Understanding the Components of a Home Network

Home networks are becoming more common. People want to be able to share a single broadband Internet connection to several computers in the house. There are many different devices that you can use to make up your home network. If you have never heard network terminology device names like router, hub, etc may seem confusing. 

The purpose of most of these devices is to control how the network passes around information. This information is sent in the form of "packets". I will refer to the term packet several times in this article. It simply means the data that the network is transporting. I will now explain the purpose of the major components of a home network. 

What is a Hub 

A hub is a device that has several Ethernet ports on the back of the device. One of these ports will likely be labeled “Uplink”. This port allows you to connect multiple hubs together, if you run out of ports on your hub. If you do not have an uplink port on your hub, the hub cannot be easily extended if you run out of ports. 

A hub is a device that attaches multiple computers on an Ethernet network. If you have a number different computers that you want to connect together, you could connect each to the hub. Any packet that is sent out by any computer on the network will immediately be transmitted to the other computers. Each computer will determine if the packet was really intended for it, and filter out packets that were intended for other computers. 

You really should not use a hub in a modern home network. You should always use a switch in place of a hub. Switches will be discussed in the next section. 

What is a Switch 

A switch is a device that has several Ethernet ports on the back of the device. One of these ports will likely be labeled “Uplink”. This port allows you to connect multiple switches together, if you run out of ports on your switch. If you do not have an uplink port on your switch, the switch cannot be easily extended if you run out of ports. 

A switch serves the same function as a hub. It allows you to connect multiple computers together, so that they can exchange packets. However, a switch is much more efficient than a hub. A switch will only send Ethernet packets to the computer that the packet was intended for. Because of this you should always use a switch in place of a hub. 

What is a Router 

A router is a device that has several Ethernet ports on the back of the device. One of the connectors will be labeled WAN. You should connect the WAN port to the Ethernet connection on a broadband source, such as a cable or DSL modem. The other ports on the router can be connected other computers or switches/hubs that will share the WAN connection. 

Routers allow you to share your broadband connection with multiple computers in your house. Rather than connecting your computer directly into your cable or DSL modem you connect the router to the cable or DSL modem. Now any computer that you connect to the router will have access to the Internet. 

If you run out of ports on your router you can always connect an additional switch to the router. To connect a switch to a router simply connects the switch’s "uplink" port to one of the routers Ethernet ports. Of course, don’t connect to the router’s WAN port. The WAN port should only be connected to something such as a cable or DSL router. 

Some routers come with additional features installed. Most routers also include a firewall. Firewalls are discussed in the next section. Some routers will also include a wireless access point (WAP). The WAP allows you to use wireless devices, such as wireless laptops, with the Internet. 

What is a Firewall 

A firewall controls traffic flow between your network and the Internet. A firewall can be either hardware or software. Windows XP SP2 or higher includes a software firewall. A hardware firewall is included with most routers. 

A firewall is a very good idea. It can protect you from inbound virus attempts. By inbound virus attempt I mean other computers that will connect to your computer and attempt to infect your computer. You do not want to run a computer directly connected to the Internet, without a firewall. There are just too many other computers out there that can connect and infect you without you even noticing. 

What is a Network Attached Storage (NAS) 

A network attached storage device is a device that allows a hard drive to be shared across the network. This hard drive is NOT attached to any of your computers. It is simply made available by the NAS. This can be a convent way to add a hard drive that can be accessed by several computers on your network. The other common way to add a network hard drive is to simply share a folder on one of your computers. However, with the NAS, you do not need to keep one of your computers on at all times. 

There are two types of NAS commonly available. The first type comes with a build in hard drive. The second accepts a USB or Fire wire external hard drive. The advantage to using a USB or Fire wire hard drive is that you can upgrade the hard drive if it ever were to become too small. 

What is a Print Server 

Just like you can buy a device to allow you to share a hard drive, you can do the same with a printer. A print server connects directly to your printer. Your printer is then shared to all of your computers on the network. This is convent because you do not need to leave the printer hooked to a computer, which must be turned on to print. 

Conclusions 

As you can see there are many different components. Perhaps the final component that I ave yet to mention is the cable. These components are connected together with CAT5 Ethernet cable.

