Abstract: Keyboard systems and methods are provided herein. In one embodiment, an overlay keyboard for touch screen devices includes a physical keyboard that can be mounted onto a touch screen device (e.g., a corded touch screen device or a touch screen mobile device) that provides a virtual keyboard (e.g., a software displayed touch screen), in which the physical keyboard can be overlaid onto the virtual keyboard of the touch screen device. When no key of the physical keyboard is pressed down, the physical keyboard does not trigger the touch screen of the touch screen device. When a key of the physical keyboard is pressed down, the physical keyboard touches the touch screen on a corresponding key of the virtual keyboard on the touch screen device, thereby causing the touch screen to detect that the corresponding key of the virtual keyboard has been pressed.

Abstract: Keyboard systems and methods are provided herein. In one embodiment, an overlay keyboard for touch screen devices includes a physical keyboard that can be mounted onto a touch screen device (e.g., a corded touch screen device or a touch screen mobile device) that provides a virtual keyboard (e.g., a software displayed touch screen), in which the physical keyboard can be overlaid onto the virtual keyboard of the touch screen device. When no key of the physical keyboard is pressed down, the physical keyboard does not trigger the touch screen of the touch screen device. When a key of the physical keyboard is pressed down, the physical keyboard touches the touch screen on a corresponding key of the virtual keyboard on the touch screen device, thereby causing the touch screen to detect that the corresponding key of the virtual keyboard has been pressed.

Abstract: A method for A/D conversion, which includes integrating by analog apparatus, amplifying and subsequently quantizing an analog input signal for producing a quantized signal having n bits, wherein n>1, and feeding back the quantized signal to the input signal. The improvement includes integrating digitally the quantized signal by an arrangement of periodic digital summation, converting the quantized signal into an analog signal, and feeding back the analog signal to the input signal. An apparatus for carrying out the method is also disclosed.

Abstract: A communications system is described in which a large number of endpoints communicate among one another in an orderly and protocol independent manner. The system is based on a short, fixed format packet which is switched among stations and within equipment in a contention-free manner without the use of general purpose processors. The system is distance independent, employs serial or parallel data paths, can use various media and can transport and switch data and digitized voice and video information in the same format and with the same equipment and transmission media. The effect of the system is to enable the construction of large metropolitan area networks which provide complete protocol conversion of all terminal types as well as transmission of data, voice, video and encrypted information.