10BASE- 2
10BASE-2, one of several physical media specified by IEEE 802.3 for use in an Ethernet local area network (LAN), consists of Thinwire coaxial cable with a maximum segment length of 185 meters. Like other specified media, 10BASE-2 supports Ethernet’s 10 Mbps data rate.
In addition to 10BASE-2, 10 megabit Ethernet can be implemented with these media types:
• 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 Institute of Electrical and Electronics Engineers (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).
10BASE-5
10BASE-5, one of several physical media specified by IEEE 802.3 for use in an Ethernet local area network (LAN), consists of Thickwire coaxial cable with a maximum segment length of 500 meters. Like other specified media, 10BASE-2 supports Ethernet’s 10 Mbps data rate.
In addition to 10BASE-5, 10 megabit Ethernet can be implemented with these media types:
• 10BASE-2 (Thinwire coaxial cable with a maximum segment length of 185 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 Institute of Electrical and Electronics Engineers (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).
IOBASE-36
10BASE-36 is a type of physical cabling defined in the IEEE 802.3 (Ethernet) standard for broadband application. Although Ethernet is inherently a baseband system, 10BASE-36 specifies the use of a 10-megahertz signal on each channel within a 75-ohm coaxial broadband cable so that bandwidth is effectively expanded. Each channel requires 3 pairs of wires in the coaxial cable. Baseband differential phase-shift keying (PSK) is used to modulate the signal on each channel. Each channel has a transmission speed of 10 Mbps. The cable can extend for up to 3,600 meters.
10BASE-F
10BASE-F, one of several physical media specified by IEEE 802.3, is the use of optical fiber in an Ethernet local area network (LAN). Like other specified media, 10BASE-F supports Ethernet’s 10 Mbps data rate.
In addition to 10BASE-F, 10 megabit Ethernet can be implemented with these media types:
• 10BASE-2 (Thinwire coaxial cable with a maximum segment length of 185 meters)
• 10BASE-5 (Thicknet coaxial cable with a maximum segment length of 500 meters)
• 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 Institute of Electrical and Electronics Engineers (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).
10BASE-T
10BASE-T, one of several physical media specified in the IEEE 802.3 standard for Ethernet local area networks (LANs), is ordinary telephone twisted pair wire. 10BASE-T supports Ethernet’s 10 Mbps transmission speed. In addition to 10BASE-T, 10 megabit Ethernet can be implemented with these media types:
• 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-36 (broadband coaxial cable carrying multiple baseband channels for a maximum length of 3,600 meters)
This designation is an Institute of Electrical and Electronics Engineers (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. 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).
100BASE-T
In 100 Mbps (megabits per second) Ethernet (known as Fast Ethernet), there are three types of physical wiring that can carry signals:
• 100BASE-T4 (four pairs of telephone twisted pair wire)
• 100BASE-TX (two pairs of data grade twisted-pair wire)
• 100BASE-FX (a two-strand optical fiber cable)
This designation is an Institute of Electrical and Electronics Engineers shorthand identifier. The "100" in the media type designation refers to the transmission speed of 100 Mbps. The "BASE" refers to baseband signalling, which means that only Ethernet signals are carried on the medium. The "T4," "TX," and "FX" refer to the physical medium that carries the signal. (Through repeaters, media segments of different physical types can be used in the same system.) The TX and FX types together are sometimes referred to as "100BASE-X." (The designation for "100BASE-T" is also sometimes seen as "100BaseT.")
1000BASE-T
1000BASE-T is Gigabit Ethernet (1 gigabit is 1000 megabits per second) on copper cables, using four pairs of Category 5 unshielded twisted pair to achieve the gigabit data rate. 1000BASE-T can be used in data centers for server switching, for uplinks from desktop computer switches, or directly to the desktop for broadband applications. A big advantage of 1000BASE-T is that existing copper cabling can be used instead of having to rewire with optical fiber.
