You don’t need to be a mechanic to drive a car but it doesn’t hurt to know a bit about some of the basic principles. It’s much the same with the internet. There’s so much jargon, so many buzzwords and such complexity that it’s tempting to give up. That’s where our Back to Basics guide comes in – we’ll explain how the internet is set up, where your PC fits in, how web browsing works and what happens when you send an email to someone. We’ll also share some handy practical tips that lift the lid on the way the internet works.
A worldwide network
The internet is a worldwide network of computers (including yours, your neighbour’s, Computeractive’s, Google’s and so on). They talk to each other using a shared ‘language’ of standards that define both the physical connections and the way they’re implemented. Though originally invented in the 1960s as military and academic networks linked up, the modern internet can be traced back around 20 years. A research scientist proposed a way of presenting pages of text joined together with hyperlinks. This would become the world wide web as we know it today.
Physical connections
The billions of computers that make up the internet are mainly connected together with cables – everything from the old telephone wire coming out of your house to a fancy fibre-optic cable that can throw data around at light speed.
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For most people, connecting to the internet means using an Asynchronous Digital Subscriber Line (ADSL). Such connections are more commonly referred to as ‘broadband’. The PC connects to a broadband router, which in turn is plugged into a micro-filter connected to a standard phone socket. This ‘splits’ the line so you can talk on the phone while still using the internet.
From here the line goes to the local telephone exchange before heading off to servers owned by your internet service provider (ISP) then out onto the rest of the internet. Fibre-optic cables span continents and oceans and can transmit trillions of bits of information per second. Satellites are also part of the mix.
Most of the time, a home PC is a sort of window shopper, wandering the internet, looking at pages ‘served’ by powerful computers called servers. When visiting sites like www.computeractive.co.uk, our server computer sends the information across the internet to your PC’s web browser when requested.
Looking at web pages
So, when www.computeractive.co.uk is typed into a web browser, how does it know how to find, request and then display that website, rather than any of the billions of others? The answer is an internet protocol address (IP address). Every computer connected to the internet has a unique IP address. They are really numbers and, as every one is different (a bit like phone numbers), it means any computer can find any other computer.
The IP address of the Computeractive website, for example, is 62.140.213.251. Of course, that’s not easy to remember so websites use something called the Domain Name System (or DNS) to ‘translate’ people-friendly addresses like www.bbc.co.uk into computer-friendly ones such as 212.58.244.142. However, it’s still possible to type IP addresses straight into a web browser’s Address or Location bar – type 212.58.244.142 and you’ll reach the BBC website.
Saturday, July 24, 2010
ABSTRACT : UNIVERSE OF COMPUTER
ABSTRACT
This paper describes a universal computer capable of simultaneously executing an arbitrary number of sub-programs, the number of such sub-programs varying as a function of time under program control or as directed by input to the computer. Three features of the computer are:
(1) The structure of the computer is a 2-dimensional modular (or iterative) network so that, if it were constructed, efficient use could be made of the high element density and "template" techniques now being considered in research on microminiature elements.
(2) Sub-programs can be spatially organized and can act simultaneously, thus facilitating the simulation or direct control of "highly-parallel" systems with many points or parts interacting simultaneously (e.g. magneto-hydrodynamic problems or pattern recognition).
(3) The computer's structure and behavior can, with simple generalizations, be formulated in a way that provides a formal basis for theoretical study of automata with changing structure (cf. the relation between Turing machines and computable numbers).
This paper describes a universal computer capable of simultaneously executing an arbitrary number of sub-programs, the number of such sub-programs varying as a function of time under program control or as directed by input to the computer. Three features of the computer are:
(1) The structure of the computer is a 2-dimensional modular (or iterative) network so that, if it were constructed, efficient use could be made of the high element density and "template" techniques now being considered in research on microminiature elements.
(2) Sub-programs can be spatially organized and can act simultaneously, thus facilitating the simulation or direct control of "highly-parallel" systems with many points or parts interacting simultaneously (e.g. magneto-hydrodynamic problems or pattern recognition).
