Early Electronic Computers Content from the guide to life, the universe and everything

Early Electronic Computers

2 Conversations

The two computers described in this entry were firsts. Colossus was the first programmable electronic computer and LEO was the first office computer. Both were British and both showed what computers could do to speed up important, if mundane, tasks.

Much of the early development of electrical logic circuits was carried out in the USA and Germany. Britain appeared to lag behind in this early computer science, but the truth is somewhat different. As early as 1937, Alan Turing was defining logic processes, which could be used in electronic systems, although the systems themselves were still to be designed. The credit for the first programmable binary 'computer' seems to belong to Germany and Konrad Zuse's Z3 of 1941. It was, however, an electromechanical calculator for the Aerodynamic Research Institute. It was neither electronic nor was it developed into an electronic system.


The Second World War provided an impetus for technical development in many fields; the one that spawned the electronic computer was code-breaking. It was a subject for the best logisticians and mathematicians, who were gathered at Bletchley Park to decipher enemy radio transmissions. The main code to break belonged to a German encrypting machine called Enigma. This was an effective high level system used to transmit information such as reports and orders to units of the German Army, Luftwaffe and Navy. In particular, it was used by the U-boats in the Battle of the Atlantic. It used settings that would only be repeated after 4,000 uses. The key to decoding it would be the settings of cylinders which formed the encoding part of the machine.

The code had already been cracked by the Polish intelligence service, who used electromechanical devices called Bombas to simulate and predict Enigma settings. The team at Bletchley Park had copies of these already and they were proving to be useful in speeding up the process of deciphering tactical messages from Enigma. Speed was of the essence as all intelligence data has a 'life' after which it is useless. Enigma was not the only system available to the Germans. For strategic or higher tactical information they used Lorenz. This encoded teleprinter transmissions and was going to be a tough nut to crack.

It was cracked, but it took weeks to get any useable information out of it. The process of finding the settings had to be speeded up. Professor Max Newman, a mathematician, thought that it would be possible to automate some parts of the process for finding the settings used for each message. Under his guidance a machine was built at Dollis Hill, the Post Office Research Laboratory, called Heath Robinson after the artist and designer of fantastic machines, William Heath Robinson. It used two high speed punched paper tapes to store possible Lorenz settings. This worked, but only if the two tapes could be synchronised.

Professor Newman was introduced to Tommy Flowers, a Post Office engineer, who had ideas of using thermionic valves (tubes1) as switches in telephones networks to replace mechanical ones. Until this time, valves had been used as amplifiers and oscillators for radios and were known to be unreliable. Tommy Flowers believed this could be improved by not turning them on and off, just on, and leaving them like that. He replaced the electromechanical relays of the Heath Robinson with valve switches. This eliminated the unavoidable mechanical and electrical delays of relays and speeded-up response times. Additionally, he used them to store the information contained on one of the paper tapes, thus removing the need for synchronisation. In spite of official scepticism, the first system took nine months to build and was ready for testing in December 1943. Tests showed it could solve encryption problems within 30 minutes! The Heath Robinson worked at a speed of 1,000 characters per second; this machine worked at 5,000 characters per second. It was christened 'Colossus' and was transferred to Bletchley Park over Christmas 1943.

The original system had 1,500 valves and was superseded by the Mark 2, with greater processing power and 2,400 valves, in June 1944. Ten of these were used, delivering vital information to Intelligence and Operational Planning until the end of the war. All ten Colossus systems were destroyed to keep them secret, eight in 1946 and the last two in 1960. The whole operation at Bletchley Park was kept secret until relatively recently, Colossus being revealed in 1970. It was this secrecy that kept the British out of the computer history books and many believe it was the USA alone that first developed electronic computers.

It is true that Colossus was not a 'general' computer, rather a dedicated code-breaking tool, but it was programmable, it was largely electronic and it worked2. As part of the deal to supply arms, food and information, the British supplied details of Colossus to the USA. Short-sighted politicians could see no civilian use for computers; the Americans, equally, saw little but limited military applications, but allowed it to develop. Reconstruction of the UK telephone network after the war found little time to allow for development and so it left the practical world of the communications industry and passed into the academic and impractical world of the University.

