Few concepts in the history of 20th-century thought are as rich with both philosophical and practical implications as the computer. And few people in the history of computing are as intellectually and personally complex as Alan Turing, the man whose brilliant mathematical imagination laid the foundation for computers as we know them. You could easily spend the rest of the millennium reading up on Turing and his ideas, but if you've only got an afternoon, this engaging, pamphlet-length summary of the man's life and work should get you nicely up to speed.
Author Paul Strathern sets Turing's accomplishments in their historical context. He starts with the long prehistory of the computer--its roots in devices such as the abacus, the slide rule, and Charles Babbage's remarkably sophisticated 19th-century "difference engine." Strathern then moves deftly through the great mathematical debates that led to Turing's formulation of the abstract "universal computing machine" in the mid-1930s. The author also lucidly presents Turing's contributions to turning that abstraction into a concrete mechanism, beginning with Turing's work on the Colossus machine, which cracked Germany's secret codes during World War II.

Strathern conveys with equal vividness the haunted private side of Turing's life--his furtive homosexuality, his difficult relationships, and his conviction in the early '50s on charges of indecency, a not-so-private scandal that apparently led to his suicide. The book owes its rich detail to the work of pioneering Turing biographer Alan Hodges, and Strathern graciously acknowledges the debt. But the accomplishment of packing Turing's big life and big ideas into such a compact package is entirely Strathern's own