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ACPI ACPI (Advanced Configuration and Power Interface} was developed jointly by Microsoft, Intel, Phoenix, Toshiba and Hewlett-Packard.  This specification is an open industry standard that defines common interfaces for motherboard and device configuration, hardware recognition and power management. Replacing APM (Advanced Power Management), PNPBIOS and MPS (Multiprocessor), ACPI has evolved from its first release in December 1996.  ACPI Rev 3.0b Specification is the current version, released in October 2006.  A key feature of ACPI is its ability to enable the (operating system) OS-directed configuration and power management (OSPM).  In contrast, the previous APM utilized the BIOS for power management requirements with minimal control by the operating system. ACPI allows the BIOS to provide processes for the operating system to control low-level information of the hardware.  This then gives ACPI nearly complete control over power management. Software developers are able to use the ACPI specification to assimilate power management features throughout the system – hardware, operating system and software programs. This integration enables the operating system to identify which programs are active and allows improved handling of all power management resources for the computer subsystems and peripherals. Additionally, ACPI facilitates thermal management of mobile, desktop and server platforms.   Prior to ACPI, only portable computers enjoyed the power management features that ACPI provides. Desktop computers and servers are now able to utilize power management elements. Systems can be placed into low consumption states whereby only memory or at other times, not even memory, is powered up. In this state ‘general purpose events’ can wake the system (i.e. keyboard, modem or real-time clock). Compliant hardware is required for ACPI, supported by ACPI Registers and the ACPI Specification. Some functions of the CPU, motherboard, chipset and operating system are required to be designed with support for ACPI.  The ACPI Specification is a complex document with over 600 pages and contains multiple components. ACPI uses its own AML (Machine Language) instead of using the native assembly language of the host system to implement power event handlers.  Microsoft Windows 98 was the first version of Windows to be ACPI compliant. Linux systems have some ACPI support.  Links –  ACPI Rev 3.0b Specification http://www.acpi.info/spec.htm  Intel’s ACPI Component Architecture http://developer.intel.com/technology/iapc/acpi/downloads.htm  ACPI for Linux http://www.lesswatts.org/projects/acpi/   ActiveX ActiveX provides an integrated platform for developers, users, and web producers. Web developers use it as a means to create programs and content for the Internet. Developers can easily insert multimedia effects, complex programs and interactive objects into a web page using Active X technology. Users may be asked to accept the use of ActiveX when they visit a site that uses ActiveX.  Microsoft developed ActiveX, a component object model (COM) technology in 1996, for Windows platforms. ActiveX replaced two common standards in Windows, OLE (Object Linking and Embedding) and COM (Component Object Model) both of which were devised to increase operability of software programs. OLE focused on communication and COM on implementation.  With ActiveX, Microsoft combined both of these technologies.  This standard permits software components to work together with one another, not dependent upon the programming language used to create them. Internet users will have awareness of ActiveX technology in the form of ActiveX controls, ActiveX documents, and ActiveX scripts.  ActiveX controls are components (or objects) that a developer can insert into a web page or other program. They allow the user to reuse packaged functionality that someone else has programmed.  ActiveX controls are a reusable component that employs the interface.  The component is not an entire program but provides a building block shared by different software. An example of ActiveX reusability is the use of command buttons, list and dialogue boxes. These controls are very important for computer security and commonly used to setup passwords.  Built-in ActiveX controls in Internet Explorer or other browsers enable the user to improve web pages with intricate formatting animation and features. ActiveX controls are used in programs written in many different programming languages such as Microsoft programming, Borland Delphi, C++, Visual Basic and other database languages. This gives it a fundamental advantage over plug-ins for Netscape and Java programs. ActiveX documents and scripting enhances web browsers. Browsing with an ActiveX aware browser with ActiveX documents enables the user to open a program with its own menus and toolbars accessible. A user is able to open a non-HTML file such as Microsoft Word or Excel with an ActiveX aware browser. ActiveX scripting supports most popular scripting languages such as Microsoft Visual Basic Script and JavaScript. It provides a combination of the behavior of one or more ActiveX controls from a browser or server. This in turn extends the programs functionality.   Ad Hoc Network The words or term ‘ad hoc’ have its origins in Latin and directly translated mean “for this” or more specifically ‘for this purpose’, implying that something is meant for a particular purpose. Rather than arranged in advance, something that is required on an ‘ad hoc’ basis is as a response to a situation or event. A ‘Network’ is defined as a series of points interconnected. Networks can interconnect with other networks and contain sub-networks. Taking the term ’ad hoc’ into the realm of computer networks, we have ‘Ad Hoc Networks’, being spontaneous networks. These networks are more often associated with wireless devices and are usually of a temporary nature. An ‘Ad Hoc Network’ can be a Local Area Network (LAN) connected by wireless devices or temporary plug-in connections. Some of these devices may be part of the network for only one session’s duration or need only be in close proximity to the network.  Traditional computer networks required a server (main computer or base station) and multiple computers connected by hardwire plug-in connections usually utilizing a router. These networks enabled file, printer and Internet sharing between the networked computers. ‘Ad Hoc Networks’ require no base station and instead discover devices within range to form a temporary network. Sony’s Playstation Portable and Nintendo DS utilize ad hoc connections for wireless multiplayer gaming. More recently, Bluetooth technology has enabled devices to communicate with computers and other devices using wireless transmission. These connections are established for the duration of one session, therefore ‘for this purpose’.  There are many examples of ‘ad hoc networks’. Computer technicians utilize ‘ad hoc networks’ to establish a link to computers that require repairs. This link may be hardwire, wireless or web linked. A conference may make use of infrared transmission for participants’ laptops to access an ‘ad hoc network’. ‘Wifi hotspots’ enable users to access the Internet from laptops or web enabled mobile phones.   ADSL Asymmetric Digital Subscriber Line (ADSL) is a form of data communication technology that utilizes fast data transmission of digital bandwidth over copper telephone lines.  An advantage of ADSL is that a single telephone connection can be used for both ADSL Internet service and voice calls at the same time. The computer connects to the web through an ADSL modem, which in turn connects to the telephone line by a splitter. The splitter or microfilter allows a single telephone connection to be used for the purpose of both ADSL service and voice calls at the same time. The voice calls would use the analog data transmission whilst the ADSL service would utilize the digital service line (DSL).  ADSL is a variant form of DSL. Digital Subscriber Line (DSL) technology brings high bandwidth information at data rates of up to 6.1 megabits. Other variations of the DSL technology besides ADSL include High bit-rate Digital Subscriber Line {HDSL} and Rate-Adaptive DSL (RADSL).  The ‘A’ in ADSL stands for asymmetrical. This means that the volume of data flow is greater in one direction than the other. With ADSL, the higher bandwidth is focused on the download speeds and upload speeds are reduced. The lower upload speed is due to users generally requiring a greater proportion of their web usage as downloads.  The design of ADSL enables the user to take advantage of the one-way nature of most multimedia communication. Large amounts of information flow toward the user and in contrast, only a small amount of interactive control information returns.  Precursors to ADSL were ISDN and dial-up. ISDN received up to 128Kbps and dial-up only 56Kbps. With either of these technologies, the ability of your computer to receive information is limited.  The telephone company receives the digital data and it is then put into analog form for the telephone line. The modem connected to the computer on receipt of this analog data then transformed it into digital format again. A bandwidth bottleneck was a common problem with both ISDN and dial-up Internet.   AGP The Accelerated Graphics Port (AGP), also called Advanced Graphics Port, was introduced by Intel in 1996 to replace the outdated PCI. With computers becoming more graphically oriented, each generation of graphics adapters leapt forward and thus placed increasing pressure on the limits of PCI. To support the demands of developing graphic interfaces, hardware support entailed a graphic card. The connection of this card to the computer was the key to the computer’s ability to render the graphics. AGP enhanced both the look and speed of a computer’s graphics allowing a dedicated way to communicate with the graphics card.  An AGP port is used to attach a graphics card to a computer’s motherboard. Its primary function is to assist in the acceleration of 3D computer graphics.  PCI was the precursor to AGP. PCI lacked functionality, as it was a shared bus. An advantage of AGP was that it provided a dedicated pathway between the slot and the processor. Despite the advantages of the AGP over the PCI, between 2004 and 2007 PCI Express replaced AGP. From 2007, new AGP cards and motherboards are still available, but are now less common with PCI Express the new standard in graphics technology.  The idea to improve ways that PCI transports data to the CPU was the foundation for AGP.  Intel addressed this by identifying the areas where data bottlenecks were created by PCI transfers. AGP efficiently cleared the traffic jams of data, thereby increasing the computer speed and ability to render graphics. This in turn reduced the overall drag on the system’s resources.  A dedicated port was a key feature of AGP. No other devices connected to the AGP other than the graphics card. This enabled the graphics card to operate at a maximum capacity with a dedicated path directly to the CPU. AGP utilized the Pipelining method of data organization that allowed the graphics card to accept and respond to numerous packets of information in a single request.  Another advantage of AGP was its feature of Sideband Addressing. When sending data, all information as in a letter, requires a To: and From: data. With PCI, all addressing information was sent within the package. This tied up resources that were required to open the data package. AGP issues eight additional lines on the data packet just for addressing, which are external and freeing those resources.  The Socket 7 Pentium and Slot 1 Pentium II processor motherboards had the first AGP slots.  In mid-October 1997, Intel introduced AGP support. Microsoft Windows 95 OEM Service Pack 2 was the first version to introduce AGP support. Windows NT 4.0 Service Pack 3 received AGP support in 1997. In 1999, Linux added AGP enhanced fast data transfers with completion of the AGPgart kernel module. Today, few new AGP featured motherboards are produced, although motherboards with older chipsets with AGP support are still produced. All new graphics processors are now designed for PCI Express, which allows for higher data transfer rates.   Algorithm Algorithm is a method of calculation. The word ‘Algorithm’ has ties back throughout history to 825AD. The word originally derives from a translation of an Arabic treatise by Mohammed ibn-Musa al-Khwarizmi, a Persian mathematician and astronomer. The Latin translation of the title ‘On Calculation with Hindu Numerals’ incorporated the translator’s interpretation of the author’s name, Al-Khwarizmi, which became Algoritmus, now recognized as an Algorithm.  The method of calculation, or Algorithm, is a procedure or formula for solving a problem. A computer program may be viewed as an algorithm, that is, a small procedure that is needed to solve a recurrent problem.  A computer algorithm is required to make a computer do something or to define the methods or techniques to carry out the task. When developing a computer program, the computer is told, step-by-step, what to do. The computer will then execute the program, following each of those steps to successfully complete the task.  An example of how an algorithm might work in real life will illustrate this concept: A friend is due to arrive at the airport from overseas. How will they get from the airport to your home? What are the possible options available? These options are classified as the different possible algorithms.  Algorithm 1 – The ‘Call Me’ Algorithm             Step 1 – Friend’s plane arrives             Step 2 – Friend calls my phone             Step 3 – Arrange to meet outside the baggage claim.  Algorithm 2 – The ‘Bus’ Algorithm             Step 1 – Friend’s plane arrives             Step 2 – At Airport bus terminal, catch but number 85 to Corner of Main and Trump Streets             Step 3 – Transfer to bus number 27             Step 4 – Get off at Brady Street             Step 5 – Walk one block south to my house.  Algorithm 3 – The ‘Taxi’ Algorithm             Step 1 – Friend’s plane arrives             Step 2 – Go to taxi stand at front of airport             Step 3 – Get in a tax.             Step 4 – Give taxi driver my address.  Algorithm 4 – The ‘Rent-a-Car’ Algorithm              Step 1 – Friend’s plane arrives             Step 2 – Go to Rental Car place             Step 3 – Rent a car             Step 4 – Follow directions/map to get to my house.  Notice that each algorithm started with ‘Friend’s plane arrives’. Each procedure or list of steps, were based upon this premise. If the first step in any of the four algorithms did not happen, then another algorithm would be required to deal with the eventuality. Selection of the best algorithm will ensure that the task is quickly completed.  Computer programming uses algorithms in many different ways. Advantages and disadvantages vary depending on the different situations and uses of algorithms. Computers spend a lot of time sorting lists. Five algorithms that are used in sorting by computers are bin, merge, bubble, shell and quicksort.  