History and Components of a Modern Mainframe Computer

Mainframe computers are critical for some of the largest corporations in the world. Each mainframe has more than one modern processor, RAM ranging from a few megabytes to multiple-score gigabytes, and disk space and other storage beyond anything on a microcomputer. A mainframe can control multiple tasks and serve thousands of users every second without downtime.

The chief difference between mainframes and other computing systems is the level of processing that takes place. Mainframes are also different in terms of data bandwidth, organization, reliability, and control. Big organizations-banking, healthcare, insurance, and telecom companies, etc.-use mainframes for processing critical commercial data.

In this article, we discuss the evolution of mainframe computers and their components.

History of mainframe computers

IBM developed a critical part of mainframe computing, the Automatic Sequenced Controlled Calculator (ASCC) for arithmetic operations, in 1944. From the late 1950s through the 1970s, several companies manufactured mainframes: IBM, Burroughs, RCA, NCR, General Electric, and Sperry Rand, for example. Since then, System / 390 by IBM is the only kind of mainframe in use. It evolved from IBM's System / 360 in 1960.

An Early mainframe occupied a huge space. New technologies have drastically reduced the size and cost of the hardware. A current-generation mainframe can fit in a small closet.

Components of a modern mainframe computer

Like a PC, a mainframe has many components for processing data: operating system, motherboard or main board, processor, controllers, storage devices, and channels.

• Motherboard: The motherboard of a mainframe computer consists of a printed circuit that allows CPU, RAM, and other hardware components to function together through a concept called "Bus architecture". The motherboard has device slots for input cards and cable interfaces for various external devices. Where PC motherboards use 32- or 64-bit buses, mainframes use 128-bit buses. General instructions regarding the internal architecture help the motherboard connect to the other devices and retrieve data using binary computation.

• Processor: A CPU acts as the central processing point in mainframe architecture and includes an Arithmetic Logic Unit (ALU) for performing arithmetic calculations. It also works as a controller for the bus architecture and handles traffic and data requests. The processing power of mainframes is much higher compared to PCs, so that they can handle huge amounts of data.

• Storage devices: Storage devices are for entering, retrieving, storing, and recording data. Many are external devices, such as hard drives, tape drives, and punch card readers, all connected to terminals of the mainframe and controlled by the CPU. Their capacity for data storage can be hundred or even thousands of times that of a PC.

• Communication controllers: Communication controllers allow remote computers to access a mainframe. With the help of networks, LAN or WAN, communication controllers establish connections with various devices, perform data transmission over communication channels, and keep track of users at terminals.

• Channels: The "channels" are the cables used to connect the CPU and the main storage to other parts of the system and make sure that data is moved in a systematic way without losing its integrity.

Modern mainframes have advanced features such as expanded service management capabilities, cross-platform integration facilities, etc. And so are suitable for critical data center operations. The cost of maintaining modern mainframes is much less compared to older models.

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The Advantages of Working With a Software Boutique Company

First of all, a boutique is a small shop where clients can find dedicated merchandise and unique items, or products which are produced in small quantities. The advantage of entering in such a shop, compared to big supermarkets, is that here you’ll also find staff ready to assist you and to give you guidance step by step. Indeed, one may say that a boutique charges higher prices, also in comparison to chain stores, which is definitely true. However, once you bought something from a boutique you’ll have the feeling that you own a unique item, which will differentiate you from the rest, and isn’t this what we all want – to be unique?

Software boutiques are a new way of defining petite software companies which are focused on a certain niche, and which are able to offer specialized support to their customers. Even more, such a firm is able to offer a unique product, tailored on the client’s needs and requirements. But, let’s see what advantages does a customer have when collaborating with a software boutique company:

Tailored product

A software boutique takes the client’s specifications and transforms them into a customized piece of software. Practically, if you are not satisfied by the mass-produced software programs which you can find, then a boutique company will tailor a product according to each and everyone of your requirements. The outcome will be a software product which is able to fit perfectly your company’s needs.

Niche focus

Generally, a boutique company is focused on a certain niche, for example developing applications and software products using Microsoft technologies. The advantage of having such a partner, is that you’ll have the confidence that he has the knowledge and proven experience to offer you the best advices regarding that specific area, and that he’s always updated with the latest technologies.

