ALAN MATHISON TURING

(1912-1954):

The solitary genius who wanted to build a brain.

A long-distance runner and cyclist, Tur­ing has been described as a self-reliant misfit [16] who ran against the social norms of his time. He was a homosexual at a time when this was not only illegal but was deemed to be a security risk. He paid the price of being found out, if that is the right expression, for Turing was deeply honest to himself and never concealed his homosex­uality.

In his trial at Knutsford in 1952 he was described as "a national asset" and "one of the most profound and original mathematic­al minds of his generation". It was true, but he was still found guilty and was given probation [17] on condition that he accepted hormone treatment - in effect, chemical castration. According to his biographer, Andrew Hodges, Turing rode the storm. But a little over two years later, on June 7, 1954, he doused an apple with cyanide and killed himself.

Turing's claim to fame is as one of the fathers of electronic computers. His 1936 paper "On Computable Numbers" is the classic in its field. He dreamed of making a "brain", his Universal Machine. His influ­ence was felt by all the early pioneers of computers from von Neumann in the USA to the teams that built the first post-war British computers. The National Physical Labora­tory's ACE computer was his concept of a Universal Machine. Today his memorial is The Turing Institute in Glasgow, dedicated to research and training in artificial intelli­gence.

Childhood

They say the child is the father of the man and that seems to have been true of Alan Mathison Turing. For long periods he was separated from his parents, especially his father. Later in life he was a confirmed solitary, one with whom many found it difficult to get along [18]. Turing was born a Londoner, in Paddington, on June 23,1912. His mother, formerly Ethel Stoney, was a distant relative of George Johnstone Stoney, the Irish physicist who gave the electron its name. Alan's father, John Mathison Turing, served the Empire through the Indian Civil Service. For the first decade of his life Alan and his elder brother, another John, stayed in Eng­land whilst their parents lived in India, except for their often long visits to England.

When Alan was about 12 years old, his father resigned from the Indian Civil Service and settled for an early retirement in France, at Dinard in Brittany. School French lessons suddenly acquired a purpose. So far he had been educated by his mother, at a private day school, and then at a preparatory school near Tunbridge Wells. He was particularly in­terested in maps and formulae.

For public school it was decided that he should go to Sherborne in Dorset. When he arrived at Southampton from France in 1926 there were no trains because of the General Strike. He set out on his bicycle and arrived on the second day. Later in life he rejected an offer of an official car in favour of his bike. Cycling and running were to be his great loves.

At Sherborne his ability at mathematics developed, as did his passion for science. He took an avid interest in astronomy to which he was introduced by a fellow student with whom he developed an intense, but doomed, friendship. Tuberculosis killed his friend in 1930. But Sherborne fulfilled its purpose and in 1931 he progressed to King's College, Cambridge - Britain's Mecca for a mathematician. Turing gained his degree in mathematics with distinction in 1934 and was awarded a research studentship of £200. This was followed in 1935, at the tender age of 22, by a coveted Fellowship4 at £300. At last the had the academic freedom to pursue his ideas.

Computable Numbers

Almost simultaneous with his election to a Fellowship was the publication of his first paper, a slight improvement on earlier work by the master mathematician John von Neumann. As it happened, von Neumann arrived in Cambridge shortly afterwards to spend the summer away from his home university of Princeton in America. Turing almost certainly attended his course of lectures; but his main problem now lay in choosing his field of research.

His interest in mathematical logic had been aroused by Newman's lectures in 1935. These included problems posed at the end of the 19th century by the German mathematician David Hilbert. One of these remained unsolved and in 1928 Hilbert himself proposed the problem - "to find a method for deciding whether or not a given formula is a logical consequ­ence of some other given formulae".

Turing solved the remaining problem and went on to postulate a logical machine that could solve any problem of logic provided it was given a suitable set of instructions. This ran counter to the prevalent belief 5 that different calculating machines were needed for different mathematical problems. Turing showed that it was possible logically, if not physically, to have one machine to do all. The concept was soon to be known as a "Turing machine". Within ten years such machines had "descended from the sky to the firm ground of informa­tion technology".

