Late 1970s - Present: Fourth Generation Computers Following the invention of the first integrated circuits always more and more components could be fitted onto one chip. LSI (Large Scale Integration) was followed by VLSI (Very Large Scale Integration) and ULSI (Ultra-Large Scale Integration), which increased the number of components squeezed onto one chip into the millions and helped diminish the size as well as the price of computers. The new chips took the idea of the integrated circuit one step further as they allowed to manufacture one microprocessor which could then be programmed to meet any number of demands. Also, ensuing the introduction of the minicomputer in the mid 1970s by the early 1980s a market for personal computers (PC) was established. As computers had become easier to use and cheaper they were no longer mainly utilized in offices and manufacturing, but also by the average consumer. Therefore the number of personal computers in use more than doubled from 2 million in 1981 to 5.5 million in 1982. Ten years later, 65 million PCs were being used. Further developments included the creation of mobile computers (laptops and palmtops) and especially networking technology. While mainframes shared time with many terminals for many applications, networking allowed individual computers to form electronic co-operations. LANs (Local Area Network) permitted computers to share memory space, information, software and communicate with each other. Although already LANs could reach enormous proportions with the invention of the Internet an information and communication-network on a global basis was established for the first time.

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ECHELON Main Stations Location Country Target/Task Relations MORWENSTOW UK INTELSAT, Atlantic, Europe, Indian Ocean NSA, GCHQ SUGAR GROVE USA INTELSAT, Atlantic, North and South America NSA YAKIMA FIRING CENTER USA INTELSAT, Pacific NSA WAIHOPAI NEW ZEALAND INTELSAT, Pacific NSA, GCSB GERALDTON AUSTRALIA INTELSAT, Pacific NSA, DSD MENWITH HILL UK Sat, Groundstation, Microwave(land based) NSA, GCHQ SHOAL BAY AUSTRALIA Indonesian Sat NSA, DSD LEITRIM CANADA Latin American Sat NSA, CSE BAD AIBLING GERMANY Sat, Groundstation NSA MISAWA JAPAN Sat NSA PINE GAP AUSTRALIA Groundstation CIA FORT MEADE USA Dictionary Processing NSA Headquarters WASHINGTON USA Dictionary Processing NSA OTTAWA CANADA Dictionary Processing CSE CHELTENHAM UK Dictionary Processing GCHQ CANBERRA AUSTRALIA Dictionary Processing DSD WELLINGTON NEW ZEALAND Dictionary Processing GCSB Headquarters

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The 19th Century: First Programmable Computing Devices Until the 19th century "early computers", probably better described as calculating machines, were basically mechanical devices and operated by hand. Early calculators like the abacus worked with a system of sliding beads arranged on a rack and the centerpiece of Leibniz's multiplier was a stepped-drum gear design. Therefore Charles Babbage's proposal of the Difference Engine (1822), which would have (it was never completed) a stored program and should perform calculations and print the results automatically, was a major breakthrough, as it for the first time suggested the automation of computers. The construction of the Difference Engine, which should perform differential equations, was inspired by Babbage's idea to apply the ability of machines to the needs of mathematics. Machines, he noted, were best at performing tasks repeatedly without mistakes, while mathematics often required the simple repetition of steps. After working on the Difference Engine for ten years Babbage was inspired to build another machine, which he called Analytical Engine. Its invention was a major step towards the design of modern computers, as it was conceived the first general-purpose computer. Instrumental to the machine's design was his assistant, Augusta Ada King, Countess of Lovelace, the first female computer programmer. The second major breakthrough in the design of computing machines in the 19th century may be attributed to the American inventor Herman Hollerith. He was concerned with finding a faster way to compute the U.S. census, which in 1880 had taken nearly seven years. Therefore Hollerith invented a method, which used cards to store data information which he fed into a machine that compiled the results automatically. The punch cards not only served as a storage method and helped reduce computational errors, but furthermore significantly increased speed. Of extraordinary importance for the evolution of digital computers and artificial intelligence have furthermore been the contributions of the English mathematician and logician George Boole. In his postulates concerning the Laws of Thought (1854) he started to theorize about the true/false nature of binary numbers. His principles make up what today is known as Boolean algebra, the collection of logic concerning AND, OR, NOT operands, on which computer switching theory and procedures are grounded. Boole also assumed that the human mind works according to these laws, it performs logical operations that could be reasoned. Ninety years later Boole's principles were applied to circuits, the blueprint for electronic computers, by Claude Shannon.

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Transistor A transistor is a solid-state device for amplifying, controlling, and generating electrical signals. Transistors are used in a wide array of electronic equipment, ranging from pocket calculators and radios to industrial robots and communications satellites.

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Satellites Communications satellites are relay stations for radio signals and provide reliable and distance-independent high-speed connections even at remote locations without high-bandwidth infrastructure. On point-to-point transmission, the transmission method originally employed on, satellites face increasing competition from fiber optic cables, so point-to-multipoint transmission increasingly becomes the ruling satellite technology. Point-to-multipoint transmission enables the quick implementation of private networks consisting of very small aperture terminals (VSAT). Such networks are independent and make mobile access possible. In the future, satellites will become stronger, cheaper and their orbits will be lower; their services might become as common as satellite TV is today. For more information about satellites, see How Satellites Work (http://octopus.gma.org/surfing/satellites) and the Tech Museum's satellite site (http://www.thetech.org/hyper/satellite). http://www.whatis.com/vsat.htm http://octopus.gma.org/surfing/satellites

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Expert system Expert systems are advanced computer programs that mimic the knowledge and reasoning capabilities of an expert in a particular discipline. Their creators strive to clone the expertise of one or several human specialists to develop a tool that can be used by the layman to solve difficult or ambiguous problems. Expert systems differ from conventional computer programs as they combine facts with rules that state relations between the facts to achieve a crude form of reasoning analogous to artificial intelligence. The three main elements of expert systems are: (1) an interface which allows interaction between the system and the user, (2) a database (also called the knowledge base) which consists of axioms and rules, and (3) the inference engine, a computer program that executes the inference-making process. The disadvantage of rule-based expert systems is that they cannot handle unanticipated events, as every condition that may be encountered must be described by a rule. They also remain limited to narrow problem domains such as troubleshooting malfunctioning equipment or medical image interpretation, but still have the advantage of being much lower in costs compared with paying an expert or a team of specialists.

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