(3) The computer's structure and behavior can, with simple generalizations, be formulated in a way that provides a formal basis for theoretical study of automata with changing structure (cf. the relation between Turing machines and computable numbers).
universal computers
Open a typical history of computing, and you will likely find the names of engineers such as Babbage, Atanasoff, Zuse, Aiken, Mauchly, and Eckert. Why then does Martin Davis's The Universal Computer contain chapters on the logicians Leibniz, Boole, Frege, Cantor, Hilbert, Gödel, and Turing? Because, Davis argues, the old histories tell only half of the story: what the engineers were able to do was to create a universal Turing machine, and it is the idea of a universal computing machine which is truly revolutionary. His book tells the story of this idea.
The story begins with Leibniz. As a student, while learning Aristotle, Leibniz began to formulate what he called "his wonderful idea": to find a way to symbolize all ideas, in such a way that one would then be able to calculate using the symbols. In a sense, his hope was to do for all human thought what algebra had done in mathematics. It is unclear how much progress Leibniz made towards this goal, but in his published works, at least, it was minimal.
The first major advance came when George Boole developed an algebra of logic. His system was able to capture a fair amount of what might be called everyday reasoning, but it still had limitations. Gottlob Frege was able to address these limitations, and in so doing, created essentially the system of first-order logic which we use today. In terms of Leibniz's dream, however, it was not possible to "calculate" easily with Frege's system: no procedure was known for determining whether a given statement is true or false.
The following chapter on Cantor is labelled a "Detour through Infinity." It presents Cantorian set theory, including his diagonal argument and a discussion of the Continuum Hypothesis, but Davis only hints at the reason for this detour. The main thread reappears with Hilbert, as the problem of finding a finite procedure for determining the validity of an expression in first-order logic becomes known as Hilbert's Decision Problem.
Gödel also appears as something of a detour. He did substantial work on other problems from Hilbert, particularly the unprovability of the consistency of arithmetic and the relative consistency of the Continuum Hypothesis. But it took Turing to answer Hilbert's Decision Problem in the negative: no finite procedure can determine the validity of any first-order sentence. In order to do this, Turing needed to conceptualize what any "finite procedure" might look like, and in so doing, he developed what have become known as Turing machines. He then realized that a Turing machine could be created which would mimic the actions of any Turing machine; thus appeared the idea of a universal computer.
Where, then, do Cantor and Gödel fit? Turing used both Cantor's diagonal argument and coding techniques similar to Gödel's in his solution of the Decision Problem. Thus the intellectual history of the universal Turing machine is most clearly read backwards: Turing used ideas from Cantor and Gödel to solve Hilbert's problem in Frege's system of logic which improved Boole's. And all of these were attempts in one way or another to fulfill Leibniz's dream of a calculation system for human reasoning.
It may be clearer in hindsight, but the story is much more interesting when read chronologically, particularly as Davis has written it. Historical background, important secondary characters (particularly Bertrand Russell and John von Neumann), and Davis's own encounters with these ideas and some of the people involved all contribute to a rich and rewarding reading experience. Among its unexpected pleasures are several odd little connections, such as Gödel's essay on Russell which argues that Leibniz must have made more progress towards his calculus of reasoning than we see in his publications, or the founding of Göttingen (Hilbert's home for forty-eight years) by the son of one of Leibniz's patrons.
The story begins with Leibniz. As a student, while learning Aristotle, Leibniz began to formulate what he called "his wonderful idea": to find a way to symbolize all ideas, in such a way that one would then be able to calculate using the symbols. In a sense, his hope was to do for all human thought what algebra had done in mathematics. It is unclear how much progress Leibniz made towards this goal, but in his published works, at least, it was minimal.
The first major advance came when George Boole developed an algebra of logic. His system was able to capture a fair amount of what might be called everyday reasoning, but it still had limitations. Gottlob Frege was able to address these limitations, and in so doing, created essentially the system of first-order logic which we use today. In terms of Leibniz's dream, however, it was not possible to "calculate" easily with Frege's system: no procedure was known for determining whether a given statement is true or false.
The following chapter on Cantor is labelled a "Detour through Infinity." It presents Cantorian set theory, including his diagonal argument and a discussion of the Continuum Hypothesis, but Davis only hints at the reason for this detour. The main thread reappears with Hilbert, as the problem of finding a finite procedure for determining the validity of an expression in first-order logic becomes known as Hilbert's Decision Problem.
