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The history of computers

For over a thousand years after the Chinese invented the abacus, not much progress was made to automate counting and mathematics. The Greeks came up with numerous mathematical formulae and theorems, but all of the newly discovered math had to be worked out by hand. A mathematician was often a person who sat in the back room of an establishment with several others and they worked on the same problem. The redundant personnel working on the same problem were there to ensure the correctness of the answer. It could take weeks or months of labourious work by hand to verify the correctness of a proposed theorem. Most of the tables of integrals, logarithms, and trigonometric values were worked out this way, their accuracy unchecked until machines could generate the tables in far less time and with more accuracy than a team of humans could ever hope to achieve.

The first mechanical calculator

Blaise Pascal, noted mathematician, thinker, and scientist, built the first mechanical adding machine in 1642 based on a design described by Hero of Alexandria (2AD) to add up the distance a carriage travelled. The basic principle of his calculator is still used today in water meters and modern-day odometers. Instead of having a carriage wheel turn the gear, he made each ten-teeth wheel accessible to be turned directly by a person's hand (later inventors added keys and a crank), with the result that when the wheels were turned in the proper sequences, a series of numbers was entered and a cumulative sum was obtained. The gear train supplied a mechanical answer equal to the answer that is obtained by using arithmetic.

This first mechanical calculator, called the Pascaline, had several disadvantages. Although it did offer a substantial improvement over manual calculations, only Pascal himself could repair the device and it cost more than the people it replaced! In addition, the first signs of technophobia emerged with mathematicians fearing the loss of their jobs due to progress.

The calculator

While Tomas of Colmar was developing the first successful commercial calculator, Charles Babbage realized as early as 1812 that many long computations consisted of operations that were regularly repeated. He theorized that it must be possible to design a calculating machine which could do these operations automatically. He produced a prototype of this "difference engine" by 1822 and with the help of the British government started work on the full machine in 1823. It was intended to be steam-powered; fully automatic, even to the printing of the resulting tables; and commanded by a fixed instruction program.

In 1833, Babbage ceased working on the difference engine because he had a better idea. His new idea was to build an "analytical engine." The analytical engine was a real parallel decimal computer which would operate on words of 50 decimals and was able to store 1000 such numbers. The machine would include a number of built-in operations such as conditional control, which allowed the instructions for the machine to be executed in a specific order rather than in numerical order. The instructions for the machine were to be stored on punched cards, similar to those used on a Jacquard loom.

A step toward automated computation was the introduction of punched cards, which were first successfully used in connection with computing in 1890 by Herman Hollerith working for the U.S. Census Bureau. He developed a device which could automatically read census information which had been punched onto card. Surprisingly, he did not get the idea from the work of Babbage, but rather from watching a train conductor punch tickets. As a result of his invention, reading errors were consequently greatly reduced, work flow was increased, and, more important, stacks of punched cards could be used as an accessible memory store of almost unlimited capacity; furthermore, different problems could be stored on different batches of cards and worked on as needed. Hollerith's tabulator became so successful that he started his own firm to market the device; this company eventually became International Business Machines (IBM).