myspace profile view counter
| About | Contact | |

Mon 27-March-2017

 Mass Storage Services:
  RAID Arrays - Storage
  SAN & NAS Storage - Services
  Tape Systems - Services

 Hosting & Web Services:
  Shared Hosting
  Dedicated Hosting
  Collocation Services

 Networks & Technology:
  BytePile Network Maps
  System Hardware
  Software Suites


  Definitions & Terms
  Frequently Asked Questions

 Tech - White Papers:
  CAT-6 Tutorial by Lucent (pdf)
  Data Speed Table
  Dbase Conf. SAN or NAS (pdf)
  DSL Types & Categories
  Ethernet (UTP) CAT Cables
  Fibre Channel Overview
  RAID 3 vs. RAID 5 in HPC
  RAID Types & Categories
  T1 & T3 RJ-48 Cables
  The SAN Book 3.0 (7MB pdf)

  Acceptable Use Policy
  Privacy Statement
  Service License Agreement

CaseLabs, The Next Generation of Enthusiast Cases

True Crypt - Free Open Source On - The Fly Encryption

Phisical Psience ΦΨ


Definitions & Terms

Logo Dumbbell Nebula

1-10  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

Abstract Syntax Notation One - ASN.1:

  • Abstract Syntax Notation One (ASN.1) is a standard way to describe a message (a unit of application data) that can be sent or received in a network. ASN.1 is divided into two parts: (1) the rules of syntax for describing the contents of a message in terms of data type and content sequence or structure and (2) how you actually encode each data item in a message. ASN.1 is defined in two ISO standards for applications intended for the Open Systems Interconnection (OSI) framework:
  • * ISO 8824/ITU X.208 specifies the syntax (for example, which data item comes first in the message and what its data type is)
  • * ISO 8825/ITU X.209 specifies the basic encoding rules for ASN.1 (for example, how to state how long a data item is)
  • In this very simple example, "Report" is the name of this type of message. SEQUENCE indicates that the message is a sequence of data items. The first four data items have the data type of OCTET STRING, meaning each is a string of eight-bit byte s (the term OCTET was used rather than BYTE because it can't be assumed that all computers will have eight bits in a byte). The bibliography data item is another definition named "Bibliography" that is used within this one. It might look like this:
  • Other data types that can be specified include: INTEGER, BOOLEAN, REAL, and BIT STRING. An ENUMERATED data type is one that takes one of several possible values. Data items can be specified as OPTIONAL (not necessarily present).

Accelerated Hub Architecture - AHA:

  • Accelerated Hub Architecture (AHA) (also called Intel Hub Architecture) is an Intel 800-series chipset design that uses a dedicated bus to transfer data between the two main processor chips instead of using the Peripheral Component Interconnect (PCI) bus, which was used in previous chipset architectures. The Accelerated Hub Architecture provides twice the bandwidth of the traditional PCI bus architecture at 266 MB per second. The Accelerated Hub Architecture consists of a memory controller hub and an input/output (I/O) controller hub (a controller directs or manages access to devices).
  • The memory controller hub provides the central processing unit (CPU) interface, the memory interface, and the accelerated graphics port (AGP) interface. The memory controller hub supports single or dual processors with up to 1 GB of memory. The memory controller hub also allows for simultaneous processing, which enables more life-like audio and video capabilities.
  • The I/O controller hub provides a direct connection from the memory to the I/O devices, which includes any built-in modem and audio controllers, hard drives, Universal Serial Bus (USB) ports, and PCI add-in cards. The I/O controller hub also includes the Alert on LAN (local area network) feature that sounds an alert when software failures or system intrusion occurs.

Acceptable Use Policy - AUP:

  • An Acceptable Use Policy (AUP) is a policy that a user must agree to follow in order to be provided with access to a network or to the Internet. It is common practice for many businesses and educational facilities to require that employees or students sign an acceptable use policy before being granted a network ID.
  • When you sign up with an Internet service provider (ISP), you will usually be presented with an AUP, which states that you agree to adhere to stipulations such as:
  • * Not using the service as part of violating any law
  • * Not attempting to break the security of any computer network or user
  • * Not posting commercial messages to Usenet groups without prior permission
  • * Not attempting to send junk e-mail or spam to anyone who doesn't want to receive it
  • * Not attempting to mail bomb a site with mass amounts of e-mail in order to flood their server
  • Users also typically agree to report any attempt to break into their accounts.