Gödel also appears as something of a detour. He did substantial work on other problems from Hilbert, particularly the unprovability of the consistency of arithmetic and the relative consistency of the Continuum Hypothesis. But it took Turing to answer Hilbert's Decision Problem in the negative: no finite procedure can determine the validity of any first-order sentence. In order to do this, Turing needed to conceptualize what any "finite procedure" might look like, and in so doing, he developed what have become known as Turing machines. He then realized that a Turing machine could be created which would mimic the actions of any Turing machine; thus appeared the idea of a universal computer.
Where, then, do Cantor and Gödel fit? Turing used both Cantor's diagonal argument and coding techniques similar to Gödel's in his solution of the Decision Problem. Thus the intellectual history of the universal Turing machine is most clearly read backwards: Turing used ideas from Cantor and Gödel to solve Hilbert's problem in Frege's system of logic which improved Boole's. And all of these were attempts in one way or another to fulfill Leibniz's dream of a calculation system for human reasoning.
It may be clearer in hindsight, but the story is much more interesting when read chronologically, particularly as Davis has written it. Historical background, important secondary characters (particularly Bertrand Russell and John von Neumann), and Davis's own encounters with these ideas and some of the people involved all contribute to a rich and rewarding reading experience. Among its unexpected pleasures are several odd little connections, such as Gödel's essay on Russell which argues that Leibniz must have made more progress towards his calculus of reasoning than we see in his publications, or the founding of Göttingen (Hilbert's home for forty-eight years) by the son of one of Leibniz's patrons.
Consumer Choice
With more than 100,000 products available, German online retailer
computeruniverse.net offers a galaxy of software, hardware, and
accessories. Whether site visitors are looking for business productivity
applications, games, DVDs, consumer electronics, stereo components,
televisions, computer displays, or digital video cameras,
computeruniverse.net is likely to sell it.
But breadth of product isn't the only thing that sets computeruniverse.net
worlds apart from other online stores. According to Alexander Koppisch,
chief executive officer, the site's real difference centers on the quality of
information. computeruniverse.net's depth of merchandise details
contrasts most high-end German computer stores' basic product
specifications and lack of insight or context for customers to find the item
best-suited to their needs.
In addition to a diverse product selection, computeruniverse.net's shoppers
include consumers and business customers in multiple countries.
The majority of site traffic comes from Germany, but German-speaking
residents and business customers in other European countries and the
rest of the world find what they want at computeruniverse.net as well.”
Breadth and Depth of Information Upholds Commitment
to Customers
"We're committed to providing as much data as possible so the customer
will find what he needs," says Koppisch. "The challenge is to provide
comprehensive, up-to-date information and pricing for all the products
we carry, as quickly as possible. That's no small feat when we offer such
a huge selection."
From the outset, computeruniverse.net founders recognized the
enormous challenge that data aggregation would present and sought a
way to automate the collection of information. The company's online
store was even purpose-built by in-house programmers to receive an
automated data feed of some kind.
According to Koppisch, "Manual data collection would have meant
copying some marketing text here or a picture there. It would be
incredibly difficult, inefficient and costly to try to gather extensive data,
keep it up-to-date and organize it consistently so that our customers
could comparison-shop."
However, in Germany there were few suppliers for product data.
computeruniverse.net executives looked at online retail competitors'
sites as a benchmark for the kind of detail a data supplier would need to
provide. The breadth of merchandise information supplied by domestic
service providers paled in comparison, so computeruniverse.net turned
to CNET Channel's DataSource™, in order to achieve its mission of
providing customers with quality information.
"Where the local providers offered information on ten products in a
category, DataSource provided details for 50 items," said Koppisch. "For
every ten features the others listed, DataSource listed two to five times
as many. Those details are crucial for a customer who's purchasing a
motherboard and needs to know which processor he can fit on it, which
RAM he can use, and how configuration will impact performance."
computeruniverse.net also relies on DataSource to provide information
about items related to the product sought, such as accessories for a
digital camera, laptop bags and other merchandise. "Those products
also are part of our commitment to helping the customer make informed
decisions, for a quality shopping experience," adds Koppisch.
