Osomapto Attojiboni by Seikh Mujibur Rahaman.

Lesson 1 : Handy Input Devices

1.1. Learning Objectives
On completion of this lesson you will be able to describe:
 Different handy input devices
 Working principle of different handy input devices.

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1.2. Introduction

Input devices get input from the external world to the computer. The input devices, which get input from the motion of the user’s hand, are known as handy input devices. Keyboard, light pen, digitizer, mouse, joystick and trackball, touch screen etc. are handy input devices. 1.3. Keyboard

The most common of all input devices is the keyboard. Several versions of keyboards are available. The best and most expensive of these is the full-stroke keyboard. This is ideal for word processing and other volume data and program entry activities.

Some popular microcomputers offer enhanced keyboard for easy entry of numbers. This is accomplished with a smaller group of keys known as numeric keypad at the right of the keyboard. These keys generally consist of the digits, a decimal point, a negative sign, and an ENTER key. This type of keyboard is ideal for accounting operations, which require a large volume of numbers

to be entered.

Keyboards generally utilize integrated circuits to perform essential functions, such as determining the combination of l s and Os, or binary code. To send to thc CPU, corresponding to each key depressed, switching between shifted and non shifted keys, repeating a key code if a key is held down for a prolonged period of time, and temporarily storing or "buffering" input when keys are typed too fast.

The keyboard arrangement provided as standard on most keyboards is the QWERTY arrangement. This arrangement was chosen to slow expert typists, since those who typed too fast would cause the keys on a mechanical typewriter to jam. Slowing down the typist was accomplished by scattering the most used around the keyboard, making frequently used combinations of letters awkward and slower to type. This QWERTY keyboard arrangement has been used for nearly a century.