AC-3 (Dolby Digital)
AC-3, also known as Dolby Digital, is a perceptual digital audio coding technique that reduces the amount of data needed to produce high-quality sound. Perceptual digital audio coding takes advantage of the fact that the human ear screens out a certain amount of sound that is perceived as noise. Reducing, eliminating, or masking this noise significantly reduces the amount of data that needs to be provided. Dolby Laboratories developed two other perceptual coding systems, AC-1 and AC-2. Building upon Dolby's two previous coding systems, AC-3 was the first coding system designed specifically for multichannel digital audio. AC-3 is the sound format for digital television (DTV), digital versatile discs (DVDs), high definition television (HDTV), and digital cable and satellite transmissions.
AC-3 is a 5.1 format, which means that it provides five full-bandwidth channels, front left, front right, center, surround left, and surround right. A low-frequency effect (LFE) channel is included for the sound needed for special effects and action sequences in movies. The LFE channel is one-tenth of the bandwidth of the other channels and is sometimes erroneously called the subwoofer channel. AC-3 also has a downmixing feature that ensures compatibility with devices that do not support the 5.1 format.
Access Point
In a wireless local area network (WLAN), an access point is a station that transmits and receives data (sometimes referred to as a transceiver). An access point connects users to other users within the network and also can serve as the point of interconnection between the WLAN and a fixed wire network. Each access point can serve multiple users within a defined network area; as people move beyond the range of one access point, they are automatically handed over to the next one. A small WLAN may only require a single access point; the number required increases as a function of the number of network users and the physical size of the network.
ACPI (Advanced Configuration and Power Interface)
A power management specification that far surpasses its predecessor, APM, by providing support for hot swap-pable devices and better control of power modes.
Acrobat Viewer/Reader
Acrobat is a program from Adobe that lets you capture a document and then view it in its original format and appearance. Acrobat is ideal for making documents or brochures that were designed for the print medium viewable electronically and capable of being shared with others on the Internet. To view an Acrobat document, which is called a Portable Document Format (PDF) file, you need Acrobat Reader. The Reader is free and can be downloaded from Adobe. You can use it as a standalone reader or as a plug-in in a Web browser.
Acrobat is actually a set of products. The latest version includes a "toolkit" that lets you scan in or otherwise capture documents created with Word, Pagemaker, and other desktop publishing products. The resulting PDF files can then be available for viewing either directly with the Reader or they can be viewed as embedded files within the browser.
Ad-Hoc Network
An ad-hoc (or "spontaneous") network is a local area network or other small network, especially one with wireless or temporary plug-in connections, in which some of the network devices are part of the network only for the duration of a communications session or, in the case of mobile or portable devices, while in some close proximity to the rest of the network. In Latin, ad hoc literally means "for this," further meaning "for this purpose only," and thus usually temporary. The term has been applied to future office or home networks in which new devices can be quickly added, using, for example, the proposed Bluetooth technology in which devices communicate with the computer and perhaps other devices using wireless transmission.
ADSL (Asymmetric Digital Subscriber Line)
A technology for transmitting digital information at high bandwidths on existing phone lines. Unlike regular dialup phone service, ADSL provides a continously-available connection. ADSL is asymmetric in that it uses most of the channel to transmit downstream to the user and only a small part to receive information from the user. ADSL simultaneously accommodates analog (voice) information on the same line. ADSL is generally offered at downstream data rates from 512 Kbps to about 6 Mbps.
Adware
Generically, adware (spelled all lower case) is any software application in which advertising banners are displayed while the program is running. The authors of these applications include additional code that delivers the ads, which can be viewed through pop-up windows or through a bar that appears on a computer screen. The justification for adware is that it helps recover programming development cost and helps to hold down the cost for the user.
Adware has been criticized because it usually includes code that tracks a user's personal information and passes it on to third parties, without the user's authorization or knowledge. This practice has been dubbed spyware and has prompted an outcry from computer security and privacy advocates, including the Electronic Privacy Information Center.
AGP (Accelerated Graphics Port)
A 32/64-bit expansion slot designed by Intel specifically for video that runs at 66 MHz and yields a throughput of at least 254 MBps. Later versions (2X, 4X, 8X) give substantially higher throughput. AIX (Advanced Interactive Executive) IBM's version of UNIX, which runs on 386 or better PCs.
Alphanumeric
In computers designed for English language users, alphanumeric (sometimes seen as alphameric) characters are those comprised by the combined set of the 26 alphabetic characters, A to Z, and the 10 Arabic numerals, 0 to 9. In some usages, the alphanumeric character set may include both upper and lower case letters, punctuation marks, and symbols (such as @, &, and *, for example). For languages other than English, alphanumeric characters include letter variations such as i and g. For some computer usages, such as file naming, alphanumeric characters are strictly limited to the 26 alphabetic characters and 10 numerals; however, for other usages, such as programming, other keyboard symbols are sometimes permitted.
AMD (Advanced Micro Devices)
Founded in 1969 and based in Sunnyvale, California, AMD designs and produces innovative microprocessors, Flash memory devices, and low-power processor solutions for the computer, communications, and consumer electronics industries.
Antivirus Software
Antivirus (or "anti-virus") software is a class of program that searches your hard drive and floppy disks for any known or potential viruses. The market for this kind of program has expanded because of Internet growth and the increasing use of the Internet by businesses concerned about protecting their computer assets.
APM (Advanced Power Management)
The BIOS routines that enable the CPU to turn on and off selected peripherals.
ASCII (American Standard Code for Information Interchange)
A widely used character encoding system first used in 1963. It uses a 7 bit code to represent characters with numbers (0 to 127), there are also ASCII extensions in use which utilise 8 bit codes to represent international characters in addition to the standard ASCII scheme.
ASP (Active Server Pages)
We are refering to ASP in the context of dynamic web pages, ASP can also refer to Application Service Provider.
When in the context of internet web sites ASP refers to a specification similar to that of CGI, ASP technology allows the site developer to create dynamic web pages through the use of ActiveX.
ASP pages are used for numerous tasks including form handling, database connectivity, even putting a date and time on a page. Jscript or VB Script are the most common scripting languages used with ASP pages.
ATAPI (Advanced Technology Attachment Packet Interface)
A series of standards that enable mass stor-age devices other than hard drives to use the IDE/ATA controllers. Extremely popular with CD-ROM drives and removable media drives.
AVI (Audio Video Interleaved)
A multimedia file type, the audio and video elements are interleaved in alternate segments within the AVI file. This has become a very popular format on the Internet for video distribution due to the fast download times and reasonable quality reproduction.
