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Glossary - A to H

Adware

A software program that is designed to run once a web page has been accessed. This is usually in the form of banner or popup advertisements. Adware can also be designed to be installed on your system without your consent or knowledge. These forms of adware are usually referred to as "spyware" and are used to monitor your surfing habits so that their software can deliver better targeted advertisements. In other instances, the software can be designed to monitor your keyboard keystrokes so that the author of the software can gain access to your password protected accounts. This type of adware is referred to as "malware" due to its malicious intent.

BIOS

Stands for Basic Input/Output System. The BIOS gives the computer a little built-in starter kit to run the rest of softwares from floppy disks (FDD) and hard disks (HDD). The BIOS is responsible for booting the computer by providing a basic set of instructions.

Blu-ray

Also known as Blu-ray Disc. This is a cutting edge optical disc format developed to enable recording, rewriting and playback of high-definition (HD) video along with a storage capacity of more than 5 times than that of traditional DVDs. A single-layer disc can hold up to 25GB while a dual-layer disc can hold up to 50GB. DVD disc technologies use a red laser to read and write data. Blu-ray uses a blue-violet laser (hence the name). The benefit of the blue-violet laser over the red laser is its ability to focus the laser spot with greater precision because of its shorter wavelength. A red laser's wavelength is 650nm while the Blu-ray's wavelength is 405nm.

Bluetooth

Radio technology that connects electronic devices without using a cable. Data and voice can be exchanged at ranges of up to 10 metres without the need for devices to be lined up together.

CD-R (Compact disc recordable)

A general term to describe compact disc computer storage systems where users may record their own data. Specific examples are CD-MO and CD- W0.

CD ROM (Compact disc read-only memory)

The familiar audio CD used to store a large amount (over 600Mb) of computer data, which can include text, pictures and/or music. CD ROM drives can only read (but not write) data from these optical discs, but other optical storage devices are now available that can be both written to and read from. Error-detection codes (EDC) and error-correction codes (ECC) provide reliability for the stored data.

CD ROM XA (Compact disc read-only memory extended architecture)

A system which enables a CD ROM to store interleaved audio and data.

CMOS settings

The CMOS settings maintain fundamental system configuration information, which is stored in a special chip on the motherboard. This chip, usually powered by a battery, can operate independently of the rest of the computer. It keeps things like the system clock up-to-date even when the power is switched off.

The CMOS settings also record what sort of disks are installed in the PC, whether or not a password is required at start-up, and which devices (e.g. floppy, hard disk, CD-ROM or network) should be used when trying to boot up the computer. If your CMOS settings are inaccurate, then your computer may not work properly.

One of the CMOS settings is called the "boot sequence". This determines whether the computer will try to boot from floppy disk or not. Accidentally booting from a floppy can introduce boot sector viruses from a disk of unknown origin, but changing this setting so that the computer routinely boots from the hard disk can cause a problem if your hard disk fails.

Cookie

The most common meaning of "Cookie" on the Internet refers to a piece of information sent by a Web Server to a Web Browser that the Browser software is expected to save and to send back to the Server whenever the browser makes additional requests from the Server.

Depending on the type of Cookie used, and the Browsers' settings, the Browser may accept or not accept the Cookie, and may save the Cookie for either a short time or a long time.

Cookies might contain information such as login or registration information, online "shopping cart" information, user preferences, etc.

Cookies are usually set to expire after a predetermined amount of time and are usually saved in memory until the Browser software is closed down, at which time they may be saved to disk if their "expire time" has not been reached.

CSS (Cascading Style Sheet)

A standard for specifying the appearance of text and other elements. CSS was developed for use with HTML in Web pages but is also used in other situations, notably in applications built using XPFE. CSS is typically used to provide a single "library" of styles that are used over and over throughout a large number of related documents, as in a web site. A CSS file might specify that all numbered lists are to appear in italics. By changing that single specification the look of a large number of documents can be easily changed.

Direct X

A set of APIs developed by Microsoft that enables programmers to write programs that access hardware features of a computer without knowing exactly what hardware will be installed on the machine where the program eventually runs. DirectX achieves this by creating an intermediate layer that translates generic hardware commands into specific commands for particular pieces of hardware. In particular, DirectX lets multimedia applications take advantage of hardware acceleration features supported by graphics accelerators. DirectX 2, released in 1996, supports the Direct3D architecture. DirectX 5, released in 1998, added new layers to the DirectX API. In addition to the low-level layer that communicates directly with multimedia hardware, DirectX 5 also included a Media layer that enables programmers to manipulate multimedia objects and streams. DirectX 9 is the latest version which runs on most operating systems, but DirectX 10 will only run on Microsoft Vista and is not backward compatible.

DLL (Dynamic link library)

A set of functions or routines that provide a programmer with a method of accessing, from within the program being developed, data files created by other applications programs such as databases. Commonly used by Microsoft Windows applications.

DMA (Direct memory access)

When large amounts of information need to be transferred between a disk drive and a computer's memory, a dedicated (special-purpose) chip called a DMA controller, or DMac, takes charge. This has direct access the system memory and can perform the transfer much faster than the system micro-processor.

