Light Pen & Trackball
Light Pen & Trackball
Light pen consists of a stylus connected by a cable to the computer terminal. When the stylus is brought into contact with the screen, a dot appears there on the screen. By moving the stylus on the screen, lines and curves can be drawn on the screen that can be stored and used as input.
An Light Pen utilizes a light-sensitive detector to select objects on a display screen. A light pen is similar to a mouse, except that with a light pen you can move the pointer and select objects on the display screen by directly pointing to the objects with the pen.
Trackball
Trackball was originally built into the keyboard. Running a hand over the trackball made the cursor on the screen to move. The cursor is used to make selection from a menu displayed on the computer screen.
The advantage of trackballs over mouse is that the trackball is stationary so it does not require much space to use it. In addition, you can place a trackball on any type of surface, including your lap. For both these reasons, trackballs are popular pointing devices for portable computers.
