A Colossus Mark II computer. The slanted control panel on the left was used to set the pin patterns on the Lorenz; the paper tape transport is on the right.

The Colossus machines were early computing devices used by British codebreakers to read encrypted German messages during World War II. Colossus was an early binary electronic digital computer. Old photo of the Colossus computer Photo source: Public record office, London. ... Old photo of the Colossus computer Photo source: Public record office, London. ... Cryptanalysis (from the Greek kryptós, hidden, and analýein, to loosen or to untie) is the study of methods for obtaining the meaning of encrypted information without access to the secret information which is normally required to do so. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ... A BlueGene supercomputer cabinet. ...

Colossus was designed by engineer Tommy Flowers at the Post Office Research Station, Dollis Hill with input from mathematician Max Newman and group at Bletchley park. The prototype, Colossus Mark I, was shown working in December 1943 and was operational at Bletchley Park by February 1944. An improved Colossus Mark II was first installed in June 1944, and ten Colossi had been constructed by the end of the war. Thomas (Tommy) Harold Flowers, MBE (22 December 1905 – 28 October 1998) was a British engineer. ... The Post Office Research Station at Dollis Hill, London, was first established in 1921 and opened by the Prime Minister Ramsay MacDonald in 1933. ... Dollis Hill is an area of north-west London. ... Maxwell Herman Alexander Newman (February 7, 1897 – February 22, 1984) was a British mathematician. ... During World War II, codebreakers at Bletchley Park solved messages from a large number of Axis code and cipher systems, including the German Enigma machine. ...

The Colossus computers were used to help decipher teleprinter messages which had been encrypted using the Lorenz SZ40/42 machine. Colossus compared two data streams, counting each match based on a programmable boolean function. The encrypted message was read at high speed from a paper tape. The other stream was generated internally, and was an electronic simulation of the Lorenz machine at various trial settings. If the match count for a setting was above a certain threshold, it would be output on an electric typewriter. Teletype machines in World War II A teleprinter (teletypewriter, teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ... This article is about algorithms for encryption and decryption. ... The Lorenz machine was used to encrypt high-level German military communications during World War II. British cryptographers at Bletchley Park were able to break the cipher. ... The adjective Boolean, coined in honor of George Boole, is used in many contexts: An evaluation that results in either of the truth values true or false. A Boolean value is a truth value, either true or false, often coded 1 and 0, respectively. ...

Purpose and origins

The Lorenz machine was used by the Germans to encrypt high-level teleprinter communications. It contained 12 wheels with a total of 501 pins.

The Colossus computers were used in the cryptanalysis of high-level German communications, messages which had been encrypted using the Lorenz SZ 40/42 cipher machine; part of the operation of Colossus was to emulate the mechanical Lorenz machine electronically. To encrypt a message with the Lorenz machine, the plaintext was combined with a stream of key bits, grouped in fives. The key stream was generated using twelve pinwheels: five were termed (by the British) χ ("chi") wheels, another five ψ ("psi") wheels, and the remaining two the "motor wheels". The χ wheels stepped regularly with each letter that was encrypted, while the ψ wheels stepped irregularly, controlled by the motor wheels. Image File history File linksMetadata Download high resolution version (2304x1728, 1837 KB) Lightened version of Image:SZ42-6-wheels. ... Image File history File linksMetadata Download high resolution version (2304x1728, 1837 KB) Lightened version of Image:SZ42-6-wheels. ... Cryptanalysis (from the Greek kryptós, hidden, and analýein, to loosen or to untie) is the study of methods for obtaining the meaning of encrypted information, without access to the secret information which is normally required to do so. ... The Lorenz machine was used to encrypt high-level German military communications during World War II. British cryptographers at Bletchley Park were able to break the cipher. ... In cryptography, plaintext is information used as input to an encryption algorithm; the output is termed ciphertext. ... This article is about the unit of information. ... The German Lorenz cipher machine contained 12 pinwheels, with a total of 501 pins . In cryptography, a pinwheel was a device for producing a short pseudorandom sequence of bits (determined by the machines initial settings), as a component in a cipher machine. ... Chi (upper case Χ, lower case χ) is the 22nd letter of the Greek alphabet. ... Look up Ψ, ψ in Wiktionary, the free dictionary. ...

