Wednesday, January 30, 2008

Networking Topologies

There are more than one ways to connect the computers with each other. The way in which, we used to connect our computer is called “Topology”. Or in other words, the “Physical layout for a network” is called network topology. Here we will discuss most common topologies one by one.
Bus Topology
In bus topology we use wire as a backbone. The recommended backbone wire is thick-wire with 4” dia. So, this wire is the medium of communication and the other terminals are connected to this wire (backbone) with thin-wires the both corners of backbone wire are closed with device called terminator. These terminators are designed to absorb the signals from the both ends. Now one of the terminals attached to the network sends data along with the particular address of the desired terminal. This data goes to all the terminals but only that terminal receives the data which’s address is attached along with the data. So, at a time, only one communication could be performed so, due to this reason bus topology is little bit slow but it is recommended where the number of terminals are small.
Ring Topology
The Ring Topology is another way to establish a network. In this topology every computer is connected to the next computer and the last computer is connected to the first computer, in this way the ring of the computers complete. Now the one of the computer pass the data/information to the next computer. The next computer receives that data if the next computer is the destination of data, it means the communication completed, but if the next computer is not the destination of data, that computer will pass the information or data to the next computer and this process (receiving the data, check it and pass it to the next computer) will continue until the destination computer receives the data. The next activity will be start when the previous one is completed successfully. The major disadvantage in this type of topology is it that if one of the computer or nodes is out of order, the entire network will also falls down. Furthermore, the troubleshooting and adding or removing the computer is also difficult task
Star Topology
In Star Topology all computer connected a device called “Hub”. The computer send information/data to the Hub and then hub transfers that data to its destination. As for as the advantages of this topology are concerned, first of all it is easy to setup and maintain. We can detect the troubleshooting easily as compare to the previously discussed topologies. And the failure of one computer will not be the cause of entire network failure. It is also easy to adding or removing computers in the network. Simply, we can attach the more computers to the hub as well as remove the computer for it. But on the other hand, this topology is costly as compare to the previously described. First of all, we need a costly hub then the more cables are required in this topology.
Tree Topology
The Tree Topology is the combination of two (Previously discussed) topologies, Bus Topology and the Star Topology. Firs, we configure different star topologies and then we connect these star configured topologies to a backbone wire. In simple, words, we can explain that same like bus topology we connect group of computer (connected with each others using star topology) where as in simple bus topology, we connect single computer to the backbone wire. If we talk about the advantages of this tree topology, its main advantage is it that it can support a large numbers of computers. But on the other hand, it is very difficult to setup and configure and the fault in the main wire (Backbone) will shut down the entire network.
Mesh Topology
In Mesh topology ever computer is directly connected to the other computers on the network. So, it is easy to communicate with one and other computers. Furthermore, there are more options (ways) available for the data/information to reach on its destination. So, its fast in speed and the fault in one computer does not effect on the entire network. But it is difficult to setup and configure if the number of nodes is large.
So, these were the main and commonly used networking topologies.

