Glossary
802.11
802.11 refers to a family of specifications developed by the IEEE for wireless LAN technology. 802.11 specifies an over-the-air interface between a wireless client and a base station or between two wireless clients. The IEEE accepted the specification in 1997.
There are several specifications in the 802.11 family:
802.11 -- applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band using either frequency hopping spread spectum (FHSS) or direct sequence spread spectrum (DSSS).
802.11a -- an extension to 802.11 that applies to wireless LANs and provides up to 54 Mbps in the 5GHz band. 802.11a uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS.
802.11b (also referred to as 802.11 High Rate or Wi-Fi) -- an extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1 Mbps) in the 2.4 GHz band. 802.11b uses only DSSS. 802.11b was a 1999 ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet.
802.11g -- applies to wireless LANs and provides 20+ Mbps in the 2.4 GHz band.
Bluetooth
A short-range radio technology aimed at simplifying communications among Internet devices and between devices and the Internet. It also aims to simplify data synchronization between Internet devices and other computers.
Products with Bluetooth technology must be qualified and pass interoperability testing by the Bluetooth Special Interest Group prior to release. Bluetooth's founding members include Ericsson, IBM, Intel, Nokia and Toshiba.
DVI
(pronounced as separate letters) (1) Short for Digital Visual Interface, a digital interface standard created by the Digital Display Working Group (DDWG) to convert analog signals into digital signals to accommodate both analog and digital monitors. Data is transmitted using the transition minimized differential signaling (TMDS) protocol, providing a digital signal from the PC's graphics subsystem to the display. The standard specifies a single plug and connector that encompass both the new digital and legacy VGA interfaces, as well as a digital-only plug connector. DVI handles bandwidths in excess of 160 MHz and thus supports UXGA and HDTV with a single set of links. Higher resolutions can be supported with a dual set of links.
(2) Short for Digital Video Interactive, a now-defunct technology developed by General Electric that enables a computer to store and display moving video images like those on television. The most difficult aspect of displaying TV-like images on a computer is overcoming the fact that each frame requires an immense amount of storage. A single frame can require up to 2MB (megabytes) of storage. Televisions display 30 frames per second, which can quickly exhaust a computer's mass storage resources. It is also difficult to transfer so much data to a display screen at a rate of 30 frames per second.
DVI overcomes these problems by using specialized processors to compress and decompress the data. DVI is a hardware -only codec (compression/decompression) technology. A competing hardware codec, which has become much more popular, is MPEG. Intel has developed a software version of the DVI algorithms, which it markets under the name Indeo.
eSATA
SATA is very effective for external storage applications, and the external SATA (eSATA) cable and connector application provides a physically secure and fast connection for external hard drives. With up to 3 Gb/s data transfers, this interface is suitable for hard drives, home networking, digital video, and home entertainment devices such as set-top boxes and personal video recorders. eSATA and internal SATA cables and connectors cannot be used interchangeably. This is an important feature since eSATA cables and connectors are designed for 5000 insertion and removal cycles while internal SATA cables and connectors are designed for only 50 insertion and removal cycles. To achieve eSATA connectivity with an external SATA drive, a SATA PCI card must be installed on the host computer.
FireWire
FireWire, also called IEEE 1394, is a high-performance connection standard for personal computers and consumer electronics. This interface uses a peer-to-peer architecture in which peripherals negotiate bus conflicts to determine which device can best control a data transfer. FireWire has two configurations:
FireWire 400, also called IEEE 1394a, transfers large amounts of data between computers and peripheral devices at rates up to 400 Mb/s. With higher bandwidth, longer distances, and a higher-powered bus, this interface is suitable for hard drives, digital video, professional audio, high-end digital still cameras, and home entertainment devices.
FireWire 800, also called IEEE 1394b, provides the highspeed connection and bandwidth required for multiple-stream, uncompressed digital video and noise-free, high-resolution digital audio. It offers maximum flexibility with long-distance cabling and configuration options not available with USB.
Gigabit Ethernet
Ethernet is a standard method of connecting computers to a local area network (LAN) using coaxial cable. As an external hard drive interface, it is most often used for network attached storage (NAS) applications in which files can be shared across a network.
Gigabit Ethernet, with its data transfer rate of 1000 Mb/s, is the latest and fastest Ethernet standard that evolved from the earlier Fast Ethernet (100 Mb/s) and Ethernet (10 Mb/s) standards. Benefits of Gigabit Ethernet include increased bandwidth, quality of service (QoS) features that promote smooth transmission of audio and video, and compatibility with existing Ethernet and Fast Ethernet networks.
HDMI
Short for High-Definition Multimedia Interface, it is the first industry-supported uncompressed, all-digital audio/video interface. It's a single cable and user-friendly connector that replaces the maze of cabling behind the home entertainment center. HDMI provides an interface between any audio/video source, such as a set-top box, DVD player, or A/V receiver and an audio and/or video monitor, such as a digital television (DTV), over a single cable. HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It transmits all ATSC HDTV standards and supports 8-channel digital audio with bandwidth to spare to accommodate future enhancements and requirements. [Source: Adapted from HDMI.org]
HDMI was defined to carry 8 channels, of 192kHz, 24-bit uncompressed audio, which exceeds all current consumer media formats. In addition, HDMI can carry any flavor of compressed audio format such as Dolby or DTS. HDMI has the capacity to support existing high-definition video formats such as 720p, 1080i, and 1080p, along with support of enhanced definition formats like 480p, as well as standard definition formats such as NTSC or PAL.
