Abstract: A memory control arrangement includes a microcontroller for performing a program memory operation and a data memory operation. The microcontroller produces address signals and a control output indicating first and second operating conditions. A program memory having a first range of memory locations stores a first program and is connected to the address lines for being addressed by the microcontroller. A data memory has second and third ranges of memory locations for storing, respectively, a second program and data for use by program variables. The data memory is connected to the address lines for selectively addressing the second and third ranges of memory locations by the address signals from the microcontroller.

Abstract: A method and apparatus for a liquid level sensor control circuit of a bioassay apparatus for controlling a position of a sampling probe with respect to a surface of a liquid in a container. The apparatus includes a sampling probe, an oscillator circuit coupled to the sampling probe for producing a first output signal having a constant frequency, a comparator coupled to the oscillator circuit for comparing the amplitude of the first output signal to a first reference amplitude and for producing a change signal when the amplitude of the first output signal changes with respect to the reference amplitude, and a controller responsive to the change signal for controlling the position of the sampling probe with respect to the surface of the liquid.