The idea of a computer or a calculating machine is not new!
4500 years ago, the Chinese invented the abacus that is still used in some parts of the world today.
Closer in time, the French mathematician Blaise Pascal (1623-1662) invented a calculating machine in 1642.
In 1822, Charles Babbage
(1791-1871) designed "on paper" a machine that could
do complex calculations by following a set of instructions and
had a memory.
This machine which he called the "Difference Engine",
has been built from Babbage's plan and can be seen at the Science
Museum in London.
In 1936, the English
mathematician Alan Turing (1912-1954) designed at the age of 24,
an imaginary machine that could do any calculations.
This machine, called the Turing machine, was using a set of instructions
and works in some way like a modern computer.
The first computers
appeared in the 1930s with the Second World War: they were quite
primitive and used triode valves.
The British built a code breaking machine, named "COLOSSUS",
based on Turin's ideas, in 1939. COLOSSUS was designed to decode
secret messages rather than do calculations.
After the war, Turing
designed the plans for a universal computer that what was called
the Automatic Computing Engine, or ACE, which
was eventually built in the National Physical Laboratory in England.
Because of his original ideas, Alan Turing is considered as one
of the fathers of computer science.
In 1946, John O. Eckert,
John W. Mauchly of the University of Pennsylvania, built a high-speed
electronic computer, known as ENIAC (Electrical Numerical Integrator
And Calculator). It was successfully used by the Army to calculate
trajectories of artillery shells. ENIAC used 18,000 vacuum tubes,
which had short live cycles and occupied a large room.
Technicians had to change the wiring in order to alter its program.
However, in spite of these limitations, ENIAC was fast (about
300 calculations/s) and was a success!
In 1945, John von Neumann (1903-1957) joined the University of Pennsylvania and designed EDVAC (Electronic Discrete Variable Automatic Computer), a computer with a memory to hold both a stored program as well as data.
In 1951, the UNIVAC I (Universal Automatic Computer) became the first commercially available computer.