Crystal clear communication and dedicated support

Having a smaller amount of projects, a boutique software company can offer its clients dedicated support, according to every client’s need through a direct communication flow. This means that the information won’t need to travel through several departments until it reaches you, so that you’ll always be updated with the status and the quality of the work.

A good communication, not only that can save time, but also can make the development process more efficient. For example if you want a specific functionality for your application, collaborating with a boutique firm, you’ll able to keep track of the development process and promptly interfere in the development process if the work isn’t going in the desired direction, or if you want to change the approach. Also, fewer the clients, better the support. Practically, a software boutique will offer you their entire attention and expertise, whenever this is required.

Every client is important

For a boutique company every client is important, and because they can’t afford to lose a client, they can’t really afford to do a bad job. Every development project is treated with care, and you’ll know for sure that your project will be handled by the best men.

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Corel DRAW – Best Desktop Publishing Software

Corel DRAW is a supreme supplier of graphics software, including the popular Corel DRAW program. Corel DRAW has tools that allow the user to both create and edit images. The type of desktop publishing tools that you use will depend on the type of project. For more information and assistance, use the Corel website.

Corel DRAW is the best Desktop publishing software that empowers users to create illustrations containing graphics, text and photographs. Corel has an extensive range of tools which enable the user to edit any shape or character with ease and precision, fit text to curves and create custom color separations. It is developed and marketed by Corporation of Ottawa. This tool can open files: Adobe PageMaker, Microsoft Publisher and Word, and other programs can print documents to Adobe PDF using the Writer printer driver, which such software can then open and edit every aspect of the original layout and design.

Several innovations to vector-based illustration originated with Corel: a node-edit tool that operates differently on different objects, fit text-to-path, stroke-before-fill, quick fill/stroke color selection palettes, perspective projections, mesh fills and complex gradient fills.

One of this software’s many strengths is the huge range of over 1,000 fonts that it comes with, provided in both TrueType and Postscript Type 1 format. Corel differentiates itself from its opponent in a number of ways: The first is its positioning as a graphics suite, rather than just a vector graphics program. A full range of editing tools allow the user to adjust contrast, color balance, change the format from RGB to CMYK, add special effects such as vignettes and special borders to bitmaps. Bitmaps can also be edited more extensively using Corel PhotoPaint, opening the bitmap directly from Corel and returning to the program after saving. It also allows a laser to cut out any drawings.

Expert believed it was the first of the Windows-based drawing programs and has built on this early start to become far-and-away the dominant drawing package on the PC. Its biggest strength – and its biggest potential limitation – is its all-encompassing approach. In the past this has led to accusations of unfocused bloating, but with version 7.0 Corel has addressed the criticisms with a far tighter and better rationalized program. Even so, there’s a huge range of functionality to cover.

Corel DRAW Download was originally developed for Microsoft Windows and currently runs on Windows XP, Windows Vista, and Windows 7. The current version, X5, was released on 23 February 2010.

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What Requirements Does a Dot Net Developer Need to Fulfill?

Microsoft Dot Net is a useful software development component. It provides tools and libraries to the software developers so that they can create Windows-based applications in a more efficient manner. A Dot Net developer is a software programmer who has specific skills using .Net to develop software and computer applications. For people who are in the midst of looking for developers for your projects, there are some areas you need to take note. You are advised to look for competent programmers who can really assist you to complete your tasks successfully.

First thing first, you need to be clear about the responsibilities of a .Net Developer before you start looking for suitable candidate. Seriously speaking, the programmer is required to:

• Work hand in hand with other software engineers and architects to develop a logical series of instructions referred to as programming code for the computer to communicate with the networks, applications and databases.

• Create new software applications to suit the business needs

• Modify, repair, test and enhance existing applications

After knowing what the developer is required to do, the next area we need to take into consideration is the academic qualification. In general, a programmer should have degree qualification in computer science, information technology or any related discipline. If the programmer is not a degree holder, you may take a look at his or her working experience. If the candidate has extensive experience dealing with .Net development tools, you can consider getting him or her in. Check with the candidate whether he or she is familiar with maintenance of ASP Applications, e-Commerce solution, online education and learning, social networking sites, corporate web applications, and so on.

