According to Robert Cringley, Steve Jobs paid Xerox Apple shares to get the invite to XeroxParc. Xerox management didn't have the vision to see the potential of their west coast division. Bill Gates, when confronted by Steve Jobs succinctly described Xerox as the neighbor who didn't care about his TV (XeroxParc technologies) and left his window open. By the time you got around (Jobs), someone else already took the TV.
Completely ignoring the fact that Bill Gates had no relationship to XEROX PARC and Jobs did. Steve Jobs asked permission and was given permission. Gates did not.