Bill Tutte, a cryptanalyst at Bletchley Park, discovered that the keystream produced by the machine exhibited statistical biases deviating from random, and that these biases could be used to break the cipher and read messages. In order to read messages, there were two tasks that needed to be performed. The first task was wheel breaking, which was discovering the pin patterns for all the wheels. These patterns were set up once on the Lorenz machine and then used for a fixed period of time and for a number of different messages. The second task was wheel setting, which could be attempted once the pin patterns were known. Each message encrypted using Lorenz was enciphered at a different start position for the wheels. The process of wheel setting found the start position for a message. Initially Colossus was used to help with wheel setting, but later it was found it could also be adapted to the process of wheel breaking as well. William Thomas Tutte (May 14, 1917 - May 2, 2002) was a British codebreaker and mathematician. ... During World War II, codebreakers at Bletchley Park solved messages from a large number of Axis code and cipher systems, including the German Enigma machine. ...

Colossus was operated in the Newmanry, the section at Bletchley Park responsible for machine methods against the Lorenz machine, headed by the mathematician Max Newman. The Newmanry was a section at Bletchley Park, the British codebreaking station during World War II. Its job was to develop and employ machine methods to help break a German teleprinter cipher machine known as Tunny on the British side, or as the Lorenz SZ 40/42 on the German... Maxwell Herman Alexander Newman (February 7, 1897 – February 22, 1984) was a British mathematician. ...

Colossus was developed out of a prior project which produced a special purpose opto-mechanical comparator machine called "Heath Robinson". The main problem with Robinson was synchronising two paper tapes, one punched with the enciphered message, the other representing the patterns produced by the wheels of the Lorenz machine, that tended to stretch when being read at over 1000 characters per second, resulting in unreliable counts. Colossus solved this problem by reproducing one of the tapes electronically. The remaining single tape could be fed through Colossus at a higher speed and could be counted much more reliably. Heath Robinson was a machine used by British codebreakers at Bletchley Park during World War II to solve messages in a German teleprinter cipher, the Lorenz SZ40/42. ... A roll of punched tape Punched tape is an old-fashioned form of data storage, consisting of a long strip of paper in which holes are punched to store data. ...

The construction of Colossus

A team headed by Tommy Flowers spent eleven months (early February 1943 to early January 1944) designing and building Colossus at the Post Office Research Station, Dollis Hill, in northwest London. After a functional test in December 1943, Colossus was dismantled and shipped north to Bletchley Park, where it was delivered on 18 January 1944, and attacked its first message on 5 February.^[1] Thomas (Tommy) Harold Flowers, MBE (22 December 1905 – 28 October 1998) was a British engineer. ... The Post Office Research Station at Dollis Hill, London, was first established in 1921 and opened by the Prime Minister Ramsay MacDonald in 1933. ... Dollis Hill is an area of north-west London. ... 1943 (MCMXLIII) was a common year starting on Friday (the link is to a full 1943 calendar). ... January 18 is the 18th day of the year in the Gregorian calendar. ... 1944 (MCMXLIV) was a leap year starting on Saturday. ... February 5 is the 36th day of the year in the Gregorian Calendar. ...

The Mark I was followed by nine Mark 2 Colossus machines, the first being installed in June 1944, and the original Mark I machine was converted into a Mark 2. An eleventh Colossus was essentially finished at the end of the war. Colossus Mark 1 contained 1,500 electronic valves. Colossus Mark 2 with 2,400 valves was both 5 times faster and simpler to operate than Mark 1 and so greatly speeded the decoding process. Mark 2 was designed while Mark 1 was being constructed. For comparison, later stored-program computers like ENIAC in 1946 used 17,468 valves and the Manchester Mark I of 1949 used about 4,200. ENIAC ENIAC, short for Electronic Numerical Integrator and Computer,[1] was the first large-scale, electronic, digital computer capable of being reprogrammed to solve a full range of computing problems,[2] although earlier computers had been built with some of these properties. ... 1946 (MCMXLVI) was a common year starting on Tuesday. ... Manchester Mark 1 was the worlds first stored program computer, which made its first successful run of a program on 21st June 1948 The Manchester Mark I was one of the earliest electronic computers, built at the University of Manchester in England, in 1949. ... 1949 (MCMXLIX) was a common year starting on Saturday (the link is to a full 1949 calendar). ...

