Computer Terms Beginning with "A"

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Source : PC.net

Abend

Short for "Abnormal end." An abend is an unexpected or abnormal end to a process. In computer software, it typically refers to a software crash when a program unexpectedly quits. For example, an error in a program's code may cause it to freeze or crash while running a certain command. The result is an unexpected (and often inconvenient) end to the program.

The term "ABEND" was initially used by IBM OS/360 systems as an error message. It is now used by Novell Netware systems and also as a general programming term.

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Access

Microsoft Access, often abbreviated "MS Access," is a popular database application for Windows. Access allows users to create custom databases that store information in an organized structure. The program also provides a visual interface for creating custom forms, tables, and SQL queries. Data can be entered into an Access database using either visual forms or a basic spreadsheet interface. The information stored within an Access database can be browsed, searched, and accessed from other programs, including Web services.

While Access is a proprietary database management system (DBMS), it is compatible with other database programs since it supports Open Database Connectivity (ODBC). This allows data to be sent to and from other database programs, such as MS SQL, FoxPro, Filemaker Pro, and Oracle databases. This compatibility also enables Access to serve as the back end for a database-driven website. In fact, Microsoft FrontPage and Expression Web, as well as ASP.NET have built-in support for Access databases. For this reason, websites hosted on Microsoft Windows servers often use Access databases for generating dynamic content.

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Access Point

Example: "The coffee shop provides an access point for customers with Wi-Fi devices."

An access point provides wireless access to a network. Devices connected to an access point can communicate with other devices on the network. They may also connect to the Internet if the access point is linked to an Internet connection, which is commonly the case. Access points that use Wi-Fi are also called base stations.

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ACL

Stands for "Access Control List." An ACL is a list of user permissions for a file, folder, or other object. It defines what users and groups can access the object and what operations they can perform. These operations typically include read, write, and execute. For example, if an ACL specifies read-only access for a specific user of a file, that user will be able open the file, but cannot write to it or run the file.

Access control lists provide a straightforward method of managing file and folder permissions. They are used by most operating systems, including Windows, Mac, and Unix systems. While ACLs are typically hidden from the user, they can often be modified using a graphical interface. For example, in Mac OS X 10.5, ACL settings can be edited by selecting a file or folder and choosing "Get Info." The access control settings can be modified within the "Sharing and Permissions" section of the window. On Unix systems, ACLs can be edited using the chmod() command.

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Active-Matrix

Active-matrix technology is used in high-quality flat-panel displays, such as laptop screens and thin computer monitors. The images on active matrix screens are created by laying diodes, or small semiconductors, over a grid of ultra-small wires. When a current passes through the diodes, they light up in different colors, depending on the strength of the current. Thousands of these diodes next to each other form an image on the screen.

To keep the diodes in an on or off state, active-matrix displays use transistors, which are not found in the lower-quality passive-matrix displays. The transistors help make the active-matrix displays brighter and give them more contrast than passive-matrix displays.

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ActiveX

This Microsoft-based technology was built to link desktop applications to the World Wide Web. Using ActiveX development tools, software developers can create interactive Web content for their applications. For example, Word and Excel documents can be viewed directly in Web browsers that supports ActiveX. While ActiveX is a useful technology, the downside is that you need to have a up-to-date version ActiveX installed on your machine in order to use ActiveX-enabled content.

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Ad Hoc Network

"Ad Hoc" is actually a Latin phrase that means "for this purpose." It is often used to describe solutions that are developed on-the-fly for a specific purpose. In computer networking, an ad hoc network refers to a network connection established for a single session and does not require a router or a wireless base station.

For example, if you need to transfer a file to your friend's laptop, you might create an ad hoc network between your computer and his laptop to transfer the file. This may be done using an Ethernet crossover cable, or the computers' wireless cards to communicate with each other. If you need to share files with more than one computer, you could set up a mutli-hop ad hoc network, which can transfer data over multiple nodes.

Basically, an ad hoc network is a temporary network connection created for a specific purpose (such as transferring data from one computer to another). If the network is set up for a longer period of time, it is just a plain old local area network (LAN).

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ADC

Stands for "Analog-to-Digital Converter." Since computers only process digital information, they require digital input. Therefore, if an analog input is sent to a computer, an analog-to-digital converter (ADC) is required. This device can take an analog signal, such as an electrical current, and digitize it into a binary format that the computer can understand.

A common use for an ADC is to convert analog video to a digital format. For example, video recorded on 8mm film or a VHS tape is stored in an analog format. In order to transfer the video to a computer, the video must be converted to a digital format. This can be done using an ADC video conversion box, which typically has composite video inputs and a Firewire output. Some digital camcorders that have analog inputs can also be used to convert video from analog to digital.

ADCs may also be used to convert analog audio streams. For example, if you want to record sounds from a microphone, the audio must be converted from the microphone's analog signal into a digital signal that the computer can understand. This is why all sound cards that have an analog audio input also require an ADC that converts the incoming audio signal to a digital format. The accuracy of the audio conversion depends on the sampling rate used in the conversion process. Higher sampling rates provide a better estimation of the analog signal, and therefore produce a higher-quality sound.