Why LINUX is virus proof

 One of the most notable differences between the two operating software’s is Windows legendary problems with malicious code, known as Viruses and Spy ware. Viruses, Spy-ware and a general lack of security are the biggest problems facing the Windows community. Under Windows Viruses and Spy-ware have the ability to execute themselves with little or no input from the user. This makes guarding against them a constant concern for any Windows user. Windows users are forced to employ third party anti virus software to help limit the possibility of the computer being rendered useless by malicious code. Anti virus software often has the negative side effect of hogging system resources, thus slowing down your entire computer, also most anti virus software requires that you pay a subscription service, and that you constantly download updates in order to stay ahead of the intruders. With Linux on the other hand problems with viruses are practically non-existent, and in reality you do not even need virus protection for your Linux machine. One reason why Viruses and Spy-ware are not a problem for Linux is simply due to the fact that there are far fewer being made for Linux. A more important reason is that running a virus on a Linux machine is more difficult and requires a lot more input from the user. With Windows you may accidentally run and execute a virus, by opening an email attachment, or by double clicking on a file that contains malicious code. However with Linux a virus would need to run in the terminal, which requires the user to give the file execute permissions, and then open it in the terminal. And in order to cause any real damage to the system the user would have to log in as root, by typing a user name and password before running the virus. Foe example to run a virus that is embedded in an email attachment the user would have to, open the attachment, then save it, then right click the file and chose properties form the menu, in properties they can give it execute permissions, they would then be able to 

open the file in the terminal to run the virus. And even then the user would only be able to damage his or her home folder, all other users data will be left untouched, and all root system files would also remain untouched, because Linux would require a root password to make changes to these files. The only way the user can damage the whole computer would be if he or she logged in as root user by providing the root user name and password to the terminal before running the virus. Unlike Windows in Linux an executable file cannot run automatically, It needs to be given execute permissions manually this significantly improves security. In Linux the only realistic reason you would need virus protection is if you share files with Windows users, and that is to protect them not you, so you are not to accidentally pass a virus to the Windows computer that you are sharing files with.

Complete Overview of Linux

This article will discuss the differences between the Linux and Windows operating software’s; we discuss some of the pro’s and con’s of each system. 

Let us first start out with a general overview of the Linux operating system. Linux at its most basic form is a computer kernel. The Kernel is the underlying computer code, used to communicate with hardware, and other system software, it also runs all of the basic functions of the computer. 

The Linux Kernel is an operating system, which runs on a wide variety of hardware and for a variety of purposes. Linux is capable of running on devices as simple as a wrist watch, or a cell phone, but it can also run on a home computer using, for example Intel, or AMD processors, and its even capable of running on high end servers using Sun Sparc CPU’s or IBM power PC processors. Some Linux distro’s can only run one processor, while others can run many at once. 

Common uses for Linux include that of a home desktop computing system, or more commonly for a server application, such as use as a web server, or mail server. You can even use Linux as a dedicated firewall to help protect other machines that are on the same network. 

A programmer student named Linus Torvalds first made Linux as a variant of the Unix operating system in 1991. Linus Torvalds made Linux open source with the GNU (GPL) (General Public License), so other programmers could download the source code free of charge and alter it any way they see fit. Thousands of coders throughout the world began downloading and altering the source code of Linux, applying patches, and bug fixes, and other improvements, to make the OS better and better. Over the years Linux has gone from a simple text based clone of Unix, to a powerful operating software, with full-featured desktop environments, and unprecedented portability, and a variety of uses. Most of the original Unix code has also been gradually written out of Linux over the years. 

As a result of Linux being open source software, there is no one version of Linux; instead there are many different versions or distributions of Linux, that are suited for a variety of different users and task. Some Distributions of Linux include Gentoo, and Slackware, which due to the lack of a complete graphical environment is best, suited for Linux experts, programmers, and other users that know their way around a command prompt. Distributions that lack a graphical environment are best suited for older computers lacking the processing power necessary to process graphics, or for computers performing processor intensive task, where it is desirable to have all of the system resources focused on the task at hand, rather than wasting resources by processing graphics. Other Linux distributions aim at making the computing experience as easy as possible. Distributions such as Ubuntu, or Linspire make Linux far easier to use, by offering full-featured graphical environments that help eliminate the need for a command prompt. Of course the downside of ease of use is less configurability, and wasted system resources on graphics processing. Other distributions such as Suse try to find a common ground between ease of use and configurability. 