At the same time, a good dot net developer must be competent in carrying out all the important tasks. It is a must for him or her to have the following skills in:

• Classic ASP

• Microsoft SQL 2000 / 2005

• MS Access

• JavaScript, XML, DHTML, AJAX and CSS

• VBScript and JScript

Frankly speaking, if the programmer does not have the above mentioned skills, most of the employers in the job market are not willing to hire him or her.

Besides the skills, we should also take serious consideration on the general qualities of the programmers. They should have qualities as follow:

• Good passion in work

Having great interest in work is important. The programmers should love and enjoy what they are doing.

• Good learning attitude

Learning is a continuous process. We can’t stop at certain stage. Good developers must have positive attitude in learning. They must always grab the opportunities to learn new technology so that good applications can be adapted.

• Some “intelligence”

Honestly speaking, intelligence is something very subjective. What I mean here is the “personality” of the person. Being a programmer, he or she must be smart and sensitive to respond to all changes. It is important for a programmer to be open-minded and willing to take new challenges from time to time.

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How to Resolve “Memory Card Error” From Canon IXUS 130

Canon IXUS 130 is a sophisticated digital camera that has a resolution of 14.1 megapixels. The camera is inbuilt with almost all advanced features, including fully wide-angle 4x zoom lens and motion blur technology. The IXUS camera is compatible with SDHC (Secure Digital High Capacity) and SDXC (Secure Digital Extreme Capacity) cards, with storage capacity as high as 2TB.

Since the storage memory of the cards is huge, data loss from these cards is simultaneously huge. One of the main reasons for data loss from cards is corruption of these cards. In most cases, you receive an error message after your card gets corrupted. However, an updated backup allows you to overcome card corruption. It allows you to restore data. But in case of unavailability of backup, you can use recovery software to recover data from a corrupted card.

As a practical case, you view the below error message on Canon IXUS 130 while attempting to view some previously stored photos on your SDHC card:

“Memory Card Error”

Every single photo saved in the memory card becomes inaccessible after the above error message appears. In addition, no more photo can be saved on card. In short, the card can not be read or written upon.

Cause:

The above error message that makes all the photos inaccessible is primarily caused due to corruption of card. Few reasons that are accountable for the above error message are virus infection, interrupted read/write operation, and human errors.

Resolution:

The resolution for the above error message is formatting of memory card in the camera itself. The process deletes all the previously saved data and allows you to save new data. While formatting proves a good resolution for users who do not require the old data, it becomes fatal for users, like photographers, detective agents, etc, who save critical data in their memory card. However, recovering formatted data now-a-days is an easy process. To do so, you need to use an advanced third-party Photo Recovery Software. A Image Recovery tool is readily available on the Internet by just one single click.

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Understanding the Significance of Computer Hardware

We are living in an age that is highly influenced by technology. Most of the activities we need to do now are automatic or computerized. Of all the technological developments achieved in the recent past, one significant tool that got developed and which will certainly keep influencing our lives is the computer. You would agree that computers play a very basic role in our daily life, just like the television and the cell phone. We are already at a stage where life will be difficult without a computer. That makes it important to understand the way a computer works, and then be informed of what we should do if it stops working. The most important part of any computer is its hardware, in the absence of which it just can not function.

If you are really keen to assess what has gone wrong with your computer when it stops working, you should understand the working and constituents of its hardware. You should especially have solid knowledge about the computer hardware when you want to undertake its troubleshooting on your own. One important part of the hardware is the RAM memory of any computer. For running any program or application, any computer needs a RAM memory. Other than that, if the computer has a RAM with specifications that are not compatible with the programs it is expected to run, its operation will be slowed down and it would almost crawl. When choosing a computer, you need to ensure that its hardware is not outdated, otherwise you'll have to upgrade it in order to be able to use the intended program.