HDMI was developed by Developed by Sony, Hitachi, Thomson (RCA), Philips, Matsushita (Panasonic), Toshiba and Silicon Image.
Hot Plugging
The ability to add and remove devices to a computer while the computer is running and have the operating system automatically recognize the change. Two external bus standards -- Universal Serial Bus (USB ) and IEEE 1394 -- support hot plugging. This is also a feature of PCMCIA.
IEEE 1394
A very fast external bus standard that supports data transfer rates of up to 400Mbps (in 1394a) and 800Mbps (in 1394b). Products supporting the 1394 standard go under different names, depending on the company. Apple, which originally developed the technology, uses the trademarked name FireWire. Other companies use other names, such as i.link and Lynx, to describe their 1394 products.
A single 1394 port can be used to connect up 63 external devices. In addition to its high speed, 1394 also supports isochronous data -- delivering data at a guaranteed rate. This makes it ideal for devices that need to transfer high levels of data in real-timme, such as video devices.
Although extremely fast and flexible, 1394 is also expensive. Like USB, 1394 supports both Plug-and-Play and hot plugging, and also provides power to peripheral devices.
IDE interface
Abbreviation of either Intelligent Drive Electronics or Integrated Drive Electronics, depending on who you ask. An IDE interface is an interface for mass storage devices, in which the controller is integrated to the disk or CD-ROM drive. Although it really refers to a general technology most people use the term to refer the ATA specification, which uses this technology. Refer to ATA for more information.
IrDA
Short for Infrared Data Association, a group of device manufacturers that developed a standard for transmitting data via infrared light waves. Increasingly, computers and other devices (such as printers) come with IrDA ports. This enables you to transfer data from one device to another without any cables. For example, if both your laptop computer and printer have IrDA ports, you can simply put your computer in front of the printer and output a document, without needing to connect the two with a cable.
IrDA ports support roughly the same transmission rates as traditional parallel ports. The only restrictions on their use is that the two devices must be within a few feet of each other and there must be a clear line of sight between them.
MIMO
Acronym for multiple-in, multiple-out. MIMO (multiple-in, multiple-out) takes advantage of multiplexing to increase wireless bandwith and range. MIMO algorithms send information out over two or more antennas and the information is received via multiple antennas as well. On normal radio, multiplexing would cause interference, but MIMO uses the additional pathways to transmit more information and then recombines the signal on the receiving end. MIMO systems provide a significant capacity gain over conventional single antenna systems, along with more reliable communication. The benefits of MIMO lead many to believe it is the most promising of emerging wireless technologies.
PCMCIA
Short for Personal Computer Memory Card International Association, and pronounced as separate letters,PCMCIA is an organization consisting of some 500 companies that has developed a standard for small, credit card-sized devices, called PC Cards. Originally designed for adding memory to portable computers, the PCMCIA standard has been expanded several times and is now suitable for many types of devices. There are in fact three types of PCMCIA. All three have the same rectangular size (85.6 by 54 millimeters), but different widths
Type I cards can be up to 3.3 mm thick, and are used primarily for adding additional ROMor RAMto a Computer.
Type II cards can be up to 5.5 mm thick. These cards are often used for modem and a fax modem cards.
Type III cards can be up to 10.5 mm thick, which is sufficiently large for portable disk drives.
In general, you can exchange PC Cards on the fly, without rebooting your computer. For example, you can slip in a fax modem card when you want to send a fax and then, when you're done, replace the fax modem card with a memory card.
USB
Short for Universal Serial Bus, an exrenal bus standard that supports data transfer rates of 12 Mbps. A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. USB also supports Plug-and-Play installation and hot plugging.
Starting in 1996, a few computer manufacturers started including USB support in their new machines. It wasn't until the release of the best-selling iMacin 1998 that USB became widespread. It is expected to completely replace serial and parallel ports.
USB2.0
Also referred to as Hi-Speed USB, USB 2.0 is an external bus that supports data rates up to 480Mbps. USB 2.0 is an extension of USB 1.1. USB 2.0 is fully compatible with USB 1.1 and uses the same cables and connectors.
Hewlett-Packard, Intel, Lucent, Microsoft, NEC and Philips jointly led the initiative to develop a higher data transfer rate than the 1.1 specification to meet the bandwidth demands of developing technologies. The USB 2.0 specification was released in April 2000.
VoIP
Short for Voice over Internet Protocol, a category of hardware and software that enables people to use the Internet as the transmission medium for telephone calls by sending voice data in packets using IP rather than by traditional circuit transmissions of the PSTN. One advantage of VoIP is that the telephone calls over the internet do not incur a surcharge beyond what the user is paying for Internet access, much in the same way that the user doesn't pay for sending individual e-mails over the Internet.
There are many Internet telephony applications available. Some, like CoolTalk and NetMeeting, come bundled with popular Web browsers. Others are stand-alone products. VoIP also is referred to as Internet telephony, IP telephony, or Voice over the Internet (VOI)
Wireless
The word wireless is dictionary defined as "having no wires". In networking terminology, wireless is the term used to describe any computer network where there is no physical wired connection between sender and receiver, but rather the network is connected by radio waves and/or microwaves to maintain communications. Wireless networking utilizes specific equipment such as NICs, APs and routers in place of wires (copper or optical fiber) for connectivity.
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