Manchester computers
Encyclopedia
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 tube
, an early form of computer memory
based on standard cathode ray tube
s (CRTs); 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 June 1948. As the world's first stored-program computer the SSEM, and the Manchester Mark 1
developed from it, 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.
for the Williams tube
, an early form of computer memory, rather than as a practical computer. Work on the machine began in 1947, and on 21 June 1948 the computer successfully ran its first program, consisting of 17 instructions written to find the highest proper factor
of 218 (262,144) by trying every integer from 218 − 1 downwards. The program ran for 52 minutes before producing the correct answer of 131,072.
The SSEM was 17 feet (5.2 m) in length, 7 in 4 in (2.24 m) tall, and weighed almost 1 long ton
. It contained 550 thermionic valves – 300 diode
s and 250 pentode
s – and had a power consumption of 3.5 kilowatts
. 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
.
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, the Ferranti Mark 1.
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 25 kilowatts. Perhaps the Manchester Mark 1's most significant innovation was its incorporation of index registers, commonplace on modern computers.
; work began in 1951. The resulting machine, which ran its first program in May 1954, was known as Meg, or the megacycle machine. It was smaller and simpler than the Mark 1, as well as quicker at solving maths problems. Ferranti
produced a commercial version marketed as the Ferranti Mercury
, in which the Williams tubes were replaced by the more reliable core memory.
s instead of valves. Initially the only devices available were germanium
point-contact transistor
s, which although less reliable than the valves they replaced consumed far less power.
Two versions of the machine were produced. The first was the world's first transistorised computer, and became operational in November 1953. The second version was completed in April 1955. The 1955 version used 200 transistors, 1,300 solid-state diode
s, and had a power consumption of 150 watts. The machine did however make use of valves to generate its 125 kHz clock waveforms and in the circuitry to read and write on its magnetic drum memory
, so it was not the first completely transistorised computer, that distinction going to 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 this improved once the more reliable junction transistor
s became available. The Transistor Computer's design was adopted by the local engineering firm of Metropolitan-Vickers
in their Metrovick 950
, in which all of 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.
engine – began at the university in 1956. The aim was to build a computer that could operate at processing speeds approaching one microsecond per instruction, one million instructions per second. Mu (or µ) is a prefix in the SI and other systems of units denoting a factor of 10−6 (one millionth).
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 7 December 1962, and was considered at that time to be the most powerful computer in the world, equivalent to four IBM 7094s. 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 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.
, something that contemporary computers were unable to do efficiently. A major factor in the MU5's much-improved performance over its predecessors was 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 £ as of ) 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 its 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 MU5, which was in operation at the university until 1980.
Von Neumann architecture
The term Von Neumann architecture, aka the Von Neumann model, derives from a computer architecture proposal by the mathematician and early computer scientist John von Neumann and others, dated June 30, 1945, entitled First Draft of a Report on the EDVAC...
electronic computers
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
developed during the 30-year period between 1947 and 1977 by a small team at the University of Manchester
University of Manchester
The University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...
, under the leadership of Tom Kilburn
Tom Kilburn
Tom Kilburn CBE, FRS was an English engineer. With Freddie Williams he worked on the Williams Tube and the world's first stored-program computer, the Small-Scale Experimental Machine , while working at the University of Manchester.-Computer engineering:Kilburn was born in Dewsbury, Yorkshire and...
. They included the world's first stored-program computer
Von Neumann architecture
The term Von Neumann architecture, aka the Von Neumann model, derives from a computer architecture proposal by the mathematician and early computer scientist John von Neumann and others, dated June 30, 1945, entitled First Draft of a Report on the EDVAC...
, 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 tube
Williams tube
The Williams tube or the Williams-Kilburn tube , developed in about 1946 or 1947, was a cathode ray tube used to electronically store binary data....
