A system and method for simulating the electrical operation of a mixed analog/digital system includes the capability for analog circuit block inputs to respond to the condition in which digital gate outputs connected to the analog circuit block input are presented in high-impedance or floating signal states, thereby providing for simulation of a wide variety of mixed analog/digital designs in which this condition occurs. In a simulated design, an analog input of one or more analog circuit blocks is transformed into an analog tri-statable input-output referred to as an ioput. The ioput is capable of driving an analog signal when the digital gate outputs connected to the analog block input are presented in a high-impedance Z state; otherwise, the ioput acts as an analog input to the analog circuit block.