3-D browser
A 3-D browser is a Web browser that allows the viewer to view and interact with six Web pages at a time by creating a virtual room on the viewer’s screen. Instead of opening six Web pages, minimizing your screen and toggling back and forth between pages, imagine you are standing inside a six-sided cube and each side of the cube is displaying a Web page. There is a Web page in front of you, a Web page on each side of you, a page above you, a page below you and a page behind you. You can use your cursor to rotate the cube and put any side of the cube directly in front of you. Links on all the pages are active, so you can click from page to page and change the "walls" of your virtual Web room. If you see something that catches your interest, you can use the zoom feature to enlarge the "wall" so that it becomes a traditional page viewed on your flat screen.
The concept of a 3-D Web browser has been promoted by former architect and chief executive officer of 2ce, Mike Rosen. Rosen hopes that the next generation of computer users, who have grown up multi-tasking in virtual reality gaming environments, will embrace a 3-D version of the Web. Besides being fun, Rosen believes that having the ability to view multiple pages will be of practical use to day traders and others whose occupations require them to view multiple Web pages throughout the day.
3G
3G is a short term for third-generation wireless, and refers to near-future developments in personal and business wireless technology, especially mobile communications. This phase is expected to reach maturity between the years 2003 and 2005.
The third generation, as its name suggests, follows the first generation (1G) and second generation (2G) in wireless communications. The 1G period began in the late 1970s and lasted through the 1980s. These systems featured the first true mobile phone systems, known at first as "cellular mobile radio telephone." These networks used analog voice signaling, and were little more sophisticated than repeater networks used by amateur radio operators. The 2G phase began in the 1990s, and much of this technology is still in use. The 2G cell phone features digital voice encoding. Examples include CDMA, TDMA, and GSM. Since its inception, 2G technology has steadily improved, with increased bandwidth, packet routing, and the introduction of multimedia. The present state of mobile wireless communications is often called 2.5G.
Ultimately, 3G is expected to include capabilities and features such as
• Enhanced multimedia (voice, data, video, and remote control)
• Usability on all popular modes (cellular telephone, e-mail, paging, fax, videoconferencing, and Web browsing)
• Broad bandwidth and high speed (upwards of 2 Mbps)
• Routing flexibility (repeater, satellite, LAN)
• Operation at approximately 2 GHz transmit and receive frequencies
• Roaming capability throughout Europe, Japan, and North America
While 3G is generally considered applicable mainly to mobile wireless, it is also relevant to fixed wireless and portable wireless. The ultimate 3G system might be operational from any location on, or over, the earth’s surface, including use in or by
• Homes
• Businesses
• Government offices
• Medical establishments
• The military
• Personal and commercial land vehicles
• Private and commercial watercraft and marine craft
• Private and commercial aircraft (except where passenger use restrictions apply)
• Portable (pedestrians, hikers, cyclists, campers)
• Space stations and spacecraft
Proponents of 3G technology promise that it will "keep people connected at all times and in all places.”
3-tier application
A 3-tier application is an application program that is organized into three major parts, each of which is distributed to a different place or places in a network. The three parts are
• The workstation or presentation interface
• The business logic
• The database and programming related to managing it
In a typical 3-tier application, the application user’s workstation contains the programming that provides the graphical user interface (GUI) and application-specific entry forms or interactive windows. (Some data that is local or unique for the workstation user is also kept on the local hard disk.)
Business logic is located on a local area network (LAN) server or other shared computer. The business logic acts as the server for client requests from workstations. In turn, it determines what data is needed (and where it is located) and acts as a client in relation to a third tier of programming that might be located on a mainframe computer.
The third tier includes the database and a program to manage read and write access to it. While the organization of an application can be more complicated than this, the 3-tier view is a convenient way to think about the parts in a large-scale program.
A 3-tier application uses the client/server computing model. With three tiers or parts, each part can be developed concurrently by different team of programmers coding in different languages from the other tier developers. Because the programming for a tier can be changed or relocated without affecting the other tiers, the 3-tier model makes it easier for an enterprise or software packager to continually evolve an application as new needs and opportunities arise. Existing applications or critical parts can be permanently or temporarily retained and encapsulated within the new tier of which it becomes a component.
42
42 is the number from Douglas Adams’ The Hitchhiker’s Guide to the Galaxy from which all meaning (”the meaning of life, the universe, and everything”) could be derived. A BBC radio script based on Adams’ book contains the following lines:
(”Cave man” lays out following sentence in Scrabble stones: ”What do you get if you multiply six by nine?”)
Arthur: Six by nine? Forty-two? You know, I’ve always felt that there was something fundamentally wrong with the Universe. (Faint and distant voice:) Base thirteen!