“Linux has two parts, they include the Kernel mentioned previously, and in most circumstances it will also include a graphical user interface, which runs atop the Kernel” . In most cases the user will communicate with the computer via the graphical user interface. 
Graphical user interface
Some of the more common graphical environments that can run on Linux include the following. The KDE GUI (Graphical user interface). Matthias Ettrich developed KDE in 1996. He wanted a GUI for the Unix desktop that would make all of the applications look and feel alike. He also wanted a desktop environment for Unix that would be easier to use than the ones available at the time. KDE is a free open source project, with millions of coders working on it throughout the world, but it also has some commercial support from companies such as Novell, Troltech, and Mandriva. KDE aims to make an easy to use desktop environment without sacrificing configurability. Windows users might note that KDE has a similar look to Windows. Another popular GUI is  GNOME. GNOME puts a heavy emphasis on simplicity, and user ability. Much like KDE GNOME is open source and is free to download. One notable feature of GNOME is the fact that it supports many different languages; GNOME supports over 100 different languages. Gnome is license under the LGPL license (lesser general public license). The license allows applications written for GNOME to use a much wider set of licenses, including some commercial applications. The name GNOME stands for GNU Network object model environment. GNOME’s look and feel is similar to that of other desktop environments. Fluxbox is another example of a Linux GUI. With less of an emphasis on ease of use and eye candy, Fluxbox aims to be a very lightweight, and a more efficient user of system resources. The interface has only a taskbar and a menu bar, which is accessed by right clicking over the desktop. Fluxbox is most popular for use with older computers that have a limited abundance of system resources. 

Although most Linux distributions offer a graphical environment, to simplify the user experience, they all also offer a way for more technically involved users to directly communicate with the Kernel via a shell or command line. The command line allows you to run the computer without a GUI, by executing commands from a text-based interface. An advantage of using the command prompt is it uses less system resources and enables your computer to focus more of its energy on the task at hand. Examples of commands include the cd command for changing your directory, or the halt command for shutting down your system, or the reboot command for restarting the computer ect. 

Now that we are more familiar with the Linux operating system, we can note the many ways in which Linux differs from the worlds most popular OS, Microsoft Windows. From this point forward we will discuss some of the more prominent ways in which Linux deferrers from Windows.

For starters there is only one company that releases a Windows operating system, and that company is Microsoft. All versions of Windows, weather Windows XP Home, Business, or Vista, all updates, security patches, and service patches for Windows comes from Microsoft. With Linux on the other hand there is not one company that releases it. Linux has millions of coders and companies throughout the world, volunteering their time to work on patches, updates, newer versions, and software applications. Although some companies, charge for TECH support, and others charge for their distribution of Linux, by packaging it with non-free software, you will always be able to get the Linux Kernel for free, and you can get full-featured Linux desktops with all the necessary applications for general use, for free as well. The vendors that charge money for their distribution of Linux are also required to release a free version in order to comply with the GPL License agreement. With Microsoft Windows on the other hand you have to pay Microsoft for the software, and you will also have to pay for most of the applications that you will use. 

Windows and Linux also differ on TECH support issues. Windows is backed by the Microsoft Corporation, which means that if you have an issue with any of their products the company should resolve it. For example if Microsoft Windows is not working right, then you should be able to call Microsoft and make use of their TECH support to fix the issue. TECH support is usually included with the purchase of the product for a certain amount of time, maybe a two year period, and from there on you may be charged for the service. Although IBM backs their Linux products, for the most part if you use Linux you are on your own. If you have a problem with Ubuntu Linux you cannot call Ubuntu and expect any help. Despite the lack of professional help, you can however receive good TECH advice, from the thousands or millions of Linux forums that are on the web. You ca also get great help from social networking sites such as Myspace, by posting questions in the many Linux groups. You can usually receive responses for your questions in a matter of hours form many qualified people.
Configurability
Configurability is another key difference between the two operating software’s. Although Windows offers its control panel to help users configure the computer to their liking, it does not match the configuring options that Linux provides especially if you are a real TECH savvy user. In Linux the Kernel is open source, so if you have the know how, you can modify it in virtually any way that you see fit. Also Linux offers a variety of Graphical environments to further suit your needs. As mentioned earlier Linux is capable of running full-featured graphical environments like KDE, or more lightweight and resource friendly GUI’s like Fluxbox, or Blackbox, to suit users with older computers. There are also versions of Linux that are designed to emulate the Windows look and feel as closely as possible. Distributions such as Linspire are best suited for users that are migrating over from the Windows world. There are also distributions that include no graphical environment at all to better suit users that need to squeeze out all of the computing power that they can get for various computing activities, and for users that are more advanced than others. All of this configurability can be problematic sometimes, as you will have to make a decision on which desktop is right for you, and to make things easier on yourself you will need to only install applications that are native to your distribution and graphical environment. 