  • A person responsible for configuring, administering, and maintaining computers, networks, and software systems.

Advanced Peer-to-Peer Networking - APPN:

  • Advanced Peer-to-Peer Networking (APPN), part of IBM's Systems Network Architecture (SNA ), is a group of protocols for setting up or configuring program-to-program communication within an IBM SNA network. Using APPN, a group of computers can be automatically configured by one of the computers acting as a network controller so that peer programs in various computers will be able to communicate with other using specified network routing.
  • APPN features include:
  • * Better distributed network control; because the organization is peer-to-peer rather than solely hierarchical, terminal failures can be isolated
  • * Dynamic peer-to-peer exchange of information about network topology, which enables easier connections, reconfigurations, and routing
  • * Dynamic definition of available network resources
  • * Automation of resouce registration and directory lookup
  • * Flexibility, which allows APPN to be used in any type of network topology
  • How Dynamic Configuration Works - APPN works with Advanced Program-to-Program Communication (APPC) software that defines how programs will communicate with each other through two interfaces: one that responds to requests from application programs that want to communicate and one that exchanges information with communications hardware. When one program wants to communicate with another, it sends out a request (called an allocate call) that includes the destination's logical unit (LU) name - the APPC program on each computer that uniquely identifies it). APPC sets up a session between the originating and destination LUs.
  • APPN network nodes are differentiated as low entry networking (LEN) nodes, end nodes (ENs), and network nodes (NNs). When the network computers are powered on and the software activated, links are established throughout the specified topology. The linked nodes exchange information automatically. If we consider a simplified APPN network, with one end node connected to a network node, the following would describe the sequence of events:
  • * Each node indicates APPN capability and defines its node type.
  • * The network node asks the end node if it requires a network node server, which handles requests for LU locations.
  • * If it responds that it does, the two nodes establish APPC sessions to exchange program-to-program information.
  • * The end node registers any other LUs defined at its node by sending the networked node formatted information gathered from the APPC session.
  • * After this sequence is completed, the network node knows the location of the EN and what LUs are located there. This information, multiplied across the network, enables LU location and routing.

ADSL - Asymmetric Digital Subscriber Line:

  • See Asymmetric Digital Subscriber Line.

AES/EBU - Audio Engineering Society/European Broadcasting Union:

  • See Audio Engineering Society/European Broadcasting Union.

AHA - Accelerated Hub Architecture:

  • See Accelerated Hub Architecture.


  • An Operating System designed by IBM and very similar to UNIX


  • Aloha, also called the Aloha method, refers to a simple communications scheme in which each source (transmitter) in a network sends data whenever there is a frame to send. If the frame successfully reaches the destination (receiver), the next frame is sent. If the frame fails to be received at the destination, it is sent again. This protocol was originally developed at the University of Hawaii for use with satellite communication systems in the Pacific.
  • In a wireless broadcast system or a half-duplex two-way link, Aloha works perfectly. But as networks become more complex, for example in an Ethernet system involving multiple sources and destinations that share a common data path, trouble occurs because data frames collide (conflict). The heavier the communications volume, the worse the collision problems become. The result is degradation of system efficiency, because when two frames collide, the data contained in both frames is lost.
  • To minimize the number of collisions, thereby optimizing network efficiency and increasing the number of subscribers that can use a given network, a scheme called slotted Aloha was developed. This system employs signals called beacons that are sent at precise intervals and tell each source when the channel is clear to send a frame. Further improvement can be realized by a more sophisticated protocol called Carrier Sense Multiple Access with Collision Detection (CSMA/CD).


  • Tape format used in Exabyte tape drives.

American National Standards Institute - ANSI:

  • American National Standards Institute (ANSI) is the primary organization for fostering the development of technology standards in the United States. ANSI works with industry groups and is the U.S. member of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC).
  • Long-established computer standards from ANSI include the American Standard Code for Information Interchange (ASCII) and the Small Computer System Interface (SCSI).

Anonymous FTP - File Transfer Protocal:

  • Using the Internet's File Transfer Protocol (FTP), anonymous FTP is a method for giving users access to files so that they don't need to identify themselves to the server. Using an FTP program or the FTP command interface, the user enters "anonymous" as a user ID. Usually, the password is defaulted or furnished by the FTP server. Anonymous FTP is a common way to get access to a server in order to view or download files that are publicly available.
  • If someone tells you to use anonymous FTP and gives you the server name, just remember to use the word "anonymous" for your user ID. Usually, you can enter anything as a password.

