It starts at disassembling. But thats not the copyright, but the authors right. Moving from A to B can be a copyright issue, if the move/copy is not staying whitin your pc.
The copyright law is about distributing something to someone else. The authors right, is using someone's idea in the full extend. (which is why you can get a patent for something). In the authors right, you cannot duplicate something someone else made and claim it to be your own because you did something with it too. With patents involved, it doesn't have to be the full product. The patent describes what the purpose/idea is behind the product, and if it matches, the rights are automatically assigned to the person holding the patent.