, an early form of computer memory
Computer storage
Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data. Data storage is one of the core functions and fundamental components of computers....
based on standard cathode ray tube
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
s (CRTs); 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
Small-Scale Experimental Machine
The Manchester Small-Scale Experimental Machine , nicknamed Baby, was the world's first stored-program computer. It was built at the Victoria University of Manchester by Frederic C...
(SSEM), ran its first program on 21 June 1948. As the world's first stored-program computer the SSEM, and the Manchester Mark 1
Manchester Mark 1
The Manchester Mark 1 was one of the earliest stored-program computers, developed at the Victoria University of Manchester from the Small-Scale Experimental Machine or "Baby" . It was also called the Manchester Automatic Digital Machine, or MADM...
developed from it, quickly attracted the attention of the United Kingdom government, who contracted the engineering firm of Ferranti
Ferranti
Ferranti or Ferranti International plc was a UK electrical engineering and equipment firm that operated for over a century from 1885 until it went bankrupt in 1993. Known primarily for defence electronics, the Company was once a constituent of the FTSE 100 Index but ceased trading in 1993.The...
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
ICL 2900 Series
The ICL 2900 Series was a range of mainframe computer systems announced by the UK manufacturer ICL on 9 October 1974. The company had started development, under the name "New Range" immediately on its formation in 1968...
of computers during the 1970s.
Small-Scale Experimental Machine (SSEM)
The Manchester Small-Scale Experimental Machine (SSEM), also known as the Baby, was designed as a test-bedTestbed
A testbed is a platform for experimentation of large development projects. Testbeds allow for rigorous, transparent, and replicable testing of scientific theories, computational tools, and new technologies.The term is used across many disciplines to describe a development environment that is...
for the Williams tube
Williams tube
The Williams tube or the Williams-Kilburn tube , developed in about 1946 or 1947, was a cathode ray tube used to electronically store binary data....
, an early form of computer memory, rather than as a practical computer. Work on the machine began in 1947, and on 21 June 1948 the computer successfully ran its first program, consisting of 17 instructions written to find the highest proper factor
Divisor
In mathematics, a divisor of an integer n, also called a factor of n, is an integer which divides n without leaving a remainder.-Explanation:...
of 218 (262,144) by trying every integer from 218 − 1 downwards. The program ran for 52 minutes before producing the correct answer of 131,072.
The SSEM was 17 feet (5.2 m) in length, 7 in 4 in (2.24 m) tall, and weighed almost 1 long ton
Long ton
Long ton is the name for the unit called the "ton" in the avoirdupois or Imperial system of measurements, as used in the United Kingdom and several other Commonwealth countries. It has been mostly replaced by the tonne, and in the United States by the short ton...
. It contained 550 thermionic valves – 300 diode
Diode
In electronics, a diode is a type of two-terminal electronic component with a nonlinear current–voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals...
s and 250 pentode
Pentode
A pentode is an electronic device having five active electrodes. The term most commonly applies to a three-grid vacuum tube , which was invented by the Dutchman Bernhard D.H. Tellegen in 1926...
s – and had a power consumption of 3.5 kilowatts
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
. Its successful operation was reported in a letter to the journal Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
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
Manchester Mark 1
The Manchester Mark 1 was one of the earliest stored-program computers, developed at the Victoria University of Manchester from the Small-Scale Experimental Machine or "Baby" . It was also called the Manchester Automatic Digital Machine, or MADM...
.
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 UK Government Chief Scientist Ben LockspeiserBen Lockspeiser
Sir Benjamin Lockspeiser KCB, FRS, MIMechE, FRAeS, was a British scientific administrator and the first President of CERN....
was given a demonstration of the prototype, and was so impressed that he immediately initiated a government contract with the local firm of Ferranti
Ferranti
Ferranti or Ferranti International plc was a UK electrical engineering and equipment firm that operated for over a century from 1885 until it went bankrupt in 1993. Known primarily for defence electronics, the Company was once a constituent of the FTSE 100 Index but ceased trading in 1993.The...
to make a commercial version of the machine, the Ferranti Mark 1.
