 James Cameron (I) (qv) got the idea for  _Terminator, The (1984)_ (qv) while shooting another film in Europe.  His vision was of a metal endoskeleton emerging from flames and most  of the script was written backwards from there. The endoskeleton  would have to be futuristic, and Cameron couldnt afford to set the  film in the future. The solution was to bring the future to the  present, hence the time travel aspect of the script was written  in.