You must take certain basic precautions while handling the hardware of computers. The most essential precaution is to ensure that the power supply to your computer is switched off, else it could cause an electric shock. Then, before you touch any part within the computer, ensure that you are not carrying any electric charge by connecting to a grounded piece of metal or you may procure an anti-static mat or wrist band available in the market. While inspecting the hardware components, you should look for broken or damaged component, as these are most likely the reasons for the computer malfunction. If a component does not fit in the slot, you are probably trying to fit it in the incorrect slot.

Once you know the hardware employed in your computer and the role it plays in the functionality of your computer, you'll be in a position to undertake its troubleshooting when it malfunctions. Each piece of hardware contributes to the successful function of the computer. To a large extent, the working of a computer depends on the quality of its hardware, making it imperative to keep it in good condition.

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The Importance Of Excel In The Workplace

Excel is perhaps the most important computer software program used in the workplace today. That’s why so many workers and prospective employees are required to learn Excel in order to enter or remain in the workplace.

From the viewpoint of the employer, particularly those in the field of information systems, the use of Excel as an end-user computing tool is essential. Not only are many business professionals using Excel to perform everyday functional tasks in the workplace, an increasing number of employers rely on Excel for decision support.

In general, Excel dominates the spreadsheet product industry with a market share estimated at 90 percent. Excel 2007 has the capacity for spreadsheets of up to a million rows by 16,000 columns, enabling the user to import and work with massive amounts of data and achieve faster calculation performance than ever before.

Outside the workplace, Excel is in broad use for everyday problem solving.

Let’s say you have a home office. You can use Excel to calculate sales tax on a purchase, calculate the cost of a trip by car, create a temperature converter, calculate the price of pizza per square inch and do analysis of inputted data. You can track your debt, income and assets, determine your debt to income ratio, calculate your net worth, and use this information to prepare for the process of applying for a mortgage on a new house. The personal uses for Excel are almost as endless as the business uses for this software – and an Excel tutorial delves into the practical uses of the program for personal and business use.

The use of spreadsheets on computers is not new. Spreadsheets, in electronic form, have been in existence since before the introduction of the personal computer. Forerunners to Excel and Lotus 1-2-3 were packages such as VisiCalc, developed and modeled on the accountant’s financial ledger. Since 1987, spreadsheet programs have been impacting the business world. Along the way, computerized spreadsheets have become a pervasive and increasingly effective tool for comparative data analysis throughout the world.

Today, end users employ Excel to create and modify spreadsheets as well as to author web pages with links and complex formatting specifications. They create macros and scripts. While some of these programs are small, one-shot calculations, many are much more critical and affect significant financial decisions and business transactions.

Widely used by businesses, service agencies, volunteer groups, private sector organizations, scientists, students, educators, trainers, researchers, journalists, accountants and others, Microsoft Excel has become a staple of end users and business professionals.

The beauty of Excel is that it can be used as a receiver of workplace or business data, or as a calculator, a decision support tool, a data converter or even a display spreadsheet for information interpretation. Excel can create a chart or graph, operate in conjunction with Mail Merge functions, import data from the Internet, create a concept map and sequentially rank information by importance.

Excel offers new data analysis and visualization tools that assist in analyzing information, spotting trends and accessing information more easily than in the past. Using conditional formatting with rich data display schemes, you can evaluate and illustrate important trends and highlight exceptions with colored gradients, data bars and icons.

Indeed, Excel can be customized to perform such a wide variety of functions that many businesses can’t operate without it. Excel training has become mandatory in many workplaces; in fact, computer software training is a must for any workplace trying to keep up with the times.

Let’s say you’re an employer with 97 workers, 17 of whom called in sick today, and you want to know the percentage represented by absentees. Excel can do that. You can learn Excel and use it to determine the ratio of male to female employees, the percentage of minorities on the payroll, and the ranking of each worker by compensation package amount, including the percentages of that package according to pay and benefits. You can use Excel to keep track of production by department, information that may assist you in future development plans. You can create additional spreadsheets to track data on vendors and customers while maintaining an ongoing inventory of product stock.

