Hewlett-Packard Introduces the HP-150, One of the First Commercially Available Touchscreen Computers

In 1983 Hewlett-Packard, Palo Alto, California, introduced the HP-150, one of the earliest commercially available touchscreen computers. 

"The screen is not a touch screen in the strict sense, but a 9" Sony CRT surrounded by infrared emitters and detectors which detect the position of any non-transparent object on the screen. In the original HP-150, these emitters & detectors were placed within small holes located in the inside of the monitor's bezel (which resulted in the bottom series of holes sometimes filling with dust and causing the touch screen to fail; until the dust was vacuumed from the holes)" (Wikipedia article on HP-150, accessed 12-30-2009).