To start shopping, visitors to computeruniverse.net can choose the product
category they prefer. They can click on the item they wish to purchase
and see exhaustive information courtesy of DataSource, including a
picture and the price, a description, and extensive feature data. Users
also can select several items and choose the comparison function to see
a side-by-side presentation of DataSource-supplied specifications.
At a Glance
Company:
Website:
Headquarters:
Founded:
Employees:
Summary of Challenges: To distinguish itself from the
competition, computeruniverse.net sought to offer the
broadest and deepest information for about 100,000
technology products running the gamut from business tools
to entertainment software.
Summary of Results: computeruniverse.net's awardwinning
online store serves customers in Germany and
abroad with merchandise details and comparison shopping
capabilities that have created consumer loyalty in the form
of repeat business, and have eliminated the need to
compete on price alone
computeruniverse.net offers a galaxy of software, hardware, and
accessories. Whether site visitors are looking for business productivity
applications, games, DVDs, consumer electronics, stereo components,
televisions, computer displays, or digital video cameras,
computeruniverse.net is likely to sell it.
But breadth of product isn't the only thing that sets computeruniverse.net
worlds apart from other online stores. According to Alexander Koppisch,
chief executive officer, the site's real difference centers on the quality of
information. computeruniverse.net's depth of merchandise details
contrasts most high-end German computer stores' basic product
specifications and lack of insight or context for customers to find the item
best-suited to their needs.
In addition to a diverse product selection, computeruniverse.net's shoppers
include consumers and business customers in multiple countries.
The majority of site traffic comes from Germany, but German-speaking
residents and business customers in other European countries and the
rest of the world find what they want at computeruniverse.net as well.”
Breadth and Depth of Information Upholds Commitment
to Customers
"We're committed to providing as much data as possible so the customer
will find what he needs," says Koppisch. "The challenge is to provide
comprehensive, up-to-date information and pricing for all the products
we carry, as quickly as possible. That's no small feat when we offer such
a huge selection."
From the outset, computeruniverse.net founders recognized the
enormous challenge that data aggregation would present and sought a
way to automate the collection of information. The company's online
store was even purpose-built by in-house programmers to receive an
automated data feed of some kind.
According to Koppisch, "Manual data collection would have meant
copying some marketing text here or a picture there. It would be
incredibly difficult, inefficient and costly to try to gather extensive data,
keep it up-to-date and organize it consistently so that our customers
could comparison-shop."
However, in Germany there were few suppliers for product data.
computeruniverse.net executives looked at online retail competitors'
sites as a benchmark for the kind of detail a data supplier would need to
provide. The breadth of merchandise information supplied by domestic
service providers paled in comparison, so computeruniverse.net turned
to CNET Channel's DataSource™, in order to achieve its mission of
providing customers with quality information.
"Where the local providers offered information on ten products in a
category, DataSource provided details for 50 items," said Koppisch. "For
every ten features the others listed, DataSource listed two to five times
as many. Those details are crucial for a customer who's purchasing a
motherboard and needs to know which processor he can fit on it, which
RAM he can use, and how configuration will impact performance."
computeruniverse.net also relies on DataSource to provide information
about items related to the product sought, such as accessories for a
digital camera, laptop bags and other merchandise. "Those products
also are part of our commitment to helping the customer make informed
decisions, for a quality shopping experience," adds Koppisch.
To start shopping, visitors to computeruniverse.net can choose the product
category they prefer. They can click on the item they wish to purchase
and see exhaustive information courtesy of DataSource, including a
picture and the price, a description, and extensive feature data. Users
also can select several items and choose the comparison function to see
a side-by-side presentation of DataSource-supplied specifications.
At a Glance
Company:
Website:
Headquarters:
Founded:
Employees:
Summary of Challenges: To distinguish itself from the
competition, computeruniverse.net sought to offer the
broadest and deepest information for about 100,000
technology products running the gamut from business tools
to entertainment software.
Summary of Results: computeruniverse.net's awardwinning
online store serves customers in Germany and
abroad with merchandise details and comparison shopping
capabilities that have created consumer loyalty in the form
of repeat business, and have eliminated the need to
compete on price alone
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