Acessing the Internet The Net connections can be based on wire-line and wireless access technolgies. Wire-line access Wire-less access copper wires Satellites coaxial cables mobile terrestrial antennas electric power lines fixed terrestrial antennas fiber-optic cables Usually several kinds of network connections are employed at once. Generally speaking, when an E-mail message is sent it travels from the user's computer via copper wires or coaxial cables ISDN lines, etc., to an Internet Service Provider, from there, via fibre-optic cables, to the nearest Internet exchange, and on into a backbone network, tunneling across the continent und diving through submarine fibre-optic cables across the Atlantic to another Internet exchange, from there, via another backbone network and across another regional network to the Internet Service Provider of the supposed message recipient, from there via cables and wires of different bandwidth arriving at its destination, a workstation permanently connected to the Internet. Finally a sound or flashing icon informs your virtual neighbor that a new message has arrived. Satellite communication Although facing competition from fiber-optic cables as cost-effective solutions for broadband data transmission services, the space industry is gaining increasing importance in global communications. As computing, telephony, and audiovisual technologies converge, new wireless technologies are rapidly deployed occupying an increasing market share and accelerating the construction of high-speed networks. Privatization of satellite communication Until recently transnational satellite communication was provided exclusively by intergovernmental organizations as Intelsat, Intersputnik and Inmarsat. Scheduled privatization of intergovernmental satellite consortia: Satellite consortia Year of foundation Members Scheduled date for privatization Intelsat 1964 200 nations under the leadership of the USA 2001 Intersputnik 1971 23 nations under the leadership of Russia ? Inmarsat 1979 158 nations (all members of the International Maritime Organization) privatized since 1999 Eutelsat 1985 Nearly 50 European nations 2001 When Intelsat began to accumulate losses because of management failures and the increasing market share of fiber-optic cables, this organizational scheme came under attack. Lead by the USA, the Western industrialized countries successfully pressed for the privatization of all satellite consortia they are members of and for competition by private carriers. As of February 2000, there are 2680 satellites in service. Within the next four years a few hundred will be added by the new private satellite systems. Most of these systems will be so-called Low Earth Orbit satellite systems, which are capable of providing global mobile data services on a high-speed level at low cost. Because of such technological improvements and increasing competition, experts expect satellite-based broadband communication to be as common, cheap, and ubiquitous as satellite TV today within the next five or ten years. Major satellite communication projects Project name Main investors Expected cost Number of satellites Date of service start-up Astrolink Lockheed Martin, TRW, Telespazio, Liberty Media Group US$ 3.6 billion 9 2003 Globalstar 13 investors including Loral Space & Communications, Qualcomm, Hyundai, Alcatel, France Telecom, China Telecom, Daimler Benz and Vodafone/Airtouch US$ 3.26 billion 48 1998 ICO 57 investors including British Telecom, Deutsche Telecom, Inmarsat, TRW and Telefonica US$ 4.5 billion 10 2001 Skybridge 9 investors including Alcatel Space, Loral Space & Communications, Toshiba, Mitsubishi and Sharp US$ 6.7 billion 80 2002 Teledesic Bill Gates, Craig McCaw, Prince Alwaleed Bin Talal Bin Abdul Aziz Alsaud, Abu Dhabi Investment Company US$ 9 billion 288 2004 Source: Analysys Satellite Communications Database

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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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John von Neumann b. December 3, 1903, Budapest, Hungary d. February 8, 1957, Washington, D.C., U.S. Mathematician who made important contributions in quantum physics, logic, meteorology, and computer science. His theory of games had a significant influence upon economics. In computer theory, von Neumann did much of the pioneering work in logical design, in the problem of obtaining reliable answers from a machine with unreliable components, the function of "memory," machine imitation of "randomness," and the problem of constructing automata that can reproduce their own kind.

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Terrestrial antennas Microwave transmission systems based on terrestrial antennas are similar to satellite transmission system. Providing reliable high-speed access, they are used for cellular phone networks. The implementation of the Wide Application Protocol (WAP) makes the wireless access to Internet services as E-Mail and even the World Wide Web via cellular phones convenient. Therefore microwave transmission systems become increasingly important.

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