 The cost effectiveness of Linux is another way it separates itself from Windows. For home use Linux is cheap and in most cases completely free, while Windows varies in cost depending on which version you buy. With Linux most of the applications will also be free, however for Windows in the majority of cases you are suppose to pay for the applications. For most cases, with Linux there is no need to enter a product activation key when performing an installation, you are free to install it on as many computers as you’d like. With Windows you are only allowed to install it on one computer and Microsoft uses product activation software to enforce this rule. When installing Window’s you must enter a product activation key, which will expire after so many uses. If you wish too, you can purchase Linux from a variety of vendors, which will include a boxed set of CDs, Manuals, and TECH support for around 40-130$. Of course If you purchase a high-end version of Linux used for servers it may cost any where from 400$- 2000$. “In 2002 computer world magazine quoted the chief technology architect at Merrill Lynch in New York, as saying “the cost of running Linux is typically a tenth of the cost of running Unix or Windows alternatively.”

Installation and hard ware issues
    Installation of Windows is generally easier, than installing Linux. “With Windows XP there are three main ways to install. There is a clean install, in which you install Windows on a blank hard drive. There is also an upgrade install, in which you start with an older version of Windows and “upgrade” to a newer one. An advantage of upgrading is that all of the files on the older system should remain intact throughout the process. You can also perform a repair install, in which case you are installing the same version of Windows on top of itself in order to fix a damaged version of Windows. There is also a recovery, which Technically is not an install; it is used to restore a copy of Windows back to its factory settings. The disadvantage of recovering Windows is the fact that you will loose all of your data, which resides on the damaged copy of Windows.”  Also with Windows you can rest assured that your hardware will most likely be supported by the operating software, although this is not much of a problem with Linux you cant be sure if Linux will support all of your hardware. With Linux installation varies greatly from Distro to Distro. You may be presented with a graphical installer or it may be a text-based installer, these variations make Linux a bit more difficult and unpredictable to install than is Windows, (although the difficulty is disappearing). You may perform a clean install of Linux or dual boot it, to co-exist with another operation software. With Linux rather than having to buy an upgrade Cd, you can install updates by downloading and then installing them while your desktop is running. With Linux it is also not necessary to reboot your computer after most upgrades, It is only necessary to reboot after an upgrade to the kernel. It is also possible to run Linux without ever needing to install it on a hard drive; there are many distributions of Linux that will allow you to run it straight off of a live cd. The advantage of this is that you do not need to alter your system in order to try Linux. You can run Linux off of the CD so you do not have to damage your Windows partition. Other advantages include the ability to rescue a broken Linux system. If your Linux computer will not boot, then you may insert a live cd and boot off it, so you can repair the damaged version of Linux. Also you may use a Linux live cd to recover files from a damaged Windows computer that will no longer boot up. Since Linux is capable of reading NTFS files you may copy files form a Windows computer to a USB flash drive or floppy drive ect. 
Applications
Another major difference between Linux and Windows is the applications that you will use with either OS. Windows includes a much wider abundance of commercially backed applications than does Linux. It is much easier to find the software that you are looking for with Windows than it is with Linux, because so many software vendors make their products compatible with Windows only. With Linux you will for the most part be forced to let go of the familiar applications that you have grown accustomed to with Windows, in favor of lesser-known open source apps that are made for Linux. Applications such as Microsoft office, Outlook, Internet Explorer, Adobe Creative suite, and chat clients such as MSN messenger, do not work natively with Linux. Although with Linux you can get Microsoft office and Adobe creative suite to work using software from codeWeavers called cross Over Office. Instead of using these applications you will need to use Linux apps such as open office, The Gimp Image Editor, The ThunderBird email client, Instead of the MSN messenger you can use the GAIM messenger, and you can use Firefox as your web browser. Also with Linux it can be difficult to install software even if it is made for Linux. This is due to the fact that Linux has so many different versions. Software that is made to install on one version probably will require some configuration in order to install on another version. An example would be if you were trying to install software that was made for the KDE graphical environment, on the GNOME GUI, This app would not easily install on the GNOME GUI, and would require some configuring on your part to successfully install it. 
Hardware
The type of hard ware that Linux and windows runs on also causes them to differ. Linux will run on many different hardware platforms, from Intel and AMD chips, to computers running IBM power Pc processors. Linux will run on the slowest 386 machines to the biggest mainframes on the planet, newer versions of Windows will not run on the same amount of hardware as Linux. Linux can even be configured to run on apples, Ipod’s, or smart phones. A disadvantage of Linux is when it comes to using hardware devices such as Printers, Scanners, or Digital camera’s. Where as the driver software for these devices will often be easily available for Windows, with Linux you are for the most part left on your own to find drivers for these devices. Most Linux users will find comfort in the fact that drivers for the latest hardware are constantly being written by coders throughout the world and are usually very quickly made available.
Linux is virus free
   One of the most notable differences between the two operating software’s is Windows legendary problems with malicious code, known as Viruses and Spy ware. Viruses, Spy-ware and a general lack of security are the biggest problems facing the Windows community. Under Windows Viruses and Spy-ware have the ability to execute themselves with little or no input from the user. This makes guarding against them a constant concern for any Windows user. Windows users are forced to employ third party anti virus software to help limit the possibility of the computer being rendered useless by malicious code. Anti virus software often has the negative side effect of hogging system resources, thus slowing down your entire computer, also most anti virus software requires that you pay a subscription service, and that you constantly download updates in order to stay ahead of the intruders. With Linux on the other hand problems with viruses are practically non-existent, and in reality you do not even need virus protection for your Linux machine. One reason why Viruses and Spy-ware are not a problem for Linux is simply due to the fact that there are far fewer being made for Linux. A more important reason is that running a virus on a Linux machine is more difficult and requires a lot more input from the user. With Windows you may accidentally run and execute a virus, by opening an email attachment, or by double clicking on a file that contains malicious code. However with Linux a virus would need to run in the terminal, which requires the user to give the file execute permissions, and then open it in the terminal. And in order to cause any real damage to the system the user would have to log in as root, by typing a user name and password before running the virus. Foe example to run a virus that is embedded in an email attachment the user would have to, open the attachment, then save it, then right click the file and chose properties form the menu, in properties they can give it execute permissions, they would then be able to 