Let’s say you want to know your business production versus cost. You don’t have to be a math wiz – you just have to learn Excel. Excel allows you to input all of the data, analyze it, sort it according to your customized format, and display the results with color, shading, backgrounds, icons and other gimmicks that offer time-saving assistance in later locating precisely the information desired. If this spreadsheet is for presentation purposes, Excel helps you put it together in such a visually appealing way that the data may seem to pop and sparkle.

The single most important thing an employer may do is learn Excel – it is one of the most essential tools of the workplace.

Excel and Microsoft are trademarks of Microsoft Corporation, registered in the U.S. and other countries. Lotus is a registered trademark of International Business Machines Corporation in the U.S. and/or other countries.

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8 Criteria to Choose the Best Antivirus Program For Your Needs

There is no best antivirus program in general. You can make the best choice of your antivirus software depending on your goals, your needs and your environment. In order to choose your best antivirus software you should look at vendor information, independent antivirus certifying agencies reviews, as well as other sources. Here are the essential criteria for the right choice.

1. Compatibility
Antivirus program has to be compatible with your PC configuration. Your PC must meet hardware and software requirements of antivirus solution.

2. Range of Protection
Antivirus software should protect your PC from as many threats and on as many viruses as it can: viruses, worms, trojans, spyware, keyloggers, adware, rootkits, password stealers, phishing attacks, spam and others.

3. Effectiveness
Antivirus protection delivery by antivirus program should be effective and efficient. You may find and compare test results released by independent antivirus certifying agencies: Virus Bulletin, AV Comparatives, ISCA Labs, Westcoast Labs and others. If some antivirus solution was scored by these agencies high and consistently near the top, then you really can not go wrong with this top rated antivirus software.

4. Easy Installation
Good antivirus program has a prompt and easy installation. Interface should be clean, easy, and intuitive to use.

5. Easy to Use
Most users want to "install and forget" their antivirus software. So the best antivirus solution should have default configurations acceptable for most users. And at the same time good antivirus program can be easily configured and tweaked by advanced users.

6. Features
The best antivirus programs have the large features set that may include:
– list of compatible versions of Operational systems and platforms,
– amount of used system resources,
– using of proactive protection without false positives and with effective utilizing of system resources,
– availability of laptop battery saving mode,
– bootable rescue disk,
– silent gamer mode, and other available options.

A comprehensive features set adds strength to antivirus solution.

7. Update
The best security solutions have Automatic Update option and automatically perform updates every hour or "as needed updates" to keep virus definitions and program code up to date.

8. Support
The best security programs have a comprehensive online and offline technical support. The program vendor should provide online knowledge base, FAQs, tutorials, user forums. The best sellers provide 24/7 support so you can ask your questions by phone, email or chat at any moment.

The best for your needs antivirus program delivers you the best security and usability with a minimal outlay of your time, money, or your PC system resources.

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Wide Area Network (WAN)

Types and Characteristics of WANs

What is a WAN?

There are two prevailing definitions of a Wide Area Network (WAN). The book definition of a WAN is a network that spans large geographical locations, typically to interconnect multiple Local Area Networks (LANs). The practical definition of a WAN is a network that traverses a public network or commercial carrier, using one of several WAN technologies

What are its Main Components?

The main components for a WAN are routers, switches and modems. These components are described below in the hardware section.

CPE – Devices on the subscriber contracts are called customer premises equipment (CPE).
The subscriber owns the CPE or leases the CPE from the service provider. A copper or fiber cable connects the CPE to the service provider's nearest exchange or central office. This cabling is often called the local loop, or "last-mile".

DTE / DCE – Devices that put data on the local loop are called data circuit-terminating equipment, or data communications equipment (DCE). The customer devices that pass the data to the DCE are called data terminal equipment (DTE). The DCE primarily provides an interface for the DTE into the communication link on the WAN cloud.

Hardware

In a WAN you will need various types of hardware components for it to function. The typical items of hardware that you will need in a WAN are:

Router – An electronic device that connects a local area network (LAN) to a wide area network (WAN) and handles the task of routing messages between the two networks. Operates at layer 3, and makes decisions using IP addresses.

Switch – A switch is a network device that selects a path or circuit for sending a unit of data to its next destination. Operates at layer 2, and uses MAC addresses to send data to correct destination.