Knowing the strengths and weaknesses of specific algorithms assists in picking the best one for a specific task.     Analog Analog or analogue is a device that has continuously changing physical properties and values. Humans see the world around us analogically. There is a continuous stream or signal of information transmitting to our senses. Vision is an analog experience, as humans perceive many and varied smooth gradations of shapes and colors. These include audio and visual. Digital, in contrast, only estimates the analog data using ones and zeros. A clock is a typical analog device.  The hands move continuously around the clock face.  This device is capable of indicating any possible time in the day.  In contrast, digital clocks only represent a predetermined number of times.  Another example is the record player (or turntable). It is an analog device as it reads bumps and grooves from a record as a continuous signal (record the exact sound).  Alternatively, a CD player is a digital device as it only reads a sequence of ones and zeros that simulate audio data (estimate the actual soundwave).  The VCR is another analog device, as it reads audio and video as a continuous stream of information from a tape.  The DVD player is digital as it again reads ones and zeros from a disc.  The reading of ones and zeros by digital devices can only estimate an audio or video signal.  This would make analog data more accurate than digital; although, digital has the added ability to manipulate data easier and preserve it better.  The other advantage is that computers are able to handle digital data and accordingly, the majority of information today is stored digitally.  By modulating the continuous transmission signal the data in analog format is transmitted.  Telephones receive sound vibrations and then turn them into electrical vibrations of the same shape as when transmitted over the telephone lines.  Radio waves work in a similar way.  Traditional telephone lines can only carry analog signals.  Computers handle data in digital form.  To receive or send signals by telephone lines, a computer requires a modem that can convert the signals from digital to analog and back again.    API Application Program Interface or Application Programming Interface (API) is a set of commands, functions and protocols.  Programmers use APIs when building software for a specific operating system.  Instead of starting from scratch, programmers can use predefined functions to work together with the operating system.  API is a concept and in itself is abstract. This means that it specifies an interface. The identifiers within that interface are indicated by the behavior; although, the API does not specify how those behaviors will be employed and put into action.  Whether Windows, Linux, Unix or Mac operating systems, each of these provide an application program interface for programmers. Video game consoles and other hardware devices that run software programs, also use API’s. Benefits to the end user ensure that those programs using the same API will have a comparable user interface.  Computer programs require support for requests of services made by it on operating systems. API is a source code interface which provides this support. Companies that provide API as part of their operating system vary in their release and publishing policies. Microsoft openly encourages software developers to write software for the Windows platform. To support this, they make their APIs freely available.  Alternatively, Sony restricts access to their APIs with only licensed PlayStation developers having access. These actions ensure that Sony control who develops games for the PlayStation 2. By protecting the API information, Sony is able to make sure quality control benefits and potential license revenue is high.  Below are some of the more common API’s:      ●  The PC BIOS call interface     ●  DirectX for Microsoft Windows     ●  Windows API     ●  Google Maps API     ●  Simple DirectMedia Layer (SDL)     ●  ASPI for SCSI device interfacing     ●  OpenGL (cross-platform 3D graphics API)     ●  Single UNIX Specification (SUS)     ●  Java Platform, Standard Edition API     ●  Java Platform, Enterprise Edition API     ●  Carbon and Cocoa for the Macintosh OS     ●  MediaWiki API     ●  iPhone API APIs are available for any operating system and are integral for the development of fully functional software   Application An application is a computer software program. Each program has a specific application or use for the user. Web browsers, email programs, games and word processors are all applications. System software is not classified as an application. Applications are considered to run above the system software. system software is compiled of assemblers, file management tools, compilers and also the operating system. Being a ‘low-level’ program, system software essentially runs in the background and is automatically installed as part of the operating system. Alternatively, the user chooses applications and installation of the application on the computer as an active decision. Application software employs the capabilities of the computer directly. It is able to undertake a task that the user wishes to perform. Application in this usage refers to both the application and implementation. Two examples of software applications would be Microsoft Word as a word processor and Windows Media Player. While Microsoft Word is a stand-a-lone application, Windows Media Player is bundled in with the system software. It is also an application, but comes as part of Microsoft Windows. A number of applications bundled together as a package are commonly referred to as an Application Suite. The most popular and well-known application suite is Microsoft Office. Depending on the edition, whether professional or home, the core applications are Microsoft Word, Excel, Access and Outlook. A common user interface is shared between the separate applications and has the capability to interact with each individual application. Web Application (webapp), is an application that is accessed by users via the web. It utilizes either an Internet or an intranet network and is reliant upon a common web browser to cause the application to be executable. An advantage to these applications is that none or minimal installation is required on the computer’s hard drive. Many application software companies traditionally distributed software as local applications. Today, more and more of these companies are using the strategy of providing web access for their software. Advantages to the user are that they have access to a software application without installing on a local hard disk drive. Instead of paying a one-off purchase price for the software, users pay a monthly or yearly fee for usage. These software companies are known as Application Service Providers (ASP). ASPs are browser-based applications usually including some basic office software. Incorporated into the application could be word processors, spreadsheets or project management tools. Google Docs is a free web application that incorporates a secure service for creation of word processing, spreadsheets and presentation documents. These applications will generate a series of web documents that are supported by common browsers.   ASP Microsoft developed Active Server Pages (ASP) as a server-side script engine. It was designed for dynamically generating web pages. Initially is it was incorporated as an add-on to Internet Information Services (IIS) in the Windows NT 4.0 Option Pack. Since the release of Windows 2000 Server, it has been included as a free component.  Built in objects are a component of ASP which makes programming of ASP websites much easier. A group of commonly used functions correspond to each object. ASP 2.0 incorporated six built in objects – Application, Request, ASPError, Response, Session and Server. Session is a cookie-based session object.  VBScript is the most common language used for ASP Pages, although any other active scripting engine can also be selected. Other scripting languages include Jscript and PerlScript.  One of the first to integrate web application execution directly to a web server, ASP provides a high performance. Compared with CGI scripts that were used previously for writing web applications, these called external executable programs.   Non-Microsoft operating systems utilize additional platforms for web application development, JavaServer Pages and more commonly, PHP. ColdFusion is a popular Java Technology and is capable of being run on several operating system platforms, including Microsoft Servers. ChilisoftASP, now known as Sun Java System Active Server Pages is owned by Sun Microsystems. Many large open source communities exist on the Internet.  User participants in these online communities produce ASP scripts, components and applications that are available for free use under certain license terms.  The successor to Microsoft’s ASP technology is ASP.NET and it is part of Microsoft’s .NET platform. With ASP.NET, programmers are able to build dynamic web sites, web applications and web services. ASP.NET code can be written using any Microsoft .NET language as it is built upon Common Language Runtime.  In the creation of Webform pages, ASP.NET uses the ASPX FILE format. This is a html file format that typically contains static HTML or XHTML that defines web controls and web user controls. Using a visiting rendering technique during compilation of the .aspx file template, ASP.NET will build a composite or control tree that represents the original template.  Increased performance benefits of ASP.NET over ASP (classic) are shown with compilation of the server-side code to one or more DLL files occurring automatically upon a web page being requested. ASP.NET simplifies the developers’ change from Windows application development to web development. This is done by ASP.NET offering the ability to build pages made up of controls that are very similar to the Windows user interface.   Aspect Ratio The aspect ratio of a monitor refers to the horizontal size compared to the vertical size of the monitor. If you look back to the history of computer monitors, a typical old and classic monitor had aspect ratio of 4:3. But for the latest widescreen LCD monitors, the aspect ratio is 16:9/16:10/15.9. HDTV and Blu-ray are in widescreen and so 4:3 is phasing out.   ATA An ATA (Analog Telephone Adapter) device converts your analogue voice signals to digital signals and transmits them over the Internet. An ATA connects to a regular telephone and a router to transfer the data packets over the Internet. Nowadays, VoIP service providers are offering ATAs that have an FXO port so you can access both your PSTN and VoIP services at the same time. Related Words ADSL; CDMA ATA Advanced Technology Attachment (ATA) is a disk drive implementation integrating the controller on the disk drive, which frees up space on the motherboard. It is a standard interface for connecting storage devices, such as hard disks and optical drives. There exist several versions of the ATA standard, all of which were developed by the Small Form Factor (SFF) Committee. An early version of ATA was conceived by Western Digital in 1986 and originally named the Integrated Drive Electronics (IDE).  ATA is also known as IDE and supports one or two hard drives, 16-bit interface and PIO modes 0, 1 and 2. ATA-2 supports faster PIO modes (3 and 4), DMA modes (1 and 2), LBA and was marketed as Fast ATA (Enhanced IDE). ATA-3 only included some minor revisions on ATA-2. Ultra-ATA supports DMA mode 3 and runs at 33 MBps. Supported by Intel, Quantum Corporation proposed the ATA/66, that doubled the ATA to 66 MBps. ATA/100 then increased the data transfer rates to 100MBps.  Many synonyms for ATA exist and include Integrated Drive Electronics (IDE), Advanced Technology Attainment Packet Interface (ATAPI) and Parallel ATA (PATA).  In 2003, Serial ATA was introduced and the original ATA was renamed Parallel ATA.  SATA’s advantages over the older Parallel ATA interface are that data transfer is faster and it has the ability to remove or add devices during operation. Cables are thinner and allow for air-cooling which makes it work more efficiently. SATA was designed as a successor to ATA and Parallel ATA and it uses a high-speed serial cable.  SATA controllers have Advanced Host Controller Interface (AHCI) as its standard interface. It allows advanced features such as hot plug and Native Command Queuing (NCQ). AHCI is required to be enabled by the motherboard and chipset for the full advantages of SATA to be effective. If AHCI is not enabled, the SATA controller will operate in ‘IDE emulation’ mode.  Windows XP packaged drivers do not support AHCI, but it is implemented by proprietary device drivers. Windows Vista and the current versions of Mac OS X and Linux include native support for AHCI.  SATA has a special connector, eSATA, which is specific for external devices. Increased data transfer rates as high as 3 Gbit/sec per device are supported.   ATX Intel created the Advanced Technology Extended (ATX) specifications in 1995. It encompassed a big change from the AT computer case and motherboard design. A number of major improvements were applied to address issues with AT that frustrated system builders. The ATX specifications have been revised many times over the years.  A full size ATX board is 305mm wide by 244mm deep with the ATX chassis able to also accept microATX boards. Intel announced the new BTX standard in 2003 that was intended as a replacement for, ATX although it was mainly adopted by computer makers like Dell, HP and Gateway. Today, ATX remains the industry standard for home computer system builders.  AT style computer cases had a power button that was directly connected to the system which made replacing the power supply difficult. The ATX power supply does not connect directly to the system power button. This allowed the computer to be turned off by software. The ATX power supply has as a safeguard, a manual switch at to the back. If this switch is turned on, energy still flows to the components even thought it appears to be off. By manually turning the switch to off and ensuring that no power flowed through to the system components.  The attachment of the power supply to the motherboard was another major improvement in the ATX. The AT had two similar connectors that connected onto the motherboard.  Short-circuiting and other irreversible damage to the motherboard were common events from these connectors and being advertently switched. The upgrade to the ATX had only one connection that also provided a 3.3-volt source.   