The Adventures of Accordion Guy in the 21st Century: Questions and answers with Neal Stephenson. I am amused to learn this —
Stephenson said that he generally knows the ending to the story from the first day, from the “very first time he puts pen to paper”. “It’s just a matter of getting there.”
— because in Snow Crash and The Diamond Age he seems to have reached a given page-count and said to himself “Time to wrap it up.”