The National Museum of Computing is a UK-based museum that is dedicated to collecting and restoringhistoric computer systems, and is home to the world's largest collection of working historic computers.[1] The museum is located onBletchley Park inMilton Keynes,Buckinghamshire.[2] It opened in 2007[3] inBlock H – the first purpose-built computer centre in the world, having housed six of the tenColossus computers that were in use at the end ofWorld War II.
Block H at Bletchley Park, home of The National Museum of Computing
As well as first-generation computers including the originalHarwell Dekatron computer—the world's oldest working digital computer—[4] andmainframes of the 1950s, 60s and 70s, the Museum houses an extensive collection of personal computers and a classroom full ofBBC Micros. It is available for corporate, group, school, and individual visitors.
Although located on the Bletchley Park campus, The National Museum of Computing is an entirely separate registered charity[5] with its own admission fee. It receives no public funding and relies on ticket sales and the generosity of donors and supporters. The museum has its own cafe and gift shop. In 2024 it was awarded full accreditation as a Nationally-styled museum byArts Council England.
TheBletchley Park estate was threatened with demolition and redevelopment in the late 1980s and early 1990s. It was saved in 1993 thanks to the efforts of the Bletchley Park Trust (BPT), which had been established in the previous year.[6] One leading member – and secretary to the Trust – was a scientist with electronics and computer engineering skills namedTony Sale (1931–2011). He had worked forMI5 and later at theScience Museum alongsideDoron Swade on a series of projects to restore some of the Science Museum's computer holdings to working order.[7] Sale became the first curator of the Bletchley Park Museum, which in its early days was supplemented by more than a score of collections varying from WWII memorabilia to model railways. One of these centred around the history of computing and contained many historic computers, several of which were maintained in working order by enthusiastic volunteers, many of whom were members of theComputer Conservation Society.[8]
In 1993, Tony Sale and a group of volunteers started to rebuild a Colossus (a 'rebuild' as it contains parts from an original) in Block H. By June 1996 they had a prototype machine working, which was formally switched on by theDuke of Kent in the presence ofTommy Flowers who built the wartime Colossi.[9] When in 2004 Block H came under threat of demolition, Sale and colleagues were able to protect it by obtaining Grade II listed building status for it.[10] This led to the detachment of the computing collection from the Bletchley Park Trust museum, and the establishment in 2005 of the Codes and Ciphers Heritage Trust, which became the National Museum of Computing in 2007. Between 1994 and 2007 a group of volunteers led byJohn Harper built a working replica of aTuring-Welchman Bombe (used to help decipherEnigma–coded messages) in the BPT museum. This was relocated to Block H in 2018.
The exhibits on display in the museum represent only a fraction of the collection, but are chosen to tell the story of computing developments in Britain. There are a number of galleries which can be visited in a broadly chronological sequence, starting with the working replicas of WWII machines that were developed and used by Bletchley Park codebreakers.
This gallery tells the story ofCryptanalysis of the Enigma.Enigma machines were used by the Germans before and during WWII for sending secret messages.Alan Turing further developed, andGordon Welchman enhanced, an idea implemented by Polish codebreakers, of a machine to assist in decrypting Enigma messages.[11] This gallery houses a fully working replica of aBombe machine, a working replica Enigma and various related artefacts.
The replica Bombe was built by a team led byJohn Harper following the release in 1995 to theBletchley Park Trust of some 2,000BTM documents and drawings relating to the Bombes that they had built during the war.[12] The replica is owned and managed by the Turing-Welchman Bombe Rebuild Trust, which provides and trains the volunteers who run and demonstrate the machine to visitors on a regular basis.[13]
Separate from the Enigma story is the less well-known endeavour of thediagnosing and deciphering of messages produced by the more secure12-rotor Lorenz SZ teleprinter cipher attachments, which is told in these two galleries. The Tunny galley exhibits one of the very few Lorenz SZ42 machines still in existence — something that nobody in theAllied side saw until after Nazi Field MarshalAlbert Kesselring surrendered in May 1945, shortly beforeVE-day.
'Tunny' was the name given to the messages, to the unseen cipher machine and to the British-built emulator of it. The gallery contains a reproduction of part of the original Lorenz listening station atKnockholt in Kent, with its multipleRCA AR-88 radio receivers,[14]pen recorders (undulators) and the sort ofpaper tape andteleprinter equipment that was used to record the messages and transmit them to Bletchley Park. Also on display is a working replica of a British Tunny machine that exactly emulated the Lorenz machine and a working replica of theHeath Robinson machine, the forerunner ofColossus.
