Abstract: An apparatus for optical encoding. An electrical input circuitry is provided for providing a pulsed electrical input signal. A light source circuitry is connected to the pulsed electrical input circuitry for utilizing the pulsed electrical input signal to produce pulses of light. Light collecting and electrical conducting circuitry is provided and synchronized with the light source circuitry. The light collecting and electrical conducting means is positioned in relation to the light source circuitry for receiving and being responsive to light produced by the pulsed light source circuitry. An electrical output signal is produced, indicating such a response. Positionable light interrupting circuitry is provided for opening and closing the optical path of light being transmitted from the light source circuitry to the light collecting and electrical conducting circuitry. The opening and closing affects the electrical output signal, the resulting pulsed electrical output signal for use in encoding.

Abstract: An application specific integrated circuit is disclosed for use with a device locatable on a serial data bus of a data communication system. Attention and synch receiving circuitry is provided for receiving an attention and synch signal being transmitted on the serial data bus for synchronizing the device in accordance with the timing of the attention and synch signals. Demodulation circuitry is provided for receiving a command byte signal and a stop bit signal being transmitted on the serial data bus. Demodulation circuitry is provided for demodulating the command byte signal. Reset circuitry is coupled to the demodulation circuitry for receiving the command byte signal if the command byte signal contains a predetermined reset code. Flush circuitry is coupled to the demodulation circuitry for receiving the command byte signal if that signal contains a predetermined flush code. The flush circuitry clears all device specific data in the integrated circuit in response to the predetermined flush code.

Abstract: An apparatus and method are disclosed for transferring data between devices located on a serial data bus of a data communication system. A first counter and flag are provided which are associated with a device on the serial data bus. The first counter and flag are coupled to the serial data bus for determining temporal periods of high signal levels on the data bus. A second counter and flag also associated with the device on the serial data bus is coupled to the data bus for determining temporal periods of low signal levels on the data bus. A logic demodulator is provided which is coupled to the first and second counter and flag for demodulating the high and low signal levels to binary data and for using this binary data to perform a pertinent function of the device. A transmitter is coupled to an output of the first and second counter and flag and to the demodulation logic for modulating binary data received from the device while performing its pertinent function.

Abstract: An apparatus and method of minimizing undesired cursor movement in a computer controlled display system are disclosed. A cursor control device capable of generating an electrical signal indicative of a position of the cursor control device is provided. At least two temporally spaced portions of the electrical signal are sampled. Each of the samples is taken within a designated period of time. The period of time designated is a function of the predicted rate of movement of the cursor control device. The sampled portions are compared with each other and to an electrical signal previously sampled. The comparisons are analyzed for determining whether the cursor should be signaled to move on the display of the computer controlled display system. Use of this digital logic hysteresis technique minimizes "jitter" of the cursor when the cursor control device is substantially stationary.