Modem – Short for modulator / demodulator, a modem that enables a computer to communicate with other computers over telephone lines. Operates at layer 1, where signals are converted from digital to analogue and vice versa for transmission and receiving.

Wan Standards

WANs operate within the OSI model using layer 1 and layer 2 levels. The data link layer and the physical layer. The physical layer protocols describe how to provide electrical, mechanical and functional connections to the services provided by the ISP. The data link layer defines how data is encapsulated for transmission to remote sites.

Encapsulation

Encapsulation is the wrapping of data in a particular protocol header. Remember that WANs operate at the physical layer and the data link layer of the osi model and that higher layer protocols such as IP are encapsulated when sent across the WAN link. Serial interfaces support a wide range of WAN encapsulation types, which must be manually specified. These types include SDLC, PPP, Frame delay etc. Regardless of WAN encapsulation used it must be identical on both sides of the point to point link.

Packet and Circuit Switching

Circuit switching and packet switching are both used in high-capacity networks.
The majority of switched networks today get data across the network
Through packet switching.

Circuit-switching is more reliable than packet-switching. Circuit switching is old and expensive, packet switching is more modern.

General Routing Issues

What is a Routing Protocol?

A routing protocol is a protocol that specifies how routers communicate and exchange information on a network. Each router has prior knowledge of its immediate neighbors and knows the structure of the network topology. The routers know this because the routing protocol shares this information.

Protocol

RIP (Routing Information Protocol) was one of the most commonly used protocols on internal networks. Routers use RIP to dynamically adapt changes to the network connections and communicate information about which networks routers can reach and the distance between them. RIP is sometimes said to stand for Rest in Pieces in reference to the reputation that RIP has for breaking unexpectedly and rendering a network unable to function.

Routing Algorithms

Distance Vector

This type of routing protocol requires that each router simply inform its neighbors of its routing table. The distance vector protocol is also known as the bellman-ford algorithm.

Link State

This type of routing protocol requires that each router maintain a partial map of the network. The link state algorithm is also know as Dijkstra's algorithm.

IGRP

IGRP is a type of distance vector routing protocol invented by cisco used to exchange routing data in a autonomous system. Distance vector protocols measure distances and compare routes. Routers that use distance vector must send all or a portion of their routing table in a routing update message at regular intervals to each neighbor router.

Addressing and Routing

What does routing mean?

Routing is the process of deciding how to move packets from one network to another.
The directions also known as routes can be learned by a router using a routing protocol then the information is passed from router to router along the route of the destination.

IP Address's

Every machine connected to the internet is assigned an IP address. An example of an IP address would be 192.168.0.1. IP addresses are displayed in decimal format to make it easier for humans to understand but computers communicate in binary form. The four numbers that separate an IP address are called Octets. Each position consists of eight bits. When added to together you get 32 ​​bit address. The purpose of each octet in an IP address is to create classes of IP addresses that can be assigned within a network. There are three main classes that we deal with Class A, B and C. The octets of an IP address are split into two parts Network and Host. In a class A address the first octet is the network portion, this determinates which network the computer belongs to, the last octets of the address are the hosts that belong to the network.

Sub netting

Sub netting allows you to create multiple networks within a class A, B or C address. The subnet address is the address used by your LAN. In a Class C network address you would have a subnet mask of 255.255.255.0. A subnet mask identifies which portion is network and which is host. For example 192.168.6.15 the first octet three octets are the Network address and the last octet being the host (Workstation). It is important to subnet a network because gateways need to forward packets to other LANS. By giving each NIC on the gateway an IP address and a Subnet mask it allows the gateways to route packets from LAN to LAN. Once the packet arrives at its destination, the gateway then uses the bits of the subnet portion of the IP address to decide which LAN to send the packets.

Circuit Switched Leased Lines

A circuit switched network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. Here are some terminologies associated with a Circuit switched network.

