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Explanatory Dictionary - ABC





ACPI - Advanced Configuration Power Interface

ACPI (Advanced Configuration Power Interface) refers to a Power Management specification developed by Intel, Microsoft and Toshiba. The specification allows an operating system to control the power distribution to peripherals such as hard drives, it was originally intended for laptops/notebooks where power saving is vital.

Since Windows 98, ACPI has replaced the older APM (Advanced Power Management) specification (used in Windows 95).

ACPI allows the operating system to communicate with the computer's BIOS and instruct the BIOS to power down peripherals, for instance when your computer goes into hibernation mode, the operating system is using the ACPI specification to control the power to the internal components.

ADSL - Asymmetric Digital Subscribers Line

Sometimes refered to as Broadband, ADSL is a connection available from Telecom companies using existing lines with fast download & upload speeds.

It works by splitting your phone line signal into two separate channels, one for normal voice usage and the other for data usage, this is achieved by placing a splitter on the existing phone line to enable multi-frequency communication.

It can reach speeds of up to 9Mbit per second for downloading and currently up to 640Kbits per second upload speed.

Another advantage of having an ADSL line is not missing calls while you're online, as both voice and data can be transferred at the same time.

AGP - Accelerated Graphics Port

An interface developed by Intel which allows a graphics card to access memory directly which along with the wider bandwidth helps improve graphics performance.

AGP has now come to replace a lot of PCI video cards due to its superior performance, most modern motherboards have an AGP slot as standard. Some motherboards come with an AGP graphics card built-in.

You will see AGP cards advertised with different specifications, including throughput (bandwidth), here is a summary of the throughput they refer to:

1X - 266MBps

2X - 533MBps

4X - 1.07GBps

8X - 2.1GBps

Obviously the higher the throughput the better, although nowadays most video cards run at 8X.

ALU - Arithmetic Logic Unit

The ALU (Arithmetic Logic Unit) is an internal part of the processor which is used for all mathematical and logical operations, the basic operations of an ALU include adding and multiplying binary values as well as performing logical operations such as AND, OR and XOR.

The algorithms for performing these mathematical and logical operations are hard coded (stored permanently) within the ALU.

ANSI - American National Standards Institute

An American body responsible for the standardisation system since 1918. ANSI establishes the United States industrial standards and it's primary task is to determine hardware and software standards, it is the US representative to ISO.

ASCII - American Standard Code for Information Interchange

A widely used character encoding system first used in 1963. It uses a 7 bit code to represent characters with numbers (0 to 127), there are also ASCII extensions in use which utilise 8 bit codes to represent international characters in addition to the standard ASCII scheme.

ASP - Active Server Pages

When in the context of internet web sites ASP refers to a specification which can be likened to CGI, ASP technology allows the site developer to create dynamic web pages through the use of ActiveX.

ASP pages are used for numerous tasks including form handling, database connectivity, even putting a date and time on a page. Jscript or VB Script are the most common scripting languages used with ASP pages.

AVI - Audio Video Interleaved

A multimedia file type, the audio and video elements are interleaved in alternate segments within the AVI file. This has become a very popular format on the Internet for video distribution due to the fast download times and reasonable quality reproduction.

BAUD

Baud rate is a value given to communication devices such as modems to describe the amount of data they can carry per second. The higher the Baud rate the more data the device can transmit per second, typically in a binary channel the baud rate is equal to the bit rate, therefore 1 baud = 1 bit a second.

BBS - Bulletin Board Service

Bulletin Board Service often referred to as forums, unlike chat you leave messages for other users to read, i.e. it is not "live".

BIOS - Basic Input Output System

The CPU in a PC needs a way of communicating with the many different hardware devices that are installed, each hardware device has its own special BIOS software which allows for this communication.

The BIOS contains special software instructions that enable the CPU to communicate with and control devices, it is usually stored in ROM and can be either built-in to the motherboard or on the device itself.

The main BIOS in a system is stored inside a microchip on your motherboard and is the first piece of software your computer runs when you (boot up) turn it on.

It uses the information stored in the CMOS memory for configuration purposes.

A Flash BIOS can be updated with new information and many motherboard manufacturers publish updates for their respective BIOS on their websites.