The standard 20-pin ATX power connector was found to be inadequate with the introduction of the Pentium 4. This was due to an increase in the electrical load requirements. The ATX standard was revised to include an extra 4-pin 12-volt connector. Major changes were effected to the back of the system case. The AT had the keyboard and expansion slots for add-on backplates. Serial and parallel ports were connected via leads that connected onto the motherboard and then mounted in spaces provided on the case. Improvements to the ATX allowed each motherboard manufacturer to place these ports into a specific rectangular area on the back of the system. The arrangement of the ports could be defined themselves. The case usually came with a snap out panel (I/O plate) that reflected one of the common arrangements. Keyboard and mouse connectors also upgraded with the ATX, the 5pin DIN serial connector and PS/2 were phased out in favor of the modern standard of USB port. Other ports gradually phasing out are the 25-pin parallel port and 9-pin serial port.  Replacing these are on-board Ethernet and audio ports.   Backbone Backbone is defined as either – the vertebrate spine or spinal column; something, such as the keel of a ship, that resembles a backbone; or a main support or major sustaining factor. A computer network or that part of it that connects other networks together is the backbone. It is that part of a communication network that carries the heaviest traffic. The backbone handles the highest-speed transmission paths in the network. In most cases the backbone will run the longest distances. Branching off from the backbone, smaller networks attach and directly connect to the end user. These are access networks. Being part of a larger computer network infrastructure, the backbone network interconnects different pieces of the network. Providing a path for information exchanges, the backbone connects between different LANs or sub-networks. Geographically, a backbone can span an area of any size. The backbone network can span from a single building or office complex to an entire country. Usually, the backbone’s capacity is greater than the connected networks. Large corporations that span many locations will have a backbone network that links each of the locations together.   The main trunk connections of the Internet are referred to as the Internet backbone. It is a collection of commercial, academic, government and other high capacity data routes interconnected. They carry data across continents and countries of the world. ARPANET was the original Internet backbone. In 1989, ARPANET shut down with the establishment of NSFNET and the US military network MILNET. NSFNET became obsolete and decommissioned in 1995. A new network architecture was created based on decentralized routing. Today, the Internet consists of many commercial ISPs and private networks including inter-university networks. Links and peering points connect them. The term Internet background is now a loosely worded term. The universal use of routing protocols allows the Internet to function without a single central network. Backbone providers provide facilities for connections for their clients and in turn connect with other backbone providers.   Bandwidth Bandwidth is a central concept in many fields – computer networking, electronics, and radio communications to name a few. It is the difference or range between the highest and lowest signals on the communication channel. The term bandwidth in digital fields such as computer networking refers to a data rate measured in bits/s. In radio communications, bandwidth is the range of frequencies that are occupied by modulated carrier waves. In Optics, it is either an individual or the entire spectral range. The capacity of the connection is represented by Bandwidth; a greater performance is due to a greater capacity, although, overall performance does depend on other factors. Promotion of network hardware by manufactures has also promoted the concept of bandwidth. Hardware such as modems or broadband Internet service, state bandwidth rating in either Mbps or Kbps. This bandwidth signifies the capacity of the connection, both actual and theoretical. One example is the V.90 modem which supports 56 Kbps of peak bandwidth. Limitations on telephone lines make it impossible for a home dial-up network to achieve this bandwidth.  In networking, an Ethernet port may theoretically supports 100Mbps bandwidth. Due to hardware and computer operating system constraints, realistically this bandwidth would not be achieved. The term high bandwidth is used by networkers to distinguish high performing Internet connects from slower dial-up access. Data rates greater than 64 Kbps are defined as high bandwidth.  Broadband is at times confused with high bandwidth. Broadband refers more to the method of communication; bandwidth refers to the quantity of data passing through the connection. Users wanting to measure the bandwidth of their network connections are able utilize a number of ‘bandwidth tests’ available on the Internet. These programs are available through public web pages. The Internet speed test measures the speed of your connection by using sample data files and test web servers. Performance tweaking of your network, when done in conjunction with these tests, assists with measuring the results. The bandwidth speed does not always compare favourably in regards to user-perceived performance of the network or any software application. Web browsers may perform slowly due to a bottleneck at the web server. It is common to attribute a slow network to performance problems, even though local area data transfer rates remain high. Popular online bandwidth tests are –  Speedtest.net Global Broadband Speed Test; CNET Bandwidth Meter and Bandwidth Place Bandwidth Speed Test.   Binary Binary means that something is composed of two parts or two pieces. It is the main principle behind digital computers. Conversion of all input to the computer is in binary numbers that are made up of the two digits: 0 and 1. The letter ‘A’ on the keyboard would be represented by 01000001. Binary numbers are converted by display screens and printers into visual characters.  Binary may also refer to – binary numeral system; binary function; binary data or executable file. The numbers 0 and 1 as in the example above represents the binary numeral system. Binary function is two mathematical arguments. Binary data is composed of digits as opposed to human readable text. An executable file contains machinery code or binary for the computer to execute.  Counting in binary using the binary numeral system is similar to counting in any other number system. Binary numbers are represented by bits (binary digits). Starting with a single digit, counting progresses through each symbol, steadily increasing. While binary uses the 0 and 1, decimal uses the 0 to 9.  An example of decimal counting would be 000, 001, 002 continuing on to 009, 010 and 011. When counting in binary, 000, 001, 010, 011, 100 and 101. The digit on the far right starts over, moving from 0 to 1 as in from 000 to 001. Moving from 001 to 010, again the digit on the far right starts over (1 to 0) and the next digit is then incremented as in from 0 to 1.  A binary file can contain any type of data for computer storage and processing purposes and encoded in binary form. If a computer document, it can contain formatted text. A binary file that only contains textual data called a plain text file. Binary files can also contain images, sounds and compressed versions of other files.   BIOS BIOS stands for Basic Input/Output System.  Its primary function is to identify and activate component hardware. BIOS is the firmware code that is run by an IBM PC when it is first powered on.  By running the BIOS first, the machine is prepared so that any other software programs stored on the computer can be loaded and executed.  By booting up with the BIOS, programs such as Windows can then be executed and assume control of the PC.  Macintosh PowerPC  and some other computers use Open Firmware instead of the standard BIOS.  In the 1970’s the term BIOS first appeared in the CP/M operating system which were an early industry standard for microcomputers.  CP/M machines had a simple boot loader in ROM.  Early microcomputers were pre-Windows and had a DOS operating system.  Most versions of DOS had a file called either IO.SYS or IBMBIO.COM.   BIOS is a coded program that is implanted on a chip.  This chip recognises and controls a number of devices.  The BIOS runs from Erasable Programmable Read-Only Memory (EPROM) or flash memory when the computer is first powered on.  At this time, it switches on a number of motherboard components and peripherals.  These include the clock generator, processors, chipset (memory controller and I/O controller) and the system memory.  All of the PCI devices initialise as well as primary graphics controller, storage controllers (IDE, SATA) and I/O controllers such as keyboard, mouse and USB.  Once all of these motherboard components have loaded, the BIOS then starts the operating system.  From this point, the BIOS transfers control of the computer system to the operating system.  The process from when the BIOS first runs through to the operating system taking control is known as the power-on self-test (POST).  In early IBM systems, POST was primarily for testing.  In modern computer systems, POST mainly configures the hardware.   Early systems optionally implemented a setup program which interfaced with the non-volatile BIOS memory (CMOS).  The CMOS held customizable data that the user could configure such as passwords, time and date.  This information was accessible by the BIOS code.   With the modern BIOS, users are able to select where the BIOS acquires its boot information.  This could be from the hard disk, floppy disk or CD device.  Alternatively, the boot information is obtained from a networked connection.  In some versions of BIOS, users are able to select which operating system they wished to load.  This could be Windows, DOS or another operating system.  Most current evolutions of BIOS include complex functions utilizing interfaces such as Advanced Configuration and Power Interface (ACPI). These functions included thermal management, power management and hot swapping.  Some motherboard manufacturers are now replacing BIOS with Extensible Firmware Interface (EFI) to provide more advanced features.   Bit A bit is a number that has the value of either 0 or 1, called a binary digit.  The bit is a unit of measurement or in modern computers, byte. It is a basic unit of information storage and communication. The symbol for bit is accepted as ‘b’ and for byte as ‘B’ in the computing industry. Bytes are a collection of eight bits.  Larger quantities of bits are measured by kilobit (kb), megabit (mb) and gigabit (gb).  Computer networks use transfer rates and refer to these as bits per second (bps). A bit is the smallest unit of data. It has a single binary value.  John Tukey a statistician and adviser to presidents first used the term in 1946. Computers are classified two ways.  One is by the number of bits that the computer can process at any one time.  The other is by the number of bits that the computer uses to represent addresses. A 32-bit classified computer may mean that its data registers are 32 bits wide. Alternatively, the computer may use 32 bits to identify each address in the memory. The ability of a computer to handle larger registers makes it faster. A computer’s capacity to use more bits for addresses, means that it is able to support larger programs. Bits are also used to describe graphics. Each bit represents one dot. Monochrome is a 1-bit image. An 8-bit image supports grayscale or 256 colors. True color is supported by either a 24-bit or 32-bit graphic. Network transmissions use the bit as a measurement. Transmission of 100 million pulses per second, equates to one hundred megabits per second. The bit transmits as a pulse of high or low voltage. By making the transistors open and close faster, the speed is increased. Internally transmitting these pulses within the computer is more simpler than over a network. Long distance and interference can impede transmission for networks.   Bitrate Bitrate is defined as the number of bits that are processed per unit of time. It is sometimes referred to as bit rate or data rate. It is measured using the ‘bits per second’ (bps) unit. Larger bitrates may be measured as ‘kilobits, megabits, gigabits or terabits’ per second. (i.e. kbps, mbps, gbps or tbps). Bitrate is measured by the ratio of bits that transfer between devices in a specified amount of time. This time measurement is typically one second.  The gross bitrate or data signalling rate is the total number of physically transferred bits per second over a communication link. This includes the useful data and protocol overhead. The net bitrate or data transfer rate is the capacity that excludes the protocol overhead. The forward error correction code rate affects the relationship between the gross bitrate and net bitrate.  Concerning the connection speed of a network, its access technology and/or communication device refers to the physical layer net bitrate. The 100mb bitrate of an Ethernet 100Base-TX and the downlink bit rate of 56000 bits of a V92 modem are just two examples. An ISDN B channel has a bitrate of 64000 bits and an 802. 11a wireless network has a bitrate of between 6 and 54 mb. Each of these examples refers to the net bitrate.  In multimedia, the bitrate usually refers to the number of bits in playback time. it is referred to as ‘a 128 kilobit audio stream’ or 100 megabit network’.  The speed of bitrate is often referenced. Speed does not measure distance/time but instead measures quantity/time. Propagation Speed is distinguished in that it depends on the transmission medium.  The amount of information or detail that is represented by bitrate in digital multimedia is that which is stored per unit of time of a recording. Several factors influence the bitrate. Different frequencies may be sampled from the original material. Data may be encoded by different schemes. Differing algorithms may be utilized to digitally compress the information. Generally, choices are made about the above factors in order to achieve the desired trade-off between minimizing the bitrate and maximizing the quality of the material when it is played.   BitTorrent BitTorrent is a protocol that used in peer-to-peer file sharing (P2P) for the distribution of large amounts of data. The advantages of this protocol are that the original distributor of the data does not incur the entire costs such as hardware, hosting and bandwidth resources.  Users are able to connect computers directly to send and receive portions of a file. This occurs through a central server (tracker). The tracker coordinates the sending and receiving of all peers (users). Although the tracker manages the connections, it has no knowledge of data or file contents that are distributed.   The main beliefs behind BitTorrent are that users would upload at the same time as they download. This philosophy’s linchpin is that in this manner, the network utilizes network bandwidth efficiently. As the number of users interested in a particular file increases, so does the effectiveness of this protocol.   