For Gigabit Ethernet, industry offerings include these types of wiring:
• 1000BASE-SX (a short laser wavelength on multimode fiber optic cable for a maximum length of 550 meters)
• 1000BASE-LX/LH (a long wavelength for a "long haul” fiber optic cable for a maximum length of 10 kilometers)
• 1000BASE-ZX (an extended wavelength single-mode optical fiber for up to 100 kilometers)
• 1000BASE-CX (two pairs of 150-ohm shielded twisted pair cable for a maximum length of 25 meters)
• 1000BASE-T (four pairs of Category 5 unshielded twisted pair cable for a maximum length of 100 meters)
The 1000BASE designation is an IEEE shorthand identifier. The "1000" in the media type designation refers to the transmission speed of 1000 Mbps. The "BASE" refers to baseband signalling, which means that only Ethernet signals are carried on the medium. (Through repeaters, media segments of different physical types can be sometimes be used in the same system.)
The designation for "1000BASE-T" is also sometimes seen as "1000BaseT."
10-Gigabit Ethernet
10-Gigabit Ethernet, being standardized in IEEE 802.3a, is a developing telecommunication technology that offers data speeds up to 10 billion bits per second. Built on the Ethernet technology used in most of today’s local area networks (LANs), 10-Gigabit Ethernet is described as a "disruptive" technology that offers a more efficient and less expensive approach to moving data on backbone connections between networks while also providing a consistent technology end-to-end. Using optical fiber, 10-Gigabit Ethernet can replace existing networks that use ATM switches and SONET multiplexers on an OC-48 SONET ring with a simpler network of 10-Gigabit Ethernet switches and at the same time improve the data rate from 2.5 Gbps to 10 Gbps.
10-Gigabit Ethernet is expected to be used to interconnect local area networks (LANs), wide area networks (WANs), and metropolitan area networks (MANs). 10-Gigabit Ethernet uses the familiar IEEE 802.3 Ethernet media access control (MAC) protocol and its frame format and size. Like Fast Ethernet and Gigabit Ethernet, 10-Gigabit Ethernet uses full-duplex transmission, which makes possible a considerable distance range. On multimode fiber, 10-Gigabit Ethernet will support distances up to 300 meters; on single mode fiber, it will support distances up to 40 kilometers. Smaller Gigabit Ethernet networks can feed into a 10-Gigabit Ethernet network.
10-high-day busy period
In designing and assessing networks, the peak load is sometimes measured using the 10HD (10-high-day) busy period method. The 10HD busy period is the average of the amount of traffic during the busiest hour of the 10 days during the year when the overall traffic is heaviest.
Another index to peak traffic is the average bouncing busy hour (ABBH).
121
In Internet e-commerce, 121 is short for one-to-one, the philosophy that treating each customer as a special individual is a more successful approach than treating customers as a group of similar individuals.
1170
”Spec 1170” was the working name of the standard UNIX programming interface specification that is now known as X/Open Programming Guide 4.2 (XPG 4.2). The specification has also been known as the ”Single UNIX Specification" and, most recently, as ”UNIX 98.” In the ”Spec 1170” or first version of the Single UNIX Specification, there were 1,170 C language functions or individual instructions.
The Single UNIX Specification is maintained by The Open Group, which certifies implementations and provides UNIX product branding following conformance assurance and testing.
1284
The IEEE 1284 parallel interface standard is the prevalent standard for connecting a computer to a printer or certain other devices over a parallel (eight bits of data at a time) physical and electrical interface. The physical connection is similar to the older Centronics interface, which it continues to support. Whereas the Centronics interface only allowed data to flow in one direction, from computer to peripheral, IEEE 1284 also supports bi-directional data flow.
When the Centronics parallel interface was first developed, the main peripheral was the printer. Since then, portable disk drives, tape drives, and CD-ROM players are among devices that have adopted the parallel interface. These new uses caused manufacturers to look at new ways to make the Centronics parallel interface better. In 1991, Lexmark, IBM, Texas Instruments, and others met to discuss a standard that would offer more speed and bi-directional communication. Their effort and the sponsorship of the Institute of Electrical and Electronics Engineers (IEEE) resulted in the IEEE 1284 committee. The IEEE 1284 standard was approved for release in March 1994.
The IEEE 1284 standard specifies five modes of operation, each mode providing data transfer in either the forward direction (computer to peripheral), backward direction (peripheral to computer), or bi-directional (one direction at a time).
• Compatibility mode is the original Centronics parallel interface and is intended for use with dot matrix printers and older laser printers. The compatibility mode can be combined with the nibble mode for bi-directional data transfer.
