Abstract: A digital joystick operates in a digital mode or an analog emulation mode. In the digital mode, the joystick generates digital data indicating the position of a control stick and the status of buttons and transmits the digital data to the computer. The joystick may be coupled to the computer through a game port or a conventional interface port. Computer software operating within the computer can receive digital data directly from the joystick if it is operating in the digital mode. When in the analog emulation modes the joystick emulates resistances related to the position of the control stick. The emulated resistance data emulates the value of corresponding resistances in a conventional joystick. The resistance values may be derived from a programmable resistor, a programmable impedance, or a programmable current source. Multiplexers may also be used to couple the appropriate resistance value to the conventional game port input.

Abstract: An improved SCUBA diving gauge. A pictograph display is provided which has a shape which conveys the type of information being displayed. The pictograph has the shape of a SCUBA tank for a tank pressure display and the shape of a person for a display of nitrogen absorbed. Pressure transducers coupled to the SCUBA tank and the external water provide the pressure readings required to produce the respective displays. The differential signal from the transducer is supplied to a processor through an auto-zeroing circuit. The auto-zeroing circuit uses a capacitor initially coupled to an amplifier reference input and single ended output to store an offset voltage. During a measurement, the capacitor is disconnected from the amplifier output and has its other lead coupled to a full scale value of the differential input to produce an output signal which is a ratio.