Analog and Digital

The word analog  denotes a phenomenon that is continuously variable, such as a sound wave. The word  digital, on the other hand, implies a discrete, exactly countable value that can be represented as a series of digits. Sound recording provides familiar examples of both approaches. Recording a phonograph record involves electromechanically transferring a physical signal  into an “analogous” physical representation. Recording a CD, on the other hand, involves sampling  the sound level at thousands of discrete instances and storing the results in a physical representation of a numeric format that can in turn be used to drive the playback device. Virtually all modern computers depend on the manipulation of discrete signals in one of two states denoted by the numbers 1 and 0.

Whether the 1 indicates the presence of an electrical charge, a voltage level, a magnetic state, a pulse of light, or some other phenomenon, at a given point there is either “something” (1) or “nothing” (0). This is the most natural way to represent a series of such states. Digital representation has several advantages over analog. Since computer circuits based on binary logic can be driven to perform calculations electronically at ever-increasing speeds, even problems where an analog computer better modeled nature can now be done more efficiently with digital machines. Data stored in digitized form is not subject to the gradual wear or distortion of the medium that plagues analog representations such as the phonograph record. Perhaps most important, because digital representations are at base simply numbers, an infinite variety of digital representations can be stored in files and manipulated, regardless of whether they started as pictures, music, or text

Converting between Analog and Digital Representations:-
Because digital devices  are the mechanism of choice for working with representations of text, graphics, and sound, a variety of devices are used to digitize analog inputs so the data can be stored  and manipulated. Conceptually, each digitizing device can be thought of as having three parts: a component that scans the input and generates an analog signal, a circuit that converts the analog signal from the input to a digital format, and a component that stores the resulting digital data for later use. For example, in the ubiquitous flatbed scanner a moving head reads varying light levels on the paper and converts them to Most natural phenomena such as light or sound intensity are analog values that vary continuously. To convert such  measurements to a digital representation, “snapshots” or sample readings must be taken at regular intervals. Sampling more frequently gives a more accurate representation of the original analog data, but at a cost in memory and processor resources. 12 analog and digital a varying level of current. This analog signal is in turn converted into a digital reading by an analog-todigital converter, which creates numeric information that represents discrete spots (pixels) representing either levels of gray or of particular colors. This information is then written to disk using the formats supported by the operating system and the software that will manipulate them.

America Online (AOL)

For millions of PC users in the 1990s, “going online” meant connecting to America Online. However, this once dominant service provider has had difficulty adapting to the changing world of the Internet. By the mid-1980s a growing number of PC users were starting to go online, mainly dialing up small bulletin board services. Generally these were run by individuals from their homes, offering a forum for discussion and a way for users to upload and download games and other free software and shareware. However, some entrepreneurs saw the possibility of creating a commercial information service that would be interesting and useful enough that users would pay a monthly subscription fee for access. Perhaps the first such enterprise to be successful was Quantum Computer Services, founded by Jim Kimsey in 1985 and soon joined by another young entrepreneur, Steve Case. Their strategy was to team up with personal computer makers such as Commodore, Apple, and IBM to provide special online services for their users. In 1989 Quantum Link changed its name to America Online.

 In 1991 Steve Case became CEO, taking over from the retiring Kimsey. Case’s approach to marketing AOL was to aim the service at novice PC users who had trouble mastering arcane DOS  commands and interacting with text-based bulletin boards and primitive terminal programs. As an alternative, AOL provided a complete software package that managed the user’s connection, presented “friendly” graphics, and offered point-andclick access to features. Chat rooms and discussion boards were also expanded and offered in a variety of formats for casual and more formal use. Gaming, too, was a major emphasis of the early AOL, with some of the first online multiplayer fantasy roleplaying games such as a version of Dungeons and Dragons called Neverwinter Nights.

A third popular application has been instant messaging , including a feature that allowed users to set up “buddy lists” of their friends and keep track of when they were online. Internet Chall enge By 1996 the World Wide Web was becoming popular. Rather than signing up with a proprietary service such as AOL, users could simply get an account with a lower-cost direct-connection service  and then use a Web browser such as Netscape to access information and services. AOL was slow in adapting to the growing use of the Internet. At first, the service provided only limited access to the Web. Gradually, however, AOL offered a more seamless Web experience, allowing users to run their own browsers and other software together with the proprietary interface.

Also, responding to competition, AOL replaced its hourly rates with a flat monthly fee . Overall, AOL increasingly struggled with trying to fulfill two distinct roles: Internet access provider and content provider. By the late 1990s AOL’s monthly rates were higher than those of “no frills” access providers such as NetZero. AOL tried to  compensate for this by offering integration of services  and news and other content not available on the open Internet. AOL also tried to shore up its user base with aggressive marketing to users who wanted to go online but were not sure how to do so. But while it was easy to get started with AOL, some users began to complain that the service would keep billing them even after they had repeatedly attempted to cancel it. Meanwhile, AOL users got little respect from the more sophisticated inhabitants of cyberspace, who often complained that the clueless “newbies” were cluttering newsgroups and chat rooms.  The hope was that the new $350 billion company would be able to leverage its huge subscriber base and rich media resources to dominate the online world.

Amazon.com

Beginning modestly in 1995 as an online bookstore, Amazon.com became one of the first success stories of the early Internet economy. Named for the world’s largest river, Amazon.com was the brainchild of  entrepreneur Jeffrey Bezos. Like a number of other entrepreneurs of the early 1990s, Bezos had been searching for a way to market to the growing number of people who were going online. He soon decided that books were a good first product, since they were popular, nonperishable, relatively compact, and easy to ship. Several million books are in print at any one time, with about 275,000 titles or editions added in 2007 in the United States alone. Traditional “brick and mortar” (physical) bookstores might carry a few thousand titles up to perhaps 200,000 for the largest chains. Bookstores in turn stock their shelves mainly through major  book distributors that serve as intermediaries between publishers and the public.

For an online bookstore such as Amazon.com, however, the number of titles that can be made available is  limited only by the amount of warehouse space the store is willing to maintain—and no intermediary between publisher and bookseller is needed. From the start, Amazon.com’s business model has capitalized on this potential for variety and the ability to serve almost any niche interest. Over the years the company’s offerings have expanded beyond books to 34 different categories of merchandise, including software, music, video, electronics, apparel, home furnishings, and even nonperishable gourmet food and groceries.

Expansion and Profitability:-
Because of its desire to build a very diverse product line, Amazon.com, unusually for a business startup, did not expect to become profitable for about five years. The growing revenues were largely poured back into expansion. In the heated atmosphere of the Internet boom of the late 1990s, many other Internet-based businesses echoed that philosophy, and many went out of business following the bursting of the so-called dot-com bubble of the early 2000s. Some analysts questioned whether even the hugely popular Amazon.com would ever be able to convert its business volume into an operating profit. However, the company achieved its first profitable year in 2003 . Since then growth has remained steady and generally impressive:

In 2005, Amazon.com earned $8.49 billion revenues with a net income of $359 million. By then the company had about 12,000 employees and had been added to the S&P 500 stock index. In 2006 the company   maintained its strategy of investing in innovation rather than focusing on short-term profits. Its latest initiatives include selling digital versions of books and magazine articles, new arrangements to sell video content, and even a venture into moviemaking. By year end, annual revenue had increased to $10.7 billion.