Colossus Computer Facts That Will Leave You Completely Speechless

Colossus was a first-generation computer that was discontinued in 1960.

Colossus was a fictional computer in the movie 'Colossus: The Forbin Project' in 1970. This was based on a novel of the same name by D. F. Jones in 1966, a coincidence, as this release pre-dates the release of Colossus computers' information.

Colossus was the name given to a set of computers that the British codebreakers developed between 1943-1945. Colossus was built to assist with the cryptanalysis of the Lorenz cipher.

Thermionic valves, or vacuum tubes, were used in Colossus to perform counting and binary operations.

It is regarded as the first electronic, programmable, and digital computer in the world, although plugs and switches programmed it and not stored programs. Tommy Flowers, the research telephone engineer of General Post Office (GPO), designed Colossus.

He created this machine for solving a problem presented by Max Newman, a mathematician at the Bletchley Park, in Government Code and Cypher School.

The use of probability by Alan Turing in cryptanalysis also inspired this design. It has been inaccurately declared that Turing designed this computer to help with Enigma's cryptanalysis.

However, Turing's machine was an electromechanical Bombe that helped decode Enigma and not Colossus. Colossus Mark 1 prototype was displayed in the working condition in 1943, and by early 1944, it was in use at Bletchley Park.

The Colossus Mark 2, an improved machine that made use of shift registers to increase the processing speed, worked on June 1, 1944, just around the time for the Normandy landings on D-Day.

With 10 Colossus computers being used by the end of the war, an 11th digital computer was being commissioned. The use of these machines at the Bletchley Park allowed the Allies to gain a lot of high-level military intelligence.

The History of Colossus Computer

The history of Colossus computers is that Colossus was first among the electronic digital machines that could contain machines, albeit limited as per modern terms.

This computer was used during World War II to decipher messages sent between German army field commanders and German High Command. Decoding these messages allowed the Allies to win this war.

Max Newman, was a codebreaker working at Bletchley Park in Government Code and Cypher School. He wanted to find a machine that would help decode the messages from German-coded radio teleprinter to ordinary language.

Tommy Flowers led several Post Office telephone engineers who worked out a way for it. Their design was then known as Colossus and made use of several vacuum tubes or valves. Colossus Mark I started working in December 1943, solving its first problem in 1944.

It had 1,500 electronic valves; Colossus Mark II, the next version, was even better. By the end of the war, there were 10 Colossus computers.

The teleprinter messages were called 'fish' by the British codebreakers. An unknown German machine coded these messages.

These coded messages and the machine was called 'Tunny'. The Colossus computer imitated this electronic machine, reading the codes from a punched tape. A variety of possibilities were tried to figure out the two-wheel settings.

When Colossus found possible wheel settings, the codebreaker designed additional programs for the Colossus computer unit, wheel patterns of the other wheel were found. Not all the decoding processes were performed, but Colossus electronic computer found the possible settings of the unseen machine. Colossus's output was also worked upon by German language specialists.

The British codebreakers found out the code machine after the war was over, Lorenz SZ42. Currently, the working copy of the rebuilt Colossus computer is placed in the National Museum of Computing located in Bletchley Park, England.

Constant radio transmissions of Tunny codes started in June 1941. The British codebreakers recognized the five-unit code that it used similar to a teleprinter system.

Further research displayed that a rotor cipher machine that had 12 wheels or rotors did the coding. For every new message or code, wheels must first be moved to new positions. The operator sending the message chose the starting position of a message.

The operator was told who had to receive the message and the start position using 12 non-coded letters. The possible number of these 12 wheels' start position was a lot.

Purpose and Origins

The purpose and origins of Colossus computers were to decipher messages that were encrypted by the Lorenz machine.

To generate the coded message or ciphertext, the coding machine combined the un-coded message or plaintext and keystream, a stream of random characters. This ciphertext would then be transmitted by radio.

An identical digital computer would receive this message that would remove the keystream producing the plaintext. Two messages would never have the same start position of the wheels if the German operators worked correctly all the time.

However, some loopholes helped the British codebreakers. On August 30 in 1941, there were two interpretations of the same message that was almost 4,000 characters long, which were transmitted with the same start positions of the wheel setting.

John Tiltman, a codebreaker, got the keystream from the two messages. Although codebreakers tried to get the details of this machine, they failed at first.

Bill Tutte, a young codebreaker was assigned this job and he succeeded after a lot of work. He gave a logical description of this unseen machine.

Then Tutte worked out that the machine created each keystream by combining five wheels' effects of two sets. He made use of Greek letters to name these wheels.

One set of five wheels was called 'chi' wheels and the other five as 'psi' wheels. He found that for every new character coded, the chi wheels moved to one position.

While the psi wheels did move as regularly as chi wheels and moved only few times. The movement of psi wheels was controlled by two wheels called motor or 'mu' wheels.

A codebreaker and mathematician at Bletchley Park, Max Newman, was assigned the job to find out how machines worked to break these Tunny messages. The machine would calculate for many likely start positions of the wheels. The largest count given by a start position in this calculation was probably correct.

