The National Museum of Computing
The National Museum of Computing is a UK-based museum that is dedicated to collecting and restoring historic computer systems, and is home to the world's largest collection of working historic computers. The museum is located on Bletchley Park in Milton Keynes, Buckinghamshire. It opened in 2007 in Block H – the first purpose-built computer centre in the world, having housed six of the ten Colossus computers that were in use at the end of World War II.
As well as first generation computers including the original Harwell Dekatron computerthe world's oldest working digital computer and mainframes of the 1950s, 60s and 70s, the Museum houses an extensive collection of personal computers and a classroom full of BBC 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 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 by Arts Council England.
Origins
The Bletchley 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, which had been established in the previous year. One leading member – and secretary to the Trust – was a scientist with electronics and computer engineering skills named Tony Sale. He had worked for MI5 and later at the Science Museum alongside Doron Swade on a series of projects to restore some of the Science Museum's computer holdings to working order. 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 the Computer Conservation Society.In 1993, Tony Sale and a group of volunteers started to rebuild a Colossus in Block H. By June 1996 they had a prototype machine working, which was formally switched on by the Duke of Kent in the presence of Tommy Flowers who built the wartime Colossi. 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. 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 by John Harper built a working replica of a Turing-Welchman Bombe in the BPT museum. This was relocated to Block H in 2018.
Exhibits
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.Tunny and Colossus Galleries
Separate from the Enigma story is the less well-known endeavour of the diagnosing and deciphering of messages produced by the more secure 12-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 the Allied side saw until after Nazi Field Marshal Albert Kesselring surrendered in May 1945, shortly before VE-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 at Knockholt in Kent, with its multiple RCA AR-88 radio receivers, pen recorders and the sort of paper tape and teleprinter 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 the Heath Robinson machine, the forerunner of Colossus.
Image:ColossusRebuild 11.jpg|thumbnail|upright=1.0|Tony Sale using the Colossus rebuild
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. He and his team spent 14 years from 1993 in building this machine.
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 defined Boolean 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 2,420 valves and its programmability, 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.
There are a number of related artefacts in this gallery.
Exhibition space
Various substantial exhibitions reside here for periods of months or years.- The National Air Traffic Services 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 train air 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 the General Post Office and British Telecom worked for half a century starting in 1947 to enhance the speed and reliability of the existing copper voice network. The exhibition took visitors on a journey through the story from the first pilots of the prototype digital exchanges, to the planned national switch from copper to fibre after 2025.
- In July 2024 an exhibition commemorating the 60th Anniversary Exhibition of Digital Equipment Corp's presence in the United Kingdom was opened here. Their offices were in Reading and this exhibition was developed in collaboration with Reading Museum, DEXODUS, and DECUS.
Innovation Hub and BBC classroom
Next door is the BBC Classroom which contains a large set of working vintage BBC Micro computers. This machine was the winning design for the BBC’s Computer Literacy Project and was first demonstrated by Acorn 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.
Funding
The museum entirely depends on voluntary and corporate donations and admission charges. Fund-raising continues and donors have included Bletchley Park Capital Partners, Fujitsu, Google UK, CreateOnline, Ceravision, Insight software, PGP Corporation, IBM, NPL, HP Labs, British Computer Society, Black Marble, and the School of Computer Science at the University of Hertfordshire.The museum conducted a crowdfunding campaign in March 2018 to raise funds to build a new gallery for the Bombe. 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.
Opening
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 museum for admission charges, with concessions available for students, over 60s, and children. Annual tickets, offering unlimited return visits for all open days, are also available.