@dzw3030: You’re almost certainly thinking of one story in http://books.google.com/books/about/No_Future_in_it.html?id=kvJBAAAAIAAJ , where an alien called Crodnobegorthsk’vk is being persuaded to buy the system you mention, and, during a demonstration, accidentally asks for some object to be delivered last week. Naturally, the system works out how to do it…
@dzw3030: You’re almost certainly thinking of one story in http://books.google.com/books/about/No_Future_in_it.html?id=kvJBAAAAIAAJ , where an alien called Crodnobegorthsk’vk is being persuaded to buy the system you mention, and, during a demonstration, accidentally asks for some object to be delivered last week. Naturally, the system works out how to do it…