What is a Touch Screen?
A touch screen allows user commands to be issued by (71) corresponding buttons on the screen. Since their introduction in the 1970s, touch screens have become popular for computer and media technology. Chances are, if you have used an (72) teller machine (ATM), owned a personal digital assistant (PDA), or played with the newer cell phones, you have already used touch screen technology.
There are several commonly used systems that allow for touch screens to work. Each method allows for commands to be translated by the computer as a(73) of touching a certain point on the screen. Many convert the coordinates of the touch locations to specific actions to be taken by the system.
One of the most common systems for touch screens is called (74). Covering the transparent panel of the screen are conductive and resistive metallic layers that have an electric current between them. When the screen is touched, the electrical current can tell the exact spot of contact and （75 ) the coordinates to the operating system. This is similar to how a mouse works with a computer, where the central operating system notes the exact point of a click and can respond by activating the action requested.
