Origins of Digital Computing: Alan Turing, Charles Babbage, and Ada Lovelace

Alan Turing continues to dazzle, enlighten and bemuse. His work is difficult to situate, straddling as it does theory, practice and philosophical speculation. The nature and extent of his influence continues to elude us, and the haunting originality of his work resists convenient typecasting. He was capable of blinding clarity as well as of near-mystical obscurity that has an ability to tantalise, madden, and stretch our horizons at the same time. His formal description of a universal computing engine predates the practical implementation of the general-purpose electronic stored-program digital computer, but his influence on its realisation is difficult to nail down This is partly due to the continuing legacy of war-time secrecy but also the general paucity of documentary records.

To help locate Turing’s ideas in the larger trajectories of computer history I propose here to revisit the back-story of computing to identify the core ideas embodied in the realisation of the modern computer. Most of these emerged explicitly in the 19th century, a surprising assertion given the accepted modernity of the field. I hope to show that making this assertion is not a presumptuous grab by history to appropriate the triumphs of the late 20th and early 21st centuries, but rather a place-holder for an intriguing set of connections between computing pre-history and the electronic era.