open the file in the terminal to run the virus. And even then the user would only be able to damage his or her home folder, all other users data will be left untouched, and all root system files would also remain untouched, because Linux would require a root password to make changes to these files. The only way the user can damage the whole computer would be if he or she logged in as root user by providing the root user name and password to the terminal before running the virus. Unlike Windows in Linux an executable file cannot run automatically, It needs to be given execute permissions manually this significantly improves security. In Linux the only realistic reason you would need virus protection is if you share files with Windows users, and that is to protect them not you, so you are not to accidentally pass a virus to the Windows computer that you are sharing files with. 

The above was a general over view of some differences between the Windows operating system, and Linux. To recap we started with the fact that Windows has only one vendor that releases the software, while Linux comes from millions of different coders throughout the world. We also commented on the fact that the Linux Kernel and much of the applications used with it are completely free of charge, where as with windows you are forced to pay for most of the software. Unlike Widows Linux is often lacking in professional Tech support, and Linux users are often left on their own to solve Technical issues. Linux users can either pay for Tech support or rely on the many Linux Forums and groups available on the Internet. Due to the fact that the kernel is open source, Linux has a huge advantage over Windows in configurability. You can configure Linux to run almost any way you see fit by manipulating the Kernel. Installing the Windows Operating software and applications is easier due to the fact that it has a universal installer. Also finding applications for Windows is easier because of its popularity most apps are available for Windows only, and are made easily available. Linux will run on a greater variety of hard ware than does Windows, from mainframe super computers running multiple IBM Power PC Chips, to a small laptop running an AMD processor. And of course the biggest difference in this writer’s opinion is the fact that Linux does not suffer from an onslaught of Viruses and other malicious code, unlike Windows which is plagued by countless number of malicious code that can easily destroy your system if not properly guarded against. 

In conclusion we will conclude that the Linux OS really is the superior software. Other than a few minor nuisances, linux out performs Windows in most categories. The fact that Linux is more secure is the tipping point, that tilts the scales in the favor of Linux. Windows simply suffers from far to many security vulnerabilities for it to be considered the better over all desktop environment.

A History Into Microsoft Products

Microsoft Windows is the name of several families of software operating systems by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces (GUIs). The most recent client version of Windows is Windows Vista. The current server version of Windows is Windows Server 2008. 

Windows 1.0 (1985) 

The first version of Windows provided a new software environment for developing and running applications that use bitmap displays and mouse pointing devices. Before Windows, PC users relied on the MS-DOS® method of typing commands at the C prompt (C:\). With Windows, users moved a mouse to point and click their way through tasks, such as starting applications. 

