The Cosmic Computer by H. Beam Piper (also known as Junkyard Planet)
VINTAGE PAPERBACK [ACE BOOKS]
70's paperback printing in excellent condition w/ some very minor shelf wear to cover.
....A poor backward planet has only one thing going for it. It was the home of the main headquarters of the Terran military during a past war ... and when they left, they left all their extra stuff. It was more expensive to move the heavy equipment over interstellar distances than it was worth. And rumors tell of a "Cosmic Computer" so powerful that it could solve everyone's problems on this little backward planet ... if only they could find it.