : It is used to open a document or program.
• Right Click : It displays a list of commands on the screen. Right clicking is used to access the properties of selected object.
• Drag and Drop : It is used to move an item on the screen.

Joystick

• A joystick is a pointing device that is used to move the cursor on a computer screen.
• A spherical ball is attached to both the bottom and top ends of the stick. In a socket, the lower spherical ball slides. You can move the joystick in all four directions.
• The joystick’s function is comparable to that of a mouse. It is primarily used in CAD (Computer-Aided Design) and playing video games on the computer.

Light Pen

• A light pen is a type of pointing device that looks like a pen. It can be used to select a menu item or to draw on the monitor screen. A photocell and an optical system are enclosed in a tiny tube.
• When the tip of a light pen is moved across a monitor screen while the pen button is pushed, the photocell sensor element identifies the screen location and provides a signal to the CPU.

Output devices

An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing to the outside world.

Some of the commonly used output devices are :

monitor, printers, plotter, speaker, headphones, projector etc. which are described below :

Monitor

Monitors, also known as Visual Display Units (VDUs), are a computer’s primary output device.

It creates images by arranging small dots, known as pixels, in a rectangular pattern. The amount of pixels determines the image’s sharpness.

The two kinds of viewing screen used for monitors are:

(1) Cathode-Ray Tube (CRT):

Pixels are minuscule visual elements that make up a CRT display. The higher the image quality or resolution, the smaller the pixels.

(2) Flat-Panel Display Cathode-Ray Tube Monitor:

 In comparison to the CRT, a flat-panel display is a type of video display with less volume, weight, and power consumption.

Printer

( Printers are output devices that allow you to print information on paper )

There are two types of printers:

Impact Printer:

Characters are printed on the ribbon, which is subsequently crushed against the paper, in impact printers.

Non-Impact Printers:

Characters are printed without the need for a ribbon in non-impact printers.

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