Bram Cohen, a programmer, created this communication protocol in April 2001. It was released in July 2001 and is maintained by BitTorrent, Inc, Cohen’s company. In November 2006, the ‘Publish Torrent’ service was introduced by BitTorrent. The service creates and hosts a torrent file and tracks its downloads.  The torrent file is seeded from an existing web-hosted media file. Web-seeding is a requirement by the client to effectively use this service. Currently, the official client is Azureus and µTorrent. Both of these clients are based on Libtorrent.   A BitTorrent protocol is implemented by a BitTorrent Client. Each of these clients prepares requests and can transmit any type of data file. This is done over a network using the protocol. The peer/user’s computer needs to be running an instance of the client.  There are marked differences between the BitTorrent download and a traditional full-file HTTP request.  Firstly, BitTorrent makes many small P2P requests over different TCP sockets. Web-browsers usually make a single HTTP GET request over only a single TCP socket. BitTorrent, also downloads in a random approach that receives a high availability status. HTTP downs using a regulated sequential approach.  These differences allow BitTorrent to run more efficiently with less demand on bandwidth and at lower costs. While there are many advantages, one disadvantage is that downloads are slower to rise to their full download speed. This is partly due to the time required to establish enough peer connections. Downloads will generally start at a slower speed, increase to extremely high speeds and then near the end of the download reduce speed again. This fluctuation in speed does limit the support for progressive downloads or streaming playback; although, it is expected that these features will not be very far away from being incorporated into BitTorrent.  Increasingly individuals and organizations are using BitTorrent to distribute their own licensed material.  This is due in part to the reduced demands on networking hardware and bandwidth. Currently, podcasting software is integrating BitTorrent to deal with demands for MP3 radio programs. Both Juice and Miro support .torrent files for automatic processing of RSS feeds. Other BitTorrent clients process web feeds and download content.  This year (2008), CBC has become the first public broadcaster in North America to make available for download using BitTorrent, a full show. BitTorrent as a protocol is still under development and new features and enhancements are expected to continue improving efficiency.  Publish Torrent – http://www.bittorrent.com/publish   Blog A blog or web log is essentially an online diary. As a verb, blog can mean to maintain or add content to a blog. Entries normally display in reverse chronological order.  Before blogging become popular, online communities used many forms to facilitate communication between users. These included Usenet, Bulletin Board System (BBS) and Internet Forum software. The above services displayed like a message forum.  Conversations were shown as running ‘threads’.  Blogs can be about any subject. They can provide commentary or news and contain text or images. Links to other blogs, web pages and other related media are other common contents. Today, blogs are used as personal online diaries published on the web.  Interactive features are prominent in modern blogs allowing readers to leave comments. Technorati is a blog search engine that as at December 2007 was tracking more than 112 million blogs.  One of the recognised earliest bloggers, Justin Hall commenced blogging back in 1994 as a student. The modern blog evolved as people kept a running account of their personal lives in an online diary. Such writers were called diarists or journalers. Many blogs/journals evolved from the Quake scene such as game programmer John Carmack and Stephen Heaslip of Blue’s News (running since 1995). In February 1997, Steve Gibson was one of the ‘hired blogger’ when he was employed full time to blog for Ritual Entertainment. Today, this is an ongoing career path with many freelance writers being hired as bloggers.  Live Journal launched in March 1999 and Blogger in August 1999. Both of these blogging communities still operate today. Google now owns Blogger. In 2001, the blogging phenomenon generated how-to manuals, which primarily focussed on techniques.   Blogging has gained increasing notice and coverage since 2002. It’s role in breaking and shaping news stories. Political events have featured prominently in many blogs worldwide. Using blogging as a vehicle, bloggers have provided commentary on televised events. Another blogging site, Global Voices Online, brings together active bloggers worldwide. It has a relationship with Reuters and has been responsible for breaking past global news stories.  One of the most popular blogs is Facebook. Its popularity has grown phenomenally in recent years. Facebook is a social community of worldwide bloggers.   Bluetooth The Bluetooth technology was developed with the intent to create a single digital wireless protocol. This protocol would be capable of connecting multiple devices and ensuring synchronization of each of these devices. Initially named MC Link (multi-communicator link), it was first developed as an internal project by Ericsson in 1996 with cooperation from Intel from 1997. A consortium was formed in 1998 with Ericsson, IBM, Intel, Toshiba and Nokia and the project was renamed Bluetooth.  Over the years the consortium has grown and is now called the Bluetooth Special Interest Group (SIG).  This group now consists of over 10,000 member companies.  SIG are the drivers for development of this technology and are a non-profit trade association which does not manufacture or sell Bluetooth enabled products. Harald Bluetooth, a tenth-century King of Denmark is the inspiration behind the naming of this technology.  As he was known for the unification of warring tribes in Denmark, so too does the Bluetooth technology unify different technologies Bluetooth utilizes short-range communication technology which makes possible voice and data transmissions from either fixed or mobile devices over short distances.  The development of this single digital wireless protocol facilitates the connection of multiple devices.  It overcomes protocol issues which previously arose from attempting to synchronize different devices. Today, Bluetooth allows the connection and exchange of information between large numbers of devices.  Over a short-range radio frequency bandwidth, mobile phones, telephones, laptops, digital cameras and even video game consoles can connect. It is designed for low power consumption over short ranges from 1 meter to 100 meters.  As Bluetooth uses a radio communication system, devices do not need to be within line of sight although this depends upon the strength of the transmission. One of the earliest applications of Bluetooth technology was the mobile phone and hands free headset.  Since these early stages, the technology has exploded with wireless computer networking, communication between PC input and output (ie printers, keyboard) and incorporation into games consoles such as Nintendo’s Wii and Sony Playstation 3. Any device requiring the use of Bluetooth technology must be compatible with certain Bluetooth profiles. Bluetooth gadgets are continually arriving with no end in sight.  A sample of these include Party Speakers from Parrot (Black Edition), S-Frame digital photo frames from Sony, SUN headset by Iqua, MBW-150 watch from Sony Ericsson (music edition) and a Virtual laser keyboard from Golan Technology.   Blu-ray Blu-ray is also knows as Blu-ray Disc (BD). It is the next-generation of optical disk formatting. It was developed by a group of the world’s leading electronics, personal computer and media manufacturers. The group, Blu-ray Disc Association (BDA) includes Apple, Hitachi, Dell, JVC, HP, LG, Mitsubishi, Pioneer, Panasonic, Philips, Sharp, Samsung, Sony, TDK and Thomson. While early formats that are still current today such as DVD, DVD+R, DVD+RW and DVD-RAM use a red laser to read and write data, Blu-ray relies upon a blue-violet laser. The name Blu-ray comes directly from the type of laser used. The Blu-ray format was initially developed for recording, rewriting and playback of high-definition video (HD). It is also able to store large quantities of data.  The traditional DVD can store a maximum of 7GB, while the new format of Blu-ray can store up to 25GB on a single-layer disc and up to 50GB on a dual-layer disc. The combination of large storage and advanced video and audio codecs increases the HD experience. An advantage of the Blu-ray format is that they can be made backward compatible with CDs and DVDs using a BD/DVD/CD compatible optical pickup unit. The blue-violet laser has a shorter wavelength of 405mm in contrast to the red laser used with DVD and CDs which is 650mm. The laser spot is focused with greater precision using the blue-violet laser allowing data to be stored in less space. The first prototypes were made public in October 2000 at the Combined Exhibition of Advanced Technologies (CEATEC), an annual exhibition held in Japan. Problems arose initially in these early prototypes as the data recording layer was close to the surface of the disc. To prevent contamination and scratches, they were required to be enclosed in plastic cartridges. The format was officially named Blu-ray in February 2002 In April 2003 the first device able to read this new format was developed by Sony and it was only made available to stores in Japan. As there was no standard for pre-recorded videos for this device, no movies were ever released.  The plastic cartridges were discontinued in January 2005 with the announcement by TDK of their development of a hard polymer coating which would prevent contamination and scratches called Durabis. Sony, Panasonic and Verbatim also have their own proprietary hard-coat technologies.  Like DVD’s, Blu-ray discs have region codes although the regions differ from the DVD format. Region A includes the Americas, East and Southeast Asia. Africa, Europe, Oceania, Middle East, French territories and Greenland are in Region B. Region C comprises China, Russia, Mongolia, Central and South Asia. Currently, two-thirds of all Blu-ray discs are region-free. Today, over 180 worldwide leading electronic, computer, video game, music and recording media companies now support Blu-ray. Disney, Fox, Paramount, Sony, Lionsgate, MGM and Warner have all released movies in the Blue-ray format. Movies are now released in both DVD and Blu-ray. Over 530 titles in the US and more than 250 in Japan have been released in Blu-ray format thus far. Link - http://www.blu-ray.com/info/ http://www.blu-ray.com/movies/ Related Words HDMI; Plasma Technology Boot To boot when used in relation to a computer or the term ‘to boot up’ refers to the process used when starting a computer. The boot procedure loads an operating system into the computer’s surface memory or random access memory (RAM). This operating system may be one of the many versions of Microsoft Windows or Macintosh, UNIX, Linux or OS/2. Once loaded, the computer allows users to run the applications which are installed on the computer. Other terms which activate the same process are reboot, booting or system boot. Larger computers such as mainframes use the term ‘initial program load’ (IPL) instead of ‘boot’.  The term ‘boot’ is thought to come from the word ‘bootstrap’. A bootstrap is a small loop at the back of a leather boot.  By pulling on this loop it is easy to pull the boot onto the foot. ‘Pulling yourself up by your own bootstraps’ is an old expressions which means to pull yourself from a small beginning to success.  A system boot is loading a small program into the computer. This small program will control the processing of loading the full operating system. Once the operating system is loaded, the control of the computer reverts to the user who can then select which application program they wish to use. Older computers required the user to insert a disk each time the computer was turned on to boot and load the operating system.  Even earlier computer systems required users to flick toggle switches to activate each stage of the system boot. Today, the action of turning a computer on will automatically activate the system boot and the loading of the operating system. Installing an operating system differs to booting as the installation is a onetime setup operation while booting happens thereafter each time the computer is turned on. The booting procedure will differ depending upon the type of operating system installed. Using Microsoft Windows as an example, the booting process will start as soon as the computer is turned on. The BIOS (basic input-output system) on the ROM (read-only memory) chip wakes up and takes control of the BIOS. The BIOS is already loaded as it is built-in to the ROM chip. The BIOS does a POST (power-on self test) to check all of the components of the computer. It will then check different locations for any special boot programs that will load the operating system. The BIOS will either check Drive A (floppy), CD drive or C (hard drive) and these will depend upon the BIOS settings. If one location does not hold the system files, the BIOS will move on to the next location. Once the boot files have been located, the BIOS will check the first sector (512 byte) which is known as the boot record or MBR (master boot record). This information is then copied across into the RAM and contains a program that gives the boot record control of the computer. The initial system file (IO.SYS) will load into RAM. Other files loaded will include SYSINIT, CONFIG.SYS and WIN.INI. Once all of the operating system files have been loaded, the computer has control and can request initial commands and then is ready for the user.   Boot disk When installing an operating system on a computer, a boot disk is required. The boot disk is a digital data storage medium which is removable. It can load and run an operating system or utility program. The computer will initially look for a boot or utility program. The modern computer is configured to attempt to boot from more than one device. It will first check the A: drive. The data storage type suitable for the A: drive would be a floppy disk.  