US Patent 7664626 Ambiguous-state support in virtual machine emulators

A method and apparatus for ambiguous-state support in virtual machine emulators executes a suspect application in a core emulation model for all versions, variations, or generations of a given computer system component and then branches at the point where ambiguous behavior is detected, i.e., at the occurrence/request/trigger of a version variable behavior by the suspect application. The state of the emulation up to the version variable behavior branch point is then copied, and each variable behavior branch is further emulated using variable specific emulation models and only from the point of ambiguity, i.e., from the point of variable behavior, forward.