DPI (Dots per inch)

A measure of page printer and scanner resolution. For example, standard laser printers offer 300 or 600dpi, inkjets 300 or 360, while a 9-pin dot matrix might offer 240. A basic scanner will provide up to 400dpi.

DHCP (Dynamic Host Configuration Protocol)

DHCP is a protocol by which a machine can obtain an IP number (and other network configuration information) from a server on the local network.

DHTML (Dynamic HyperText Markup Language)

DHTML refers to web pages that use a combination of HTML, JavaScript, and CSS to create features such as letting the user drag items around on the web page, some simple kinds of animation, and many more.

DNS (Domain Name System)

The Domain Name System is the system that translates Internet domain names into IP numbers. A "DNS Server" is a server that performs this kind of translation.

Domain Name

The unique name that identifies an Internet site. Domain Names always have 2 or more parts, separated by dots. The part on the left is the most specific, and the part on the right is the most general. A given machine may have more than one Domain Name but a given Domain Name points to only one machine.

DVD (Digital Versatile Disc)

A disc format that holds a minimum of 4.7GB (gigabytes), enough for a full-length movie. The DVD specification supports disks with capacities of from 4.7GB to 17GB and access rates of 600 KBps to 1.3 MBps. The discs can be dual layered and double sided. One of the best features of DVD drives is that they are backward-compatible with CD-ROMs. This means that DVD players can play old CD-ROMs, CD-i disks, and video CDs, as well as new DVD-ROMs. Newer DVD players, called second-generation or DVD-2 drives, can also read CD-R and CD-RW disks. DVD uses MPEG-2 to compress video data.

EIDE

(Enhanced Integrated Development Environment), also called EIDE, is a term that Western Digital coined in 1994 to represent a particular set of extensions it devised to the original AT Attachment standard. At that time, the official ATA standard was rather limiting, and work was progressing towards the new ATA-2 standard. Western Digital decided that it did not want to wait for the new standard, and also that it could better position itself as a market leader by creating a new feature set for (then) future drives. The name "Enhanced IDE" was presumably selected to build upon the common name for ATA then in popular use: IDE.

FAT

Stands for File Allocation Table. Basically this is a table of contents in a directory that tells the computer what all is in there. Look at your Netscape cache, you'll see a FAT. It'll be the first file.

FAT 16

This was an older FAT (File Allocation Table) that was designed for use in the MS-DOS system. FAT 16 was used in many Windows Operating Systems up to Windows ME. Its biggest downfall was that it could only handle small partition sizes.

FAT 32

A new version of the file allocation table (FAT) available in Windows 95 OSR 2 and Windows 98. FAT32 increases the number of bits used to address clusters and also reduces the size of each cluster. The result is that it can support larger disks (up to 2 terabytes) and better storage efficiency (less slack space).

FTP (File Transfer Protocol)

A very common method of moving files between two Internet sites.

FTP is a way to login to another Internet site for the purposes of retrieving and/or sending files. There are many Internet sites that have established publicly accessible repositories of material that can be obtained using FTP, by logging in using the account name "anonymous", thus these sites are called "anonymous ftp servers".

FTP was invented and in wide use long before the advent of the World Wide Web and originally was always used from a text-only interface.

Gateway

The technical meaning is a hardware or software set-up that translates between two dissimilar protocols, for example America Online has a gateway that translates between its internal, proprietary e-mail format and Internet e-mail format.

GM (General Midi)

The Midi standard allows computers and digital music devices to communicate effectively. Most Midi transmissions consist of 'note events': rather than defining exactly how the result will sound (like an audio recording), these messages simply tell the music device what notes to play. The device will then play the notes using whatever 'voice' it has been set to use. Midi signals can also be sent to specify the voice, but 'voice 128' may be a tuba on one synthesiser and a violin on another, so the same Midi file will not produce the same result on all equipment. GM is a set of rules, or 'protocol', which makes sure different synthesisers that support GM will respond in the same way to the same codes.

GIF (Graphic Interchange Format)

A common format for image files, especially suitable for images containing large areas of the same color. GIF format files of simple images are often smaller than the same file would be if stored in JPEG format, but GIF format does not store photographic images as well as JPEG.

HTML (HyperText Markup Language)

The coding language used to create Hypertext documents for use on the World Wide Web. HTML looks a lot like old-fashioned typesetting code, where you surround a block of text with codes that indicate how it should appear.

The "hyper" in Hypertext comes from the fact that in HTML you can specify that a block of text, or an image, is linked to another file on the Internet. HTML files are meant to be viewed using a "Web Browser".

HTML is loosely based on a more comprehensive system for markup called SGML, and is expected to eventually be replaced by XML-based XHTML standards.

HTTP (HyperText Transfer Protocol)

The protocol for moving hypertextfiles across the Internet. Requires a HTTP client program on one end, and an HTTP server program (such as Apache) on the other end. HTTP is the most important protocol used in the World Wide Web (WWW).