The Colossus gallery houses the fully working rebuild of a Colossus Mark 2. During his work to save Bletchley Park, Tony Sale recognised the pioneering nature of the ten Colossus machines that had been designed and built during WWII to assist in breaking messages enciphered by the Lorenz machines.[15] He and his team spent 14 years from 1993 in building this machine.[16]
As its name implies, Colossus is a large machine which weighed five tonnes. It was designed and built for the single purpose of assisting with deciphering messages enciphered with the 'Tunny' machines. At the heart of the machine is a set of five counters that, for each transit of the looped paper tape containing the message, count the number of times that definedBoolean expressions deliver a specified value. These Boolean expressions were programmed by operating a panel of some 190 switches. The looped message tape would be run continuously, being read at 5000 characters per second. A cryptanalyst would specify different Boolean expressions for evaluation according to the results produced. With its 2,420valves (vacuum tubes) and itsprogrammability, the machine on display is a recreation of the world’s first large-scale, electronic programmable digital computer, albeit a special purpose, not a general purpose machine.[17]
There are a number of related artefacts in this gallery.
This gallery continues the story of valve or tube-based computers and exhibits three large machines and many other related items. The three unique large machines are:
EDSAC replica under construction, October 2024
EDSAC – a replica nearing completion. The machine is owned and managed by the EDSAC Replica Project,[18] which provides and trains the volunteers who are building it and, eventually, will run and demonstrate it.
The original EDSAC (Electronic Delay Storage Automatic Calculator) was constructed by theCambridge University Mathematical Laboratory under SirMaurice Wilkes.[19] Wilkes had readJohn von Neumann's seminal paperFirst Draft of a Report on the EDVAC and attended theMoore School Lectures in Summer 1946. Starting in 1947, he designed and built the machine to serve a user community from many different departments of the university. The EDSAC ran its first programs on 6 May 1949 and is therefore claimed to be the first practical general-purposestored-program electronic computer.
The vast increase in computing power that EDSAC and its successorEDSAC 2 supplied, contributed to the winning of threeNobel Prizes – John Kendrew and Max Perutz (Chemistry, 1962) for the discovery of the structure of myoglobin, Andrew Huxley (Medicine, 1963) for quantitative analysis of excitation and conduction in nerves and Martin Ryle (Physics, 1974) for the development of aperture synthesis in radio astronomy. All acknowledged EDSAC in their Nobel Prize speeches.[20]
Harwell Dekatron computer (AKA Witch) - the world's oldest working computer
Harwell Dekatron[21] (aka the WITCH) from 1951. The world’s oldest original working digital computer.[22] Planned in 1949 to automate the tedious work performed by teams of bright young graduates using mechanical calculators. Simplicity, reliability and unattended operation were the design priorities. Speed was a lesser consideration. This pioneering computer first ran in 1951 and by 1952 was using 828 Dekatron tubes for program and data storage, relays for sequence control and valve-based electronics for calculations. When it was pitched against a human mathematician to check the machine’s operation, the human kept up with it for 30 minutes, but then retired exhausted as the machine carried on remorselessly. It once ran unattended for ten days over a Christmas/New Year holiday period.
It was used atAEA Harwell until 1957, when a competition was held for colleges to see who could make best use of it. The competition was won by Wolverhampton and Staffordshire Technical College (later becoming Wolverhampton University) and they gave it its second name of the WITCH (Wolverhampton Instrument for Teaching Computation from Harwell). The WITCH was used in computer education for over 15 years until 1973.
For a while the machine was on display at Birmingham Museum of Science and Industry, following which it was disassembled and put into storage at Birmingham City Council Museums’ Collection Centre. In 2009 the machine was spotted by TNMOC volunteers who recognised what it was, and made a plan to bring it to TNMOC for restoration in full public view. This was completed in 2012.[23]
Hollerith Electronic Computer (HEC 1) from 1951 (As of September 2024[update] temporarily away from the museum). A relatively recent arrival, nearly as old as the WITCH, but not working.[24]
HEC was based on an original design by Andrew Booth of Birkbeck College, London University.[25] His design for a small scientific computer was adapted by Raymond Bird at BTM in 1951 to become a prototype commercial computer designed to work with the punched card equipment familiar to BTM's customers. The first production machine was delivered early in 1955, and the subsequent 1200 series of computers were highly successful.
Williams (or Williams-Kilburn) Tube, the first truly random access computer memory technology
The HEC and EDSAC had a huge bearing on the development of computing in the UK. In particular, EDSAC led directly toLEO, the world’s first computer to run a business. The WITCH had less influence on the development of computers but in the 1960s and 1970s, and again now, is a great educational tool.