Colossus dispensed with the second tape of the Heath Robinson design by generating the wheel patterns electronically, and processing 5,000 characters per second with the paper tape moving at 40 ft/s = 12 m/s = 30 mph. The circuits were synchronized by a clock signal generated by the punched tape. The speed of calculation was thus limited by the mechanics of the tape reader. Designer Tommy Flowers tested the tape reader up to 9700 character/s (60 mph) before the tape disintegrated. He settled on 5000 characters/second as the desirable speed for regular operation. Sometimes, two or more Colossus computers tried different possibilities simultaneously in what now is called parallel computing, greatly speeding the decoding process. In synchronous digital electronics, such as most computers, a clock signal is a signal used to coordinate the actions of two or more circuits. ... Thomas (Tommy) Harold Flowers, MBE (22 December 1905 – 28 October 1998) was a British engineer. ... Parallel computing is the simultaneous execution of the same task (split up and specially adapted) on multiple processors in order to obtain results faster. ...

Colossus included the first ever use of shift registers and systolic arrays, enabling five simultaneous tests, each involving up to 100 Boolean calculations, on each of the five channels on the punched tape (although in normal operation only one or two channels were examined in any run). In digital circuits a shift register is a group of registers set up in a linear fashion which have their inputs and outputs connected together in such a way that the data is shifted down the line when the circuit is activated. ... To meet Wikipedias quality standards, this article may require cleanup. ... In abstract algebra, a Boolean algebra is an algebraic structure (a collection of elements and operations on them obeying defining axioms) that captures essential properties of both set operations and logic operations. ...

Initially Colossus was only used to determine the initial wheel positions used for a particular message (termed wheel setting). The Mark 2 included mechanisms intended to help determine pin patterns (wheel breaking). Both models were programmable using switches and plug panels in a way the Robinsons had not been.

Design and operation

In 1994, a team led by Tony Sale began a reconstruction of a Colossus.

Colossus used state-of-the-art vacuum tubes (thermionic valves), thyratrons and photomultipliers to optically read a paper tape and then applied a programmable logical function to every character, counting how often this function returned "true". Although machines with many valves were known to have high failure rates, it was recognised that valve failures occurred most frequently with the current surge at power on, so the Colossus machines, once turned on, were never powered down unless they malfunctioned. Download high resolution version (1200x1600, 445 KB)A rebuild of a Colossus Mk II by Tony Sale and team, located at Bletchley Park museum. ... Download high resolution version (1200x1600, 445 KB)A rebuild of a Colossus Mk II by Tony Sale and team, located at Bletchley Park museum. ... In electronics, a vacuum tube or (outside North America) thermionic valve or just valve, is a device generally used to amplify, switch or otherwise modify, a signal by controlling the movement of electrons in an evacuated space. ... In electronics, a vacuum tube or (outside North America) thermionic valve or just valve, is a device generally used to amplify, switch or otherwise modify, a signal by controlling the movement of electrons in an evacuated space. ... A thyratron is a type of gas filled tube used as a high energy electrical switch. ... Photomultipliers, or photomultiplier tubes (PMT) are extremely sensitive detectors of light in the ultraviolet, visible and near infrared. ...