The computer will then check the D: drive which will usually be a CD/DVD ROM and the data storage type will be a CD. Lastly, the computer will check the C: drive for the boot or utility program. Depending on the computer system, other types of media may be used such as magnetic or paper tape drives, zip drives and USB flash drives. Boot disks are more commonly used as part of installing an operating system. Data recovery and data purging also require a boot disk. When hardware or software are troubleshooting, the user may be prompted to insert a boot disk. Other times a boot disk may be required will be when customizing the operating environment. The computer will have a built-in software program that is able to load the first 256 bytes of contents on a floppy disk or other media. It will execute it if it is a workable program. This program may be designed to load a larger program such as a full operating system. Each type of operating system will require different contents on the boot disk. Depending on whether your operating system is MS-DOS/PC-DOS, Windows or Linux it will have different requirements. Each will require a valid boot sector on the boot disk media. Windows requires the file winini.sys. Early versions of MS-DOS require command.com, IO.SYS and MSDOS.SYS. FreeDOS needs command.com and kernel.sys. Another operating system called Linux calls for a bootloader such as SYSLINUX or GRUB, a Linux kernel and initrd (initial ram disk). Whether operating your system in Windows XP or Windows 98, it is important to have the relevant boot disk for that operating system. In most cases, as part of an operating system installation, the user will be prompted to make a boot disk. The use of this boot disk may be for data recovery or operating system rescue purposes.   Brightness Brightness is an attribute of visual perception in which a source appears to produce a given amount of light. The brightness of a monitor is measured in nits or candelas per square meter (cd/m2).   Broadband The term broadband is most commonly used when referring to broadband internet access.  It has different meanings when used in relation to telecommunications, data communications, video, DSL and Ethernet. In telecommunications, broadband is a relative term that means a signalling method that handles a wide range of frequencies. The width of the broadband bandwidth increases the information carrying capability. Morse code would be carried by a narrow signal. A signal that is able to carry speech would have a broader signal band. Increasing the bandwidth further will enable it to carry music. Broadband in relation to video usually refers to streaming internet videos. These video files have a high bitrate that requires broadband internet for users to be able to view them. With analog video, cable television would be a broadband system requiring multiple channels modulated at fixed frequencies. Broadband networks and broadband internet are data communications that utilize ADSL or a fiberoptic cable to transmit data faster than the older generation modems operating at 56kb/s (kilobits per second). Broadband internet access is commonly shortened to Broadband. Earlier versions of internet access used the telephone line connected to a modem and then to the computer. A major disadvantage of this technology was that the telephone was engaged fully with accessing the internet and no inward or outward telephone calls were accessible. With the advent of Broadband technology, internet speeds increased dramatically.  The earlier dial-up modems of 56kb/s speed became obsolete.  Computer users were able to access the internet at high speeds ranging from 64kb/s up to 1.0Mb/s. Broadband or high speed internet has a high rate of data transmission. The method of delivering broadband depends on the technology used. DSL and cable modems are the standard broadband technologies.  Other newer ones include VDSL or VHDSL (very high speed DSL) and optical fire connections. Depending on location, satellite broadband is proving more viable in rural locations. Broadband technology is growing rapidly with Wi-Fi hot spots and networks available at many locations worldwide and mobile phones now being internet enabled. Wi-Fi is a wireless technology which facilitates access without cabling to the internet and other applications. Advances in Wi-Fi broadband technology include WiMAX (Worldwide Interoperability for Microwave Access) and EV-DO (Evolution-Data Optimized). Today, Broadband is the internet access standard of choice with every increasing options. High speed access has made possible technologies such as VOIP (Voice over Internet Protocol). Lower cost telephone calls using VOIP on broadband internet has become increasingly popular.   Browser A browser or web browser is a software application. It allows a user to display information such as text, videos, music or images in the form of a web page. This web page is sited at a website which forms part of the World Wide Web (WWW) or it may be located on a local area network (LAN). WorldWideWeb was the first web browser developed in 1991 by Tim Berners-Lee. There are now many web browser applications available. The most common one, Internet Explorer, forms part of the Microsoft operating system. Until recently the full version of this browser was included as part of the operating system installation. The most recent Microsoft Operating System, Vista now contains a basic version of the browser and the full version is also available separately as a standalone software application.  There are numerous web browsers available for download from the Internet for installation on a personal computer. A few popular web browsers are Mozilla Firefox, Safari, Opera, Flock, AOL Explorer and Netscape Navigator. Web browsers access web pages available on the Internet. These web pages are a HTML (hypertext markup language) file format that enables the web browser to display the content on a personal computer. Early web browsers supported a simplified HTML format. The advent of the rapidly development of web browsers expanded opportunities for development of non-standard HTML formats. This initially led to problems of web browser interoperability. The majority of browsers support additional formats such as JPEG (Joint Photographic Experts Group), PNG (Portable Network Graphics) and GIF (Graphics Interchange Format) image formats. The functionality of the browser can be extended by the installation of plug-ins. Web browser plug-ins are available for Java and Shockwave to name a few. These plug-ins can be used to view image, sound or video features of a web page. Most of the popular browsers such as Internet Explorer and Mozilla Firefox are able to support additional components. These components include Usenet news, email and IRC (internet relay chat). Additional protocols that supported include SMTP (simple mail transfer protocol), IMAP (internet message access protocol), POP (post office protocol) and NNTP (network news transfer protocol). More than mere web browsers, with these additional functionality features, they become internet or application suites. Although browsers are usually associated with the Internet, they can also be used in private networks or intranets. The HTTP or URL address would be located within the closed network instead of on a web server on the World Wide Web. Internet Explorer’s market share peaked in 2004 with over 92% of the market Browser competition has increased and a direct effect is a steady decline in market popularity. In February 2008, Internet Explorer still held 74.88% of the market share. Mozilla Firefox with 17.27% and Safari with 5.7% are becoming more popular as an alternative browser. Recent browser developments released in 2007 were Maxthon 2.0, Netscape Navigator 9, Netsurf 1.0, Flock 1.0 and Safari 3.0.  In 2008, Konqueror 4 and Safari 3.1. Current beta versions of Opera 9.5, Firefox 3.0 and Internet Explorer 8 are now available.   Buffer The buffer in computer terms is a temporary storage area. Its purpose is to act as a holding area for data.  This region of memory (buffer) is used to hold data briefly while moving from one place to another. The buffer or temporary data storage area usually resides in the RAM (random access memory). To ensure an uninterrupted flow of information, the buffer acts as a temporary storage area between software programs or hardware devices.  The data is able to be more quickly accessed from the buffer within RAM than retrieving it directly from the hard drive. Reading and writing data to hard drives can be relatively slow compared to RAM. By using the buffer, programs and devices can speed up data retrieval. Software programs such as word processors and other programs that have an “undo” command feature use the buffer to track changes within a document. The document on the screen is temporarily stored in the buffer, until the user saves the file to the hard drive. Most word processor programs will intermittently save a temporary copy of a document in progress. It is important to save documents regularly so that in the event of a computer crash or power interruption any data stored in the buffer will be lost. Internet and streaming online multimedia content is another example where the buffer makes the process of viewing a file more efficient. Without a buffer, the entire file would have to be loaded onto the computer before playing. If the file was able to play while still loading, the playback would have breaks and jumps. In some cases, hardware devices may have their own built-in RAM or buffer such as printers. Smaller basic printers will generally have a smaller buffer. A larger printer will have a buffer that is capable of handling larger jobs. Print spooling is where a document is sent from the computer to the printers’ buffer and is then maintained in a print cue awaiting printing. The buffer is utilized by many hardware devices. A CD burner will use the buffer by transferring data to the buffer prior to being written onto the disc. The buffer receives input from the keyboard for each key stroke and retains the information until the data is saved to the hard drive. Other applications utilize the buffer with hardware such as disk drives, playing sound on the speaker or data sharing through a network. The buffer acts in a FIFO (first in, first out) processing of data. The cache is sometimes confused with the buffer. The buffer acts as a temporary storage area only, once the data has been sent on to its destination, it is gone from the buffer. The cache acts more as a repository for data that will be read from multiple times. A buffer overflow can occur when a volume of data is sent to be stored in the buffer in excess of the available buffer data space. To remedy this situation, the buffer can be increased, although this will reduce the amount of RAM available to handle other computer processes.   Bus A bus originally was an electrically parallel system. It had electrical conductors that were similar to the pins on the CPU (central processing unit). There have been a number of generations of buses culminating in the modern day bus. Buses are able to connect more than two devices together. These devices may be the CPU, main memory or I/O (input/output) devices. The three types of signal include data, address and control. Some general purpose buses are VME, FutureBus, Multibus and SCSI. These buses are able to connect a large range of devices to a computer. The majority of buses are backplane devices in that they are a circuit board with parallel connectors. Other boards are able to plug into it perpendicularly. Buses such as SCSI are frontplane devices in that they are cable based and are in a separate chassis. The first original bus was VMEbus and it was developed in the 1970s. As a new technology it was much faster than the other devices plugged into it. Although CPU (central processing unit) and RAM (random access memory) speeds quickly increased. In answer to these technological advancements, development of Futurebus started in 1979 and further redesigns lasted up until 1994 with strong interest from the US Navy. The Futurebus did not develop further beyond 1994. Multibus was developed by Intel primarily for industrial computer systems.  A Multibus compatible industry developed with a large number of companies manufacturing CPU, memory and other peripheral boards specifically designed for it. Sun Microsystems was one company that designed their own specific Multibus boards which were incorporated into their Sun 1 and Sun 2 workstations. Buses are able to support multiple transfer modes. A block transfer is fast, as the address portion is sent only once for the entire block. It initially starts with the address and then sends a series of data values. Other bus designs will multiplex the address and data lines. On high performance buses, split transfer is another method. It usually is associated with a read. This means that the read is requested of the bus and then the bus is realeased. The bus is now available for other transactions of data.   There are many different types of buses. A parallel bus carries data words in parallel on multiple wires. A serial bus carries data in bit-serial form. Both VMEbus and Multibus are internal parallel buses. PCIExpress and Firewire are internal serial buses. External buses are available with ATA (advanced technology attachments) handling both parallel and serial buses for disk/tape peripheral attachments.   Byte A byte is a unit of measurement for information storage. It consists of eight bits and in computing terms it is a unit of memory addressing. A bit is a small unit and is comparable to a single character from the Western character set. In the 1960s with the popularity of IBM’s system, bytes were between five to twelve bits. Computer technology exploded with microcomputers and microprocessors in the 1980s the 8 bits became the common size for a byte. Another common term when referring to a byte is octet. Dr Werner Buchholz first used the term byte in 1956. In the early phases of design for the IBM Stretch computer, the term byte referred to a 4-bit byte size field. This field allowed between one to sixteen bits. Later the design was reduced to a 3-bit byte size field, with a byte represented from one to eight bits. Today, the byte is represented by the fixed eight-bit byte size. Early computer scientists had a fondness for making up and changing the spelling of words. A byte is the smallest amount of data that a computer can take at a time. A bite of data or a byte as it was eventually termed. ‘b’ is the symbol for byte. When referring to larger amounts of data, multiples of a byte are used. Kilobytes (Kb) consist of 1,024 bytes. A megabyte (Mb) consists of 1,024 x 1,024 bytes. Other multiples of bytes include gigabyte, terabyte, petabyte, exabyte and zegabyte. A few of these terms might appear familiar. A kilobyte may be used in the size of a word processing file. Megabyte may refer to size of memory or RAM (random access memory) in a computer or for a large graphic or image. The size of a hard drive is in multiples of gigabytes, such as 80 or 120 Gb. An advertisement for a computer will refer to a 32-bit Pentium processor, 250Mb of RAM and 80 Gb of hard disk space.   