The Staffordshire University Computing Futures Museum Manchester Page
The Manchester computers were an innovative series of stored-program electronic computers developed during the 30-year period between 1947 and 1977 by a small team at the University of Manchester, under the leadership of Tom Kilburn. They included the world's first stored-program computer, the world's first transistorised computer, and what was the world's fastest computer at the time of its inauguration in 1962.
The project began with two aims: to prove the practicality of the Williams Kilburn tube store, an early form of computer memory based on a standard cathode ray tube (CRT), and to construct a machine which could be used to investigate how computers might be able to assist in the solution of mathematical problems. The first of the series, the Small-Scale Experimental Machine (SSEM), ran its first program on 21.06.1948. As it was the world's first stored-program computer, the SSEM (Baby) quickly attracted the attention of the United Kingdom Government, who contracted the engineering firm of Ferranti to produce a commercial version. The resulting machine, the Ferranti Mark 1, was the world's first commercially available general-purpose computer. The collaboration with Ferranti eventually led to an industrial partnership with the computer company ICL, who made use of many of the ideas developed at the university, particularly in the design of their 2900 series of computers during the 1970s.
The Small-Scale Experimental Machine (SSEM)
The Manchester Small-Scale Experimental Machine (SSEM), also known as the Baby, was designed as a test-bed for the Williams Kilburn tube store, rather than as a practical computer.
This is a replica of the Baby at the Manchester Museum of Industry and Technology.
Work on the machine began in 1947, and on 21.06.1948 the computer successfully ran its first program, consisting of 17 instructions written to find the highest proper factor of 2^18 (262,144) by trying every integer from (2^18 - 1) downwards. The program ran for 52 minutes before producing the correct answer of 131,072. The SSEM was 5.2m long, 2.24m tall, contained 550 thermionic valves (300 diodes and 250 pentodes), and consumed 3.5Kw of power. Its successful operation was reported in a letter to the journal Nature published in September 1948, establishing it as the world's first stored-program computer. It quickly evolved into a more practical machine, the Manchester Mark 1.
The Manchester Mark 1
Development of the Manchester Mark 1 began in August 1948, with the initial aim of providing the university with a more realistic computing facility. In October 1948 the UK Government Chief Scientist Ben Lockspeiser was given a demonstration of the prototype, and was so impressed that he immediately initiated a government contract with the local firm of Ferranti to make a commercial version of the machine,
Two versions of the Manchester Mark 1 were produced, the first of which, the Intermediary Version, was operational by April 1949. The Final Specification machine, which was fully working by October 1949, contained 4,050 valves and had a power consumption of 25Kw. Perhaps the Manchester Mark 1's most significant innovation was its incorporation of index registers.
the 1951 Ferranti Mark 1. In the second photograph Alan Turing is shown programming the Ferranti Mark I with two engineers on 24.05.1953.
Program Sheet and computer output. Turing has written "How did this happen?" on part of the printout.
Meg and Mercury
As a result of experience gained from the Mark 1, the developers concluded that computers would be used more in scientific roles than pure mathematics. They therefore embarked in 1951 on the design of a new machine which would include a floating point unit. The resulting machine, which ran its first program in May 1954, was known as the Megacycle Machine (Meg). It was smaller and simpler than the Mark 1, as well as quicker at solving mathematics problems.
Ferranti produced a commercial version marketed in 1957 as the Ferranti Mercury, in which the Williams Kilburn tube stores were replaced by the more reliable core store.
Ferranti also built another vacuum tube computer, the Ferranti Pegasus. The Pegasus 1 was first delivered in 1956 and the Pegasus 2 in 1959. Ferranti sold twenty-six Pegasus 1 computers and twelve Pegasus 2 computers, making it Ferranti's most popular valve computer.
The Transistor Computer
Work on building a smaller and cheaper computer began in 1952, in parallel with Meg's ongoing development. Two of Kilburn's team, R.L. Grimsdale and D.C. Webb, were assigned to the task of designing and building a machine using the newly developed transistors instead of vacuum tubes. Initially the only devices available were germanium point-contact transistors, which although less reliable than the vacuum tubes they replaced consumed far less power. Two versions of the machine were produced.