The first machine was named 'Heath Robinson' and did not work really well. Two punched paper tapes had to work together.

One paper tape had continuously looped ciphertext. The other paper tape had wheel patterns made by a coding machine. These tapes would either stretch or break while going at 2000 characters per second.

Tommy Flowers worked in northwest London at the Post Office Research Station, Dollis Hill. When he was asked to take a look at the Heath Robinson machine, Flowers thought it was weak.

He went on to design an electronic machine that did the same work. The machine would make coding machine patterns by electronic but only using one paper tape. He showed his design to Max Newman in February 1943.

The machine needed 1500 vacuum tubes or thermionic valves. Tommy Flowers and his Colossus team started working on the Colossus project in February of 1943.

The message on the tape had to be read at a particular speed. Flowers was able to test the tape reader at speed of 53 mph (85 kph) up to 9,700 letters per second after which the tape broke. He then selected 5,000 characters per second for good work.

At this character count, the paper tape moved at 27.3 mph (43.9 kph). A single drove the electronic circuits, made from reading the punched tape's sprocket holes.

Design And Use

Colossus was the first digital electronic computer designed for cryptanalysis in World War II.

In December 1943, the first Colossus digital computer started at Dollis Hill. Then they took apart the Colossus machine and transported it to Bletchley Park, which reached there on January 18, 1944. Don Horwood and Harry Fensom reconstructed the completed machine.

It read its first message on February 5. After Mark 1, there were nine Mark 2 digital computers. On June 1, 1944, Colossus Mark 2 first worked.

Colossus was first only used for finding the starting position of the wheel or wheel setting for a message. Codebreakers found a way in which the Mark 2 would find the cam patterns on wheels. There were 10 Colossus computers at Bletchley Park by the end of the war.

Colossus machines made use of parts that were quite new in 1944. The machines used photomultipliers, vacuum tubes, and thyratrons.

Machines that contained several vacuum tubes were known to break. They mostly break while turning it on, Colossus machines were turned off only when a part broke.

Although Colossus digital computers were the first ones to have a program, they did not change a lot like later computers. The program was not inbuilt and a person had to use switches, plugs, and wires to change the program. Also, these fantastic machines were not for general purposes.

They performed only one kind of code-breaking, Boolean operations, and counting. It took a long time for computers to be used for many other purposes.

Colossus computers were under curtains during the war and many years after it. This is the reason for the exclusion of Colossus from the history of computing hardware for many years.

As not a lot of people knew about the design of Colossus, it had little impact on the designs of later computers. The early design of EDVAC had the most impact on later computer designs.

After the Colossus was built, a few people got to know that high-speed electronic digital computing devices can now be constructed that did not break a lot. Only this information was enough to impact the early computer designs in Britain and likely in the United States.

The destruction of most of Colossus was ordered by Winston Churchill. Then, Flowers burned the Colossus at Dollis Hill.

The parts of Colossus Mark 1 that were taken apart were sent to the Post Office. Two copied Tunny machines and two Colossus computers were kept.

The Ultra Secret by Colonel Winterbotham came out in 1975, which broke the secrecy about the Colossus. Later in the '70s, details of Colossus were made public.

Origin Of The Name

The name Colossus comes from antiquity and these computers were very large, so they were named Colossus.

For almost 32 years the existence of Colossus was not known to many people, because those codes were still in use by the security services in Britain, as per B. Jack Copeland, a Bletchley Park historian. The Bletchley Park Colossus team also helped to keep this secret for many years.

Ken Myers was also a part of this team and he waited until the late 1970s to share his story of contribution to his wife.

Only in October 1975, the British Government releases Colossus' photographs.

Colossus was a huge machine, taking up an entire room, which is why it was named 'Colossus'. There were over 500 people who worked on 10 Colossus computers, deciphering around 63 million characters of German messages by end of the war.

Tony Sale and his team built working Colossus Mark 2. Although machines and plans were destroyed, a lot of materials were not destroyed.

It was mainly in the notebooks of engineers and a lot of it was in the United States. The redesigning optical tape reader might have been a hard task, but its designer, Dr. Arnold Lynch was able to design it again from his first writings.

This rebuilt Colossus computer is in H Block Bletchley Park at the National Museum of Computing, Milton Keynes in Buckinghamshire. This is where the ninth Colossus was used during the war.

To mark the start of fundraising for the National Museum of Computing and to celebrate the end of work, there was a competition called Cipher challenge held in November 2007. This was a challenge for the rebuilt Colossus and radio amateurs around the world.

Joachim Schueth easily won this challenge, who was well-prepared for this event and developed his own code-breaking code and signal processing using Ada. The Colossus could not win because of using the old World War radio equipment.

So, due to poor reception, the team was delayed by a day.

The winner's laptop was so fast and he also had his code running, which took him less than one minute to figure all the 12 wheel settings. The laptop was almost 240 times faster than the old Colossus computer.

This challenge also gave verification on the success of the rebuilt Colossus. As per Tony Sale, the Colossus performed as well as it did six decades ago.