Chaos computing is a new circuit design scheme of using chaos computing units to achieve reconfigurable logic gates. The computing unit can function as different kinds of logic gates by changing external parameters. In this paper, the possibilities of expanding the function of a chaotic NOR gate proposed in the literature is studied. The numerical model for the circuit design was built by constructing differential equations fit for Matlab integration mechanism. Besides, numerical model for integrator saturation was built to make results of numerical simulation conform to that of circuit simulation. Analysis of the impact of integrator saturation was done. With the analysis and by changing the control voltage, NAND function was expanded for the original chaotic logic gate that was only able to function as a NOR gate. By adding the function control signal to the input end and setting the voltage of it to different levels, the computing unit becomes a real time reconfigurable one.