The first version was the world's first transistorised computer, and it became operational in November 1953. The second version, completed in April 1955, contained 200 transistors and 1,300 solid-state diodes, and it consumed 150w. The machine did, however, still make use of valves to generate its 125KHz clock waveforms, and to read and write on its magnetic drum memory, so it was not the first completely transistorised computer (that was the Harwell CADET of 1955). Problems with the reliability of early batches of transistors meant that the machine's mean time between failures was about 90 minutes, but there was an improvement once the more reliable junction transistors became available.
The Transistor Computer's design was adopted by the local engineering firm of Metropolitan-Vickers (Metrovick) in their Metrovick 950, in which all the circuitry was modified to make use of junction transistors. Six Metrovick 950s were built, the first completed in 1956. They were successfully deployed within various departments of the company and were in use for about five years.
Muse and Atlas
The development of a "Microecond Engine" (MUSE) began at the university in 1956. The aim was to build a computer that could operate at processing speeds approaching one microsecond per instruction, i.e. one million instructions per second. At the end of 1958 Ferranti agreed to collaborate with Manchester University on the project, and the computer was shortly afterwards renamed Atlas, with the joint venture under the control of Tom Kilburn.
The first Atlas was officially commissioned on 07.12.1962, and was considered at that time to be the most powerful computer in the world. It was said that whenever Atlas went offline half of the UK's computer capacity was lost. Its fastest instructions took 1.59 microseconds to execute, and the machine's use of virtual storage and paging allowed each concurrent user to have up to one million words of storage space available. Atlas pioneered many hardware and software concepts still in common use today, including the Atlas Supervisor, considered by many to be the first recognisable modern operating system. Two other Atlas machines were built, one for a joint British Petroleum/University of London consortium, and the other for the Atlas Computer Laboratory at Chilton near Oxford.
A derivative system was built by Ferranti for Cambridge University, called the Titan or Atlas 2, which had a different memory organisation, and ran a time-sharing operating system developed by Cambridge Computer Laboratory. The University of Manchester's Atlas was decommissioned in 1971, but the last was in service until 1974. Parts of the Chilton Atlas are preserved by the National Museums of Scotland in Edinburgh.
Work on the MU5 began in 1966. It was designed to be about 20 times faster than Atlas, and was optimised for running compiled programs rather than hand-written machine code, something that contemporary computers were unable to do efficiently. A major factor in the MU5's much-improved performance over its predecessors was use of an instruction pipeline and its incorporation of associative memory, which greatly speeded up access to its main store. The Science Research Council (SRC) awarded Manchester University a five-year grant of £630,466 in 1968 (equivalent to about £8.2 million in 2010) to develop the MU5, and ICL made its production facilities available to the university. Development work began in 1969, and by 1971 the design team had grown from the initial nucleus of six members of the University's Computer Science department to 16, supported by 25 research students and 19 ICL engineers. MU5 was fully operational by October 1974, coinciding with ICL's announcement that it was working on the development of a new range of computers, the 2900 series. ICL's 2980 in particular, first delivered in June 1975, owed a great deal to the design of the MU5, which remained in operation at the university until 1980.
The MU5 was the last large-scale machine to be designed and built at Manchester University. The development of its successor, the MU6, was funded by a grant of £219,300 awarded by the SRC in 1979 (equivalent to about £827,000 in 2010). MU6 was intended to be a range of processors with MU6-V at the top end and a personal processor, MU6-P, at the bottom end, but only the MU6-P and a mid-range processor, the MU6-G, were produced.
Summary of the Manchester University designs
1948 Small-Scale Experimental Machine, also known as the "Baby", which evolved into the Manchester Mark 1
1951 Ferranti Mark 1
1953 Transistor computer
1956 Metrovick 950
1957 Ferranti Mercury
1959 Ferranti Pegasus 2
1962 Ferranti Atlas and Titan
1974 ICL 2900 Series
Alan Mathison Turing (1912 - 1954)
Alan Mathison Turing, OBE, FRS, born 23rd June 1912, died 07 June 1954, was an English mathematician, logician, cryptanalyst and computer scientist. He was highly influential in the development of computer science: he provided a formalisation of the concept of the algorithm, explored the limits of computation using the Turing Machine, and played a significant role in the creation of the modern computer. During the Second World War, Turing worked for the Government Code and Cypher School at Bletchley Park, Britain's codebreaking centre. For a time he was head of Hut 8, the section responsible for German naval cryptanalysis. He devised a number of techniques for breaking German ciphers, including the method of the Turing bombe, an electromechanical machine that could find settings for the Enigma machine. After the war he worked at the National Physical Laboratory, where he created one of the first designs for a stored-program computer, the ACE, and later worked on the Manchester Mark I at Manchester University.