• Nibble mode allows data transfer back to the computer. The nibble mode uses the status lines to send 2 nibble (4bit units) of data to the computer in two data transfer cycles. This mode is best used with printers.
• Byte mode uses software drivers to disable the drivers that control the data lines in order for data to be sent from the printer to the computer. The data is sent at the same speed as when data is sent from the computer to the printer. One byte of data is transferred instead of the two data cycles required by the nibble mode.
• ECP mode (Enhanced Capability Port mode) is an advanced bi-directional mode for use with printers and scanners. It allows data compression for images, FIFO (first in, first out) for items in a queue, and high-speed, bi-directional communication. Data transfer occurs at two to four megabytes per second. An advanced feature is channel addressing. This is used for multifunction devices such as printer/fax/modem devices. For example, if a printer/fax/modem device needs to print and send data over the modem at the same time, the channel address software driver of the ECP mode assigns a new channel to the modem so that both devices can work simultaneously.
• EPP mode (Enhanced Parallel Port mode) was designed by Intel, Xircom, and Zenith Data Systems to provide a high-performance parallel interface that could also be used with the standard interface. EPP mode was adopted as part of the IEEE 1284 standard. The EPP mode uses data cycles that transfer data between the computer and the peripheral and address cycles that assign address, channel, or command information. This allows data transfer speeds of 500 kilobytes to 2 megabytes per second, depending on the speed of the slowest interface. The EPP mode is bi-directional. It is suited for network adapters, data acquisition, portable hard drives, and other devices that need speed.
The computer must determine what the capabilities of the attached peripheral are and which mode to utilize. The concept developed to determine these factors is called negotiation. Negotiation is a sequence of events on the parallel port interface that determines which IEEE 1284 modes the device can handle. An older device will not respond to the negotiation sequence and compatibility mode is selected to operate that device. A newer device will respond to the negotiation sequence and a more advanced mode can be set.
2.5G
2.5G describes the state of wireless technology and capability usually associated with General Packet Radio Services (GPRS)—that is, between the second and third generations of wireless technology. The second generation or 2G-level of wireless is usually identified as Global System for Mobile (GSM) service and the third generation or 3G-level is usually identified as Universal Mobile Telecommunication Service (UMTS). Each generation provides a higher data rate and additional capabilities. There is also a fourth generation (4G) of technology in the planning and research stages.
GPRS offers data speeds at 28 Kbps (and possibly higher) and is expected to be introduced in the 2001 through 2003 timeframe.
2000
The year 2000 (also known as "Y2K") raised questions for anyone who depended on a program in which the year was represented by a two-digit number, such as "97" for 1997. Many programs written years ago (when storage limitations encouraged such information economies) are still being used. The problem was that when the two-digit space allocated for "99" rolled over to 2000, the next number was "00." Frequently, program logic assumes that the year number gets larger, not smaller—so "00" was anticipated to wreak havoc in a program that hadn’t been modified to account for the millennium.
So pervasive was the problem in the world’s legacy application payroll, billing, and other programs that a new industry sprang up dedicated to helping companies solve the problem. IBM and other major computer manufacturers, software houses, and consultants offered tools and services to address this problem.
2001
Midnight UTC on January 1, 2001 marked the beginning of the third millennium on the Western world’s Gregorian calendar. 2001 is also the name of the 1968 movie, written by Arthur C. Clarke and directed by Stanley Kubrick, that shaped views of the future for several decades, especially about what future computers might be like. HAL (officially HAL 9000) is the human-like computer that manages the spaceship in the movie. HAL (the script says that HAL stands for "Heuristically Programmed ALgorithmic computer” but the letters in the name are one letter away from "IBM") is programmed to think and talk like a human being, an artificial intelligence combining people skills with ruthless calculation. As the movie became part of history and the real 2001 approached, new views of technology tended toward the envisionment of a globally networked "intelligence" for which William Gibson’s matrix in his fictional Neuromancer and the real World Wide Web seemed to be harbingers.
24X7
24×7 means ”24 hours a day, 7 days a week” and is used to describe a service, such as computer server monitoring, that is continuous, is always available (day or night), or involves products that can run constantly without disruption or downtime.