Colossus was the first of the electronic digital machines to feature limited programmability. However, it was not a fully general purpose computer, not being Turing-complete, even though Alan Turing on whose research this definition was based, worked at Bletchley Park where Colossus was put into operation. It was not then realized that Turing-completeness was significant; most of the other pioneering modern computing machines were not either (e.g. the Atanasoff-Berry Computer, the Harvard Mark I electro-mechanical relay machine, the Bell Labs relay machines (by George Stibitz et al), Konrad Zuse's first two designs, and so on). The notion of a computer as a general purpose machine, and not simply a massive calculator devoted to solving difficult but single-minded problems, did not become prominent until a few years later. In computability theory a programming language or any other logical system is called Turing-complete if it has a computational power equivalent to a universal Turing machine. ... Alan Mathison Turing, OBE (June 23, 1912 – June 7, 1954), was an English mathematician, logician, and cryptographer. ... During World War II, codebreakers at Bletchley Park solved messages from a large number of Axis code and cipher systems, including the German Enigma machine. ... Atanasoff-Berry Computer replica at 1st floor of Durham Center, Iowa State University electronic digital computing device[1]. The machine, conceived in 1937, was capable of solving up to 29 simultaneous linear equations and was successfully tested, though its input/output mechanism was still unreliable in 1942 when its inventors... Portion of the Harvard-IBM Mark 1, left side. ... Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. ... Konrad Zuse (1992) Statue in Bad Hersfeld Konrad Zuse (June 22, 1910 – December 18, 1995) was a German engineer and computer pioneer. ... A calculator is a device for performing calculations. ...

Colossus was preceded by several computers, many of them first in some category. Zuse's Z3 was the first functional fully program-controlled computer, and was based on electromechanical relays, as were the (less advanced) Bell Labs machines of the late 1930s (George Stibitz, et al). The ABC Computer was electronic and binary (digital) but not programmable. Assorted analog computers were semiprogrammable; some of these much predated the 1930s (eg, Vannevar Bush). Babbage's Analytical engine antedated all these (in the mid-1800s), and was both digital and programmable, but was only partially constructed and never functioned at the time (a replica of his Difference engine No. 2, built in 1991, does work, however). Colossus was the first combining digital, (partially) programmable, and electronic. Konrad Zuse (1992) Statue in Bad Hersfeld Konrad Zuse (June 22, 1910 – December 18, 1995) was a German engineer and computer pioneer. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... A BlueGene supercomputer cabinet. ... Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. ... George Stibitz George Stibitz (April 20, 1904 – January 31, 1995) is internationally recognized as the father of the modern digital computer. ... The Atanasoff-Berry Computer was the first electronic digital computer [1]. It was built by Dr. John Vincent Atanasoff and Clifford E. Berry at Iowa State University during 1937-42. ... A page from the Bombardiers Information File (BIF) that describes the components and controls of the Norden bombsight. ... Vannevar Bush (March 11, 1890 – June 30, 1974) was an American engineer and science administrator, known for his political role in the development of the atomic bomb, and the idea of the memex—seen as a pioneering concept for the World Wide Web. ... The analytical engine, an important step in the history of computers, is the design of a mechanical modern general-purpose computer by the British professor of mathematics Charles Babbage. ... Part of Babbages Difference engine, assembled after his death by Babbages son, using parts found in his laboratory. ...

The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ... // Electronics is the study of electron mechanics. ... A computer program is a collection of instructions that describe a task, or set of tasks, to be carried out by a computer. ... In computability theory, an abstract machine or programming language is called Turing complete, Turing equivalent, or (computationally) universal if it has a computational power equivalent to a universal Turing machine (a simplified model of a programmable computer). ... Konrad Zuse (1992) Statue in Bad Hersfeld Konrad Zuse (June 22, 1910 – December 18, 1995) was a German engineer and computer pioneer. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... Film stock is the term for photographic film on which films are recorded. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... Atanasoff-Berry Computer replica at 1st floor of Durham Center, Iowa State University electronic digital computing device[1]. The machine, conceived in 1937, was capable of solving up to 29 simultaneous linear equations and was successfully tested, though its input/output mechanism was still unreliable in 1942 when its inventors... Portion of the Harvard-IBM Mark 1, left side. ... ENIAC ENIAC, short for Electronic Numerical Integrator and Computer,[1] was the first large-scale, electronic, digital computer capable of being reprogrammed to solve a full range of computing problems,[2] although earlier computers had been built with some of these properties. ... Read-only memory (often referred to as its acronym ROM) is a class of storage media used in computers and other electronic devices. ...