While ADCs convert analog inputs into a digital format that computers can recognize, sometimes a computer must output an analog signal. For this type of conversion, a digital-to-analog converter (DAC) is used.

Important: ADC can also stand for "Apple Display Connector," which was a proprietary video connector developed by Apple. It combined DVI, USB, and AC power into a single cable. Apple stopped producing computers with ADC ports in 2004 in favor of the standard DVI connection.

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Add-on

An add-on is a software extension that adds extra features to a program. It may extend certain functions within the program, add new items to the program's interface, or give the program additional capabilities. For example, Mozilla Firefox, a popular Web browser, supports add-ons such as the Google toolbar, ad blockers, and Web developer tools. Some computer games support add-ons that provide extra maps, new characters, or give the player game-editing capabilities.

Most add-ons are available as self-installing packages. This means the user can simply double-click the add-on package to install the files for the corresponding program. Other add-ons may require the user to manually move files into specific directories. While not all programs support add-ons, many programs are now developed with add-on support, since it provides a simple way for other developers to extend the functions of the program.

However, not all software programs refer to these extra features as "add-ons." For example, Dreamweaver supports "extensions," which add extra Web development features, while Excel can import "Add-Ins" that provide the user with extra spreadsheet tools. Many programs also support plug-ins, which may be considered a type of add-on.

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ADF

Stands for "Automatic Document Feeder." An ADF is used in copiers and scanners to feed pages into the machine. It allows multiple pages to be copied or scanned at one time without the need to place each individual page in the copier or scanner.

A flatbed scanner, on the other hand, requires each page to be individually placed on the scanning surface. While this is convenient for single pages, copying 80 pages would require a lot of manual page-loading! Some copy machines include both an automatic document feeder and a flatbed scanning surface so that either method can be used.

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ADSL

Stands for "Asymmetric Digital Subscriber Line." ADSL is a type of DSL, which is a method of transferring data over copper telephone lines. While symmetrical DSL (SDSL) uploads and downloads data at the same speed, ADSL has different maximum data transfer rates for uploading and downloading data.

For example, an ADSL connection may allow download rates of 1.5Mbps, while upload speeds may only reach 256Kbps. Since most users download much more data than they upload, this difference usually does not make a noticeable impact on Internet access speeds. However, for Web servers or other computers that send a lot of data upstream, ADSL would be an inefficient choice.

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Adware

Adware is free software that is supported by advertisements. Common adware programs are toolbars that sit on your desktop or work in conjunction with your Web browser. They include features like advanced searching of the Web or your hard drive and better organization of your bookmarks and shortcuts. Adware can also be more advanced programs such as games or utilities. They are free to use, but require you to watch advertisements as long as the programs are open. Since the ads often allow you to click to a Web site, adware typically requires an active Internet connection to run.

Most adware is safe to use, but some can serve as spyware, gathering information about you from your hard drive, the Web sites you visit, or your keystrokes. Spyware programs can then send the information over the Internet to another computer. So be careful what adware you install on your computer. Make sure it is from a reputable company and read the privacy agreement that comes with it.

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Affiliate

Website affiliates are what drive Internet marketing. Companies run affiliate programs to generate leads and sales from other Websites. They pay the sites who host their ads a commission for products sold through the links on their sites. For example, if a site owner signs up for Amazon.com's affiliate program, he will receive ad banners or links from Amazon.com that he can place anywhere on his site. Then, if a visitor clicks on the Amazon.com banner or a link on his site and buys something, he will receive a commission. Unfortunately for Website owners, affiliate commisions are seldom above 5%, since most Web sales are made with small profit margins.

The introduction of Website affiliate programs in the late 1990s brought Internet marketing to a new level. The first companies that offered these programs saw sales increase dramatically. After all, these companies basically get free advertising and only pay their affiliates a percentage of the sales they generate. It is a win-win situation for the company that runs the affiliate program. The only drawback is that the programs take a lot of work (and sometimes a lot of money) to set up and maintain. Thus, smaller companies may not find it very beneficial to offer an affiliate program.

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AGP

Stands for "Accelerated Graphics Port." This is a graphics card expansion port designed by Intel that resides on the motherboard of a computer. PCI graphics ports typically run at 33 MHz and have a maximum transfer rate of 132 MB/sec. AGP ports, on the other hand, run at 66 MHz and can transfer data up to 528 MB/sec. This allows games and applications to store and retrieve larger, more realistic 3D shapes and textures without slowing down the animation on the screen. Additionally, AGP cards can store graphics in system memory rather than video memory, which also helps improve performance. Becuase of these advantages, AGP cards will typically have better performance per MB of VRAM than PCI graphics cards.

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AIFF

Stands for "Audio Interchange File Format." AIFF is an audio format originally developed by Apple Computer for storing high-quality sampled audio data. AIFF files are similar to Windows WAVE files in both size and quality. Both AIFF and WAVE files can hold CD quality audio and therefore can be burned onto an audio CD. Though the AIFF format was created by Apple, audio programs on both the Mac and PC can typically read the files.