 What role does Doc play for Sandra?
Silently, so as not to shock anyone with illusions about well dressed young women, Sandra Lea Grayling cursed the day she had persuaded the Chicago Space Mirror that there would be all sorts of human interest stories to be picked up at the first international grandmaster chess tournament in which an electronic computing machine was entered. 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. This tournament hall seemed to Sandra much further out of the world. Samples: "They say the Machine has been programmed to play nothing but pure Barcza System and Indian Defenses—and the Dragon Formation if anyone pushes the King Pawn." "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. "As for the Machine—you do know, I suppose, that it is not a humanoid metal robot, walking about clanking and squeaking like a late medieval knight in armor?" "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. The equivalent of those in the Machine is the directions fed into it before it plays a game." Once again, you see, you have the human factor, in this case working for the Machine." At that moment the waiter arrived with a second coffee and wine-and-seltzer. Jandorf seized Doc's new demitasse, drained it, set it back on the tray with a flourish and drew himself up. I have challenged it also to a few games of rapid-transit—an offer no true grandmaster would dare ignore. "Oh yes," Sandra assured him, "but there are some other questions I very much want to ask you, Mr. Jandorf." While Sandra arranged for an interview with Jandorf after the day's playing session, Doc reordered his coffee. "One expects it of Jandorf," he explained to Sandra with a philosophic shrug when the shock-headed man was gone. Wild horses couldn't keep Jandorf away from a press interview. That's a minor variety of chess where each player gets only ten seconds to make a move.
 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.