Networking Models

In our previous posts we have talked about the “Networking”. Here we will learn about the Network Models. There are two main Network Models, these Network models also known as Network Architectures. These Network models/architectures are Client/Server and Peer-to-Peer.
First we talk about the Client/Server model and see what are the advantages and disadvantages of this model. In client/server model, there are two types involves one is the client and other server. Mostly, we find and server with high processing speed. On the other end, we find clients computers, connected to the server. So, the server’s min task is to provide the services to its client computers. When they request, the server also manages the resources available on the networks. Such as hardware resources software resources and it also provides the large storage for the clients connected to it. So, we can say the client computers are depending on the server to utilize the resources of a network. If we talk about a large network, working on this mode, Client/Server we will find more than more than one server and too many clients connected to these servers. Here the servers performs and manage specific tasks assigns to them, for example one server will manage the printers and printing requests, the other will manage the software installed on it and third will manage the storage resources So, these types of severs are called “Dedicated Servers”, means dedicated to one or more than one jobs. But mostly, in a small office networks we find one server with heavy resources and the clients connected to the server.
Now, lets see some advantages and disadvantages of Client/Server Model.
First of all in a Client/Server model we can handle a large number of users and if the users increase, we can increase the servers too and assign the specific tasks to these servers.
This model also provides the high security level and can restrict the users access. For example, it can give the permission to add or edit the data and programs and it can give the permission just to read – only data.
Here in Client/Server model we use only one expensive server and the clients may be low cost. Because all the major activities performed on the sever side, so, the low resources clients can used for the users.
In offices and large organizations, many users work on a single database. So, we install that database on the server and all the users can use that data simultaneously. And when the data is stored on a single place, its easy to maintain the backups for that data
There are some disadvantages of Client/Server model. In this model we need a costly server with high resources. And in addition we need to hire a network administrator to manage the server and networking. If the server is out of order the all the network will shut down because the entire client computer are depend on the server.
The second networking model is called “Peer-to-peer” model. The major difference between the Client/Server model and Peer-to-peer model is it, that in peer to peer model there is no any server but all the computer get and provide the services to other computers.
In Peer-to-Peer Network we connect the peripheral devices (additional devices such as printers and Scanners) with any computer and other can use these peripheral devices peer-to-peer network model is recommended where the number of computers are between 2 to 12.
In this model we don’t need to manage an expensive server and network administrator, because its setup is simple and easy.
But it is not recommended where the number of users is large due to the following reasons/disadvantages.
First of all, it cannot perform fast speed because the resources of computer are shared and used by more than one user; so, it reduces the speed of entire network
Peer to peer model cannot supper the security management. So, the data is not secured as it is on Client/Server model. Its also difficult to arrange the backups from different computers because data is not present at a single place as we find the Client/Server model.
So, in the end we can conclude that in small offices where we have users between two to twelve, peer-to-peer network model is recommended and in the organizations where we have large number of users, Client/Server model is suitable

Monday, January 28, 2008

Internet And Its History

In our previous topic, we have talked about the networking, now here we will discuss that what is Internet? And what is the history of Internet. We can simply say that Internet is the network of millions networking around the world. Or in other words, the millions of computer from all over the world are connected with each other to share the data in its all forms. Such as text, images, audio and video. These networks use telephone lines, Fiber – optic cables and satellite communications for communicate with each others. And to utilize these major forms of media, there is the need of both hardware and software. So, as for as the use of Internet increased, the globalization of the World became towards the reality.
If we have a glance over the history of Internet, we will come to know, that US department of defense designed a network called ARPANT (Advanced Research Project Agency Network) in 1960. And its purpose was to share the researches and work of Scientist from the different locations. So, with the help of this (ARPANT) it seems as they were sitting and working together. So, it was the first step towards the modern ways of sharing information.
The other networks related to the military points of view came into existence with the passage of time and the period of between 1970 and 1980 was very important period as for as the history of Internet concerned. Because in this period (1970 – 1980) mostly military related networks emerged into ARPANT. On the other end, networking was gaining the popularity and almost all the major Universities and Research Centers also joined the ARPANT. And now, we can say that ARPANT become the “Network of Networks”.
A major point was taken place in 1989, when ARPANT was replaced with National Science Foundation’s Network (NSFNET). Prior to this the Internet was serving the Scientists, Teachers, University students and Military Officers. In short, the users of Internet were limited but in 1989, when the NSFNET came into existence all the civilians communities started to get benefits of Internet. With this, as the number of Internet users grow and the popularity of Internet also grown. The period of 1990 to 2000 was the period when the rapidly growth and the popularity of Internet was on its peck. After the 2000, the period of modern Internet was starting. Prior to 2000, Internet was being used for the informational purposes, mostly the users join it when they need information or to communication purpose such as E-Mail or Chatting. But after 2000, Internet became the source entertainment too. Now, where it provides information and communications, it also provides the entertainments.