His father, Julius Mathison Turing, was a member of the Indian Civil Service at Chatrapur, Orissa, India. Julius and wife Sara (née Stoney; 1881–1976, daughter of Edward Waller Stoney, chief engineer of the Madras Railways) wanted Alan to be brought up in England, so they returned to Maida Vale, London, where Alan Turing was born on 23rd June 1912, as recorded by a blue plaque on the outside of the building, now the Colonnade Hotel. His father's civil service commission was still active, and during Turing's childhood years his parents frequently travelled between Hastings, England and India, leaving their two sons to stay with a retired Army couple. Very early in life, Turing showed signs of the genius he was to display more prominently later.
His parents enrolled him at St Michael's, a day school, at the age of six. The headmistress recognised his talent very early, as did many of his subsequent educators.
In 1926, at the age of 14, he went on to Sherborne School, a famous independent school in the market town of Sherborne in Dorset. His first day of term coincided with the General Strike in Britain, but so determined was he to attend school on his first day that he rode his bicycle unaccompanied about 100Km from Southampton to Sherborne, stopping overnight at an inn. Turing's natural inclination toward mathematics and science did not earn him respect with some of the teachers at Sherborne, whose definition of education placed more emphasis on the classics. His headmaster wrote to his parents: "I hope he will not fall between two stools. If he is to stay at Public School, he must aim at becoming educated. If he is to be solely a Scientific Specialist, he is wasting his time at a Public School". Despite this, Turing continued to show remarkable ability in the studies he loved, solving advanced problems in 1927 without having even studied elementary calculus. In 1928, aged 16, Turing encountered Albert Einstein's work; not only did he grasp Einstein's arguments, but he extrapolated Einstein's questioning of Newton's laws of motion from a text in which this was never made explicit. Turing's hopes and ambitions at school were raised by the close friendship he developed with a slightly older fellow student, Christopher Morcom, who was Turing's first homosexual love interest. Morcom died suddenly only a few weeks into their last term at Sherborne, from complications of bovine tuberculosis, contracted after drinking infected cow's milk. Turing's religious faith was shattered and he became an atheist. He adopted the conviction that all phenomena, including the workings of the human brain, must be materialistic, but he still believed in the survival of the spirit after death.
After Sherborne, Turing went to study at King's College, Cambridge. He was an undergraduate there from 1931 to 1934, graduating with first class honours in Mathematics, and in 1935 he was elected a fellow at King's College on the strength of a dissertation on the central limit theorem. In his momentous paper "On Computable Numbers, with an Application to the Entscheidungsproblem", Turing reformulated Kurt Gödel's 1931 results on the limits of proof and computation, replacing Gödel's universal arithmetic-based formal language with his own arguments using theoretical constructs using his concept named the Turing machine, a formal device with a very simple set of operations. He proved that the Turing Machine would be capable of performing any conceivable mathematical computation, if it had infinite memory, and the task could be formulated as an algorithm. He went on to prove that there was no solution to Gödel's Entscheidungsproblem by first showing that the halting problem for Turing machines is undecidable: in general it is not possible to decide algorithmically whether the operation of a given Turing machine will ever halt. While his proof was published subsequent to Alonzo Church's equivalent proof using lambda calculus, Turing was unaware of Church's work at the time. Turing extended his ideas with the notion of the Universal Turing Machine, a machine that would be able to perform the tasks of any other machine. Turing machines are still used in the theory of computation to explore what tasks are computable, and which numbers are definable.
From September 1936 to July 1938 Turing spent most of his time at the Institute for Advanced Study, Princeton, New Jersey, USA studying under Alonzo Church. As well as his pure mathematical work, he studied cryptology and also built several stages of an electro-mechanical binary multiplier. In June 1938 he obtained his PhD from Princeton; his dissertation introduced the notion of relative computing, where Turing machines are augmented with so-called oracles, allowing a study of problems that cannot be solved by a Turing machine.
Back in Cambridge Umiversity, he attended lectures by Ludwig Wittgenstein about the foundations of mathematics. The two argued and disagreed, with Turing defending formalism and Wittgenstein arguing that mathematics does not discover any absolute truths but rather invents them.
