Even though Leonardo da Vinci made drawings of gear-driven calculators, he never built any, and it was in 1623 that Wilhelm Schickard invented the calculating clock. Later on, in 1642, Blaise Pascal invented the Pascaline, a gear-driven calculador that could only add. Then Leibniz built a four-function calculator (addition, subtraction, multiplication, and division) that he called the Stepped Reckoner, which used fluted drums instead of gears. (Kopplin, 2002).
In 1801, Joseph Marie Jacquard invented the punched cards, which are still in use like in presidential ballots. By 1822, Charles Babbage obtained government funding to build what he called the Difference Engine, a steam-driven calculator. It was very difficult to build, and the machine was never finished. Then Babbage invented the Analytic Engine, using Jacquard's punched cards, adding the key function of the conditional statement. Babbage was a friend of Ada Byron, who is recognized as the first programmer thanks to her writings for the proponed Analytic Engine, which was never built. When the United States needed to speed up the census procedure, Herman Hollerith won a contest by using an invention of his own that used punched cards called the Hollerith Desk. "Hollerith's technique was successful and the 1890 census was completed in only 3 years at a savings of 5 million dollars." (Kopplin, 2002). Hollerith founded the company, the Tabulating Machine Company, which eventually became International Business Machines (IBM).
IBM developed mechanical calculators for businessess, but the U.S. military needed more optimized calculators for scientific computation. As a result of this need, "the Harvard Mark I was built as a partnership between Harvard and IBM in 1944". (Kopplin, 2002). It was an electro-mechanical computer so it was very big and very noisy. It was also the first programmable digital computer made in the United States. In 1953, the first high-level language called Flowmatic was invented by Grace Hopper. This language was later known as COBOL. After using vaccum tubes and transistors for a while, then came the integrated circuit. "The primary advantage of an integrated circuit is not that the transistors (switches) are miniscule (that's the secondary advantage), but rather that millions of transistors can be created and interconnected in a mass-production process". (Kopplin, 2002). The integrated circuit was used by the early 1980's.
One of the first attempts to build an all-electronic digital computer was undertaken by J.V. Atanasoff in 1937. By 1941 he and Clifford Berry built such a machine. It was the first to use binary arithmetic, but it was not programmable. During World War II the computer named Colossus was built by Britain for code breaking. "American and British computer pioneers were still arguing over who was first to do what, when in 1965 the work of the German Konrad Zuse was published for the first time in English." (Kopplin, 2002). Zuse built several computers in Nazi Germany. "The title of forefather of today's all-electronic digital computers is usually awarded to ENIAC, which stood for Electronic Numerical Integrator and Calculator. ENIAC was built at the University of Pennsylvania between 1943 and 1945 by two professors, John Mauchly and the 24 year old J. Presper Eckert, who got funding from the war department after promising they could build a machine that would replace all