 What role does Doc play for Sandra?
Her last assignment had been to interview the pilot pair riding the first American manned circum-lunar satellite—and the five alternate pairs who hadn't made the flight. "I heard the Russians have been programmed—with hypnotic cramming and somno-briefing. Sandra's chief difficulty was that she knew absolutely nothing about the game of chess—a point that she had slid over in conferring with the powers at the Space Mirror , but that now had begun to weigh on her. "Yes, Doc, but...." The Machine is probably programmed to recognize such situations and do something of the same sort, though we can't be sure from the information World Business Machines has released.
 He plays an informative role.
 He plays a comedic role.  He plays a condescending role.  He plays an entertaining role.  He plays an informative role.