GRIDpad. Released in 1989. Built by the GRiD Systems Corporation, this early tablet PC ran MS-DOS, supported stylus input on a 10-inch monochrome screen and had enough juice for about 3 hours of battery life. Critics regarded it as a creative breakthrough in laptop computer design, but the price prevented the device from being widely consumed. At $2,370 each, the GRIDpad was followed by similarly overpriced and underpowered rivals, which included the Momenta Pentop (1991), the Compaq Concerto (1992) and the AT&T EO PC (1993).