BIT - Binary DigIT

This refers to a binary digit i.e it would either be a 1 or a 0, 8 bits make a Byte. It refers to information stored or processed in a digital system. For instance if you have a 64 bit processor then it can process 64 bits (8 bytes) of data every clock cycle.

Bitmap

This is a common graphic format used by computers, it can be likened to a map of bits (hence the name) the graphic/picture is made up of a number of individual dots (bits) to form an image. The file extension for these type of files is .bmp, these can get very large in file-size (i.e. kilobytes) and if storage space is a factor then it is best to convert the image into a more compressed format such as JPEG.

BPS - Bits Per Second

A measurement used by modems and communication ports to measure transfer speeds, the higher the BPS the more data can be transmitted through the device/line. If you want to know the capacity in bytes then you would simply divide the BPS by 8, For example if you have a modem stating 56Kbs (57344 bits a second) then 57344/8 gives 7168 (around 7 kilobytes per second).

Browser

This is the program you use to surf the internet.

There are several internet browsers available, some of the most popular are Internet Explorer, Firefox, Netscape Navigator and Opera.

Different browsers render web pages slightly differently, for example some sites may require a certain browser to function correctly and some sites may not function at all with some browsers.

Bus - Internal Bus

When in the context of PCs a bus refers to a set of conductors (hard wired) on the circuit board of the device (motherboard).

The bus is split into two 'channels' one that transfers the data and one that specifies where the data should be transferred to. The Internal Bus connects all of the PC's components to the CPU and memory banks.

The bus width refers to the amount of bits that can be transferred at any one time, for example, a 32-bit bus can transfer 32 bits of data simultaneously.

The bus speed (frequency) is usually measured in MHz, for example say a bus has a speed of 100Mhz and a width of 32 bits then the bus can transfer 3,200,000,000 bits of data per second!!

When in the context of networking a bus refers to the cable (backbone) that connects all devices together.

An FSB (FrontSide Bus) transfers data between the CPU, the memory bank and other components.

A BSB (BackSide Bus) transfers data between the CPU and the L2 Cache.

Byte

A Byte is made up of 8 bits, and is the measurement unit used to describe the storage capacity and transfer rate of digital systems. One Kilobyte is 1024 bytes, One Megabyte is 1024 Kilobytes and so on.

CGI - Common Gateway Interface

CGI refers to a specification that allows a web server and a CGI program to communicate and transfer data.

CGI programs provide interactivity for users of a web site, a typical example of a CGI implementation is a contact form where the data the user enters into a web form gets transferred to the CGI program and then processed.

The transfer of data can be done using the ACTION parameter of a HTML form, the two options are GET and POST, the former sending the data as part of the URL and the latter sending the data via the HTTP headers.

CMOS - Complimentary Metal Oxide Semiconductor

When in the context of computing CMOS refers to a chip that stores information about your PC including the time, date and configuration data, this technology is used due to the low power consumption.

The CMOS device is backed up by a battery to retain the information when the system is switched off.

The information (typically 64 Bytes) in the CMOS device is accessed by the BIOS when the machine is booted up (turned on), the CMOS settings (information) can be changed by the user by the way of a setup program usually accessed with a key sequence when the machine is first booted.

Different systems use different key sequences to access the CMOS settings (BIOS settings), you can find out the key sequence for your particular system from either the manual that came with your machine or your motherboard manual.

CODEC - COmpressor / DECompressor

CODEC in the context of computing is an acronym for COmpressor/DECompressor and refers to a small piece of code (program) which is used to compress and decompress data, you will normally come across these when using Audio and Video. You may be prompted during internet use to download a CODEC if you visit a site that requires a certain CODEC not already installed on your PC.

COOKIE

Cookies are small text files that are placed on your computer by websites for various different reasons. For instance Yahoo use cookies for reasons such as storing your preferences for Yahoo related services, and to access certain information when you sign in to a personalised service such as My Yahoo.

Other websites will often use cookies for identifying purposes, demographic statistics and also when you are shopping online to remember what you have in your basket.

CPS - Characters Per Second

This is commonly used to describe a printer's speed, referring to how many characters can be processed per second. The higher the CPS the faster the performance of the device.

Cursor - Flashing Cursor

This refers to the small blinking vertical or horizontal line which shows the position on the screen where text will appear the next time you type a character on the keyboard. The cursor can be moved around the screen using the cursor (arrow) keys or alternatively using a mouse.