Influence and fate

The use to which the Colossi were put was of the highest secrecy, and the Colossus itself was highly secret, and remained so for many years after the War. Thus, Colossus could not be included in the history of computing hardware for many years, and Flowers and his associates also were deprived of the recognition they were due. Computing hardware has been an important component of the process of calculation and data storage since it became useful for numerical values to be processed and shared. ...

Being not widely known, it therefore had little direct influence on the development of later computers; EDVAC was the early design which had the most influence on subsequent computer architecture. The EDVAC as installed in Building 328 at the Ballistics Research Laboratory. ...

However, the technology of Colossus, and the knowledge that reliable high-speed electronic digital computing devices were feasible, had a significant influence on the development of early computers in Britain. A number of people who were associated with the project and knew all about Colossus played significant roles in early computer work in Britain. In 1972, Herman Goldstine wrote that: 1972 (MCMLXXII) was a leap year starting on Saturday. ... Herman Heine Goldstine (September 13, 1913 – June 16, 2004) was one of the original developers of ENIAC. He worked closely with John von Neumann. ...

"Britain had such vitality that it could immediately after the war embark on so many well-conceived and well-executed projects in the computer field".^[2]

In writing that, Goldstine was unaware of Colossus, and its legacy to those projects of people such as Alan Turing (with the Pilot ACE and ACE), and Max Newman and I. J. Good (with the Manchester Mark I and other early Manchester computers). Brian Randell later wrote that: Alan Mathison Turing, OBE (June 23, 1912 – June 7, 1954), was an English mathematician, logician, and cryptographer. ... The Pilot ACE was one of the first computers built in the United Kingdom, at the National Physical Laboratory (NPL) in the late 1940s. ... The ACE (Automatic Computing Engine) was the first computer designed in Britain; it was designed by Alan Turing in 1946. ... Irving John (Jack) Good (born 9 December 1916) is a British statistician who worked also as a cryptographer and developer of the Colossus computer at Bletchley Park. ... Manchester Mark 1 was the worlds first stored program computer, which made its first successful run of a program on 21st June 1948 The Manchester Mark I was one of the earliest electronic computers, built at the University of Manchester in England, in 1949. ... Brian Randell is a computer scientist, specializing in research in software fault tolerance and dependability. ...

"the COLOSSUS project was an important source of this vitality, one that has been largely unappreciated, as has the significance of its places in the chronology of the invention of the digital computer".^[3]

Colossus documentation and hardware were classified from the moment of their creation and remained so after the War, when Winston Churchill specifically ordered the destruction of most of the Colossus machines into 'pieces no bigger than a man's hand'; Tommy Flowers personally burned blueprints in a furnace at Dollis Hill. Some parts, sanitised as to their original use, were taken to Newman's Computing Machine Laboratory at Manchester University. The Colossus Mark I was dismantled and parts returned to the Post Office. Two Colossus computers, along with two replica Tunny machines, were retained, moving to GCHQ's new headquarters at Eastcote in April 1946, and moving again with GCHQ to Cheltenham between 1952 and 1954.^[4] One of the Colossi, known as Colossus Blue, was dismantled in 1959; the other in 1960.^[4] In their later years, the Colossi were used for training, but before that, there had been attempts to adapt them, with varying success, to other purposes.^[5] Jack Good relates how he was the first to use it after the war, persuading the NSA that Colossus could be used to perform a function for which they were planning to build a special purpose machine.^[4] Colossus was also used to perform character counts on one-time pad tape to ensure their randomness.^[4] A typical classified document. ... Churchill redirects here. ... University of Manchester Motto: Cognitio Sapientia Hvmanitas Knowledge, wisdom, humanity. ... The Government Communications Headquarters (GCHQ) (previously named the Government Code and Cipher School (GC&CS)) is the main British intelligence service providing signals intelligence (SIGINT). ... Eastcote is a place in the London Borough of Hillingdon. ... For the parliamentary constituency, see Cheltenham (UK Parliament constituency). ... NSA can stand for: National Security Agency of the USA The British Librarys National Sound Archive This page concerning a three-letter acronym or abbreviation is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

