VAX Emulation, how does it work?
vtVAX creates a virtual equivalent of the original VAX system inside a modern general purpose computer (Intel or AMD processor based X86 architecture). Your VAX-based software recognizing the system it used to run in continues to operate unchanged.
No changes ⇒ no problems.
It really is that simple. The process of course, not the technology behind it. By creating the exact equivalent of the VAX you are replacing, your software is presented with the hardware interfaces it is used to working with. Which means your software does not need to change.