2600
2600 is the frequency in hertz (cycles per second) that AT&T formerly put as a steady signal on any long-distance telephone line that was not currently in use. Prior to widespread use of out-of-band signaling, AT&T used in-band signaling, meaning that signals about telephone connections were transmitted on the same line as the voice conversations. Since no signal at all on a line could indicate a pause in a voice conversation, some other way was needed for the phone company to know when a line was free for use. So AT&T put a steady 2600 hertz signal on all free lines. Knowing this, certain people developed a way to use a whistle or other device to generate a 2600 hertz tone on a line that was already in use, making it possible to call anywhere in the world on the line without anyone being charged. Cracking the phone system became a hobby for some in the mostly under-20 set who came to be known as phreaks.
In the 1960s, a breakfast cereal named Captain Crunch included a free premium: a small whistle that generated a 2600 hertz signal. By dialing a number and then blowing the whistle, you could fool the phone company into thinking the line was not being used while, in fact, you were now free to make a call to any destination in the world. Today, long-distance companies use Signaling System 7, which puts all channel signals on a separate signaling channel, making it more difficult to break into the phone system.
3270
The 3270 Information Display System, a product from IBM, was, prior to the arrival of the PC, the way that almost the entire corporate world interfaced with a computer. In its day (the early 1970s), a 3270 display terminal was considered a vast improvement over its predecessor, the 2260.
The 3277 terminal was a non-graphical (text only) monochrome (black screen with green letters) display that buffered data so that key strokes could be saved until the ENTER key was pressed. (Previous terminals sent every key stroke immediately to the computer to which the terminal was attached.) The 3277 was also field-oriented rather than line-oriented which meant that a program could write an output data stream to the terminal based on application-oriented fields rather than having to create the display output line by line. A number of 3277s could be attached to a control unit or cluster controller which in turn was attached to an IBM mainframe computer. Terminals could be attached to the computer on a relatively high-bandwidth local link called a channel or "remotely" over a telecommunication link that was either dedicated (leased) or dial-up.
After the personal computer arrived with its own self-sufficient operating system and applications, it gradually replaced the 3270 system in much of the corporate world (although there are almost certainly are some working 3270s in use as this is being written). A 3270 terminal became the most prominent example of what became known as a "dumb terminal," since it relied entirely on its attachment to a mainframe (and sometimes a minicomputer) for its "brains." The PC attached to a mainframe then became known generically as an "intelligent workstation." It could run its own programs independently of the mainframe and it could also interface with mainframe applications. There was one product attempt to blend the two, called the 3270 PC.
The terminals themselves were the 3277 (which attached to a control unit), a 3275 standalone terminal (for locations where only a single terminal was needed), the 3278 (a sleeker version of the 3277), and the 3279 color terminal. The control units were the 3271 (channel attachment), 3272 (telecommunication attachment), and the 3274 (a control unit with a smaller form factor that could handle up to 32 terminals). For about 15 years, the 3270 family, one of IBM’s most successful products ever, was a ubiquitous feature of offices the world over. The PC changed all that.
However, many thousands of corporate legacy application programs written to interact with users at 3270s are being used from PCs equipped with software known generally as 3270 emulation. TN3270 is a program that provides PC users remote (Telnet) connection to an IBM computer that is running 3270 applications.
3-D
In computers, 3-D (three dimensions or three-dimensional) describes an image that provides the perception of depth. When 3-D images are made interactive so that users feel involved with the scene, the experience is called virtual reality. You usually need a special plug-in viewer for your Web browser to view and interact with 3-D images. Virtual reality experiences may also require additional equipment.
3-D image creation can be viewed as a three-phase process of tessellation, geometry, and rendering. In the first phase, models are created of individual objects using linked points that are made into a number of individual polygons (tiles). In the next stage, the polygons are transformed in various ways and lighting effects are applied. In the third stage, the transformed images are rendered into objects with very fine detail.
Popular products for creating 3-D effects include Extreme 3D, LightWave 3D, Ray Dream Studio, 3D Studio MAX, Softimage 3D, and Visual Reality. The Virtual Reality Modelling Language (VRML) allows the creator to specify images and the rules for their display and interaction using textual language statements.