Frame relay is a telecommunication service designed for cost-efficient data transmission between local area networks (LANs)

Basic rate interference is a service used by small business for internet connectivity. An ISDN BRI provides two 64 Kbps digital channels to the user.
Primary rate interface (PRI) is a telecommunications standard for carrying voice and data transmissions between two locations
All data and voice channels are ISDN and operate at 64kbit / s

Packet Switching

Http://www.raduniversity.com/networks/2004/PacketSwitching/main.htm – _Toc80455261

Packet switching refers to protocols in which messages are broken up into small packets before they are sent. Each packet is then transmitted over the Internet. At the destination the packages are reassembled into the original message. Packet switching main difference from Circuit Switching is that that the communication lines are not dedicated to passing messages from the source to the destination. In Packet Switching, different messages can use the same network resources within the same time period.

Http://en.wikipedia.org/wiki/Asynchronous_Transfer_Mode

Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and protocolwhich encodes data into small fixed-sized cells.

ISDN is used to carry voice, data, video and images across a telephone network. ISDN stands for integrated services Digital Network. Isdn also provides users with a 128kbps bandwidth. This is done through frame relay. Frame relay complements and provides a service between ISDN, which offers bandwidth at 128 Kbps and Asynchronous Transfer Mode which operates in somewhat similar fashion to frame relay but at speeds from 155.520 Mbps or 622.080 Mbps. Frame relay is based on the older X.25 packet switching technology and is used to transmit analogue signals such as telephone conversations.

PSDN stands for packet switched data network and is a data communication network. Packet switched networks do not establish a physical communication signal like the public telephone circuit (circuit switched network) Packets are sent on a fixed length basis and assigned with a source and a destination address. The packages then explicitly on the routers to read the address and route the packets through the network.

Mobile and Broadband Services

Digital Subscriber Line (DSL) is mainly used to bring high bandwidth connections to homes and small business's over a copper wire telephone line. This is can only be achieved if you stay within the range of the telephone exchange. DSL offers download rates of up to 6mbps allowing continuous transmission of video, audio and 3D effects. DSL is set to replace ISDN and compete with the cable modem in providing multimedia to homes. DSL works by connecting your telephone line to the telephone office over copper wires that are twisted together.

Asymmetric Digital Subscribers Line is most commonly used for home users. It provides a high download speed but a lower upload speed. Using ADSL, up to 6.1 megabits per second of data can be sent downstream and up to 640 Kbps upstream.

Http://en.wikipedia.org/wiki/Symmetric_Digital_Subscriber_Line

Symmetric Digital Subscriber Line is a digital subcriber line which runs over one pair of copper wires. The main difference between ADSL and SDSL is the difference in upload and download speeds. SDSL allows the same upstream data rate and downstream data rate as ADSL upstream can be very slow.

[Http://searchnetworking.techtarget.com/sDefinition/0],,sid7_gci558545,00.html

HDSL High bit-rate Digital Subscriber Line, one of the earliest forms of DSL, is used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of HDSL is that that provides equal bandwidth in both directions.

IDSL is a system in which data is transmitted at 128 Kbps on a regular copper telephone line from a user to a destination using digital transmission.

The Local Loop enables operators to connect directly to the consumer via copper local loops and then add their own equipment to offer broadband and other services. This process involves operators accessing local exchange buildings to connect to a network of copper lines which connect them to homes and businesses. BT is an Example of a Local Exchange. The local loop connecting the telephone exchange to most subscribers is capable of carrying frequencies well beyond the 3.4 kHz upper limit.

Benefits of using DSL

DSL can provide a virtual instantaneous transmission of voice, data and video over ordinary copper phone lines. A DSL connection can eliminate delays while waiting to download information and graphics from the Internet. It provides users with a cost effective high speed Internet connection. Another benefit is that a DSL connection is always on-line (like a LAN connection) with no waiting time for dialing or connecting.

There are now more than 10 million broadband connections in the UK. By December 2005 there were 9.792 million broadband connections in the UK and the average broadband take up rate during the three months to December was more than 70,000 per week.

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How to Retrieve Deleted Text Messages & Not Go Crazy in the Process

It’s happened to all of us. We’ve deleted a text message only to realize a short while later that we either deleted the wrong message, or we need to retrieve information off one of the deleted text messages. We then frantically search out ways online how to retrieve deleted text messages hoping to find an easy solution. We pour through websites pulling our hair out because we can’t find an easy solution.