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 25 kilowatts. Perhaps the Manchester Mark 1's most significant innovation was its incorporation of index registers, commonplace on modern computers.
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 maths. They therefore embarked on the design of a new machine which would include a floating point unitFloating point unit
A floating-point unit is a part of a computer system specially designed to carry out operations on floating point numbers. Typical operations are addition, subtraction, multiplication, division, and square root...
; work began in 1951. The resulting machine, which ran its first program in May 1954, was known as Meg, or the megacycle machine. It was smaller and simpler than the Mark 1, as well as quicker at solving maths problems. Ferranti
Ferranti
Ferranti or Ferranti International plc was a UK electrical engineering and equipment firm that operated for over a century from 1885 until it went bankrupt in 1993. Known primarily for defence electronics, the Company was once a constituent of the FTSE 100 Index but ceased trading in 1993.The...
produced a commercial version marketed as the Ferranti Mercury
Ferranti Mercury
The Mercury was an early 1950s commercial computer built by Ferranti. It was the successor to the Ferranti Mark 1, adding a floating point unit for improved performance, and increased reliability by replacing the Williams tube memory with core memory and using more solid state components...
, in which the Williams tubes were replaced by the more reliable core memory.
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 transistorTransistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
s instead of valves. Initially the only devices available were germanium
Germanium
Germanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. The isolated element is a semiconductor, with an appearance most similar to elemental silicon....
point-contact transistor
Point-contact transistor
A point-contact transistor was the first type of solid-state electronic transistor ever constructed. It was made by researchers John Bardeen and Walter Houser Brattain at Bell Laboratories in December 1947. They worked in a group led by physicist William Bradford Shockley...
s, which although less reliable than the valves they replaced consumed far less power.
Two versions of the machine were produced. The first was the world's first transistorised computer, and became operational in November 1953. The second version was completed in April 1955. The 1955 version used 200 transistors, 1,300 solid-state diode
Diode
In electronics, a diode is a type of two-terminal electronic component with a nonlinear current–voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals...
s, and had a power consumption of 150 watts. The machine did however make use of valves to generate its 125 kHz clock waveforms and in the circuitry to read and write on its magnetic drum memory
Drum memory
Drum memory is a magnetic data storage device and was an early form of computer memory widely used in the 1950s and into the 1960s, invented by Gustav Tauschek in 1932 in Austria....
, so it was not the first completely transistorised computer, that distinction going to the Harwell CADET
Harwell CADET
The Harwell CADET was the first fully transistorised computer in Europe, and may have been the first fully transistorised computer in the world....
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 this improved once the more reliable junction transistor
Bipolar junction transistor
|- align = "center"| || PNP|- align = "center"| || NPNA bipolar transistor is a three-terminal electronic device constructed of doped semiconductor material and may be used in amplifying or switching applications. Bipolar transistors are so named because their operation involves both electrons...
s became available. The Transistor Computer's design was adopted by the local engineering firm of Metropolitan-Vickers
Metropolitan-Vickers
Metropolitan-Vickers, Metrovick, or Metrovicks, was a British heavy electrical engineering company of the early-to-mid 20th century formerly known as British Westinghouse. Highly diversified, they were particularly well known for their industrial electrical equipment such as generators, steam...
in their Metrovick 950
Metrovick 950
The Metrovick 950 was a transistorized computer, built from 1956 onwards by British company Metropolitan-Vickers, to the extent of six or seven machines, which were "used commercially within the company" or "mainly for internal use"...
, in which all of 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
Development of MUSE – a name derived from microsecondMicrosecond
A microsecond is an SI unit of time equal to one millionth of a second. Its symbol is µs.A microsecond is equal to 1000 nanoseconds or 1/1000 millisecond...
engine – began at the university in 1956. The aim was to build a computer that could operate at processing speeds approaching one microsecond per instruction, one million instructions per second. Mu (or µ) is a prefix in the SI and other systems of units denoting a factor of 10−6 (one millionth).
