In the nineteenth century, machines changed the world. Suddenly, people could travel more easily and contact one another more quickly. Work changed, too, and many people got jobs in factories. It was the start of the Industrial Age – the age of machines and factories.

The second half of the twentieth century saw the start of the Computer Age. At first, computers were very difficult to use, and only a few people understood them. But soon, computers began to appear in offices and then homes. Today, they are everywhere. Some people still say that they have never used a computer, but they probably use computers every day – they just do not realize it. This is because there are computers in so many things: cars, televisions, radios, washing machines…

When the first computers were built in the 1940s and 1950s, they were as big as a room. In 1949, the magazine Popular Mechanics made a prediction: ‘One day,’ they said, ‘computers will be really small; in fact, they will weigh less than 1.5 tonnes.’ Now, computer chips can be smaller than the full stop at the end of this sentence. Over the past fifty or sixty years, computers have changed much more than people thought possible.

In the beginning

For thousands of years, humans have needed to count. Families needed to know how many animals, how much food, and how much land they had. This information was important when people wanted to buy and sell things, and also when people died or got married. There were many different ways to count and write down the numbers. The Sumerians had three different ways: they used one for land, one for fruit and vegetables, and one for animals. They could count, but they had no easy way to do calculations.

Around 1900 to 1800 BC, the Babylonians invented a new way to count using place values. This meant that two things decided the size of a number: the digits (the numbers from 0 to 9), and the place where they were put. Today, we still use place values to count. We can write any number using only ten digits: for example, 134 means 1 x 100, 3 x 10, and 4 x 1. Computers also use place values when they do calculations. They only use two digits (0 and 1): for example, 11011 means 1 x 16, 1 x 8, 0 x 4, 1 x 2, and 1 x 1 (=27). Without place values, fast calculations are impossible.

Between 1000 and 500 BC, the Babylonians invented the abacus. It used small stones which they put in lines. Each line of stones showed a different place value. To do calculations they moved stones from one line to another. Later, different kinds of abacuses were made of wood and used coloured balls. It is also possible that the abacus was first invented in China, but nobody really knows.

Although an abacus can be very fast, it is not really a machine because it does not make calculations automatically. In the seventeenth century, people began to build calculating machines. In 1642, the French mathematician Blaise Pascal made an Arithmetic Machine. He used it to count money. During the ten next years, Pascal made fifty more machines.

In the 1670s, a German called Leibnitz continued Pascal’s work and made a better machine. Leibnitz’s machine was called the Step Reckoner. It could do much more difficult calculations than Pascal’s Arithmetic Machine. Interestingly, Leibnitz’s machine only used two digits (0 and 1) for its calculations – just like modern computers! In fact, calculating machines like Leibnitz’s Step Reckoner were used for the next hundred years, until cheap computers began to appear.

The first computers

The word ‘computer’ used to mean a person, not a machine. In the nineteenth century, builders and technicians needed to know the answers to very difficult calculations in order to do their work. they did not have the time to do these calculations themselves, so they bought books of answers. The people who did the calculations and wrote the books were called computers.

In the 1820s, a British mathematician called Charles Babbage invented a machine that did very difficult calculations automatically. He called his machine a Difference Engine. He began to build his machine, but he did not finish it because he had a better idea. (Babbage never finished anything – he always had a better idea and started working on something new!) In fact, more than a hundred and fifty years later, some technicians from the Science Museum in London built Babbage’s Difference Engine. It is still in the museum today. The machine weighs about three tonnes, and it is nearly two metres tall and three metres wide. And it works: in the early 1990s, it did a calculation and gave the right answer – 31 digits long!

Babbage did not finish making the Difference Engine because he started work on a machine called an Analytical Engine. The Analytical Engine could do more: for example, it had a kind of memory. This meant that it was possible to write programs for it, building on each answer and doing more and more difficult calculations. For this reason, the Analytical Engine is often seen as the first real computer. However, Babbage never finished building this machine either!

A woman called Ada Lovelace worked with Babbage. She was the daughter of Lord Byron, a famous English writer. Most people did not understand Babbage’s ideas, but Ada did, because she was an excellent mathematician. She knew that she could do extraordinary calculations with the Analytical Machine, and she wrote a program for it. Although the machine was never built, Ada Lovelace was still the first computer programmer in the world. In 1979, a modern computer programming language was named ADA.

Babbage’s ideas were ahead of their time. Slowly, over the next one hundred years, inventors began to build better calculating machines. One of the best inventors of the 1930s was a German called Konrad Zuse. In 1938, he built his first machine, the Z1, in his parents’ living room in Berlin. His later machines, the Z3 and Z4, were like modern computers in many ways. They used only two digits (0 and 1) to do all the calculations. Also, Zuse wrote programs for his machines by making holes in old cinema film. When he put the film through the machines, they could ‘read’ the programs and do very long and difficult calculations.

Alan Turing

Alan Turing was born in 1912 in London. He studied mathematics at Cambridge University. In 1937, he wrote a report which talked about a Turing Machine. This was a machine that could read programs and follow any number of instructions. It was only an idea, and he did not have plans to build the machine, but his 1937 report was very important in the history of computing.

In 1939, Turing began to work for the British Government. During the Second World War (1939-1945), the Germans often sent messages from one group of soldiers to another. These messages gave important information and instructions, so of course they were secret. Although the British could get the messages, at first they could not understand them because they were written in a secret code. Turing began working on a computer to break this code.

Turing worked with other mathematicians at a secret place called Bletchley Park. They knew that the Germans were using machines called Enigma machines to send messages in code. To read and understand these messages you had to have another Enigma machine – and, of course, only the German had these.

Turing and the other people at Bletchley built a machine called the Bombe. (Some Polish mathematicians had already built a machine called Bombe to try to break the Enigma code. They worked with the British to build a new and better machine.) by 1942, the workers at Bletchley Park could read and understand all the German messages which used the Enigma code. The film Enigma, made in 2001, is about this time at Bletchley Park, and the race to discover the code.

In 1943, the Germans started using a different code. The British called this code Fish. It was much more difficult to understand than the Enigma code. The Bombe machine could not break this code, so the workers at Bletchley Park needed a new computer. In one year, they built Colossus. This was one of the world’s first electronic computers which could read and understand programs.

Colossus got its name because of its size: it was as big as a room. It was able to understand difficult codes because it could do thousands of calculations every second. Without Colossus, it took three people six weeks to understand a message written in the Fish code; using Colossus, the British needed only two hours to understand it. A modern PC cannot do the same any faster.