[[RF.Spice A/D]] has two distinct and independent simulation engines: the mixed-mode simulator and the event-driven digital simulator. Each of these two simulators has its own schematic mode and both are based on the Berkeley Spice and XSpice engine codes. The mixed-mode simulator simulates analog, RF and mixed analog/digital circuits. If your circuit is pure analog or RF or contains both analog and digital parts, then the mixed-mode schematic and simulator are used. If your circuit is pure digital, then the digital schematic and simulator are evoked, which allow for interactive inputs and outputs. The selection of the appropriate schematic mode and simulation engine is done automatically by [[RF.Spice A/D]]. In other words, you don't have to specify the type of your circuit or choose a particular simulation engine type.
You can run both of [[RF.Spice]]'s mixed-mode and [[Digital Simulation|digital simulation]] engines in either of its two simulation modes, that is, either as a live simulation or in a predefine test. However, digital circuit analysis is more effective as a live simulation, whereby you can step time by the clock cycles and observe your circuit's response using live digital timing diagrams.
== RF.Spice A/D vs. B2.Spice A/D ==