Keyboard, Pointing Devices Input devices in computer science – GCE A level Cameroon Lesson

I. INPUT DEVICES

Topic: Input devices in computer science – GCE A level Cameroon Lesson. An input device can be defined as an electromechanical device that allows the user to feed data into the computer for analysis and storage, and to give commands to the computer. The computer accepts input in two ways; manually and directly. In the case of manual data entry, the user enters the data into the computer by hand, for example, by using the keyboard and the mouse. kamerpower.com

A user can also enter the data directly by transferring information automatically from a source document (like from check using MICR) into the computer. Some of the commonly used input devices are keyboard, pointing devices like mouse and joystick, speech recognition system, digital camera, scanners and so on.

I.1 Keyboard

A keyboard is the most common data entry device. The keyboard is designed like a regular typewriter with a few additional keys. The data are entered into the computer by using various keys.

There are different types of keyboard layouts such as QWERTY, DVORAK and AZERTY, but the most common layout is the QWERTY.

Working of a Keyboard

At its essence, a keyboard consists of a series of switches connected to a small keyboard microprocessor that monitors the state of each switch and initiates a specific response to a change in that state. When the user presses a key, it causes a change in the amount of current flowing through the circuit associated specifically with that key. The keyboard microprocessor detects this change in the current flow.

Input devices in computer science – GCE A level Cameroon Lesson

I.2 Pointing Devices

Pointing Devices – Input devices in computer science : GCE A level. A pointing device is used to communicate with the computer by pointing to the locations on the monitor. Such devices do not require keying of characters, instead the user can move a cursor on the screen and perform move, click or drag operations. Some of the commonly used pointing devices are mouse, trackball, joystick, light pen, touch screen and trackpad.

I.2.1 Mouse

A mouse is a small rectangular-shaped hand-held pointing device, It usually contains two or three buttons, which can be used to input commands or the data.The mouse may be classified as a mechanical mouse or an optical mouse, based on the technology it uses.

• A mechanical mouse uses a rubber ball at the bottom surface, which rotates as the mouse is moved along a flat surface to move the cursor.
• An optical mouse uses a light beam instead of a rotating ball to detect the movement across a specially patterned mouse pad.

I.2.2 Trackball

A trackball is another pointing device that resembles a ball nestled in a square cradle and serves as an alternative to a mouse. In general, the trackball is like a mouse turned upside down. It has a ball, which can be rotated by fingers in any direction, and the cursor moves accordingly.

I.2.3 Joystick

A joystick is a device that moves in all directions and controls the movement of the cursor. The basic design of a joystick consists of a stick that is attached to a plastic base with a flexible rubber sheath. This plastic base houses a circuit board beneath the stick.

I.2.4 Light Pen

A light pen (sometimes called a mouse pen) is a hand-held electro-optical pointing device, which when touched or aimed closely at a connected computer monitor will allow the computer to determine the position of the pen on the screen. It facilitates drawing images and selects objects on the display screen by directly pointing to the objects. It is a pen-like device, which is connected to the machine by a cable. kamerpower.com

I.2.5 Touch Screen

A touch screen is a special kind of display screen device, which is placed on the computer monitor to allow direct selection or activation of the computer when the user touches the screen.

I.2.6 Trackpad

A trackpad (also referred to as touchpad) is a stationary pointing device that works by sensing the movement of fingers across a small sensitive surface and translating them into the pointer movement on the screen. It is generally used in laptops, but can also be connected to the PC through a cord.

NOTE: The device manufactured by Apple is referred to as trackpad while the device manufactured by others is known as touchpad.