A software-based simulation system is provided, which can provide the combined functionality of a South Bridge test module and a North Bridge test module based solely on either one of the two modules, i.e., either the South Bridge test module or the North Bridge test module without having to use both. This software-based simulation system is characterized in the use of a PCI master modeling circuit and a PCI slave modeling circuit which are capable of simulating the functionality of the North Bridge chipset in the case that only the South Bridge chipset and no North Bridge chipset is included in the simulation system, and are further capable of simulating the functionality of the South Bridge chipset in the case that only the North Bridge chipset and no South Bridge chipset is included in the simulation system.