ANSI - American National Standards Institute:

  • See American National Standards Institute.


  • Antialiasing is the smoothing of the image or sound roughness caused by aliasing . With images, approaches include adjusting pixel positions or setting pixel intensities so that there is a more gradual transition between the color of a line and the background color. With sound, aliases are removed by eliminating frequencies above half the sampling frequencies.

APIPA - (Automatic Private IP Addressing):

  • See Automatic Private IP Addressing.

APL - A Programming Language:

  • See A Programming Language.

APPN - Advanced Peer-to-Peer Networking:

  • See Advanced Peer-to-Peer Networking.

A Programming Language - APL:

  • A Programming Language (APL) is a general-purpose, third-generation (3GL) programming language that allows certain data manipulations to be expressed with a special non-ASCII set of symbols, resulting in programs that are shorter than would be possible using most other languages. APL's notation allows matrix manipulation as well as recursion functions to be built into simple expressions rather than requiring multiple language statements. APL is more frequently thought of as a language for scientific computation, but it can be used for other purposes as well. Programs can be developed interactively and are usually interpreted rather than compiled. The special symbols require keyboard support and specific editors so that the symbols can be displayed and printed.


  • ASCII (American Standard Code for Information Interchange) is the most common format for text files in computers and on the Internet. In an ASCII file, each alphabetic, numeric, or special character is represented with a 7-bit binary number (a string of seven 0s or 1s). 128 possible characters are defined.
  • UNIX and DOS-based operating systems use ASCII for text files. Windows NT and 2000 uses a newer code, Unicode. IBM's S/390 systems use a proprietary 8-bit code called EBCDIC. Conversion programs allow different operating systems to change a file from one code to another. ASCII was developed by the American National Standards Institute (ANSI).

Asimov's Three Laws of Robotics:

  • Science-fiction author Isaac Asimov is often given credit for being the first person to use the term robotics in a short story composed in the 1940s. In the story, Asimov suggested three principles to guide the behavior of robots and smart machines. Asimov's Three Laws of Robotics, as they are called, have survived to the present:
  • 1. Robots must never harm human beings.
  • 2. Robots must follow instructions from humans without violating rule 1.
  • 3. Robots must protect themselves without violating the other rules.
  • Also see artificial intelligence, mechatronics, nanorobot, and robot.


  • See Abstract Syntax Notation One

ASP - Active Server Page:

  • An Active Server Page is an HTML page that includes one or more scripts (small embedded programs) that are processed on a Microsoft Web server before the page is sent to the user. An ASP is somewhat similar to a server-side include or a common gateway interface (CGI ) application in that all involve programs that run on the server, usually tailoring a page for the user. Typically, the script in the Web page at the server uses input received as the result of the user's request for the page to access data from a database and then builds or customizes the page on the fly before sending it to the requestor.
  • ASP is a feature of the Microsoft Internet Information Server (IIS), but, since the server-side script is just building a regular HTML page, it can be delivered to almost any browser. You can create an ASP file by including a script written in VBScript or JScript in an HTML file or by using ActiveX Data Objects (ADO s) program statements in the HTML file. You name the HTML file with the ".asp" file suffix. Microsoft recommends the use of the server-side ASP rather than a client-side script, where there is actually a choice, because the server-side script will result in an easily displayable HTML page. Client-side scripts (for example, with JavaScript) may not work as intended on older browsers.

Asymmetric Digital Subscriber Line - ADSL:

  • Asymmetric Digital Subscriber Line (ADSL) is a technology for transmitting digital information at a high bandwidth on existing phone lines to homes and businesses. Unlike regular dialup phone service, ADSL provides continously-available, "always on" connection. ADSL is asymmetric in that it uses most of the channel to transmit downstream to the user and only a small part to receive information from the user. ADSL simultaneously accommodates analog (voice) information on the same line. ADSL is generally offered at downstream data rates from 512 Kbps to about 6 Mbps. A form of ADSL, known as Universal ADSL or G.lite, has been approved as a standard by the ITU-TS.
  • ADSL was specifically designed to exploit the one-way nature of most multimedia communication in which large amounts of information flow toward the user and only a small amount of interactive control information is returned. Several experiments with ADSL to real users began in 1996. In 1998, wide-scale installations began in several parts of the U.S. In 2000 and beyond, ADSL and other forms of DSL are expected to become generally available in urban areas. With ADSL (and other forms of DSL), telephone companies are competing with cable companies and their cable modem services.


