The American ENIAC is customarily regarded as the first electronic computer. In this fascinating volume, Jack Copeland rewrites the history of computer science, arguing that in reality Colossus--the giant computer built in Bletchley Park by the British secret service during World War II--predates ENIAC by two years. Until very recently, much about the Colossus machine was shrouded in secrecy, largely because the code-breaking algorithms employed during...