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 7 December 1962, and was considered at that time to be the most powerful computer in the world, equivalent to four IBM 7094s. 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
Virtual memory
In computing, virtual memory is a memory management technique developed for multitasking kernels. This technique virtualizes a computer architecture's various forms of computer data storage , allowing a program to be designed as though there is only one kind of memory, "virtual" memory, which...
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 machines were built: one for a joint British Petroleum
BP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...
/University of London
University of London
-20th century:Shortly after 6 Burlington Gardens was vacated, the University went through a period of rapid expansion. Bedford College, Royal Holloway and the London School of Economics all joined in 1900, Regent's Park College, which had affiliated in 1841 became an official divinity school of the...
consortium, and the other for the Atlas Computer Laboratory
Atlas Computer Laboratory
The Atlas Computer Laboratory on the Chilton, Oxfordshire campus shared by the Harwell Laboratory was one of the major computer laboratories in the world, which operated between 1961 and 1975 to provide a service to British scientists at a time when powerful computers were not usually available...
at Chilton near Oxford
Oxford
The city of Oxford is the county town of Oxfordshire, England. The city, made prominent by its medieval university, has a population of just under 165,000, with 153,900 living within the district boundary. It lies about 50 miles north-west of London. The rivers Cherwell and Thames run through...
. A derivative system was built by Ferranti for Cambridge University
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
, called the Titan
Titan (computer)
Titan was the prototype of the Atlas 2 computer developed by Ferranti and the University of Cambridge Mathematical Laboratory in Cambridge, England...
or Atlas 2, which had a different memory organisation, and ran a time-sharing
Time-sharing
Time-sharing is the sharing of a computing resource among many users by means of multiprogramming and multi-tasking. Its introduction in the 1960s, and emergence as the prominent model of computing in the 1970s, represents a major technological shift in the history of computing.By allowing a large...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer 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
National Museums of Scotland
National Museums Scotland is the organization that runs several national museums of Scotland. It is one of the country's National Collections, and holds internationally important collections of natural sciences, decorative arts, world cultures, science and technology, and Scottish history and...
in Edinburgh.
MU5
Work on 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 codeMachine code
Machine code or machine language is a system of impartible instructions executed directly by a computer's central processing unit. Each instruction performs a very specific task, typically either an operation on a unit of data Machine code or machine language is a system of impartible instructions...
, something that contemporary computers were unable to do efficiently. A major factor in the MU5's much-improved performance over its predecessors was its incorporation of associative memory
Content-addressable memory
Content-addressable memory is a special type of computer memory used in certain very high speed searching applications. It is also known as associative memory, associative storage, or associative array, although the last term is more often used for a programming data structure...
, 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 £ as of ) 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 its 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 2900 Series
The ICL 2900 Series was a range of mainframe computer systems announced by the UK manufacturer ICL on 9 October 1974. The company had started development, under the name "New Range" immediately on its formation in 1968...
. ICL's 2980 in particular, first delivered in June 1975, owed a great deal to the design of MU5, which was in operation at the university until 1980.
MU6
MU5 was the last large-scale machine to be designed and built at Manchester University. The development of its successor, MU6, was funded by a grant of £219,300 awarded by the SRC in 1979 (equivalent to about £ as of ). 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. Only MU6-P and a mid-range processor, MU6-G, were ever produced, and ran between 1982 and 1987, but the university did not have the resources to build the remaining machines in-house and the system was never commercially developed.Summary
| Year | University Prototype | Year | Commercial Computer |
|---|---|---|---|
| 1948 | Small-Scale Experimental Machine, aka "Baby", which evolved into the Manchester Mark 1 | 1951 | Ferranti Mark 1 |
| 1953 | Transistor computer | 1956 | Metrovick 950 |
| 1954 | Meg | 1957 | Ferranti Mercury |
| 1959 | Muse | 1962 | Ferranti Atlas, Titan |
| 1974 | MU5 | 1974 | ICL 2900 Series |