Ultimately we walk away dismayed because either we were not able to find any solutions on how to retrieve deleted text messages, or the solutions we found seemed to require so much “detective” work, that the solution itself should be on a an episode of CSI.

Are there really any “easy” ways to retrieve deleted messages?

The good news is that YES, there are a couple options that do exist which enable anyone to easily recover deleted texts, and both are not only very affordable, but both work exactly as advertised.

Before we dig into the solutions, there is one solution that is often discussed, which does not work, although many people do still talk about it.

What does NOT work?

Going to your own phone carrier is not going to be a viable option. Yes, they are required by law to keep records of your communication (SMS, call, etc.), but they are not required to turn over their logs to you, unless requested by a court of law. You cannot call up AT&T, Verizon or Sprint and tell them you want to retrieve a deleted text message from last week because there is something really important within the contents of the message. It just wont work.

The only information AT&T, Verizon, Sprint, or any other cell phone carrier is going to provide you is the number, date, and time of a call or message. You can plead all you want, but they will not be able to do anything, so it’s not worth your time to attempt this approach.

What DOES work?

There are actually two options available for anyone who is looking for information on how to retrieve deleted text messages. These options rank from the “quick and easy” to the more difficult, but also the most effective.

1) Quick & easy method.

The ‘quick & easy method’ is to buy a SIM card reader, often referred to as a SIM card spy device. This device looks like a USB reader, and the way it works is you remove the SIM card out of your phone, and then place the SIM card into the SIM card reader, and then plug the reader into your computer. Using the included software (of the SIM card reader), you’ll be able to immediately retrieve and read deleted text messages. The time frame will vary, based on what new information is overwritten on the SIM card, but you’ll at least be able to retrieve and read the last 15-20 messages and scan through your call history and contacts, even if they were all deleted.

Positives of this approach?

  • Very easy.
  • Enables you to quickly recover deleted messages.
  • Does not require software to be installed prior to the message being deleted.

Negatives of this approach?

  • A bit costly.
  • Limited cell phone support.
  • Does not work on CDMA networks.

2) More difficult, but most effective method.

The more difficult, but most effective method’ is to purchase a cell phone monitoring app that is often used to spy on cheating spouses, monitor teen cell phone use, track cell phone location, and locate missing or stolen cell phones. These apps (often called spy apps or spy phone software) are often used by people who want an easy and convenient way to back up and store all their own personal cell phone data. The reason why this method is fast becoming a popular way to back up their own personal cell phone data is because everything happens automatically. There is no “syncing” required, or any buttons or settings to worry about. Your cell phone data (text messages, call history, etc.) are automatically backed up every single day. This means if you ever delete a text message, and then need to quickly recover it, all you have to do is log onto your account and then in just a few clicks, you’ll have full contents of every message that was either sent or received from your phone. In addition, you’ll get access to all your call logs and contacts.

The reason why this is a more difficult method, is because it requires that you download the software from your cell phone’s web browser and install the application on your phone. Not everyone is comfortable downloading cell phone apps from the internet using their phone’s web browser. However, once you do complete the download, the actual installation is similar to installing an app on your computer. If you are willing to roll the dice and go with this method, you’ll be very happy with the results. It’s essentially a real time person back up solution that requires absolutely ZERO work on your part. Everything is done for you. The only drawback with this approach is that it does require you to install the software BEFORE you delete the text message that you want to retrieve. This means you need to be proactive and install the software ahead of time.

Positives of this approach?

  • Extremely effective.
  • Affordable.
  • Full contents of text messages are retrieved.
  • Large amount of cell phones are supported, including the popular models such as Android, BlackBerry, iPhone, Nokia, and more.

Negatives of this approach?

  • Can be difficult if not familiar with installing cell phone apps.
  • Software must be installed prior to message being deleted.
  • Requires a data connection such as 3G or Edge
  • May increase data fees if a large amount of text messages are sent on a daily basis.

There you go. Now you know how to retrieve deleted text messages using a couple different approaches. The next time someone asks you how to retrieve deleted text messages, you’ll know what options exist, and which one is the best for that particular situation.

Good luck!

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