Alan Turing artwork

Turing anniversary books - the best and the rest

Books published to mark the 100th anniversary of Alan Turing's birth in June this year take different approaches to telling the computing pioneer’s story.

Everyone knows something of Alan Turing: the shy, socially inept, stuttering genius who saved his country in its blackest hour by cracking German naval Enigma codes at Bletchley Park, but was then harassed into committing suicide by an ungrateful state. Many will also have some vague inkling that Turing 'invented the computer' - though most would be challenged to explain his actual contribution.

Naturally, such a poignant story arouses widespread interest and repetition (thus the 4.2 million Google hits on his name). In one book on Bletchley Park, 'Bletchley Park People', a Post Office engineer claims that he "believes that he can pinpoint the actual moment when Alan Turing conceived the idea of the modern computer". The engineers, deciding the 'the Prof' should see the workshops where the real work was done, grabbed him. "He wore his usual faraway look as he went in. One lad picked up a valve and said, 'Now Prof, this is what we call a thermionic valve. It's an electronic device ...'. [Turing] just stood there goggle-eyed, then all of a sudden his face changed. He just sort of went rigid, stared into the middle-distance, and still holding this valve in this hand said, 'You know, I could make a computer with these'. We think, and I certainly think, that's where the computer started."

The scene owes more to the style of Hollywood biopics than history. No doubt the story of the encounter, even Turing's strange countenance, is real. But the attribution of the conception of the computer onto this chance meeting with an electronic valve is a backwards projection of later knowledge of the idea that Turing 'invented the computer'.

The titles of two new books suggest that they may be able to clarify what that means. But while Turing's name appears in the titles of both books, he plays only a minor role.

'Turing's Cathedral', by George Dyson, and 'Alan Turing and his Contemporaries', edited by Simon Lavington, share this characteristic - but not much more. Dyson opens his book thus: "There are two kinds of creations myths: those where life arises out of the mud, and those where life falls from the sky. In this creation myth, computers arose from the mud, and code fell from the sky".

Lavington opens his collaborative book rather more prosaically: "The years 1945-55 saw the emergence of a radically new kind of device: the high-speed stored-program digital computer. The brilliant mathematician and code-breaker Alan Turing was just one of several British pioneers whose prototype machines led the way."

If you want dazzling prose and a dizzying trip across the intellectual currents that led to the building of the first US computers, read Dyson. If you want a curiously downbeat assessment of the technical characteristics of the first British post-war computers, then Lavington is for you.

Dyson's prose reaches its most pretentious tones when explaining mathematics or when he paints an impression of his idea of the digital universe. However, it drops down a notch or two for most of the book to provide a very readable account of the work done at the Institute of Advanced Studies at Princeton, led by John von Neumann - whose name competes with that of Turing as a label for a theoretical concept of the modern computer. Indeed, this is really a book about von Neumann, not Turing. However, Dyson does make clear that von Neumann was fully aware of 'On Computable Numbers' and of its implications for building computers.

In Dyson's view, the birth of the computer took place in Princeton a couple of years after the first British computers: "The first epoch in the digital era began with the introduction of the random-access storage matrix in 1951. The second era began with the introduction of the Internet. With the introduction of [content] addressing, a third era in computation has begun."

The weakness of this account is that it compresses the history of computing into a then and a now, with nothing of relevance in between. Dyson's Holy Trinity of the future is Google, Amazon and Facebook. A look at the missing years would show that names in IT rise and fall with dizzying speed.

There's no reason to assume that the same thing won't apply to today's market leaders. Indeed, Facebook looks as if it has already peaked. Dyson would have done better to stick with the past and resisted the urge to make his book up to date. History bites back.

Lavington's book is completely different. It is like listening to a soporific lecture. The authors aim to give an account of Turing's contribution to the development of early post-war computers, but the odd, skimpy and unbalanced selection of content means that they fail. The book will interest those fascinated by the instruction sets of early British computers. But even then, it is only slightly satisfying as the book is pretty thin and covers the story only superficially.

There is one attempt to inject some excitement into the narrative, but despite the liberal use of exclamation marks, it doesn't quite come off. "On the morning of Monday 21 June 1948, the 'highest factor' program gave the correct result. They tried another run and it was correct. What excitement! "Quick!" said Tom Kilburn to Geoff Toothill, "Go and fetch Freddie!" Williams was fetched from his office, and for the third time the program ran correctly. That was a momentous day: the first time ever in the world that a universal stored-program electronic computer had successfully worked!" It's pretty pedestrian prose.

Alan Turing: The Enigma

The contrast of Dyson's and Lavington's styles will tell you a lot about why the US became the central driving force of the computer industry rather than Britain. However, if you want to learn about Turing, neither is a particularly good place to start.

For all the new books, the story of Turing is still best told by Andrew Hodges in his biography, 'Alan Turing: The Enigma'. First published in 1983, the book stands the test of time. It is a labour of love and is a compelling, if lengthy, read. Turing's life is handled with sensitivity and insight. His work is described in comprehensible language. A magnificent achievement and still the essential text.

However, so much material has been released on Turing's wartime work in recent years that it would have been worth some updating. The 'centenary issue' is in fact a reprint of the 1992 edition and the only 'new' material is in a short preface dating from 20'years ago.

Another 'new' book, 'Alan M Turing', is also a recycled text, originally written in 1959 by Turing's mother, Sara Turing, then in her seventies. The account is well written and tackles some of Turing's mathematical work. However, his wartime contribution was then still entirely secret and inevitably we get only the positive view of things.

The rather one-sided account of the loving mother is contrasted by a more irascible one written by Turing's brother, John. "It is sufficiently obvious to any discerning reader ' that a false note has been struck somewhere: could Alan have been quite that paragon of virtue that my mother describes?" he asks before recounting some of the hassles of having a rather odd brother. "I am concerned only with Alan's behaviour as it affected other people and it was not, in my view, so amusing for those people that were on the receiving end."

The reader who wants to know more about Turing's mathematical work will find many of his papers now in book form. However, all but skilled mathematicians will quiver and quake when faced with his 'Systems of Logic Based on Numerals', Turing's PhD thesis. Similarly, his seminal 'On Computable Numbers' appears rather opaque, though the basic idea is actually quite straightforward. An excellent way to tackle it is with Charles Petzold's 'The Annotated Turing'.

The most readable of Turing's important documents is his post-war 'Proposed Electronic Calculator', outlining his ideas for an electronic computer at the National Physical Laboratory. Lavington says: "Historians now judge it to be the first substantially complete description of a practical stored-program computer." Its non-publication by the NPL, however, meant that it had little influence on subsequent computer developments.

Ironically this document of Turing's is the most difficult to get in published form. It can be read online at www.alanturing.net/turing_archive/archive/p/p01/p01.php *

Paul Gannon is the author of 'Colossus: Bletchley Park's Greatest Secret' and 'Inside Room 40'.

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