Information about Colossus began to emerge publicly in the late 1970s, after the secrecy imposed by the Official Secrets Act ended in 1976. More recently, a 500-page technical report on the Tunny cipher and its cryptanalysis – entitled General Report on Tunny – was released by GCHQ to the national Public Record Office in October 2000; the complete report is available online,^[6] and it contains a fascinating paean to Colossus by the cryptographers who worked with it: Template:A year The 1970s decade refers to the years from 1970 to 1979, inclusive. ... Official Secrets Act warning sign, Foulness. ... 1976 (MCMLXXVI) was a leap year starting on Thursday. ... The Government Communications Headquarters (GCHQ) (previously named the Government Code and Cipher School (GC&CS)) is the main British intelligence service providing signals intelligence (SIGINT). ... The Kew building. ... 2000 (MM) was a leap year starting on Saturday of the Gregorian calendar. ...

It is regretted that it is not possible to give an adequate idea of the fascination of a Colossus at work; its sheer bulk and apparent complexity; the fantastic speed of thin paper tape round the glittering pulleys; the childish pleasure of not-not, span, print main header and other gadgets; the wizardry of purely mechanical decoding letter by letter (one novice thought she was being hoaxed); the uncanny action of the typewriter in printing the correct scores without and beyond human aid; the stepping of the display; periods of eager expectation culminating in the sudden appearance of the longed-for score; and the strange rhythms characterizing every type of run: the stately break-in, the erratic short run, the regularity of wheel-breaking, the stolid rectangle interrupted by the wild leaps of the carriage-return, the frantic chatter of a motor run, even the ludicrous frenzy of hosts of bogus scores.^[7]

Reconstruction

A construction of a replica of a Colossus Mark II has been undertaken by a team led by Tony Sale. The reconstruction is on display in the Bletchley Park Museum in Milton Keynes, Buckinghamshire. During World War II, codebreakers at Bletchley Park solved messages from a large number of Axis code and cipher systems, including the German Enigma machine. ... Milton Keynes is a large town in northern Buckinghamshire, in South East England, about 45 miles/75 km north-west of London, and roughly halfway between London and Birmingham. ... Buckinghamshire (abbreviated Bucks) is one of the home counties in South East England. ...

See also

• History of computing hardware
• Z3
• Supercomputer

Computing hardware has been an important component of the process of calculation and data storage since it became useful for numerical values to be processed and shared. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... A supercomputer is a computer that leads the world in terms of processing capacity, particularly speed of calculation, at the time of its introduction. ...

Footnotes

1. ^ Jack Copeland, "Machine against Machine", p. 75 (entire article pp. 64-77) in B. Jack Copeland, ed., Colossus: The Secrets of Bletchley Park's Codebreaking Computers, Oxford University Press, 2006
2. ^ The Computer from Pascal to von Neuman (pp. 321)
3. ^ The COLOSSUS, pp. 87
4. ^ ^{a b c d} Copeland, 2006, p. 173-175
5. ^ Horwood, 1973
6. ^ Jack Good; Donald Michie, and Geoffrey Timms (1945). General Report on Tunny.
7. ^ http://www.alanturing.net/turing_archive/archive/t/t17/TR17-003.html.

References

• W. W. Chandler, The Installation and Maintenance of Colossus (IEEE Annals of the History of Computing, Vol. 5 (No. 3), 1983, pp. 260–262)
• Allen W. M. Coombs, The Making of Colossus (Annals of the History of Computing, Vol. 5 (No. 3), 1983, pp.253-259)
• Jack Copeland, Colossus: Its Origins and Originators (IEEE Annals of the History of Computing, 26(4), October–December 2004, pp. 38–45).
• Jack Copeland, Colossus and the Dawning of the Computer Age, in Action This Day, 2001, ISBN 0-593-04982-9.
• B. Jack Copeland (editor), Colossus: The Secrets of Bletchley Park's Codebreaking Computers, 2006, Oxford University Press, ISBN 0-19-284055-X.
• I. J. Good, Early Work on Computers at Bletchley (IEEE Annals of the History of Computing, Vol. 1 (No. 1), 1979, pp. 38–48)
• I. J. Good, Pioneering Work on Computers at Bletchley (in Nicholas Metropolis, J. Howlett, Gian-Carlo Rota, (editors), A History of Computing in the Twentieth Century, Academic Press, New York, 1980)
• T. H. Flowers, The Design of Colossus (Annals of the History of Computing, Vol. 5 (No. 3), 1983, pp. 239–252)
• D C Horwood, A technical description of COLOSSUS I, August 1973, PRO HW 25/24.
• Brian Randell, Colossus: Godfather of the Computer, 1977 (reprinted in The Origins of Digital Computers: Selected Papers, Springer-Verlag, New York, 1982)
• Brian Randell, The COLOSSUS (in A History of Computing in the Twentieth Century)
• Albert W. Small, The Special Fish Report (December, 1944) describe the operation of Colossus to break Tunny messages

