Touch screen: A computer screen designed or modified to recognize the location of a touch on its
surface. It incorporates the use of a touch sensitive monitor to control all computer functions. There is no
need for a keyboard or any prior computer experience.

Every where you look today you see the power of touch at work. Touch Screens are being used in
a variety of settings including Education, Medical, Point of Sale, Gaming, Manufacturing, Retail and
information Kiosks. From your favourite restaurant to your family doctor, people are realizing that Touch
screens are the most user-friendly and intuitive interface available.

*advantages:- protect against weather
-graphical(the user need not to remember the name of an item or what it looks
-Their interfaces have the advantage of great flexibility (touch screens are the
proven way for the public to interact with any kind of system), ease-of-use, and
lack of hardware (keyboards, mice) to malfunction or break with overuse.
-create graphics easier

*disadvantages: text strings(must display a keyboard; hard to use and waste of screen space)
- prohibitivily tiring over extended periods.(user must hold their hands in
midmair to point the screen)
*considerations: resolution, optical clarity, response time, environmental resistance, cost
*type of technologies:
resistive: proven track record, good optical quality, very accurate, fast response time, and easy
to install.
capacitive: high resolution, adapt to a range of displays, and are easy to seal against
environmental condition
surface-acoustic-wave(SAW): must be touched by some type of energy absorbing object
to register a touch(a hand)
scanning infrared: works with any solid objects to register touch, reliable, durable, good
clarity, low resolution
other technologies: metrix, weight-scale,etc.
*touch screen controller: ISA Bus card and Serial Controller.

How dose a touch screen work:The principles by which touch screens operate are relatively simple:
Displayed on the screen is a series of options, and the computer knows the location(by X-Y
coordinates) of each. The operator then touches the screen directly over the option he wants to choose,
and some type of device determines the location of the spot touched, again by X-Y coordinates. By
comparing the coordinates of the position the operator touched with those of all the choices offered, the
computer can determine which option the operator selected and can act on that selection, just as if
the operator had depressed a key or used a lightpen to make his choice.

Touch Screen Hardware
The touch screen is an additional pointing device. It is a transparent membrane sensor and is
overlaid to the monitor\'s picture tube. The touch screen connects to its controller, while the monitor is an
output device and is connected to its VGA card. Two kinds of touch screen controllers are
ISA Bus Card is an add-on card, and can be plug into any ISA slot. Selective IRQ3
through IRQ7 makes the card work without any conflict to the system. There is no
external power supply needed, only one cable connection is between the card and the touch
screen. Using bus card can leave COM port available for any other peripherals, such as
mouse, moden, display pole, bar code reader and serial printer,etc.
Serial Controller is a small hand-out box. Via a Y-shape cable, the power is supplied by the
keyboard connector. The controller is hooked up to any COM port. Takes the both, or either of, signals
from the touch screen and mouse, and then communicates to the PC system via the COM port.
The advantage of using serial controller is that you don\'t have to open the system case to
install it; it also can be used to your Notebook computer.

Touch Screen Software:The touch screen is a pointing device, which is similar to a mouse. Run our
setup program, that makes touch screen driver replace the mouse driver. There are no coding
changes that are required to switch existing mouse-driven applications into touch screen applications.
To develop a touch screen application, one can use any mouse CASE tools, just like working in a
mouse software development, there is no special need for touch screen interface at all! The touch
driver handles both touch screen and mouse hardware. They can work at the same time. The
drivers, for example, are Driver for Windows 95, Driver for Windows 3.x, Driver for DOS,
Driver for ELODEV(ISA bus card only)
The calibration utility is also bundled. That helps user