From September 1938 Turing also started to work part-time with the Government Code and Cypher School (GCCS) at the Adelphi in London. He worked on the problem of the German Enigma machine, and collaborated with Dilly Knox, a senior GCCS codebreaker. On 4th September 1939, the day after the UK declared war on Germany, Turing reported to Bletchley Park, the wartime station of GCCS.
During World War 2 Turing was a main participant in the efforts to break German ciphers, based at Bletchley Park. Building on the cryptanalysis work carried out in Poland by Marian Rejewski, Jerzy Rózycki and Henryk Zygalski from Cipher Bureau before the war, he contributed several insights into breaking the ciphers of both the Enigma machine and the Lorenz SZ 40/42 (a Teleprinter cipher attachment codenamed Tunny by the British). For a time he was head of Hut 8, the section responsible for reading German naval signals. Turing had something of a reputation for eccentricity at Bletchley Park.
In the first week of June each year he would get a bad attack of hay fever, and he would cycle to the office wearing standard issue gas mask to filter out the pollen. His bicycle had a fault: the chain would come off at regular intervals. Instead of having it mended he would count the number of times the pedals went round and would get off the bicycle just in time to adjust the chain by hand. Instead of getting the bicycle repaired, he argued that a faulty bike would not be stolen. Another of his eccentricities is that he chained his mug to the radiator pipes, also to prevent it being stolen. Turing did not like talking to women, or indeed anybody less intelligent than himself.
He was also a long-distance runner, and while working at Bletchley Park occasionally ran the 64Km to London when he was needed for high-level meetings.
The Polish bomby
The Turing Bombe operated by a WRNS staff member at Bletchley Park
Reconstructed Turing Bombe
Menu wiring at the rear of the Turing Bombe
A typical menu put up at the back of a Turing Bombe to aid the wiring connections
A checking machine used to prove that the Enigma settings revealed by the stopping of a Turing Bombe had been correctly decrypted
Within weeks of arriving at Bletchley Park, Turing had specified an electromechanical machine which could help break the Enigma cipher faster than the Polish bomby of 1932. The Turing bombe was named after the original Polish-designed bomby and built upon its design, using an enhancement suggested by mathematician Gordon Welchman. This machine in multiple copies became the major automated tool used to attack Enigma-encrypted message traffic. The bombe searched for all possibly correct settings used for an Enigma message (i.e. rotor order, rotor settings, etc.), and used a suitable crib (a fragment of probable plaintext guessed at by the cryptanalists, e.g. weather forecasts, "Heil Hitler", etc.). For each possible setting of the rotors (which had of the order of 10^19 states, or 10^22 for the four-rotor U-boat variant), the bombe performed a chain of logical deductions based on the crib, implemented electrically. The bombe detected when a contradiction had occurred, and ruled out that setting, moving onto the next. Most of the possible settings would cause contradictions and be discarded, leaving only a few to be investigated in detail. When a possible encryption was found, the machine stopped, when the settings would be confirmed to give plaintext German. Turing's bombe was first installed on 18th March 1940, and more than two hundred bombes were in operation by the end of the war.
A typical perforated sheet manufactured in Banbury. Impossible combinations of Enigma settings were revealed by the holes in a sheet, and the decryption aid became known as Banburismus
Turing decided to tackle the particularly difficult problem of German naval Enigma "because no one else was doing anything about it and I could have it to myself". In December 1939, Turing solved the essential part of the naval indicator system, which was more complex than the indicator systems used by the other services. The same night that he solved the naval indicator system he conceived the idea of Banburismus, a sequential statistical technique using perforated sheets made at Banbury, to assist in the breaking of naval Enigma. He did this "though I was not sure that it would work in practice, and was not in fact sure until some days had actually broken". For this he invented a measure of weight of evidence that he called the Ban. Banburismus could rule out certain orders of the Enigma rotors, sbstantially reducing the time needed to test settings on the bombes.
A poster for the 2001 film Enigma. Kate Winslet may have been portraying Joan Clarke
In 1941 Turing proposed marriage to his Hut 8 co-worker Joan Elisabeth Lowther Clarke (1917 - 1996), a fellow mathematician, but their engagement was short-lived. After admitting his homosexuality to his fiancée, who was reportedly "unfazed" by the revelation, Turing decided that he could not go through with the marriage. After her move to GCHQ at the end of the war, Clarke met Lieutenant Colonel J (Jock) K.R. Murray, and they married in 1952.