Turing's paper was called "On Comput­able Numbers" for short. Alan Turing had solved a major problem to mathematics with a fresh, direct and "simple" approach. Though it would take a little time to establish his reputation, that reputation was now assured.

He was not the only one to tackle the problem, however, for it had just been solved by an established American mathematician, Alonzo Church, at Princeton University. Though Turing's approach was radically different from Church's, the discovery of Church's work must have been a painful experience. Max Newman wrote to Church asking for help in getting Turing to Princeton so that he could be at the centre of things for a time and "so that he should not develop into a confirmed solitary"6. Alan Turing duly sailed for America on September 23, 1936.

Princeton University had acquired the status of being the place for a mathematician to be. The Institute for Advanced Study had been set up there in 1932 and the double institute, as it could be viewed, attracted leading scientists; Einstein was there, for example.

As with many great ideas when they are new, "Computable Numbers" did not cause a sensation though Church's review of it coined the expression "Turing machine". Turing described his work at a poorly-attended seminar and the paper was pub­lished whilst he was at Princeton. He was offered a second year in America, accepted, and submitted for a Ph.D. after a brief return to Cambridge.

Bletchley Park

By the time he received his Ph.D. in June 1938, a number of things had happened which set his course for the next few years. Von Neumann had become aware of, and admired, "Computable Numbers" and had offered him a research assistantship at the Institute of Advanced Study. Turing had built an electronic multiplier and developed his earlier interest in codes and ciphers. And Hitler's war was threatening.

Bravely he turned down von Neumann's offer and returned to Cambridge in the hope that "Hitler will not have invaded England before I come back". He arrived at Southampton on July 18 with his electronic multiplier wrapped in brown paper. Within weeks he was on a course at the Government Code and Cipher School, one of sixty or so people earmarked for recruitment if war should break out 7. The day after war was declared he reported to Bletchley Park in Buckinghamshire, the home of the Code and Cipher School, and set to work on the German ciphers. He was ideal for the job.

The British effort at breaking the German codes initially depended on work done in Poland. It is a complex story and one that has already been described, for example by Hodges in his biography of Turing. The Germans used a machine called Enigma to encipher their messages but the Poles had, in effect, obtained a logical copy of the basic machine. To break the cipher they had built other machines which, because of the tick­ing noises they made, came to be known as bombs. The Germans increased the com­plexity of Enigma and rendered the Polish bombs ineffective.

The Bletchley team, especially Alan Tur­ing and Gordon Welchman, brought new ideas to the problem and new bombs were designed and built. According to Hodges they were "impressive and rather beautiful machines, making noises like that of a thousand knitting needles". There began what Hodges has termed the "relay race" as each side sought to stay one step ahead of the other8 but with the Germans never believing that Enigma had been broken, only that spies were at work.

When America came into the war Turing was dispatched on the Queen Elizabeth to brief them 9 on the cipher breaking work.. During his visit he spent a couple of months at Bell Laboratories, meeting Nyquist and Claude Shannon amongst others. Mean­while Max Newman had arrived at Bletchley and had started work on electronic counting machines which became known as the Robinsons. These were followed by a series of electronic computers, each known as Col­ossus. Turing played little, if any, part. He moved on to a new pet project on speech encipherment which reduced speech to meaningless noise and then recovered it. He designed the machine, built it, called it Delilah - and it worked.

By the end of the war Turing had returned to his pre-war ideas, developed now into a Universal Turing Machine. Strengthened by his experiences with electronics he faced the question of whether this could now become something more than an intellectual con­cept. Could it become a real machine? He wanted to build an electronic "brain", essen­tially what we would now recognize as an automatic digital computer with internal program storage.