This article needs to be cleaned up to conform to a higher standard of quality. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Oxford University Press (OUP) is a highly-respected publishing house and a department of the University of Oxford in England. ... Irving John (Jack) Good (born 9 December 1916) is a British statistician who worked also as a cryptographer and developer of the Colossus computer at Bletchley Park. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Irving John (Jack) Good (born 9 December 1916) is a British statistician who worked also as a cryptographer and developer of the Colossus computer at Bletchley Park. ... Thomas (Tommy) Harold Flowers, MBE (22 December 1905 – 28 October 1998) was a British engineer. ... Brian Randell is a computer scientist, specializing in research in software fault tolerance and dependability. ... Springer Science+Business Media or Springer (IPA: ) is a worldwide publishing company based in Germany which focuses on academic journals and books in the fields of science, technology, mathematics, and medicine. ... Brian Randell is a computer scientist, specializing in research in software fault tolerance and dependability. ...

Further reading

• Harvey G. Cragon, From Fish to Colossus: How the German Lorenz Cipher was Broken at Bletchley Park (Cragon Books, Dallas, 2003; ISBN 0-9743045-0-6) – A detailed description of the cryptanalysis of Tunny, and some details of Colossus (contains some minor errors)
• Ted Enever, Britain's Best Kept Secret: Ultra's Base at Bletchley Park (Sutton Publishing, Gloucestershire, 1999; ISBN 0-7509-2355-5) – A guided tour of the history and geography of the Park, written by one of the founder members of the Bletchley Park Trust
• Tony Sale, The Colossus Computer 1943–1996: How It Helped to Break the German Lorenz Cipher in WWII (M.&M. Baldwin, Kidderminster, 2004; ISBN 0-947712-36-4) – A slender (20 page) booklet, containing the same material as Tony Sale's website (see below)
• Michael Smith, Station X, 1998. ISBN 0-330-41929-3.
• Paul Gannon, "Colossus Bletchley Park's Greatest Secret" 2006 Atlantic Books; ISBN 1-84354-330-3.
• Jack Copeland: Colossus. The Secrets of Bletchley Park's Codebreaking Computers. Oxford University Press 2006. ISBN 0-19-284055-X

Other meanings

There was a fictional computer named Colossus in the movie Colossus: The Forbin Project. Also see List of fictional computers. Colossus was a fictional computer featured in the 1969 apocalyptic science fiction movie, Colossus: The Forbin Project loosely based on the 1967 novel Colossus by Dennis Feltham Jones. ... This page is intended to be a list of computers in fiction and science fiction. ...

External links

• Tony Sale's Codes and Ciphers Contains a great deal of information, including:
  • Colossus, the revolution in code breaking
  • Lorenz Cipher and the Colossus
    • The machine age comes to Fish codebreaking
    • The Colossus Rebuild Project
    • The Colossus Rebuild Project: Evolving to the Colossus Mk 2
    • Walk around Colossus A detailed tour of the replica Colossus – make sure to click on the "More Text" links on each image to see the informative detailed text about that part of Colossus
  • IEEE lecture – Transcript of a lecture Tony Sale gave describing the reconstruction project
• BBC news article reporting on the replica Colossus
• Was the Manchester Baby conceived at Bletchley Park?