Parts from both aManchester Mark 1 computer and anAtlas supercomputer which was a world first withvirtual memory and which, for a time was the world's most powerful computer.[27]
This gallery contains many machines of the 1960s, -70s and -80s and one or two from the 1990s. Many machines are in working order and include:
Marconi TAC.[28] Designed in 1959/60 this was one of the first transistorised computers made in the UK. The machine on show was one of a pair of machines that were used as a monitoring system for theWylfa nuclear power station onAnglesey.[29] They ran live24/7 from 1968 to 2004.
Elliott 803B
Elliott 803.[30][31] one of the first UK all transistor machines from around 1962. Despite having spent about 15 years in a farm barn, it was restored to working order and it is now demonstrated playing music, drawing graphs on aCalcomp plotter and solving mathematical problems.
Elliott 903
Elliott 903[32] which first came into production in 1965. It is an 18 bit discrete component machine, typically equipped with 8 or 16K of core store memory. As a desk-sized machine it was popular with universities and colleges as a teaching machine, with small research laboratories as a scientific processor, and also as a versatile system for use in industrial process control. The machine was usually programmed in symbolic assembly code,ALGOL orFORTRAN II. The machine on display was donated to the museum in 2011 by the late Oliver Harlow, who had it in storage for many years, and then used it from the 1970s into the 1980s.
IBM 1130
IBM 1130[33] introduced in 1965. This is a rare survivingIBM computer — as most were leased, and scrapped at end of lease period. An estimated 10,000 systems are believed to have been built during a working life spanning nearly 20 years.[34] IBM 1130s for the US market were manufactured inSan Jose, but for the rest of the world they were manufactured in Greenock, Scotland.[35]
As well as being used in small to medium sized offices, it was marketed to price-sensitive, computing-intensive technical markets, like engineering and education, where colleges and universities used them for in both scientific and 'office' roles.[36]
The machine at TNMOC is on long term loan from Liverpool University who purchased it in 1968. After a period of non-academic use it was transferred to the Nuclear Physics Department around 1982 where it was used to digitisebubble chamber trace photos produced atCERN. Before it arrived at the museum, it had been in storage for over 25 years.
ICL 2966 mainframe
ICL 2966 (1970s/1980s) This huge machine — occupying almost a third of the floor space of the gallery — is a true mainframe which is rare sight today.ICL was formed in 1968 from the merger ofICT andEEC. It produced the2900 Series as a successor to the1900 Series and System 4 ranges. The design was influenced by many sources, particularly theManchester University MU5. The system provided a Virtual Machine Environment (VME)operating system and the ability to run 1900 Series computer software.[37]
The museum's 2966 was donated byTarmac who used it as a 1900, until it was decommissioned in 1999, due in part, to fears that it would be affected by the ′Millennium Bug′. Almost all large mainframes were broken up for scrap when they reached the end of their working lives, but Tony Sale, one of the founders of the Computer Conservation Society (CCS), who was directing the Colossus Rebuild, managed to persuadeICL to pay for its transport to Bletchley Park.
Nearly ten years passed before The National Museum of Computing was formed and the system was taken out of storage and set up in the this gallery in 2008. Unfortunately the damp conditions in the semi-derelict buildings that the machine lived in for so many years took their toll. The long and difficult process of restoring the system to working order has been underway since its relocation. Themagnetic disc units for these machines require specially filtered and temperature-controlled air which is not available in the 1944-vintage Block H building. Instead, asolid-state device that acts as a virtual disc system was built. The configuration from Tarmac did not include any video terminals, but three original ICL terminals were acquired and restored. The machine is run as a 1900 under theGeorge 3 operating system. Visitors can now use the terminals to play noughts and crosses against the computer, and to explore the twisty windy passages of the classic Colossal Cave adventure game.[38]
This gallery exhibits many of the familiar home and business computers of the 1980s and 1990s.[40] Visitors can play some of the popular home computer games of the time as well. On show are, amongst others:
A display showing the evolution of portable computers, the earliest of which were described as ″Desktops with a Handle″. Examples are shown fromOsborne, IBM,Kaypro,Amstrad and others. These were used primarily for business applications.
A timeline of world events contemporaneous with these developments.
Various substantial exhibitions reside here for periods of months or years.
The National Air Traffic Services (NATS) Engineering Training College used to be located at Bletchley Park. It provided an exhibition in this gallery which used the actual equipment — with its panoramic three-screen display — that was used to trainair traffic controllers.
Following that there was an exhibition entitled "Flowers to Fibre" that was developed jointly by the museum and the Communications Museum Trust. Tommy Flowers — of Colossus fame — and his successors at theGeneral Post Office (GPO) andBritish Telecom (BT) worked for half a century starting in 1947 to enhance the speed and reliability of the existingcopper voice network. The exhibition took visitors on a journey through the story from the first pilots of the prototype digitalexchanges, to the planned national switch from copper tofibre after 2025.
