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Late 1970s - Present: Fourth Generation Computers |
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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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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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