Input devices

1. Keyboard: - A keyboard is the primary input device through which data or instructions are entered into the computer. Most keyboards use a QWERTY layout. The layout is called QWERTY because such keyboard has those keys as the first six letters on the top of alphabetic line of keyboard. The most commonly used keyboard is 101 key keyboard developed by IBM, this keyboard consists of Typewriter keys. Function keys. Cursor controls keys. Caps lock key, Numeric keys, Esc, Esc, Pause, print screen etc.
Now days there are enhanced or extended keyboards with at least 103 keys.

2. Mouse: - A mouse is a small input device which is used for pointing or drawing. It is connected to the computer by small cable. As we move the mouse across the flat surface, mouse pointer or cursor moves across the screen. Once the mouse pointer is in the desired location we can press the mouse buttons to perform some operation.
A mouse is one of the most important and popular input device for graphical user interface such as apple/Macintosh and windows in which we can perform various complex operations with simple mouse clicks.
3. Joystick: - A joystick is a pointing device, used mostly for playing games on ca computer. The joystick has a rectangular plastic vase which is attached to a vertical stem. Control buttons are located on the base or to the top of stem. The stem can be moved to all directions to control the movement of an object on the screen. The buttons produce different types of events on the screen depending on the type of application software begin used.
4. Light pen: - A Light pen is a pen-like-pointing device. It has a light sensitive detector at its tip.
When the light pen tip is placed against the screen, it is capable of sensing its position on the screen or the monitor. As the tip of the pen is moved over the screen surface, the light sensitive detector detects the light emitted from the screen. Thus, desired objects can be selected by directly pointing to the objects with the pen. The light pen is very useful in drawing graphics in CAD applications.
5. Digitizing Tablet:- it is also called digitizers. Graphics tablets or touch tablets. It is used to enter graphic information into the computer. Digitizing tablets are very useful in Computer Aided Design (CAD) applications.
Digitizing tablet contains a flat drawing surface on a baseboard with a pen-like-pointing device called stylus.
6. Optical scanner:- an optical scanner is an optical input device , that used light-sensing equipment to scan or image the hard copy data and converts them into digital form (computer usable form). Optical character recognition software’s or graphics software are used to manipulate (process, store and print) those data. A commonly used scanner is “flatbed” where the scanning device moves across or reads across a stationery document. It is similar to a photo-copier.
7. Speech Recognition Device: - this device converts speech into digital form. In combination with appropriate software, speech recognition device enables user to operate computers with voice commands.
8. Trackball: - a trackball is a popular pointing device. It consists of a ball and other three buttons near to the ball. It is similar to the mouse but with mouse the ball is rolled by moving the entire unit over the subsurface whereas, with a trackball the ball is rolled with the hand.
A trackball is used as portable pointing device for portable computers.
9. Digital Camera: - digital camera can be used to input images into the computer. It takes a still photograph, stores it and then sends that photo or image as digital input to the computer. The computer sores those images in the form of digital files.
10. Touch Screen: - it is a type of display screen that consists of touch sensitive display panel covering the screen. You can use your fingers to select and operate on the objects on the screen. So, touch screen replaces the use of mouse or light pen as a pointing device.
10. Touchpad: - A touchpad is a small touch sensitive pad that is use as a pointing device in some portable computers. It uses pressure sensors to track the position of a device on its surface. Each position on the touch pad is translated to the specific location on the screen.
The touchpad is less expensive compared to the other electromagnetic digitizing tablets.