Acessing the Internet
The Net connections can be based on wire-line and wireless access technolgies.
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
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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
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Source: Analysys Satellite Communications Database
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1940s - Early 1950s: First Generation Computers
Probably the most important contributor concerning the theoretical basis for the digital computers that were developed in the 1940s was Alan Turing, an English mathematician and logician. In 1936 he created the Turing machine, which was originally conceived as a mathematical tool that could infallibly recognize undecidable propositions. Although he instead proved that there cannot exist any universal method of determination, Turing's machine represented an idealized mathematical model that reduced the logical structure of any computing device to its essentials. His basic scheme of an input/output device, memory, and central processing unit became the basis for all subsequent digital computers.
The onset of the Second World War led to an increased funding for computer projects, which hastened technical progress, as governments sought to develop computers to exploit their potential strategic importance.
By 1941 the German engineer Konrad Zuse had developed a computer, the Z3, to design airplanes and missiles. Two years later the British completed a secret code-breaking computer called Colossus to decode German messages and by 1944 the Harvard engineer Howard H. Aiken had produced an all-electronic calculator, whose purpose was to create ballistic charts for the U.S. Navy.
Also spurred by the war the Electronic Numerical Integrator and Computer (ENIAC), a general-purpose computer, was produced by a partnership between the U.S. government and the University of Pennsylvania (1943). Consisting of 18.000 vacuum tubes, 70.000 resistors and 5 million soldered joints, the computer was such a massive piece of machinery (floor space: 1,000 square feet) that it consumed 160 kilowatts of electrical power, enough energy to dim lights in an entire section of a bigger town.
Concepts in computer design that remained central to computer engineering for the next 40 years were developed by the Hungarian-American mathematician John von Neumann in the mid-1940s. By 1945 he created the Electronic Discrete Variable Automatic Computer (EDVAC) with a memory to hold both a stored program as well as data. The key element of the Neumann architecture was the central processing unit (CPU), which allowed all computer functions to be coordinated through a single source. One of the first commercially available computers to take advantage of the development of the CPU was the UNIVAC I (1951). Both the U.S. Census bureau and General Electric owned UNIVACs (Universal Automatic Computer).
Characteristic for first generation computers was the fact, that instructions were made-to-order for the specific task for which the computer was to be used. Each computer had a different binary-coded program called a machine language that told it how to operate. Therefore computers were difficult to program and limited in versatility and speed. Another feature of early computers was that they used vacuum tubes and magnetic drums for storage.
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The 18th Century: Powered Machines and the Industrial Revolution
The invention of the steam engine by James Watt in 1776 represented a major advance in the development of powered machines. It was first applied to an industrial operation - the spinning of cotton - in 1785. A new kind of work-slave it not only marked the beginning of the Industrial Revolution, but also the coming age of mass production.
In the England of the 18th century five important inventions in the textile industry advanced the automation of work processes. 1) John Kay's flying shuttle in 1733 , which permitted the weaving of larger widths of cloth and significantly increased weaving speed, 2) Edmund Cartwright's power loom in 1785, which increased weaving speed still further, 3) James Hargreaves' spinning jenny in 1764, 4) Richard Arkwright's water frame and 5) Samuel Crompton's spinning mule in 1779, whereby the last three inventions improved the speed and quality of thread-spinning operations. Those developments, combined with the invention of the steam engine, in short time led to the creation of new machine-slaves and the mechanization of the production of most major goods, such as iron, paper, leather, glass and bricks.
Large-scale machine production was soon applied in many manufacturing sectors and resulted in a reduction of production costs. Yet the widespread use of the novel work-slaves also led to new demands concerning the work force's qualifications. The utilization of machines enabled a differentiated kind of division of labor and eventuated in a (further) specialization of skills. While before many goods were produced by skilled craftsmen the use of modern machinery increased the demand for semiskilled and unskilled workers. Also, the nature of the work process altered from one mainly dependent on physical power to one primarily dominated by technology and an increasing proportion of the labor force employed to operate machines.
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World Wide Web (WWW)
Probably the most significant Internet service, the World Wide Web is not the essence of the Internet, but a subset of it. It is constituted by documents that are linked together in a way you can switch from one document to another by simply clicking on the link connecting these documents. This is made possible by the Hypertext Mark-up Language (HTML), the authoring language used in creating World Wide Web-based documents. These so-called hypertexts can combine text documents, graphics, videos, sounds, and Java applets, so making multimedia content possible.
Especially on the World Wide Web, documents are often retrieved by entering keywords into so-called search engines, sets of programs that fetch documents from as many servers as possible and index the stored information. (For regularly updated lists of the 100 most popular words that people are entering into search engines, click  here). No search engine can retrieve all information on the whole World Wide Web; every search engine covers just a small part of it.
Among other things that is the reason why the World Wide Web is not simply a very huge database, as is sometimes said, because it lacks consistency. There is virtually almost infinite storage capacity on the Internet, that is true, a capacity, which might become an almost everlasting too, a prospect, which is sometimes consoling, but threatening too.
According to the Internet domain survey of the Internet Software Consortium the number of Internet host computers is growing rapidly. In October 1969 the first two computers were connected; this number grows to 376.000 in January 1991 and 72,398.092 in January 2000.
World Wide Web History Project, http://www.webhistory.org/home.html
 http://www.searchwords.com/
http://www.islandnet.com/deathnet/
http://www.salonmagazine.com/21st/feature/199...
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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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Bandwidth
The bandwidth of a transmitted communications signal is a measure of the range of frequencies the signal occupies. The term is also used in reference to the frequency-response characteristics of a communications receiving system. All transmitted signals, whether analog or digital, have a certain bandwidth. The same is true of receiving systems.
Generally speaking, bandwidth is directly proportional to the amount of data transmitted or received per unit time. In a qualitative sense, bandwidth is proportional to the complexity of the data for a given level of system performance. For example, it takes more bandwidth to download a photograph in one second than it takes to download a page of text in one second. Large sound files, computer programs, and animated videos require still more bandwidth for acceptable system performance. Virtual reality (VR) and full-length three-dimensional audio/visual presentations require the most bandwidth of all.
In digital systems, bandwidth is data speed in bits per second (bps).
Source: Whatis.com
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