H. Beam Piper 
The Cosmic Computer 

The search for a lost super-computer named MERLIN said to have once ended war and brought prosperity becomes the obsession of a poverty-stricken society. Merlin means everything to them: power, pleasures, and profits unlimited. "If we could only find Merlin, " the inhabitants say to each other, "all our problems would be solved." But young Conn Maxwell has a few clues about the location and the true nature of Merlin and the sure knowledge that finding the Cosmic Computer would be the worst thing that could possibly happen.