In their infancy computers used to fill entire rooms
The computer seems the very essence of the modern world, especially as the gadgets we sit before and carry around shrink as fast as they become more powerful.
But if truth be told the computer has had a long and honourable history that stretches back to the closing years of the World War II.
And, say conservations and computer history enthusiasts, Britain played a big part in the development of the modern computer.
"The layman when asked about the introduction of steam power will usually reel off Newcomen, Watt and Trevithick," said Chris Burton, of the Computer Conservation Society.
"But when it comes to computer pioneers they are absolutely baffled," he said. "They have no idea."
When pushed, he said, they might be able to remember the name of Alan Turing but few know of any others beyond that.
Turing established the conceptual and philosophical basis for the rise of computers in a seminal 1936 paper called "On Computable Numbers". But it took a large cast of engineers and scientists to solve the real world problems that arise when those ideas are turned into whirring, clicking reality.
At Bletchley Park forerunners of modern computers were built to help the Allies crack German codes.
Colossus was crucial for D-Day operations
Although Turing worked at Bletchley and helped create the Bombe that cracked messages enciphered with Enigma machines he had little to do with Colossus - a programmable machine that tackled the encrypted messages sent by the German High Command.
Conceived, designed and built by Tommy Flowers, Allen Coombs and Max Newman, the first Colossus was working in 1943 - three years ahead of the rival pioneering American machine known as Eniac.
For a long time the Electronic Numerical Integrator And Computer (Eniac) was better known than Colossus because the Official Secrets Act prevented those that worked on it talking publicly about their achievements.
Kevin Murrell, a trustee for the National Museum of Computing where a rebuilt Colossus is housed, said Bletchley was just one of the locations where the UK's computer pioneers did their influential work.
Colossus, he said, amounted to about one-third of all effort being put into those early machines. Similar pioneering efforts were underway at Manchester and Cambridge.
Cakes and computers
At Cambridge, Maurice Wilkes and his colleagues were working on the Electronic Delay Storage Automatic Calculator (Edsac) - another recognisably modern machine that used tubes of mercury five feet in length as a data storage medium.
Edsac ran its first programs in 1949 and was developed to act as the heart of a number crunching service for Cambridge scientists.
Some principles of computing date from Victorian times.
The creation of Edsac was backed by baking and catering giant J Lyons which bought a copy of the finished machine and turned it into the world's first business computer - the Lyons Electronic Office (Leo).
"It was the first programmable computer that went into routine operation," said science writer Georgina Ferry, author of a book about the genesis of Leo.
"What was innovative about Leo was not the hardware," she said, "but the systems and the way they used it."
John Pinkerton, David Caminer, Ernest Lenaerts, Derek Hemy and others at Lyons pioneered the use of computers in the dull repetitive tasks formerly carried out by legions of clerks. One of its first roles was to calculate how much each worker at the hundreds of Lyons tearooms was to be paid.
Steadily more and more of those basic tasks were studied by Caminer and his team and broken down into steps Leo could replicate. In the process Caminer and his colleagues created systems engineering.
"Leo led the world in business computing," she said.
At the University of Manchester engineers such as Tom Kilburn, Freddie Williams, Geoff Tootill, Alec Robinson, Dai Edwards and others worked to create what became the Small Scale Experimental Machine (SSEM) or Baby.
The Baby was recognisably modern electronic computer because it could easily be re-programmed to carry out different tasks. By contrast older machines either just carried out one function or had to be re-wired to change what they did.
A replica of the original Baby now resides at the Museum of Science and Industry in Manchester.
"When we wrote the proposal to build the replica machine an explicit goal which was to re-run the first program as a tangible tribute to the pioneers that brought this about," said Chris Burton who led the effort to re-build the SSEM.
Mr Burton said none of them had any idea about the influence their work would have.
"They did it to help engineers, forecasters and scientists to do their calculations," he said. "They had no idea of the fantastic proliferation that we have had since."