In July 2024 an exhibition commemorating the 60th Anniversary Exhibition of Digital Equipment Corp's (DEC) presence in the United Kingdom was opened here. Their offices were in Reading and this exhibition was developed in collaboration withReading Museum, DEXODUS,[41] andDECUS.
These are two adjacent and interconnected education areas. The Innovation Hub was equipped byFujitsu as part of its Education Ambassador Programme. It contains an array of Fujitsu technology including tablets, hybrid devices, laptops and desktop PCs.
Next door is the BBC Classroom which contains a large set of working vintageBBC Micro computers. This machine was the winning design for the BBC’s Computer Literacy Project[42] and was first demonstrated byAcorn Computers in 1981. The resulting series of computers became a mainstay of British schools in the 1980s. More than 1.5 million were sold, and their rugged design ensured that they survived the school environment. This classroom is used for workshops, activities and talks for a wide range of groups including school and academic groups, families and special interest groups.
This gallery was sponsored by the UK'sNational Physical Laboratory.[43] It tells the story of how, in 1965,Donald Davies, a member of the team there responsible for building Alan Turing'sAutomatic Computing Engine (ACE) thought of the idea of a network of interconnected data terminals to accesstime-shared computers.[44] Rather than a large number of lines, each carrying only a small amount of data, his conception was for the data to be broken up into short messages in a fixed format, which he named ′packets′, with computer 'nodes' running software to switch the packets at high-speeds between physical circuits.[45] This concept ofpacket switching was first presented in public in the US at the inauguralACM symposium in Gatlinburg, 1967, and in the UK at theIFIP Congress, 1968, in Edinburgh.[46] Davies' design ofdata communication forcomputer networks was adopted byARPA, a research agency of the US Department of Defense and incorporated into its design ofARPANET, the forerunner of theInternet.[47] ARPANET's first link was established between theUniversity of California andStanford Research Institute in November 1969, by which time theNPL's packet-switched network was already operational.[48][49]
The museum conducted acrowdfunding campaign in March 2018 to raise funds to build a new gallery for the Bombe.[51] The campaign raised over £43,000 via crowd-funding and an additional £20,000 via direct donations.
The museum secured £500,000 from the Post Office Remembrance Fellowship, conditional on the raising a further £150,000 in matched funding. This was for the restoration of the 80-year-old roof over the Tunny and Colossus galleries and the refurbishment of several museum spaces. In January 2023 they launched a crowdfunding appeal for the matched funding and raised sufficient for the work to start early in 2024.[52]
The Museum is normally open to the public 4 days a week: Tuesdays, Thursdays, Saturdays, and Sundays, from 10:30am to 4:30pm during the winter period, extending to 5pm during the summer months. Demonstrations and talks in the Bombe, Tunny, and Colossus galleries usually occur on the hour, with slight changes depending on the number of visitors. Guided tours operate at 2pm on Tuesdays, Thursdays and Sundays. Booking for tours is recommended as there are limited places.
See the museumwebsite for admission charges, with concessions available for students, over 60s, and children (under 5s free). Annual tickets, offering unlimited return visits for all open days, are also available.
^Sale, Tony (2004) [1998],The Colossus Computer 1943–1996 and how it helped to break the German Lorenz cipher in WWII, Cleobury Mortimer: M & M Baldwin,ISBN0-947712-36-4
^Copeland, B. Jack, ed. (2006),Colossus: The Secrets of Bletchley Park's Codebreaking Computers, Oxford: Oxford University Press, pp. 1–6,ISBN978-0-19-284055-4
^Ward, Michael ‘Mike’ (19 November 2012)."Technology Correspondent".News. UK: BBC. Retrieved20 November 2012.
^Murrell, Kevin (2016).Adapt and Survive: A Lesson from History in Positioning in the Computing Industry. The National Museum of Computing.ISBN978-0956795649.
^Davies, D. W. (1966)."Proposal for a Digital Communication Network"(PDF).all users of the network will provide themselves with some kind of error control ... Computer developments in the distant future might result in one type of network being able to carry speech and digital messages efficiently.
^Hempstead, C.; Worthington, W., eds. (2005).Encyclopedia of 20th-Century Technology. Vol. 1,A–L. Routledge. p. 574.ISBN9781135455514.It was a seminal meeting as the NPL proposal illustrated how the communications for such a resource-sharing computer network could be realized.
^John S, Quarterman; Josiah C, Hoskins (1986)."Notable computer networks".Communications of the ACM.29 (10):932–971.doi:10.1145/6617.6618.S2CID25341056.The first packet-switching network was implemented at the National Physical Laboratories in the United Kingdom. It was quickly followed by the ARPANET in 1969.