C++ C++ is a popular general purpose programming language. It is a compiled language and creates machine code for the specific machine hardware. This language is multi-paradigm and statistically typed free form. It is able to support procedural programming, object-orientation and data abstraction in addition to general programming. It was first developed in 1979 by Bjarne Stroustrup at Bell Labs as an enhancement to the C program language. It was named as ‘C with Classes’ and renamed C++ in 1983. It has enhancement classes with features such as function, name and operator overloading, templates, exception handling, virtual functions and multiple inheritance. Other features include references, constants, user-controlled free-store memory control, and improved type checking. Similar features from BCPL (B Computer Programming Language) such as the BCPL style single-line comments with two forward slashes (//). C++ was ratified in 1998 as ISO/IEC 14882:1998. Further developments continued with the current 2003 version, ISO/IEC 14882:2003 and a new version in development known informally as C++0x. Predecessors to C and C++ were APL (A Programming Language) and BCPL (B Computer Programming Language). Although APL was different in concept to C++, BCPL was similar in that it was used to create machine code. BCPL was more efficient than C. Advantages of C++ was that it was available for a larger variety of processors and platforms.  BCPL was very fast but was a low level programming language. C++ operates on both low-level and high-level programming. Inspiration for C++ came from features of Simula as programming language developed in the early 1960s. Its capacity for large software development was integrated into the development of C++. The Annotated C++ Reference Manual was published in 1990. As this programming language has evolved, so has the standard library. These included the stream I/O library which replaced C functions such as printf and scanf. In 2005, the Library Technical Report 1 (TR1) was released. This was not an official part of the standard but provides additional extensions to the original standard library. C++ is a royalty free programming language, although the standard document is not freely available. The key philosophies behind C++ are that it is designed to be a statically typed general purpose language that is efficient. It is able to support multiple programming styles and gives the programmer choices that are not platform specific.   Cache Cache is pronounced the same as ‘cash’. It is a collection of data that is duplicated within the cache and has its original data stored elsewhere. This temporary storage area holds frequently accessed data. This data can be accessed more quickly from reading the cache than re-fetching the data from its original location and expedites data access. The word ‘cache’ originated in 1967 from an article about memory improvement in the Model 85 to be published in the IBM Systems Journal. Lyle R Johnson, the Journal Editor, found the term ‘high-speed buffer’ undescriptive and suggested the term ‘cache’ (meaning ‘to hide’). The article was published in 1968 and the term ‘cache’ entered computer literature as a standard. The cache is a block of memory which is used for temporary data storage which is often required for retrieval. Both software and hardware have access to a cache. CPU’s (central processing unit) have used one or more caches since the 1980s. The CPU cache is managed by hardware. Other caches such as the page cache are managed by software. Fast local hard drives will use the operating system kernel to cache data. Accessing slower data storage devices such as tape drives or remote servers, a local hard drive will cache data to speed up data processing.  Hierarchical storage management is a technique which moves data between high speed and low speed storage media. This is the main concept behind cache. Caches are available for many computing activities. Web browsers recently visited websites using a cache. Using proxy caches, Internet Providers are able to save bandwidth on frequently accessed web pages. Search engines such as Google often provide a cache link next to search results to enable viewing web pages which may be temporarily unavailable from a web server. The cache is able to hold a quantity of data which can be increased. Each item of data is classified as an entry. The entries are a copy of the data held in a storage device. A tag is attached to each entry that identifies the data item in its original location. To access this data quickly, the device or software will first check the cache. In the event an entry is found with a corresponding tag of the required data, this entry will be accessed from the cache. This is called a cache hit. Alternatively, the cache may not hold the desired data and this is called a cache miss. In this event, the cache will fetch the data from the storage device and copy it into the cache for future access. If the cache is full, an entry which has been least recently used will be ejected from the cache to make room. The term buffer is sometimes confused with cache. The difference is that the buffer is temporary memory storage for one time use until the data has been transferred to another location or device.   CDMA Code division multiple access (CDMA) is a channel access method and should not be confused with now defunct CDMA mobile phone standard. A basic model of data communication is that several transmitters are able to send information at the same time over a single communication channel. This is called multiplexing and allows several users to share a bandwidth of frequencies. CDMA uses spread-spectrum technology. This technology generates energy in a specific bandwidth and it is intentionally spread in a frequency domain and results in a signal with a wider bandwidth. CDMA also uses a special coding scheme where each transmitter is assigned a code. It allows many users to multiplex over the same channel. Other technology such as TDMA (time division multiple access) and FDMA (frequency-division multiple access) use alternate methods. CDMA uses the spread-spectrum signalling with a modulated coded signal that is a lot higher data bandwidth than the actual data. One early application of CDMA is GPS (global positioning system). Before GPS, CDMA was initially a military technology and was used during World War II. Qualcomm created the communication chips for the CDMA technology and became privy to this classified technology. Once the technology became public, Qualcomm patented it and produced the technology commercially. The OmniTRACS satellite system uses CDMA for transportation of logistics. As bandwidth is a limited resource, the majority of modulation schemes try to minimize this signal. CDMA uses the spread spectrum technique and is able to use a greater transmission bandwidth. Initially, CDMA was used primarily for military applications such as guidance and communication systems. Spread spectrum ensured security and also a resistance to transmission jamming. CDMA is also effective in rejecting narrowband interference. This form of interference only affects a small portion of the spread spectrum signal and can be removed with minimal loss of information. The CDMA signal is also resistant to multipath fading as the signal occupies a large bandwidth. The loss of information by either of these instances is easily overcome and data recovered.   CGI The Common Gateway Interface (CGI) is a standard that interfaces external software applications with an information server or web server. The CGI standard originated in 1995 as part of a discussion between software and web site developers. The key contributors were Rob McCool (author of NCSA HTTP web server), John Franks (author of GN web server), Ari Luotonen (developer of CERN http web server), Tony Sanders (author of Plexus web server) and George Phillips (web server maintainer at University of British Columbia). The initial CGI specification was drafted by Rob McCool and it is still hosted by NCSA. A HTML document is retrieved by the web. It is a text file that does not change and is static. A CGI program is implemented in real time and it generates dynamic information as output. Executable applications commonly used with CGI commands include online database forms and email forms. The commands are embed in a HTML web page generate output to the web server. An information or web server responds to requests from web browsers. Depending upon the request, the server returns the appropriate outcome. The server will identify if a request is for a file stored on disk, if so, then it will retrieve that file. Alternatively, the request may identify an executable command. In this instance, the server will run the command and return the output. The CGI standard characterises the method of executing the command. The main drawback to the CGI standard was that is was low-tech. The command would call up a newly created process. This process would involve time to execute the command and would tie up memory in excess of the output generated. CGI that were called often had the potential to overwhelm web servers. Web servers usually contain a cgi-bin directory in the directory tree base that holds the executable files able to be called by the CGI standard. Development in web technologies has grown with many popular web servers developing their own extensions. These extensions allow third-party software to run inside the web server. A key example is web browsers such as Internet Explorer, Netscape or Mozilla Firefox’s plug-ins. These extension interfaces are not as standardized as CGI but are able to be implemented on multiple web servers. Another alternative is FastCGI, a CGI script accelerator. A CGI program is able to be written in any language – C++, Fortran, PERL, Unix shell, Visual Basic, or Apple Script. If a programming language such as C++ or Visual Basic is used to write the CGI program, the source code must be resident in the cgi-bin. Alternatively, if a scripting language is used such as PERL or Unix shell, then only the script needs to reside in the cgi-bin directory. CGI scripts are easier to debug or modify than a compiled program.   Chipset The chipset controls communication between the processor and external devices. It has an integral role in shaping system performance. It has a number of integrated circuits which are designed to perform related functions. An integrated circuit is a small electronic device and is manufactured from semiconductor material. Jack Kilby of Texas Instruments and Robert Noyce of Fairchild Semiconductors developed the first integrated circuit in the 1950s. Dado Banato founded Chips and Technologies in the 1980s and pioneered the manufacture of chipsets for PC compatible computers. In the 1980s and 1990s, chipset referred to customized audio and graphics chips such as Commodore Amiga Original Chip Set or the SEGA System 16 chipset. Modern chipsets now replace the functions of one or more older chipsets. A chipset is a group of specialized chips that are designed to work together. They are commonly found on a computers motherboard or an expansion card. On the motherboard, the term chipset refers to a pair of chips that represent the north bridge and the south bridge. The north bridge associates the CPU with high speed devices such as graphics controllers and main memory. The south bridge links to lower speed peripheral buses (PCI or ISA) and on-chip integrated peripherals such as Ethernet, USB and audio devices. The chipset manufacturer is independent from the motherboard manufacturer. PC Compatible chipset manufacturers are Via Technologies, AMD, NVIDIA, Intel, Broadcom and SIS. Manufacturers for Apple and Unix include Sun, SGI and NeXT. Computer systems are able to share commonly used chipsets which are found in different computing specialties and operating system platforms. Any decisions regarding a computer system are reliant upon the chipset and CPU. The CPU is the brains of the computer and the chipset is its heart. The chipset controls the flow of information between the CPU and the system memory on the motherboard. The chipset is responsible for efficient data transfer and advanced power management to name a few. Chipsets are also integrated into modem and video cards. These chipsets differ in purpose but are of a similar principal in that they are integrated circuitry to perform a number of functions. AMD manufacture other chipsets for AMD processors such as the AMD 790FX, Intel processors ATI CrossFire Xpress 320 and Graphics processors such as ATI Radeon HD 3800. Intel manufacture chipsets for the Intel processors 975X for the dual core. NVIDIA produce chipsets for both AMD and Intel processors and graphic cards. SIS (Silicon Integrated Systems) and Via Technologies manufacture chipsets for both Intel and AMD processors.   Clock Speed The clock speed or clock rate is the rate of cycles per second in which a computer performs its basic operations. This rate is measured in hertz (Hz) and is a measurement of frequency. It is a basic unit of frequency in the International System of Units (SI) and is used worldwide for both computing and scientific situations. The hertz was named after Heinrich Hertz a German physicist, in honour of his scientific contributions to electromagnetism in 1930 by the International Electrotechnical Commision (IEC). In 1960, the General Conference on Weights and Measures (CGPM) adopted this term to replace the previous name of cycles per second (cps). By the 1970s, the term cycles per second was largely replaced by hertz. In computing and more specifically computer processing speed, the term gigahertz has become a common term. Clock speeds are stated in either megahertz (MHz) or gigahertz (GHz). One megahertz is equal to one million cycles per second. One gigahertz represents one billion cycles per second. The clock speed determines the rate or speed that a microprocessor executes instructions. All computers have an internal clock. This internal clock regulates the speed that instructions are carried out and will coordinate the individual computer components.  The CPU requires a specific number of clock cycles to undertake each instruction. The speed of the clock determines the number of instructions a CPU is able to execute per second. The clock is a quartz crystal. When electricity is passed through it, the clock vibrates at a specific frequency. The vibration emits a pulse or beat similar to a metronome. This pulse is sent to each component that is synchronized with it. The clock speed is able to coordinate and organise large amounts of data that is transmitted within the computer by the beat of the clock or clock cycle. Early computers had only one system clock. Advances in CPU technology created issues as other components could not process and send information at these increased speeds. Modern computers allow for asynchronous operation. Motherboards are able to have separate clocks for different components. Components such as video, system bus and expansion bus will have their own separate clock in addition to the CPU’s clock. Their individual clocks are able to optimize transfer rates and data exchange. CPU manufacturers will determine the clock rate of a CPU by testing at the end of the manufacturing process. Each CPU is labelled as complying with a set of standards such as 2.5 GHz clock rate.     