  • In general, Asynchronous (pronounced ay-SIHN-kro-nuhs, from Greek asyn-, meaning "not with," and chronos, meaning "time") is an adjective describing objects or events that are not coordinated in time. In information technology, the term has several different usages.
  • 1) In telecommunication signaling within a network or between networks, an asynchronous signal is one that is transmitted at a different clock rate than another signal. (plesiochronous signals are almost but not quite in synchronization - and a method is used to adjust them - and synchronous signals are those that run at the same clock rate.
  • 2) In computer programs, asynchronous operation means that a process operates independently of other processes, whereas synchronous operation means that the process runs only as a result of some other process being completed or handing off operation. A typical activity that might use a synchronous protocol would be a transmission of files from one point to another. As each transmission is received, a response is returned indicating success or the need to resend. Each successive transmission of data requires a response to the previous transmission before a new one can be initiated.

Asynchronous Transfer Mode - ATM:

  • Asynchronous Transfer Mode (ATM) is a dedicated-connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology. Individually, a cell is processed asynchronously relative to other related cells and is queued before being multiplexed over the transmission path.
  • Because ATM is designed to be easily implemented by hardware (rather than software), faster processing and switch speeds are possible. The prespecified bit rates are either 155.520 Mbps or 622.080 Mbps. Speeds on ATM networks can reach 10 Gbps. Along with Synchronous Optical Network (SONET) and several other technologies, ATM is a key component of broadband ISDN (BISDN).

ATM - Asynchronous Transfer Mode:

  • See Asynchronous Transfer Mode.

Attachment Unit interface - AUI:

  • The Attachment Unit Interface (AUI) is the 15-PIN physical connector interface between a computer's network interface card (NIC) and an Ethernet cable. On 10BASE-5 ("thicknet") Ethernet, a short cable is used to connect the AUI on the computer with a transceiver on the main cable. In 10BASE-2 or "thinnet" Ethernet networks, the NIC connects directly to the Ethernet coaxial cable at the back of the computer.
  • IEEE 802.3 , the Ethernet standard, defines the AUI 15-pin physical layer interface. This interface is also called a DB-15 interface or a DIX interface (DIX refers to the three major companies who helped standardize Ethernet: Digital Equipment Corporation, Intel, and Xerox).

Audio Engineering Society/European Broadcasting Union - AES/EBU:

  • AES/EBU (Audio Engineering Society/European Broadcasting Union) is the name of a digital audio transfer standard. The AES and EBU developed the specifications for the standard.
  • The AES/EBU digital interface is usually implemented using 3-PIN XLR connectors, the same type connector used in a professional microphone. One cable carries both left- and right-channel audio data to the receiving device. AES/EBU is an alternative to the S/PDIF standard.

AUI - (Attachment Unit Interface):

  • See Attachment Unit Interface.

AUP - Acceptable Use Policy:

  • See Acceptable Use Policy.

Automatic Private IP Addressing:

  • Automatic Private IP Addressing (APIPA) is a feature of Windows-based operating systems (included in Windows 98, ME, 2000, and XP) that enables a computer to automatically assign itself an IP address when there is no Dynamic Host Configuration Protocol (DHCP) server available to perform that function. APIPA serves as a DHCP server failover mechanism and makes it easier to configure and support small local area networks (LANs).
  • If no DHCP server is currently available (either because the server is temporarily down or because none exists on the network), the computer selects an IP address from a range of addresses (from - reserved by the Internet Assigned Numbers Authority (IANA) for that purpose. The client uses Address Resolution Protocol (ARP ) to ensure that the chosen address is not already being used by another network computer. Once the computer has assigned itself an IP address, it can communicate over TCP/IP with other computers on the LAN that are either configured for APIPA or are manually set to the correct address range and a subnet mask value of APIPA is enabled by default, but can be disabled in some cases. DHCP messages notify the user when they are switched between DHCP addressing and APIPA.


MySQL Database Powered Powered by Apache Full with PHP Modules Powered by Perl linux-logo
Last Update - 10 April 2012 All Rights Reserved. Copyright © 2002 Inc.