Wednesday, January 23, 2008

Networking And Its Benefits

When we connect two or more than two computers with each other it called “Net Working”.
Now the question arises why we need networking? Infect, networking has lot of plus points and has advantages over the single PC. First of all, networking increases the productivity of entire network. For example, we are working n a file and now we want to present that file to our manager or boss. So, what e will do? First of all we will arrange some floppy disk or pen drive then we will write it on that floppy or pen drive, again we will convert it to the required computer. So, this activity involves more than three steps. But if we want to do it in a networking environment we will just copy the file on the desired computer drive, which, will be shared on the network. So, it reduces the time and increases the productivity.
Then next advantage of networking is cost saving benefit. Networking is a less expensive thing as computer to the other exercise to perform the same activity. We don’t need the floppy drives, we don’t need to pen drive, we don’t need the individual printer and scanner, means to say that in a small office environment where we have only tem computers. We can use only one printer and can print from any computer. In networking environment, we also save the disk space. We only share a main hard disk (Server’s hard disk) and install main programs on that server hard disk and then there is no need to install the software an individual computer. In networking environment its easy to maintain the computers if we don’t have networking we need to pay consultation on individual computers but in networking, environment, we need only one computer expert called network administrator. He can easily manage all the connected computers. He pays special attention to server (because all the important data and programs are saved on the shared server and he can also restrict the users to that the users can’t harm the computers. Other great advantage of networking is the sharing of devices. As we have talked about it already, that without networking we need individual printers for individual computers. But in networking environment, we only attach the devices with server, or another computer, which, is the part of network. And all the users can utilize that resources (devices). Same way, we place the software and the data store on the server and all the users use that software and data from that server. In a network, everybody can communicate with the other members of network. They can chat, they can discuss about the serious matters just sitting on his/her seat and all is possible in a networking environment. Networking also provides lot of securities because all the important data and all the software are installed on the server and network administrator can easily manage the security of that important data. But imagine, without networking network administrator has to take back ups from individual computers.

Saturday, January 19, 2008

Computer Software

There are two types of computer software.
1) System Software
2) Application Software

System Software is the software, which, are compulsory to run the computer, or in other words there are the software required by the computer hardware. These software manage the computer resources. Main example of these software are operation systems and drivers. Just take the example of operating system. Operating system works like bridge between hardware and application software. Without system software, we cannot use application software.
Application Software helps us to manage/perform our tasks according to our requirements. Or in other words, we develop these software according to our requirements. i.e. to manage our accounts or to maintain the inventory system. Every body cannot develop these software. So, there are software houses where the professionals programmers and developers develop the software according to our requirements. the person who uses these software is called the user and who develop the system software is called developer or programmer. Developing a program or system is not an easy task but we can do it with a proper managed way. This way or steps to develop any system is called “System Development Life Cycle. At the very first state we identify the requirements. This is the very important stage because all the future steps depend on this initial step. Then we find out more than one solution to develop the system so we can select the best amount the all other possible ways. In this stage we get more and more information about the system, which, we are going to develop. And we arrange some meetings with clients and the users of the system so, that we can get collect more and more information. After this stage we write a report (called feasibility report) in which, we describe all the possible solutions and then also mention the best solution. Then we forward this report to the project manager for approval so, project manager passes this report and amend where it necessary. Then the programmer winds up the information and requirement then the programmer observes the previous system, it may be in the shape of manual reports or may be the system, which, user wants to upgrade. Next stage is the logical design stage. In this stage developer logically develop the system and after it convert logical design to physical system construction. After it programmer writes the coding of the system so, that if some other programmer want to amend the programs. Next the testing and the implementation of the system comes. Some time they direct implement the system but the parallel implementation is recommended. Parallel implementation means that don’t stop the previous running system in the company and start new developed system and after some time, when the user/client satisfied with the system then stop the previous system. And in the end maintenance and up gradation of the system is required time to time