Of course he was now not alone in thinking such thoughts, for in America the ENIAC was now built and plans had been published for another machine to be called EDVAC. Such news probably influenced the National Physical Laboratory in its plan to build a national computer with Turing's help: a Universal Turing Machine. It was to be known as the Automatic Computing Engine or ACE. Turing's design used binary arithmetic and was to have the simplest possible hardware based on the logical func­tions And, Or and Not, and a large and fast memory. The rest would be performed by the sets of instructions, the programs. As a design it was unique and owed little to the other pioneer computers10.

Funds were allocated in 1946 to begin work on a small machine, later known a Pilot ACE. Internal politics and delays did not augur well, however, for the urgency of wartime had not carried forward into peace. Turing left before even the Pilot ACE was completed. He was on sabbatical11 at Cam­bridge when the new computer team at Manchester University offered him a posi­tion. He accepted in May 1948 and joined them in the autumn. The Manchester pro­totype ran its first program on June 21, 1948, and in February 1951 the first of the Ferranti Mkl computers was delivered, based on the university machine. Pilot ACE (which is now in the Science Museum, London) ran its first program on May 10, 1950, and the full ACE was not completed until late in 1957. At Manchester, Turing came to spend much of his time in develop­ing programming techniques, even doing manual arithmetic in base 32.

Turing was always a loner. Many found him difficult to get on with. He received the OBE in June 1946 as official thanks for his wartime work. It came through the post. And in March 1951 he was elected a Fellow of the Royal Society, probably a more fitting tribute. Glasgow's Turing Institute opened in 1984.

Task I

Speak on the history of development of the first British and American computers.

Task II

Describe features and functions of Universal Turing Machine.

JACK KILBY

“I had the fortunate experience of being the first person with the right idea and the right resources available at the right time in history…I'm grateful to the innovative thinkers who came before me, and I admire the innovators who have followed."

The Begining

Born in Jefferson City, Missouri in 1923 Jack St Clair Kilby grew up in Great Bend, Kansas. His interest in electronics can be traced to his high school days when his father was running a small power company scattered across the western part of Kansas. One year, a big ice storm took down all the telephone and many of the power lines, so Jack and his father began to work with amateur radio operators to provide some communications.

Kilby entered the University of Illinois Electrical Engineering Department in the fall of 1941. He completed his first two years before entering the Army. After the war, he returned to campus in January 1946; he earned his bachelor’s degree in electrical engineering in 1947. He began his career with the Centralab Division of Globe Union Inc. in Milwaukee, developing ceramic-base, silk-screen circuits2 for consumer electronic products. He worked in the area of miniaturization, looking for ways to develop smaller and more effective electrical components.

In 1952, Centralab, which had acquired a license for manufacturing transistors from Bell Laboratories, sent Kilby to a transistor symposium at Bell Labs’ headquarters in Murray Hill, New Jersey. There, Kilby saw first-hand the ground-breaking technology that was invented by Bell Labs scientists John Bardeen, Walter Brattain and William Shockley in 1947. When he returned to Centralab, he began working on germanium transistors that could be used in hearing aids manufactured by Centralab.

Although germanium was originally the material of choice for transistors, it proved not to be the element that would make the best integrated circuits. In 1954, scientists working on transistor research at Bell Labs found silicon to be a better choice. Not only was it a superior semiconductive element, it was also more available than germanium, thereby reducing the costs of components manufactured.

Kilby agreed with the Bell Labs scientists and embraced silicon as well as the wave of the future. However, Centralab didn’t seem likely to change from germanium-based components any time soon. Although Kilby was pleased with his work at Centralab, he realized he wanted to be with a company that was working on the leading edge of the coming technology.

Kilby found what he was looking for at Texas Instruments (TI), which also had acquired a Bell Labs license for manufacturing transistors and had several military contracts for developing silicon transistors. He joined Texas Instruments in 1958, and was employed by them until he retired in the early 1970s.

Date: 2015-12-24; view: 816