The historyof computing began with an analog computer. In 1623 German scientist WilhemSchikard invented a machine that used 11 complete and 6 incompletesprocket wheels that could add, and with the help of logarithm tables,multiply and divide.
French philosopher, mathematician,and physicist Blaise Pascal invented a machine in 1642 that added and subtracted,automatically carrying and borrowing digits from column to column. Pascal built 50 copies of his machine, but most served as curiosities inparlors of the wealthy. Seventeenth-century German mathematicianGottfried Leibnitz designed a special gearing system to enable multiplicationon Pascal's machine.
Another early mechanical computerwas the Difference Engine, designed in the early 1820's by British mathematicianand scientist Charles Babbage. Although never completed by Babbage,the Difference Engine was intended to be a machine with a twenty decimalcapacity that could solve mathematical problems. Babbage also madeplans for another machine, the Analytical Engine, considered to be themechanical forerunner of the modern computer. The Analytical Enginewas designed to perform all arithmetic operations efficiently; howeverBabbage's lack of political skills kept him from attaining the approvaland funds to build it. In the end neither computer was ever finished. If one of them had been finished it would probably have been consideredthe first machine operated computer ever built. 
In the 1930's American mathematicianHoward Aiken developed the Mark 1 calculating machine, which was builtby I.B.M. This electronic calculating machine used relays and electromagnetcomponents to replace mechanical components. In later machines, Aikenused vacuum tubes and solid state transistors (tiny little electrical switches)to manipulate the Binary numbers. Aiken also introduced computersto universities by establishing the first computer science program at HarvardUniversity. Aiken never trusted the concept of storing a programwithin the computer. Instead his computer had to read numbers frompunched cards. 
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