Abstract: An electronic accessory assembly to be used with a host electronic instrument provides previously recorded data from a non-volatile memory as to the accessory's operational capabilities. This memory is accessed by a host device either when the host device is powered up, or when an new accessory is connected to the host device. The host device then uses this information along with the operational requirements of the user to set the operational parameters of the accessory/host combination to optimally perform the functions required by the user.

Abstract: A high performance attenuator configuration divides a signal path into a plurality of parallel attenuator paths, each path having a predetermined attenuation value. A switch for each attenuator path is provided to couple selectively one of the attenuator paths to an input connector. Each attenuator path has an FET buffer amplifier, and the outputs of the FET buffer amplifiers are input to an electronic switch or multiplexer. The electronic switch selects the FET buffer amplifier output to be passed on to an output drive circuit.

Abstract: A method and apparatus for minimizing the self heating distortion of a compensated differential transconductance amplifier having an error voltage generator is provided. In a preferred embodiment, the bases of a first pair of transistors are coupled together and to an adjustment voltage source. The bases of a second pair of transistors are coupled together and to a reference voltage source. The collectors of the transistor pairs are coupled together to form a differential current output. The output currents of the compensated amplifier are segregated into two currents, one originating in the error voltage generator, a second current being the remainder. The first current is directed to flow through the first pair of transistors, the second current is directed to flow through the second pair of transistors.

Abstract: An improved differential f.sub.T doubler amplifier is provided having two error amplifiers in series connection with the main signal amplifier for cancelling the nonlinear currents generated by the main signal amplifier. The error amplifiers receive a differential error voltage provided by a pair of transistors which sense the error voltage in the main signal amplifier.

Abstract: A focus control circuit particularly well suited for use with a cathode-ray tube having a quadrapole lens includes automatic tracking focus and astigmatism features to ensure a well-focused display with minimum focus readjustment.

Abstract: A resistor device comprises a first film of resistive material deposited on a dielectric substrate and having two terminal portions for connection to an electrical circuit, and a second film of resistive material deposited on the substrate in thermally-conductive contact with the first film and electrically isolated therefrom. The material of one of the films has a relatively high temperature coefficient of resistance, so that the resistance of that film can be utilized as an indication of the temperature of the other film.