CMOS Complementary metal-oxide-semiconductor (CMOS) is pronounced as “see-moss”. CMOS technology is a major class of integrated circuits which are used in microprocessors, static RAM (random access memory), microcontrollers, and other digital logic circuits. Analog circuits such as data converters, transceivers and image sensors also use CMOS technology. The patent for CMOS was obtained by Frank Wanlass in 1967 in the United States. Two significant features of CMOS are that it has low static power consumption and high noise immunity. The transistor only draws power when it switches between on or off. With minimal power usage, CMOS devices do generate low levels of waste heat. CMOS are composed of semiconductor materials such as silicon and germanium. Elements are added to the manufacturing process that increase its conductivity. This process is called doping. Common dopants are arsenic, antimony, bismuth and phosphorous. Depending on the type of dopant or level used will establish whether the semiconductor is N (NMOS) or P (PMOS) type. N-type is a current that is conducted by excess free electrons. P-type is a current that is conducted by electron vacancies. CMOS semiconductors have both NMOS and PMOS circuits. Only one of these circuit types is active at any time, which reduces the amount of power. Chips that use only one type of transistor require more power. This technology has proved popular with CMOS chips used in battery powered devices. The CMOS battery serves to hold CMOS memory such as date, time and system setup parameters in personal computers. There are four main types of CMOS batteries, external lithium, barrel style solder, PS2 6v and the coin cell. The most common type of battery is the Coin cell. It is the size of a coin and its small thin shape makes it ideal for use in computers. CMOS batteries have a standard lifetime of approximately 10 years, although this varies depending on the computers use and environment. Modern commercial CMOS products are integrated circuits that are composed of millions of transistors. It is a rectangular piece of silicon no more than 4 centimetres and is called a chip or CMOS chip.   Codec A Codec is a specialised program that is able to encode or decode a digital data stream or signal. It is an acronym for compression/decompression. The codec is able to reduce the amount of bytes that are used by large files or programs. There are many codec schemes. These are used to minimize file transfer times and are often used in conjunction with the Internet. Programs for the Internet such as QuickTime and NetMeeting use codecs. Other codecs are meant to maximize data that is to be stored in a CD-ROM or disk space. An endec is a similar concept that is used for hardware. Early codecs were hardware coded. They encoded analog signals into Pulse code modulation (PCM) and then decoded. The term codec is now applied to software that converts between digital signal formats. A codec is able to encode and decode. When encoding, the codec uses compression which eliminates redundancies in the data. Any file whether text, programs, images, video or audio can be compressed. Compression reduces the size of a file by a factor of 100. A 20 megabyte file may be reduced to 200 kilobytes. Decoding is when the codec uses decompression to ‘undo’ the compression. Videoconferencing and other streaming media applications use codecs extensively. The video camera uses an analog to digital converter (ADC) to convert signals from analogue to digital. These signals then pass through a video compressor for either transmission or storage. The signal is then run through a video decompressor in a receiving device. To display the file, the signal passes through a digital to analogue converter (DAC). This whole process or video conferencing unit is called a codec. Audio files follow the same process and these codecs are used in the sound cards of computers. The raw encoded structure of audio and video data is called essence. There are many codecs available with some available free for download and others at a cost. Often, multimedia data streams require both audio and video data as well as some metadata that will synchronize both the audio and video. A container is needed to handle these three streams as they will each use different programs or processes. They will be encapsulated within a container format. AVI is often mistaken to be a codec, but is actually a container format. Other popular containers are QuickTime, RealMedia, DivX and MP4. Links: http://www.free-codecs.com/   Contrast Ratio The contrast ratio refers to the ratio of the brightest (white) to the darkest (black) on a screen. The higher the number the darker the black is displayed. For example, 800:1 represents that the white pixels of the monitor is 800 times brighter than a perfectly black pixel. “Brightness is measured in nits. The average LCD currently is in the range of 250-280 nits. Ultra-bright models are capable of 450 nits. A higher nit level isn’t always good. In a darker room, 450 nits would make you reach for your sun glasses.” - Ahinc.com   CPU The CPU (Central Processing Unit) is also called a processor. A broad definition of CPU is that it is able to execute computer programs. It has its grounding in the early computers in the 1960s. The design and implementation of CPUs have considerably changed over the years, although their fundamental functions have remained constant. The introduction of the integrated circuit (IC) allowed for the miniaturization in the design of CPUs. Early CPUs were designed specifically for a particular computer and included a number of components and small integrated circuits on one or more circuit boards. This was costly as CPUs were not able to be used in different computer designs. Modern CPUs are used in personal computers, laptops, cell phones, toys, cars and robotics to name a few. The CPU is housed in a single chip called a microprocessor and usually has only one integrated circuit. The smaller size means a faster switching time and this is reflected in the overall speed of the CPU and since the 1970s, the microprocessor class of CPUs has eclipsed all other CPU implementations. The CPU is an internal component of the computer and in appearance are small, square and have a large number of metallic pins on the underside. To reduce heat emission a heat sink fan is attached on top of the CPU. It is inserted into a CPU socket with the pins facing down on the motherboard. The motherboard manufacturer’s specifications will determine the CPU requirements. A computers most important component is the CPU. The CPU is the brains of the computer. Its main function is to execute a program or a sequence of stored instructions. A CPU has two key components. The arithmetic logic unit (ALU) performs arithmetic and logical operations. The control unit (CU) is able to extract instructions from memory. Calling on the ALU when necessary, the CU decodes and executes the instructions. In operation, all CPUs undertake four key steps – fetch, decode, execute and writeback. The CPU will fetch from memory the instructions of what the CPU is required to do. The instruction is then broken up (decoded) into parts that are important to other areas of the CPU. The execute step brings together each part of the CPU to perform the instructed operation. In the writeback step, the CPU will ‘write back’ the results into either the internal CPU register or into the main memory.   CRT A cathode ray tube (CRT) is used in many devices such as televisions and computer monitors. It is a vacuum tube that contains an electron gun. A fluorescent screen is able to accelerate and deflect the electron beam. The CRT forms images by using the light emitted from the fluorescent screen. The images can take the form of electrical waveforms when the CRT is used in an oscilloscope or as pictures when used in television or computer monitors. German physicist, Ferdinand Braun invented the earliest CRT, known as a Braun Tube in 1897. The Braun CRT used a cold-cathode diode. In 1922 the first CRT using a hot cathode was developed by John Johnson and Harry Weinhart of Western Electric as a commercial product. The key component of a CRT is the electron gun. It produces an electron beam which is a stream of electrons that are focussed into a thin beam. The electron gun is located at the rear of the CRT and is connected by a circular array of connection pins at its end. The processing of the CRT’s single electron beam enables the display of moving pictures that appear in natural colours. CRTs are usually bowl shaped with the exception of a flat CRT which was incorporated by Sony in 1982. In the flat CRT unit, the electron gun is located below the display surface at right angles. Due to this change in placement of the electron gun, complex electronics were required to ensure an undistorted picture. The CRT is enclosed in an outer glass envelope and it has a dual function. It allows light to generate out of the computer monitor. The glass envelope is leaded as it must block dangerous x-rays. These x-rays are generated by the electrons impacting within the CRT face. Colour CRTs require higher voltages and with high voltages the amount of x-rays produced also increase. Modern CRTs incorporate the leaded glass, protective circuits and other shielding to ensure that x-ray emissions are within approved safety limits. CRT’s have been widely used in television and computer monitors up till 2007. Plasma and LCD screens have increased in popularity and have impacted directly on the CRT market share. Modern computer monitors and televisions predominantly utilise the LCD screen technology. Both Sony and Samsung no longer produce any CRT models. Sony discontinued production of CRT computer monitors and German manufacturer Loewe ceased manufacture of CRT TVs in 2005. Although LCD units do require less power for each display area, CRTs are still popular in computer gaming, printing and broadcasting industries and in many graphics fields. This is due to their superior colour reliability and contrast. CRTs have a better resolution when viewed from angles and in displaying moving images.   CRT (Cathode Ray Tube) Cathode Ray Tube (CRT) is a very common type of display unit. The technology behind CRT monitors is quite old and closely resembles a television. These monitors are fairly big and heavy and are slowly phasing out.   Data Transfer Rate The speed that data is able to be transmitted between devices is called Data Transfer Rate. These devices include hard drives, modems, controllers, cables, printers, scanners and optical drives. Most computerized components will feature a data transfer rate. Another term for Data Transfer Rate is ‘throughput’. In modern computing and telecommunications advances in technology both hardware and software are increasing. Computer programs and files are becoming larger. Hardware components require higher data transfer rates. The advent of the World Wide Web (WWW) has increased the demand for faster and higher data transfer rates. Incorporating both hardware and software requirements to ensure that data transfer rates are compatible to ensure problem free computing is becoming a challenge. The selection of new components and upgrading of old components must include consideration of the data transfer rates and their compatibility. A combination of components such as multiple hard drives with differing data transfer rates will degrade the transfer of information. The computer system will adopt the lower data transfer rate to ensure that data is not lost during transfer. Choosing the same model and manufacturer when selecting a hard drive will ensure no loss of data. In networking, the data transfer rate can become a key administrative troubleshooting tool. The response time of a network will identify potential slowdowns or problems that exist within the network. The administrator is able to analyse the data transfer rates and use this information to make the network more efficient. Measurement of this data is expressed in kilobits (kbps) or megabits (mbps) per second. If larger amounts of data are transmitted, the measures will be in kilobytes (KB/sec), megabytes (MB/sec) or gigabytes (GB/sec) per second. Fibre optic loopbacks assist in measuring and performing data transfer tests. 1 kilobit (kb)                =                      1,024 bits 1 kilobyte (KB)            =                              8 kb 1 megabit (mb)             =                          128 kb 1 megabyte (MB)         =                             8 mb 1 gigabit (gb)                =                         128 mb 1 gigabyte (GB)            =                              8 gb 1 terabit (tb)                 =                          128 gb 1 terabyte (TB)             =                               8 tb In 2006, the highest data transfer rate of 14 terabits per second was recorded over a single optical fibre by Japan’s Nippon Telegraph and Telephone.   Database Driven Sites Where a database of information is used to control the content and functionality of the site.   Diagonal Size The diagonal size of a monitor refers to the distance between two opposite corners of the monitor screen. It’s common for this to be expressed in inches. Related Words CRT (Cathode Ray Tube) Direct3D Like other APIs, Direct3D is also a part of DirectX API which is used for rendering three dimensional graphics in performance oriented application such as games. This is the API which allows applications to run in full mode instead of running in an embedded window. Related Words DirectDraw; DirectInput; DirectMusic; DirectPlay; DirectSound DirectDraw DirectDraw is an API which provides support for hardware-accelerated 2 dimensional graphics and allows direct access video display memory. In actual fact DirectDraw is a dedicated memory manager which allows allocation and manipulation of system and graphics memory.   DirectInput Like DirectDraw and DirectPlay, DirectInput is also an API for receiving input commands from users via input devices such as the keyboard, joystick, mouse and other input devices. Related Words DirectDraw; DirectPlay DirectMusic The functionality of this API in DirectX is somewhat similar to DirectSound as these APIs deals with audio. DirectMusic has capabilities beyond DirectSound which allow music and sound effects to be composed and played. The playback behavior can be flexibly controlled using this API. Related Words DirectDraw; DirectInput; DirectPlay; DirectSound DirectPlay DirectPlay is another API in Microsoft DirectX which is a network communication library used for game development. It also acts as an interface between applications and communication services to let games be connected over Internet or a local network. Related Words DirectDraw DirectSound DirectSound allows direct interaction between an application and the sound card drivers which in turn enable applications to generate sound and music. This API is also used by a number of professional audio applications. Related Words DirectDraw; DirectInput; DirectPlay DirectX Media As the name indicates, this component of DirectX enables developers to enhance multimedia performance to a great extent. Basically, DirectX Media is a set of DirectX APIs which are completely related to multimedia. They are: DirectAnimation:  For 2D web animation DirectShow: For high quality multimedia playback and streaming Direct3D Retained Mode: Allows developers to deal with high quality 3-D graphics Related Words Direct3D; DirectDraw; DirectInput; DirectMusic; DirectPlay; DirectSound Dot Pitch Dot pitch refers to the distance between two pixels. Dot pitch is usually given as a fraction of a millimeter, such as 0.28 mm or 0.35 mm. A crispier image is produced when the Dot Pitch is lower. In simple terms, the smaller the distance between two pixels, the sharper the image. Related Words Brightness; Contrast Ratio ; CRT (Cathode Ray Tube) DVI The term DVI stands for Digital Video Interface which is made up of up to 24-pins, which carries digital/analog/integrated video signals and delivers improved visual quality for display units such as LCD monitors and digital projectors. DVI comes in three different flavors: DVI-A, DVI-D and DVI-I.   