For the literal-minded and those unfamiliar with terms like ”base thirteen,” this is a number system in which the number 10 is equivalent to our more familiar decimal 13. A base-13 number 42, therefore, is the same as four 13s plus 2, or decimal 54. So ”six by nine” (six times nine) or decimal 54 is, in base 13, 42. For the mystically inclined, 42 in base 13 is the same as 110110 in binary (base 2). This could mean almost anything, and many Adams fans have spent untold hours discovering all of the places where the number ”42” pops up. For example, there are many mentions of the number in the Book of Revelations. Others have made a game of finding 42s, such as these:
• The angle at which light reflects off of water to create a rainbow is 42 degrees.
• Two physical constants in the universe are the speed of light and the diameter of a proton. It takes light 10 to the minus 42nd power seconds to cross the diameter of a proton.
• A barrel holds 42 gallons.
(It should be noted that all of these 42′s are base 10, not base 13.)
404
404 is a frequently-seen status code that tells a Web user that a requested page is ”Not found.” 404 and other status codes are part of the Web’s Hypertext Transfer Protocol (HTTP), written in 1992 by the Web’s inventor, Tim Berners-Lee. He took many of the status codes from the earlier Internet protocol for transferring files, the File Transfer Protocol (FTP).
What to Do If You Get a 404
If the site no longer exists, there’s nothing you can do. However, it only takes one mistyped character to result in a 404. See whether the ”.htm” should be an ”.html” or vice versa. If you’re linking from a Web site, you can do a ”View source” to make sure it wasn’t miscoded. Whether or not it is, you may want to send a note to the Webmaster so that the link can be fixed for the next users.
How to Handle 404s If You Have a Web Site
Here are some things you can do:
• Use a Web site analysis tool such as Web Trends or Weblog to identify links that result in 404s, then fix the links.
• If you change the Uniform Resource Locator (URL) for a page on your site, retain the old URL as a redirect file, putting a message on it and inserting a META element with a REFRESH to change to the new URL in a specified number of seconds.
• You can create the page contents for a 404 status code page and substitute it for the 404 page that the browser usually provides. This will allow you to personalize the message and encourage the user to send a note to the Webmaster so that the situation can be fixed.
4G
4G is the short term for fourth-generation wireless, the stage of broadband mobile communications that will follow the still-burgeoning third generation (3G) that is expected to reach maturity between 2003-2005. 4G services are expected to be introduced first in Japan, as early as 2006—four years ahead of the previous target date. The major distinction of 4G over 3G communications is increased data transmission rates, just as it is for 3G over 2G and 2.5G (the present state of wireless services, hovering somewhere between 2G and 3G). According to NTT-DoCoMo, the leading Japanese wireless company, the current download speed for i-mode (mobile internet service) data is—theoretically—9.6 Kbps, although in practice the rates tend to be slower. 3G rates are expected to reach speeds 200 times that, and 4G to yield further increases, reaching 20-40 Mbps (about 10-20 times the current rates of ADSL service).
4G is expected to deliver more advanced versions of the same improvements promised by 3G, such as enhanced multimedia, smooth streaming video, universal access, and portability across all types of devices. Industry insiders are reluctant to predict the direction that less-than-immediate future technology might take, but 4G enhancements are expected to include worldwide roaming capability. As was projected for the ultimate 3G system, 4G might actually connect the entire globe and be operable from any location on—or above—the surface of the earth.
64-bit processor
A 64-bit processor is a microprocessor with a word size of 64 bits, a requirement for memory and data intensive applications such as computer-aided design (CAD) applications, database management systems, technical and scientific applications, and high-performance servers. 64-bit computer architecture provides higher performance than 32bit architecture by handling twice as many bits of information in the same clock cycle.
The 64-bit processor is backwards compatible with older applications and operating systems; it detects whether an application or operating system is 16-bit, 32-bit, or 64-bit and computes accordingly. This is essential for enterprise situations where purchasing new software is not feasible.
Intel, IBM, Sun Microsystems, Hewlett Packard, and AMD currently develop or offer 64-bit processors.
80
If you occasionally see a mysterious "80" on the name of a Web server that is handling your request for Web pages, this is a bit of technical stuff showing through when perhaps it shouldn’t. A Web server sits and waits for requests from a client (such as your Web browser). Most Web servers are set up to "awaken" and respond to requests from clients whose Uniform Resource Locator (URL) requests include "port 80” as part of their information. When you see the "80" showing up in the server address at the bottom of your screen, all it means is that the server uses the usual default port number. (You don’t usually see this because some servers can be set up so that this number is not visible to the browser user.)