In July 1942 Turing devised a technique termed Turingery (or jokingly Turingismus) for use in decrypting the Lorenz cipher messages produced by the Germans' new Geheimschreiber (secret writer) machine. This was codenamed Tunny at Bletchley Park. He also introduced the Tunny team to Tommy Flowers who under the guidance of Max Newman, went on to build the Colossus computer, the world's first programmable digital electronic computer, which replaced a simpler prior machine (the Heath Robinson) and whose superior speed allowed brute-force decryption techniques to be applied usefully to the daily changing cyphers. A frequent misconception is that Turing was a key figure in the design of Colossus, but this was not the case.
Turing travelled to the United States in November 1942, where he worked with U.S. Navy cryptanalysts on Naval Enigma and bombe construction in Washington, and assisted at Bell Labs with the development of secure speech devices. He returned to Bletchley Park in March 1943. In the latter part of the war he moved to work at Hanslope Park, where he further developed his knowledge of electronics with the assistance of engineer Donald Bailey. Together they undertook the design and construction of a portable secure voice communications machine codenamed Delilah. It lacked capability for use with long-distance radio transmissions, but in any case Delilah was completed too late to be used during the war. Turing also consulted with Bell Labs on the development of SIGSALY, a secure voice system that was used in the later years of the war.
The NPL ACE Pilot
In 1945, Turing was awarded the OBE for his wartime services, but his work remained secret for many years. From 1945 to 1947 he lived in Church Sreet, Hampton and worked at the National Physical Laboratory, where he helped with the design of the Automatic Computing Engine (ACE). He presented a paper on 19th February 1946 which presented the first detailed design of a stored-program computer. Although ACE was a feasible design, the secrecy surrounding the wartime work at Bletchley Park led to delays in starting the project and he became disillusioned with it. He also disagreed with his boss at NPL, Sir Charles Darwin, who made the statement "there will only be the need for five computers in the world, and of course the British computer will be at NPL". In late 1947 he returned to Cambridge for a sabbatical year. While he was at Cambridge, the ACE Pilot was built in his absence at NPL, and it executed its first program on 10th May 1950. The ACE was the basis of the later English Electric DEUCE and the Malvern MOSAIC.
The old campus at Manchester University
Turing programming the Manchester Mark I with two Ferranti engineers
In 1948 he was appointed Reader in the Mathematics Department at Manchester. In 1949 he became Deputy Director of the Computing Laboratory at the University of Manchester, and worked on software for the Manchester Mark 1. During this time he continued to do more abstract work, and in "Computing machinery and intelligence" (Mind, October 1950), Turing addressed the problem of artificial intelligence, and proposed an experiment now known as the Turing Test, an attempt to define a standard for a machine to be called "intelligent". The idea was that a computer could be said to "think" if it could fool an interrogator into thinking that the conversation was with a human. In the paper, Turing suggested that rather than building a program to simulate the adult mind, it would rather be better to produce a simpler one to simulate a child's mind and then to subject it to a course of education. A reversed form of the Turing Test is widely used on the Internet: the CAPTCHA test is intended to determine whether the user is a human or a computer. In 1948, working with his former undergraduate colleague, D. G. Champernowne, Turing began writing a chess program for a computer that did not yet exist. In 1952, lacking a computer powerful enough to execute the program, Turing played a game in which he simulated the computer, taking about half an hour per move. The game was recorded. The program lost to Turing's colleague Alick Glennie, although it is said that it won a game against Champernowne's wife.
His Turing test was a significant and characteristically provocative and remains a lasting contribution to the continuing debate about artificial intelligence.
Later Turing became interested in mathematical biology, and worked from 1952 until his death in 1954 on morphogenesis. He published a paper on the Chemical Basis of Morphogenesis in 1952, putting forth the Turing hypothesis of pattern formation. His central interest in the field was understanding Fibonacci phyllotaxis, the existence of Fibonacci numbers in plant structures. He used reaction–diffusion equations which are now central to the field of pattern formation, and predicted oscillating chemical reactions such as the Belousov–Zhabotinsky reaction, which were first observed in the 1960s. Later papers went unpublished until 1992 when the Collected Works of A.M. Turing was published. His contribution is now considered to be a seminal piece of work in this field.