DVI-A (Analog only): transmits only analog signals and is normally found with CRT monitors. (Very rare) DVI-D (Digital Only): As the name suggests, DVI-D transmit only digital signals without any analog signals. DVI-I (Integrated): The most commonly found connector which can transmit both, analog and digital signals and can be used with either analog or digital display units.   Gmail Gmail is Google's free email service and online mail client. A Gmail account provides a robust spam filter, interesting conversation categorization options, enormous storage capacity, and much more.   HDMI HDMI stands for High Definition Multimedia Interface and is a compact audio/video connector which transmits uncompressed digital streams. HDMI is commonly used to connect devices like: Computers, Set-top boxes, Blu-ray Disc player, and Gaming consoles etc. Related Words DVI LCD Liquid Crystal Display (LCD) is another type of monitor but compared to CRT monitors LCD monitors are thin, compact flat and lightweight. They consume low power and they occupy less space. Related Words CRT (Cathode Ray Tube) MAC Address MAC is short for Media Access Control. A MAC address is a unique name given to each node on a network. A node on a network refers to any point on the network where data can be routed and therefore switches, modems and VOIP phones as well as PCs (or "clients") have MAC addresses.   NAS NAS is an acronym for Network Attached Server. A NAS drive is essentially a hard disk drive with a built in network interface. As the term indicates, NAS drives are used for data storage. A NAS drive is directly connected to a network through a router. NAS drives are a practical file storage solution because data is kept at a single location and is made available to all clients on the network. The clients on the network can be computers running Windows, Linux or Mac OS, or they can be devices like a printer. NAS drives are being used by large corporations and home networks alike, to store, share and make back-up copies of data. NAS drives offer the following benefits: Store data in a centralized location Increase network performance Easily share data between different clients Easy to use and administer The computers connected to the network don’t need to be on in order to access data owned by that user   Plasma Technology Plasma is the latest technology that is being implemented in large TV displays. In this technology, plasma refers to tiny cells made up of free-flowing ions and electrons. These plasma cells are injected between two glass plates that are filled with noble gases such as neon and xenon. We provide more insight into the differences between LCD and Plasma TVs in this article on HDTV technology. Related Words CRT (Cathode Ray Tube); LCD Protected Mode (Vista) Protected Mode is an Internet Explorer 7 (IE7) setting, only available with Vista. It has been designed to defend systems against ‘elevation of privilege’ attacks. It prevents hackers from getting access to a system and installing unwanted programs or using/ deleting information. With Protected Mode enabled, IE7 cannot modify user files and settings without user confirmation. With Protected Mode enabled, the user is required to confirm any kind of activity that tries to install new programs on the computer. “Are you sure you really want to do this?” Vista + IE7 in Protected Mode will ask. The fact that user consent is required for permitting actions of this kind ensures that the possibility of automated scripts running or unwanted applications being installed, is reduced drastically. Protected Mode gives you an indication of what a particular website is trying to do, so that you have a chance of stopping it and checking its trustworthiness before you proceed with the action. By default it is enabled for all security zones excluding the Trusted Zone.   proxy server Proxy servers receive requests from client computers to access websites and return results while masquerading as both the client to the visited website, and as the server to the client computer. They effectively make it so the client computer only interacts with the proxy server to access the whole Internet. While proxy servers enable you to surf anonymously, they may slow down your online experience.   PSTN Public Switched Telephone Network is an older international telephone system that employs a series of copper wires to carry voice signals over analog telephony. This is considered to be the first generation telephone network. Newer telephone networks are based on digital technologies such as FDDI and ISDN which provide much more reliable, crisper sound quality. Related Words ATA; CDMA QXGA Quad eXtended Graphics Array (QXGA) is another computer display standard like others that I have mentioned above, but QXGA delivers much higher pixels and also seeks a heavy system requirement. WQXGA is often found in monitors like the Dell 3008WFP (30” Widescreen Flat Panel Monitor) which delivers optimal resolution of 2560 x 1600, as well as Apple’s Cinema Display.   RAID RAID stands for Redundant Array of Independant Disks. The idea of RAID was first thought of at the University California at Berkeley in 1987. It's purpose was to improve storage subsystem reliability and performance. The concept initially consisted of clustering small inexpensive disk drives into an array such that the array could appear to the system as a single large expensive drive. The result of this initial testing found that the array of drives could actually deliver the same or better performance than the traditional individual hard drive. However, there was a problem with this implementation. The resulting Mean Time Before Failure of the array was actually reduced due to the probability of any one drive of the array failing. As a result of this finding, the Berkeley scientists proposed five levels or methods of RAID to provide a balance of performance and data protection.   ReadyBoost ReadyBoost is a feature of Microsoft Windows Vista that uses a high speed USB flash drive to cache data. Using ReadyBoost is not quite the same as adding physical memory.       ReadyBoost works on the principle that a computer can access memory from the USB much faster than it can access from the hard drive. ReadyBoost works on the ‘intelligent memory management’ of Windows Superfetch. When a removable memory device is plugged into a port on the system, Vista checks to see if the card is fast enough to work with ReadyBoost. Once this is confirmed, the system asks you if you want to use the card to speed up performance. Part of the USB can be allocated for memory and the rest can be used for storing files.     Refresh Rate The refresh rate of a monitor refers to the number of times an image is displayed on a monitor, repainted or refreshed per second. The refresh rate of a monitor is expressed in hertz. For example, a refresh rate of 85 indicates that the image is refreshed 85 times in a second. If your monitor supports low refresh rates, the screen will have irritating flickers and significantly strain your eyes.   Response Time Response Time refers to the amount of time it takes the crystals to change from one color to another (from fully white to black and vice versa) and the amount of time is measured in milliseconds. The lower the response time, the faster the screen refreshes. The latest display panels offer much lower response times and hence, higher quality displays.   RSS RSS stands for Really Simple Syndication. Many weblogs and news sites syndicate their content through RSS feeds. When a site is updated with new information, the RSS feed displays this information and spreads it to anyone who has subscribed to the feed. The gadget on the sidebar can take a feed from any site that offers RSS and then display new headlines periodically. Anyone can subscribe to a feed for free. Feeds are like a quick link back to a website; only the link actually represents the whole of an article. Why do sites offer RSS feeds? They want return visitors, and by giving you their content everyday through email or your favorite RSS reader, you will likely return. Most sites allow you to subscribe via email, which gives their content the best exposure over time. You can also click on the RSS feed link they provide on their site to be taken to their actual feed. From there, you will have options to subscribe depending on which Internet browser you are using.   SSID An SSID is probably best thought of as the name of your network. All PCs connected to the network use that name. SSID stands for Service Set Identifier and it is a 32 bit character that is attached to the header of any packet sent over that network. That is how you can search for the network when you first set it up. The vast majority of wireless routers ship with factory default settings that include a known SSID. For that reason, anyone in your local area who happens to have purchased and set up the same router make and model will have the same settings (if they retain the default settings). Anyone looking for a free Internet ride can also search very easily for known product default SSIDs.   SVGA Super Video Graphics Array or Super VGA (SVGA) can be defined as the second incarnation of VGA. VESA (Video Electronics Standards Association) was responsible for extending IBM’s VGA display standard in 1987. SVGA in general refers to a resolution of 800x600 pixels. Over the span of time, SVGA quickly extended to a resolution of 1024x768 pixels and so on. Related Words QXGA SXGA Super eXtended Graphics Array (SXGA) refers to the display standard of monitors having the resolution of 1280x1024 pixels. Related Words QXGA; SVGA SXGA+ Super eXtended Graphics Array Plus (SXGA+) is a another computer display standard which offers 1400x1500 resolution and is commonly used on 14” and 15” LCD screens of notebooks. Related Words QXGA; SVGA; SXGA TFT LCD TFT LCD (Thin Film Transistor Liquid Crystal Display) monitors deliver much improved image quality compared to CRT and LCD monitors. TFT LCD is a variant of liquid crystal display which implements TFT technology. “TFT-based displays have a transistor for each pixel on the screen. This allows the electrical current that illuminates the display to be turned on and off at a faster rate, which makes the display brighter and shows motion smoother. LCDs that use TFT technology are called "active-matrix" displays, which are higher-quality than older "passive-matrix" displays. So if you ever see a TFTAMLCD monitor at your local computer store, it is a "thin-film transistor active-matrix liquid crystal display." Basically, it is a high-quality flat screen monitor.”Source: Tech Terms Dictionary.   UAC UAC, which might seem like an annoyance, is actually one of the most important security features of Windows Vista. It is a powerful component of Windows Security System (WSC) that lets you exert better control over the continued well-being of your system. The UAC is a dialog box that continually pops up and asks you for your permission (or password depending on your user account setting) whenever you try to adjust a setting or install a program. The idea is that viruses cannot make changes to your system without you getting to know about it. The UAC is modeled on similar features found in Mac OS X and UNIX. It ensures that your system is safer, even though you may feel irritation at having to give permission or type in your password every time.   UXGA UXGA stands for Ultra eXtended Graphics Array and this display standard refers to the 1600x1200 pixels resolution of a monitor. For most of the 22” CRT monitors and 20”/21” desktop LCD monitors, UXGA is the native resolution. Related Words QXGA; SVGA; SXGA; SXGA+; TFT LCD VGA Video Graphics Array (VGA) refers to display hardware first introduced with the IBM PS/2 line in 1987, VGA is now the display standard for almost all PCs. The term VGA also refers to the 15-+pin plugs and socket which establishes the connection between a computer and monitor. All PC display adapters support VGA. When you boot your system, the system starts in VGA mode until it switches to the higher resolution mode. The resolution of VGA display is 640x480 pixels with 16 or 256 colors. Related Words SVGA; SXGA; SXGA+; UXGA VGA Connector A VGA Connector is a three-row 15 pin analog connector which is the most common connection type found with computer monitors. A VGA Connector is also known as “HD-15”, where HD stands for High Density. Related Words DVI; HDMI VoIP VoIP stands for Voice over Internet Protocol, a technological innovation that allows you to make long distance phone calls using a computer or notebook over high speed Internet access. The voice modulations are converted into digital packets and are transmitted over the Internet to its destination. With a VoIP phone you can make international calls at a much lower rate as compared to the other modes of communication. Related Words ADSL; PSTN; WI-Fi VoWLAN VoWLAN stands for Voice over Wireless Local Network Areas.  IP phones convert voice to data packets and transfer that over the Internet to another landline or cell phone.  These phones have an extended feature of Wi-Fi, where the data can be transferred from the antenna to a data network through Wi-Fi radio waves or through data wire to the destination. Related Words Analog ; ATA; Broadband WI-Fi Wireless fidelity is the transmission of data through the radio waves in the free space. PCs, notebooks and other devices can access the Internet anywhere in or around a Wi-Fi hotspot, so long as it’s shared or they have the password to gain access. Related Words Bandwidth XGA In 1990, IBM introduced an upgraded display standard called XGA (eXtended Graphics Array). The initial version of XGA expanded upon IBM’s VGA and added support for 800x600 pixels resolutions with 65,536 colors and 1024x768 pixels resolutions with 256 colors. XGA is not a replacement for SVGA. Later when XGA-2 came into existence, true color mode was added for 640x480 and 1024x768, delivering higher refresh rates and superior color. Related Words SVGA; SXGA; SXGA+; UAC; UXGA; VGA XGA+ eXtended Graphics Array Plus (XGA+) is another computer display standard, the next step after XGA. XGA+ refers to the 1152x864 resolution and this display standard is often used on 17” CRT monitors. Related Words SVGA; SXGA; SXGA+; UAC; UXGA; VGA; XGA