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Manchester computers

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Between 1947 and 1977, a small research team at the University of Manchester changed computing forever. Led by Tom Kilburn, they developed a series of innovative electronic computers. These machines were not just tools for solving math problems. They were experimental platforms used to test groundbreaking ideas. The team aimed to prove the practicality of the Williams tube. This was an early form of computer memory that used cathode-ray tubes, or CRTs. Their work led to several world firsts. They created the first stored-program computer and the first transistorised computer. They also built the world's fastest computer in 1962.

The first machine in this series was the Manchester Baby. It was designed as a test-bed for the Williams tube memory. Work on the Baby began in 1947. On 21 June 1948, it ran its first program. This program used 17 instructions to find the highest proper factor of 218. The calculation took 52 minutes to complete. The machine was quite large and heavy. It weighed almost one long ton. To function, it used 550 thermionic valves. These valves included 300 diodes and 250 pentodes. The Baby consumed 3.5 kilowatts of power during operation.

Following the success of the Baby, the team developed the Manchester Mark 1. This machine was intended to be a more practical computing facility. In October 1948, the UK Government Chief Scientist, Ben Lockspeiser, saw a prototype. He was so impressed that he started a contract with the firm Ferranti. This partnership produced the Ferranti Mark 1, the first commercial general-purpose computer. The Mark 1 introduced index registers. This is a feature that is commonplace on modern computers today. The Final Specification version of the Mark 1 was fully working by October 1949. It contained 4,050 valves and used 25 kilowatts of power.

As the team gained experience, they shifted focus toward scientific computing. In 1951, they began designing a machine with a floating-point unit. This resulted in the Meg, or the megacycle machine, in 1954. The Meg was smaller and faster than the Mark 1. Ferranti later produced a commercial version called the Ferranti Mercury. This version replaced the Williams tubes with more reliable core memory. Around this same time, researchers worked on the Manchester TC. This project aimed to build a smaller, cheaper computer using transistors. The first version became operational on 16 November 1953. It used 92 point-contact transistors and 550 diodes.

While transistors were efficient, they were not always reliable at first. Early transistors in the Manchester TC caused failures about every 90 minutes. Reliability improved when the team began using junction transistors. The 1955 version of the TC used 250 junction transistors and 1,300 solid-state diodes. This version consumed only 150 watts of power. This was a massive reduction from the older valve-based machines. The design of the TC was later used by Metropolitan-Vickers. They built the Metrovick 950 using junction transistors. Six of these machines were completed starting in 1956.

In 1956, development began on a machine called MUSE, or the microsecond engine. The goal was to reach processing speeds of one million instructions per second. Ferranti joined the project, and the machine was renamed Atlas. The first Atlas was commissioned on 7 December 1962. It was the most powerful computer in the world at that time. Atlas was equivalent to the power of four IBM 7094 computers. It pioneered the use of virtual storage and paging. This allowed each user to have one million words of storage space. Atlas also introduced the Atlas Supervisor, a very early modern operating system.

The MU5 project was the successor to the Atlas system. In 1968, the Science Research Council gave the university a grant of £630,466. By 1971, the project staff grew to 60 people. The MU5 processor used associative memory to speed up data access. This was helpful because the processor cycle was five times faster than the main memory. The MU5 also used a specialized operating system called MUSS. This system was highly adaptable and could run on different processors. The MU5 was fully operational by October 1974. Its design heavily influenced the ICL 2900 series of computers.

The legacy of the Manchester computers connects directly to modern technology. Many of the concepts used in the Atlas, such as virtual memory, are still used today. The design of the MU5 helped shape the development of the ICL 2980. Even the project's influence reached into the 1980s with the MU6 series. These machines were built in locations like Manchester and Chilton near Oxford. Today, parts of the Atlas computer are preserved in museums. The work done by this small team created the foundation for the digital age.

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