In January 1952 Turing met Arnold Murray outside a cinema in Manchester. After a lunch date, Turing invited Murray to spend the weekend with him at his house, an invitation which Murray accepted, although he did not turn up. The pair met again in Manchester the following Monday, when Murray agreed to accompany Turing to Turing's house. A few weeks later Murray visited Turing's house again, and apparently spent the night there. After Murray helped an accomplice to break into his house, Turing reported the crime to the police. During the investigation, Turing acknowledged a sexual relationship with Murray. Homosexual acts were illegal in the United Kingdom at that time, and so both were charged with gross indecency under Section 11 of the Criminal Law Amendment Act 1885, the same crime for which Oscar Wilde had been convicted more than fifty years earlier. Turing was given a choice between imprisonment, or probation conditional on his agreement to undergo hormonal treatment designed to reduce libido. He accepted injections of the female hormone oestrogen. Turing's conviction led to the removal of his security clearance, and barred him from continuing with his cryptographic consultancy for GCHQ. At the time, there was acute public anxiety about spies and homosexual entrapment by Soviet agents, because of the recent exposure of the first two members of the Cambridge Five, Guy Burgess and Donald Maclean, as KGB double agents. As all persons who had worked at Bletchley Park had signed the Official Secrets Act, he was forbidden from discussing his war work.
On 8 June 1954, Turing's cleaner found him dead; he had died the previous day. A post-mortem examination established that the cause of death was cyanide poisoning. When his body was discovered an apple lay half-eaten beside his bed, and although the apple was not tested for cyanide, it is speculated that this was the means by which a fatal dose was delivered. An inquest determined that he had committed suicide. It is known that Turing was fascinated by a line from the 1937 film Snow White and the Seven Dwarfs, his favourite fairy tale, "dip the apple in the brew, let the sleeping death seep through". This was the tenth anniversary of D-Day, when his work at Bletchley Park had been so successful.
The blue plaque on Turing's home at Wilmslow in Cheshire
Street sign in Alan Turing Way, Manchester
Turing has been honoured by many Universities, and in various ways in Manchester, the city where he worked towards the end of his life. In 1994 a stretch of the A6010 road (the Manchester city intermediate ring road) was named Alan Turing Way. A bridge carrying this road was widened, and carries the name Alan Turing Bridge. In 1999 Time Magazine named Turing as one of the 100 Most Important People of the 20th Century for his role in the creation of the modern computer, and stated: "The fact remains that everyone who taps at a keyboard, and opens a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine."
The Alan Turing Memorial in Sackville Park, and close-up showing the Enigma cipher 5-letter groups and the fateful apple
Inscription on the plinth of the Alan Turing Memorial
A statue of Turing was unveiled in Manchester on 23rd June 2001 in Sackville Park, between the University of Manchester building on Whitworth Street and the Canal Street gay village. The memorial statue depicts the "father of Computer Science" sitting on a bench at a central position in the park. The statue was unveiled on Turing's birthday. Turing is shown holding an apple, a symbol classically used to represent forbidden love, the object that inspired Isaac Newton's theory of gravitation, and the means of Turing's own death. The cast bronze bench carries in relief the text "Alan Mathison Turing 1912–1954", and the motto "Founder of Computer Science" as it would appear if encoded by an Enigma machine: "IEKYF ROMSI ADXUO KVKZC GUBJ". A plinth at the statue's feet says "Father of computer science, mathematician, logician, wartime codebreaker, victim of prejudice". There is also a Bertrand Russell quotation saying "Mathematics, rightly viewed, possesses not only truth, but supreme beauty - a beauty cold and austere, like that of sculpture". The sculptor buried his old Amstrad computer under the plinth, as a tribute to "the godfather of all modern computers".
Slate statue of Alan Turing by Stephen Kettle, unveiled 19.06.2007 at Bletchley Park
In 2002 Turing was ranked twenty-first in the BBC nationwide poll of the 100 Greatest Britons. A 1.5-ton life-size statue of Turing was unveiled on 19th June 2007 at Bletchley Park. Built from approximately half a million pieces of Welsh slate, it was sculpted by Stephen Kettle, having been commissioned by the late American billionaire Sidney Frank.
On 10th September 2009, following an Internet campaign, Prime Minister Gordon Brown made an official public apology on behalf of the British government for the way in which Turing was treated after the war.
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The Staffordshire University Computing Futures Museum Manchester Page to Dr John
03 31 October 2010 updated by Dr John Wilcock