This first section outlines the historical events leading to the development of the microprocessor and, specifically, the extremely powerful and current 80386, 80486, and Pentium microprocessors. Although a study of history is not essential to understanding the microprocessor, it furnishes interesting reading and provides a historical retrospective of the evolution of the computer.
The idea of a computing system is not new--it has been around long before electrical and electronic devices. The idea of calculating with a machine dates to at least 500 BC when the Babylonians invented the abacus, the first mechanical calculator. The abacus was used by the ancient Babylonian priesthood to keep track of their vast storehouses of grain. The abacus, which was used extensively and is still in use today, was not improved until 1643, when Blaise Pascal, the mathematician, invented a calculator constructed of gears and wheels. Each gear contained 10 teeth that, when moved one complete revolution, advanced a second gear one place. This is the same principal employed in the odometer mechanism in the automobile and is the basis of all mechanical calculators. Incidentally, the Pascal programming language is named in honor of Blaise Pascal for his pioneering work in mathematics and with the mechanical calculator.
The arrival of first practical geared, mechanical machines used to automatically compute information dates to the early 1800's. Realize that this is before humans invented the light bulb or before much was known about electricity. In this dawn of the computer age, humans dreamed of mechanical machines that computed numerical facts using a program--not merely calculating facts as with a calculator.
It was discovered in 1937, through plans and journals, that one early pioneer of mechanical computing machinery was Charles Babbage. Babbage was commissioned in 1823 by the Royal Astronomical Society of Great Britain to produce a programmable calculating machine. This machine was to generate navigational tables for the Royal Navy. He accepted the challenge and began to create what he called his "Analytical Engine". This engine was a mechanical computer that stored 1000 twenty-digit decimal numbers and a variable program that could modify the machine to perform various calculating tasks. Input to his engine was through punched cards, much as computers in the 1950's and 1960's used punched cards. It is assumed that he obtained the idea of using punched cards from Jacquard, a Frenchman who used punched cards, in 1801, as input to a weaving machine that is today called Jacquard's loom. Jacquard's loom used punched cards to weave intricate patterns in the cloth that it produced. The punched cards programmed the loom.
After many years of work, Babbages's dream began to fade when he realized that the machinists of his day were unable to create the mechanical parts needed to complete his work. The Analytical Engine required more than 50,000 machined parts, which could not be made with enough precision to allow his engine to function reliably.
The late 1800's saw the advent of the electric motor and with it came a multitude of motor-driven adding machines all based on the mechanical calculator developed by Blaise Pascal. These mechanical calculators were common pieces of office equipment until well into the early 1970's, when the small hand-held electronic calculator, first introduced by Bomar, appeared. Monroe was also a leading pioneer of electronic calculator's, but their machines were desktop, four-function models the size of cash registers.
In 1889 Herman Hollerith developed the punched-card for storing data. He also developed a mechanical machine--driven by one of the new electric motors--that counted, sorted, and collated information stored on punched cards. The idea of calculating by machinery intrigued the United States government so much that Hollerith was commissioned to use his punched-card system to store and tabulate information for the 1890 census.
In 1896, Hollerith formed a company called the Tabulating Machine Company. This company developed a line of machines that used punched-cards for tabulation. After a number of mergers, the Tabulating Machine Company was formed into the International Business Machines Corporation, now referred to more commonly as IBM, Inc. We often refer to the punched-cards used in computer systems as Hollerith cards in honor of Herman Hollerith. The 12-bit code used on a punched-card is called the Hollerith code
Mechanical machines driven by electric motors continued to dominate the information processing world until the advent of the first electronic calculating machine in 1942 by a German inventor named Konrad Zuse. His calculating computer, the Z3, was used in aircraft and missile design during World War II for the German war effort. Had Zuse been given funding my the German government, he most likely would have developed a much more powerful computer system. Zuse is today finally receiving some belated honor for his pioneering work in the area of digital electronics that began in the 1930's.
It has been recently discovered (through the declassification of British military documents) that the first truly electronic computer was placed into operation in 1943 to break secret German military codes. This first electronic computer system, which used vacuum tubes, was invented by Alan Turing. Turing called his machine Colossus, most likely because of its size. A problem with Colossus was that its design allowed it to break secret German military codes, but it could not solve other problems. Colossus was not programmable, it was a fixed-program computer system, which we today often call a special-purpose computer.
The first general-purpose, programmable electronic computer system was developed in 1947 at the University of Pennsylvania. This first, of the modern computers, was called the ENIAC (Electronics Numerical Integrator and Calculator). The ENIAC was a huge machine containing over 17,000 vacuum tubes and over 500 miles of wires. This massive machine weighted over 30 tons, yet only performed about 100,000 operations per second. The ENIAC thrust the world into the age of electronic computers. The ENIAC was programmed by rewiring its circuits. This programming required a many days to accomplish by many workers who changed electrical connections on plug-boards that looked much like early telephone switchboards. Another problem with the ENIAC was the life of the vacuum tube components, which required almost constant maintenance.