Output Devices

There are two types of output devices. One is called Soft copy outputs and the second is Hard copy outputs.
Soft Copy Outputs
System reports and the Preview reports are Called Softcopy Output reports. The main output device of this category is Monitors and Screens. These monitors and screens are different from each other by the colors, size, resolution and graphic cards or display adapters. The 256 colors combinations are used in these monitors. The most commonly used size for monitors is 15” or 14” and unto the large sizes of monitors.
Cathode-Ray-Tubes are the most common monitor type. In this technique, bits converted to the electrons by the electron gun. When this electrons stick on the phosphor coated surface, it creates images on the monitor screen. This technique is also used in TV sets.
FPD (Flat Panel Displayer)
These types of monitor are lightweight but expensive as compare to the CRT (Cathode Ray Tube) monitors. But this type is suitable for the portable computers. The most common of this type are LCD (Liquid Crystal Displayers). In this technique, there are two glass plates and between these plates, there is a liquid crystal stuffed. This liquid crystal stuffed layer between the two glass plates creates the image. So, these are the most common soft copy output devices now we talk about he hard copy outputs. Printers there are also two types of printers. First type is Impact Printers and the second is Non-Impact printers.
Impact Printers
Impact printers works just like the typewriters. There is ribbon between the hammers like characters and when these characters struck like hammer on the inked ribbon, it prints the character on the plane paper. Or in other words, there is an ink ribbon between a plane paper and characters. And when character struck on the ribbon, it leaves the image on the paper. These types of the printers are slow in printing but this printing is not as expensive as compare to the other printers type (non-impact printers). So, impact printers are used where the heave printing is required. Though, print slowly, but the cost per page is too much low as compare to other printers. The quality of this printing is also not too good; I mean it gives poor printing quality. But yet have its own benefits.
Non – Impact Printers
Non – Impact Printers work like the photocopier machine. It gives the speedy printing and the qualities of these printers are too much good as compare to the impact printing quality. But this type of printing is costly. These printers are not recommended where the heavy printing is required.
Speakers
Speakers are also one of the types of output devices. It used to out put the audio formatted files. There are lot speakers types are available in the market. So, these are the most commonly used output devices.

Friday, January 18, 2008

Input Devices

When we talk about the computer, we must talk about the data, data processing and information. And to enter data in computer for processing and results first, we need some devices. So, all the devices used to enter the data (in any form) are called input devices. First it is compulsory to describe that there are four forms of data. These types are Text, Image, Audio and Video. Now, we have different devices to enter these four types of data. Here we discuss most commonly used these input devices.
Key Boards

The most commonly used input device is “Key Board”. The Key Board is used to mostly enter text data type. The first line of buttons on Key Boards (in most key boards) is function buttons key. These function keys are from F1 to Pause/Break key button. These function keys are shortcut keys to execute different commands according to the software and operating systems. For example in most applications F1 key is used to get some help and F2 key is used to execute the exe etc. on the top left corner we find the escape key, mostly used to skip some commands or to have escape from previous screen.
Then there on the Key Board, we find a Tab Key. This tab key used to set stops on the paper. Caps Lock key used to turn on and off the Upper and Lower case of alphabet character (A – Z). If it turned to on, the character will be typed in the upper case and when it pressed to off (if the light under the Caps Lock button is turned on it means its turned to on and if that light is off it means that caps lock is turned off) the characters will be typed in lower case. Shift Key works with the combination with other keys available on the keyboard. If we press any character + shift key the character will be typed in the upper case. Ctrl Key also works with the combination of other keys. This key is mostly used to run commands according to the software commands. Alt Key also works with the combination of other keys. This key is mostly used to run commands according to the software commands. Back Space and Del Keys used to erases one character. Different in both keys is only it that the Del Key erases one right character from cursor where as the Back Space key erases one character from the left side of current cursor position. Enter Key is used to execute the programs and also used to start typing from anew line. End Key used to move the cursor at the end of current line where as Home Key move the cursor at the start of current line. Arrow Keys there are four arrow keys on the Keyboards. Right arrow, Left arrow, up arrow and the Down Arrow. Right arrow move the cursor one space right to the current position of the cursor, Left arrow moves the cursor towards the one left character. Up arrow moves the cursor to up line and down arrow moves the cursor towards next down line. Page Up and Page Down as the p arrow key moves cursor to next up line, page up move the cursor to the next page up and page down moves the cursor to the next down page. Ins key, when pushed on, it over-writes the per-existing characters. Print Screen used to print/the current screen in image form and the Scroll Key is used to scrolled all text and images appears on the screen but not let the cursor to scroll. Pause Key used to pause the swiftly moving information. For example, if we type dir in the Dos. Mode computer will show the list of directories and files too fast that we can’t read this information. So, we can pause this information until we read it. And there are also alphabets from A to Z, numeric keys from 0 to 9 and finally the mathematical operators keys such as +, -, *, etc.
Now, the multimedia Keyboards are also available in the market. In these multimedia Keyboards we have play/pause/still/stop/forward/rewind/volume up. Volume down function keys is available for audio and video format files. The next type of input devices is Pointing Devices.
Mouse is the most common example of pointing devices. It looks like a mouse and it moves the cursor as we move it. In which direction we will move mouse, the cursor will also move towards that direction. There are also two click points available on the mouse. One is called right click and the other is called the left click. When we want to open/execute any icon, we position the cursor to that icon with the movement of mouse and then we will click the button to complete the task. We can also select the text and images with mouse. In some mouse, we find a scrolling wheel in the middle of right and left clicking points. Scrolling this wheel we can scroll the screen to up and down.
Track Ball mostly used on the laptops. It is just like a moveable ball and we move the cursor with the movement of this track ball.
Pointing Stick looks like a pencil eraser, placed between the G, H and B keys. It also used to move the cursor to our desired position s we move it with our fingers.
Joy Stick is used to control the video games or in other words joystick is a video game controller.
Touch Screen mostly used with laptops as we move our finger over the touch screen the cursor also move towards that directions.
Light Pen is just like a pen connected with computer with a wire (wireless light pens are also available) as we position it to our desired position; we press a button on it to perform our desired task.
Pen Based System with the help of this device we are able to directly put data in our handwriting as we write, our writing stores in computer.

