COMPONENTS OF COMPUTER (INPUT DEVICES)

INPUT DEVICES

These are hardware components used in entering data into the computer for processing. They convert data from human-readable form into machine readable format. They take information from the user of the computer, convert it into electronic signals and transmit it to the processor.

Examples of input devices are keyboard, mouse, joystick, microphone, digital camera, light pen, scanner, paper tape, fax machine, graphic tablet, trackball, digitizer, electronic whiteboard, touchpad, etc.

KEYBOARD

This is the most common and useful input device. It is used to enter data into the computer.

A keyboard contains specially arranged keys for typing letters and numbers. It looks like the traditional typewriter.

Types of keyboard

Computer keyboard include the following types

Standard keyboard
Enhanced keyboard
USB keyboard
PS/2 keyboard
Wireless keyboard
Multimedia keyboard, etc.
Standard keyboard: This is an old keyboard technology containing about 80 keys including just ten function keys.
Enhanced keyboard: This is the type of keyboard that contains over 100 keys. It has 12 function keys. It is mostly in use nowadays.
USB keyboard: This is a keyboard that has a USB connector. It is connected to the system unit through the USB port. Most modern keyboard are USB keyboard.
PS/2 keyboard: This uses PS/2 connector to connect to the system unit. The PS/2 connector has 6 pins that enters into the 6 holes in the PS/2 port of the system unit. PS/2 keyboard are no longer common as most system units now come with USB ports and HDMI ports.
Wireless keyboard: This connects to the system unit through wireless technology like Bluetooth, infrared or Wi-Fi. The system unit must have a compatible technology before the keyboard can be used with it.
Multimedia keyboard: This is an enhanced keyboard which contains keys for playing and controlling sound and video. With multimedia keyboards, actions like CD eject, volume, mute, next track, etc can be carried out without the use of the mouse.

Keys on the keyboard

The keys on the keyboard can be grouped into the following.

Alphanumeric keys
Function keys
Numeric keys
Special control keys
Cursor keys
Alphanumeric Keys: These are keys used in typing letters of the alphabet and numbers. These keys also include used in typing special symbols like #, @, &, %. $, ), +, etc.
Function keys: These are keys located at the top most row on the keyboard. They are labeled F1, F2, F3…..F12. The keys are used to carry out operations as assigned or defined by the software in use.
Numeric keys: These are located at the right-hand of the keyboard. They are used in typing numbers (0 – 9) as well as mathematical operations like +, -, /, and #. They also contain keys like Enter, Ins, Del, Pg. up, Pg. down, numlock, home and end key.
Special Keys: These keys are located in between alphanumeric and numeric keys. They consist of the following keys – Esc, Del, Enter, Pause/Break, Scroll lock, Tab, Print screen, Caps lock, etc.
Cursor Keys: These are the keys labeled arrow right, arrow up, arrow left, and arrow down. They are used to control the movement of cursor or arrows. A cursor is the blinking spot on the screen where the next character can be entered or inserted.

MOUSE

This is a small palm-sized input device that can be moved across a flat surface to control the movement of the pointer on the screen. It functions by detecting two-dimensional motion relative to its supporting surface.

It consists of an object held under one of the user’s hands with one or more buttons. The left button which also called primary button and right button which is also known as secondary button are separated with a wheel in the middle used for quick scrolling.

Types of mouse

There are three basic types of mouse. These are:

Mechanical
Optical mouse
Opti mechanical

Mouse Techniques

Pointing: This refers to moving the mouse to position the mouse pointer on an object.
Right clicking: This refers to pressing and releasing the right mouse button.
Double clicking: This means pressing and releasing the left mouse button twice quickly.
Dragging: To drag with a mouse, move the mouse to position the mouse pointer on the object to be dragged, press and hold the left mouse button and then move the mouse to a new location before releasing the button.
Left clicking (Also Known as clicking): This refers to pressing and releasing the left mouse button.

SCANNER

This is an input device used for capturing text, picture and document into the computer. It used light-sensitive equipment to scan paper or other medium by converting the image into digital signals. It is like a photocopying medium but instead of producing copy on paper, it sends the copy into the computer memory for further processing.

MICROPHONE

This is an input device that converts sound into electrical signal. They are used in much application such as telephone, tape recorder, hearing aids, motion picture production and in computer for recording voice, speech recognition, etc.

JOYSTICK

This is an input device consisting of a hand-held stick which moves about from one end to another and transmits its angle in two or three dimensions to a computer. It has two or more button located on the base and sometimes on the top of the stick. Joysticks are sometimes used in playing computer games, controlling machines like elevate, crane trucks, etc.

LIGHT PEN

This is a photoelectric input device used to send data into the computer for processing through the screen. It can be used to display, modify or delete images on the screen. Light pen is mostly used in Computer-Aided Design (CAD) applications by architect and engineers. The light pen has a wand which is connected to the system unit. It is then pointed at the screen to select items or choose commands by either pressing a chip on the side of the light pen or pressing the light pen against the surface of the screen which send signals to the computer whenever. It records a light.

GRAPHIC TABLET

This is also a digitizing tablet. It is a flat plastic rectangle with subsurface electronic. It is used in conjunction with a pointing device called stylus. In many engineering and design applications when the stylus is moved on the surface of the tablet, the location of the device is translated to a specific screen position.

TRACK BALL

This is a pointing device that can be roughly being described as a mouse on its back. It consists of a ball resting on to rollers which translates the ball’s motion into vertical and horizontal motions on the screen. The only difference between a mechanical mouse and a trackball is that the user can exert fingertip control to get a fine work.

TOUCHPAD

This is also called track pad. It is a flat rectangular surface to control the movement of the pointer or arrow on the screen. It is common with laptops and notebook.