802.11
In wireless LAN (WLAN) technology, 802.11 refers to a family of specifications developed by a working group of the Institute of Electrical and Electronics Engineers (IEEE). There are three specifications in the family: 802.11, 802.11a, and 802.11b. All three specify the use of CSMA/CA (carrier sense multiple access with collision avoidance) as the path-sharing protocol.
The 802.11 and 802.11b specifications apply to wireless Ethernet LANs, and operate at frequencies in the 2.4-GHz region of the radio spectrum. Data speeds are generally 1 Mbps or 2 Mbps for 802.11, and 5.5 Mbps or 11 Mbps for 802.11b, although speeds up to about 20 Mbps are realizable with 802.11b. The 802.11b standard is backward compatible with 802.11. The modulation used in 802.11 has historically been phase-shift keying (PSK). The modulation method selected for 802.11b is known as complementary code keying (CCK), which allows higher data speeds and is less susceptible to multipath-propagation interference.
The 802.11a specification applies to wireless ATM systems and operates at radio frequencies between 5 GHz and 6 GHz. A modulation scheme known as OFDM (orthogonal frequency-division multiplexing) makes possible data speeds as high as 54 Mbps, but most commonly, communications take place at 6 Mbps, 12 Mbps, or 24 Mbps. Also see HiperLAN.
802.3
802.3 is a standard specification for Ethernet, a method of physical communication in a local area network (LAN), which is maintained by the Institute of Electrical and Electronics Engineers (IEEE). In general, 802.3 specifies the physical media and the working characteristics of Ethernet. The original Ethernet supports a data rate of 10 megabits per second (Mbps) and specifies these possible physical media:
• 10BASE-2 (Thinwire coaxial cable with a maximum segment length of 185 meters)
• 10BASE-5 (Thickwire coaxial cable with a maximum segment length of 500 meters)
• 10BASE-F (optical fiber cable)
• 10BASE-T (ordinary telephone twisted pair wire)
• 10BASE-36 (broadband multi-channel coaxial cable with a maximum segment length of 3,600 meters)
This designation is an IEEE shorthand identifier. The "10" in the media type designation refers to the transmission speed of 10 Mbps. The "BASE" refers to baseband signalling, which means that only Ethernet signals are carried on the medium (or, with 10BASE-36, on a single channel). The "T" represents twisted-pair; the "F" represents fiber optic cable; and the "2", "5", and "36" refer to the coaxial cable segment length (the 185 meter length has been rounded up to "2" for 200).
8-VSB
8-VSB (8-level vestigial sideband) is a standard radio frequency (RF) modulation format chosen by the Advanced Television Systems Committee (ATSC) for the transmission of digital television (DTV) to consumers in the United States and other adopting countries. In the US, the standard is specified by the Federal Communications Commission (FCC) for all digital television broadcasting. Countries in Europe and elsewhere have adopted an alternative format called Coded Orthogonal Frequency Division Multiplexing (COFDM).
The main ATSC standards for DTV are 8-VSB, which is used in the transmission of video data, MPEG-2 for video signal compression, and Dolby Digital for audio coding.
The 8-VSB mode includes eight amplitude levels that support up to 19.28 Mbps of data in a single 6 Mhz channel. There is also a 16-VSB mode that has 16 amplitude levels and supports up to 38.57 Mbps of data on a 6 Mhz channel. 8-VSB is considered effective for the simultaneous transmission of more than one DTV program (multicasting) and the transmission of data along with a television program (datacasting) because it supports large data payloads. The ATSC adopted the VSB transmission system because of its large bandwidth, which is needed to transmit HDTV (high definition television) programming. Detractors claim that this larger bandwidth is irrelevant if customers cannot view the transmitted program because of multipath effects. When a signal is transmitted, it is met with obstructions such as canyons, buildings, and even people, which scatter the signal, causing it to take two or more paths to reach its final destination, the television set. The late arrival of the scattered portions of the signal causes ghost images. For this reason, some consumers in metropolitan areas or areas with rugged terrain opt for cable television instead of fighting their antennas for better reception. Because a VSB signal is transmitted on one carrier, it scatters like water blasted on a wall when met with obstacles, which is not a problem with Coded Orthogonal Frequency Division Multiplexing (COFDM), the European standard modulation technique, because it transmits a signal on multiple carriers.
VSB advocates state that simply buying an outdoor antenna that rotates solves the multipath interference problem, but critics worry that customers do not want to buy an expensive rotating outdoor antenna to view free television programs. They also worry that the poor reception and the added expense of an outdoor antenna are slowing the transition to DTV in ATSC-compliant countries. The VSB scheme also does not support mobile television viewing. VSB equipment manufacturers are working on solutions to these two problems.