There is another family of input devices which is called the “Direct Input Devices” using these devices we can very fast input our data with less struggle. Most commonly input devices are Scanners, Digital Cameras and Microphone. Scanners scan the data and directly store it in the computer we can scan and images papers etc. Scanners converts that papers into digital computer acceptable form and then store it in computer for future use or further process. Other direct input device is Microphone used to store audio data type. It input the all sound/audio data type into computer. And finally we have Digital Cameras, which, we use to input images and video type o data to out computers. We can input our still images as well as our video data types.
So, these are the most commonly used input devices

Main Functions of Computer

The word ‘Computer” is abstracted from the word “Compute” which, means calculate. But if we restrict computer definition that computer is a device, which, helps us in solving our mathematical problems, it would be injustice with the computer. Though, there is no doubt that computer helps us to solve our mathematical problems but to solving and helping in our mathematical problems is just one of the works, performed by computer. So, we can say that computer is device, which can help us in:
Programming, Processing and storing the data we can develop programs according to our requirements and needs. We can process our data on computer to make it information and computer stores data, which is also very important role. All these functions of computer are very important and play very vital role to create “Global Village”. It takes the data for processing then process it, stores it and shows/provides information. These mentioned tasks of computer are called “Input”, when we enter some data in computer it called “Input” after inputting the data, next step is process (we can store the unprocessed data too) then it process the data. It called “Processing” and next it gives results after processing, which called “Output”. And finally, computer stores the data for future use.
There are two major parts of computer.
1) Hardware
2) Software

So, we can say that computer is the combination of hardware and software and it takes inputs give results after processing and stores data for future use

Global Village and the role of Computer

Today the world is called as “Global Village” and it is possible due to the rapidly growth of sharing information. Now, the question arise that what is the “Sharing Information”. First, Let me define what is information. To know about the information it is compulsory to have some knowledge about the data and data processing. Data is a collection of raw material about any particular thing or person or in other words unprocessed or unorganized information is called data. When we have collected the data our next step is to arrange it so that I become some useful information. To do so, we need some processing on it (our collected data) and when we process the data, it becomes useful information. So the sharing of this information leads us towards the globalization of world. In the present era, every passing moment has a story in itself. Every second gives us lot of to know and the events from all over the world are ready to share them. So, the circle completes in this way:
1) First, Collection of row figures and facts about the rapidly changing events
2) Process on these collections of data so it becomes some useful information.
3) Share this useful processed data (Information)
All these above mentioned steps leads us towards the “Globalization of World” it was not possible prior the invention of computer. But as the computer become a common device in all over world. The information (in any sort or form) compiled and ready for share so, if the current world is called “Global Village”. It is only due to the computer because it helps us in above-mentioned three steps, which, leads us towards the “Global Village”. For example, it helps us to collect the figures and facts (Data). Then we can process data according to our requirement so, that our data become some useful information and finally it plays a very vital role to share that information. So, it would be rightly to said that “Globalization” is just due to the device called ‘Computer”