LEO - Lyons Electronic Office

J Lyons & Co were owners of a chain of tea shops and food manufacturers. This large organisation was, as many others were, administered by using large amounts of paper and clerical staff. Always innovative in administration, Lyons looked for a way to speed up and simplify their administration. In 1947, two managers with wide experience of clerical procedures, Thomas Thompson and Oliver Standingford, went to the USA to investigate the use of electronic computers. The report they produced for the Lyons board said that electronic computers would improve efficiency. For £100,000, Lyons could build one themselves which would save some £50,000 per year.

After looking at the available systems, mostly used for academic and scientific calculations, they entered into partnership with Cambridge University to learn more about electronic computers. They used this knowledge and hired specialists who were capable of designing a computer, then built one in a room at head office. Design and construction started in January 1949. It was ground-breaking work as both hardware and software had to be developed. This was recorded, flow-charted and logged until it was ready for its proving trial. The complete machine used over 5,000 thermionic valves and used mercury delay lines as storage. The first operational run of the computer took place on 5 September, 1951, when an application known as Bakeries Valuations was run. At first unreliable, it was tried, tested and improved until, in December, 1953, it was good enough to run a weekly payroll program. It proved its value by taking 1.5 seconds to calculate an employee's pay, a task which took an experienced clerk eight minutes.

As news of this achievement spread, other companies asked Lyons to do some of their complex mathematical tasks. Lyons even branched off into computer manufacture and developed LEO into two improved models: LEO II and LEO III. Peripherals such as mark readers and printers were also developed. Despite the obvious links to programming and programmers, there was a great difference in the way it was managed. Its job was to give managers prompt, accurate statistics rather than to mechanise administration. It was a management information system. The programmers knew this and never let the technology do the controlling.

Lyons' computer people were not computer professionals but were clerks, managers or management trainees. They knew the business. LEO was not an especially powerful computer, but it worked efficiently and without major mishap because the programming techniques devised by Lyons were efficient and the programmers were well aware of the results required. They even thought about the effect of the turn of the millennium on two digit year notation back in 1959.

All good fairy stories have a happy ending, but, for LEO, it was not to be. Lyons overexpanded, borrowed heavily and gained finance by allowing the merger of LEO with English Electric computers in 1963. The US corporate giants were encroaching on LEO's market with better, well-engineered and cheaper systems. These would be tailored to the client's requirements by in-house programmers who had little practical experience of administration. Government concerns led to the incorporation of 'International Computers Limited' (ICL), a single UK computer 'giant' to compete with the imports. Sadly, the link with business fell away, too. Lyons fell foul of international finance and was taken over by Allied Breweries in 1978. The name survived until 1998.

The Lost Link

Once again, the British led the field until the Americans caught up and bettered them. These two computers were designed not by 'computer people', but by specialists in search of a more efficient way of working out mathematical and logical problems. Much scorn is placed on them as the systems are said to be not flexible enough for business. This may be true, but the business they did proved worthwhile and resulted in greater efficiency. The main aim for both was speed; a reduction in the time it took to work out complex problems in the case of Colossus and in large volume, simple calculations in the case of LEO. LEO has to be seen as the more flexible, but it was a generation away from Colossus. Perhaps we may see the return of computers designed for businessmen by businessmen.

1In this entry, they will be referred to as 'valves' rather than 'tubes'.2To show its power, a Colossus decoding task was put onto a modern Pentium PC and it took twice as long as Colossus to generate the same result!

Bookmark on your Personal Space

Edited Entry


Infinite Improbability Drive

Infinite Improbability Drive

Read a random Edited Entry

Categorised In:

Written by

Edited by

h2g2 Editors

Write an Entry

"The Hitchhiker's Guide to the Galaxy is a wholly remarkable book. It has been compiled and recompiled many times and under many different editorships. It contains contributions from countless numbers of travellers and researchers."

Write an entry
Read more