 The Achilles' heel, however, was the LCD, which was not backlit, had poor contrast, and was frequently accused of serving better as a mirror than as a display screen.Usable outdoors or in bright offices only, a flashlight, it was joked, was often necessary to see the contents of the screen.Another product killer was the incompatible serial port chip, an Intel 82C51, which was used to conserve power, instead of the 8250 used in the IBM PC.