In addition, Windows users could switch among several concurrently running applications. The product included a set of desktop applications, including the MS-DOS file management program, a calendar, card file, notepad, calculator, clock, and telecommunications programs, which helped users, manage day-to-day activities. 

Windows 2.0 (1987) 

Windows 2.0 took advantage of the improved processing speed of the Intel 286 processor, expanded memory, and inter-application communication capabilities made possible through Dynamic Data Exchange (DDE). With improved graphics support, users could now overlap windows, control screen layout, and use keyboard combinations to move rapidly through Windows operations. Many developers wrote their first Windows–based applications for this release. 

Windows 3.0 (1990) 

The third major release of the Windows platform from Microsoft offered improved performance, advanced graphics with 16 colors, and full support of the more powerful Intel 386 processor. A new wave of 386 PCs helped drive the popularity of Windows 3.0, which offered a wide range of useful features and capabilities, including: 

Program Manager, File Manager, and Print Manager. 

A completely rewritten application development environment. 

An improved set of Windows icons. 

Windows NT 3.1 (1993) 

When Microsoft Windows NT® was released to manufacturing on July 27, 1993, Microsoft met an important milestone: the completion of a project begun in the late 1980s to build an advanced new operating system from scratch. 

Windows NT was the first Windows operating system to combine support for high-end, client/server business applications with the industry's leading personal productivity applications. 

Windows for Workgroups 3.11 (1993) 

A superset of Windows 3.1, Windows for Workgroups 3.11 added peer-to-peer workgroup and domain networking support. For the first time, Windows–based PCs were network-aware and became an integral part of the emerging client/server computing evolution. 

Windows for Workgroups was used in local area networks (LANs) and on standalone PCs and laptop computers. It added features of special interest to corporate users, such as centralized configuration and security, significantly improved support for Novell NetWare networks, and remote access service (RAS) 

Windows NT Workstation 3.5 (1994) 

The Windows NT Workstation 3.5 release provided the highest degree of protection yet for critical business applications and data. With support for the OpenGL graphics standard, this operating system helped power high-end applications for software development, engineering, financial analysis, scientific, and business-critical tasks. 

Windows 95 (1995) 

Windows 95 was the successor to the three existing general-purpose desktop operating systems from Microsoft—Windows 3.1, Windows for Workgroups, and MS-DOS. Windows 95 integrated a 32-bit TCP/IP (Transmission Control Protocol/Internet Protocol) stack for built-in Internet support, dial-up networking, and new Plug and Play capabilities that made it easy for users to install hardware and software. 

The 32-bit operating system also offered enhanced multimedia capabilities, more powerful features for mobile computing, and integrated networking. 

Windows NT Workstation 4.0 (1996) 

This upgrade to the Microsoft business desktop operating system brought increased ease of use and simplified management, higher network throughput, and tools for developing and managing intranets. Windows NT Workstation 4.0 included the popular Windows 95 user interface yet provided improved networking support for easier and more secure access to the Internet and corporate intranets. 

Windows 98 (1998) 

Windows 98 was the upgrade from Windows 95. Described as an operating system that "Works Better, Plays Better," Windows 98 was the first version of Windows designed specifically for consumers. 

With Windows 98, users could find information more easily on their PCs as well as the Internet. Other ease-of-use improvements included the ability to open and close applications more quickly, support for reading DVD discs, and support for universal serial bus (USB) devices 

Windows 98 Second Edition (1999) 

Windows 98 SE, as it was often abbreviated, was an incremental update to Windows 98. It offered consumers a variety of new and enhanced hardware compatibility and Internet-related features. 

Windows 98 SE helped improve users' online experience with the Internet Explorer 5.0 browser technology and Microsoft Windows NetMeeting® 3.0 conferencing software. It also included Microsoft DirectX® API 6.1, which provided improved support for Windows multimedia, and offered home networking capabilities through Internet connection sharing (ICS) 

Windows Millennium Edition (Windows Me) (2000) 

Designed for home computer users, Windows Me offered consumers numerous music, video, and home networking enhancements and reliability improvements. 

Windows Me was the last Microsoft operating system to be based on the Windows 95 code base. Microsoft announced that all future operating system products would be based on the Windows NT and Windows 2000 kernel. 

Windows 2000 Professional (2000) 

Windows 2000 added major improvements in reliability, ease of use, Internet compatibility, and support for mobile computing. 

Among other improvements, Windows 2000 Professional simplified hardware installation by adding support for a wide variety of new Plug and Play hardware, including advanced networking and wireless products, USB devices, IEEE 1394 devices, and infrared devices. 

Windows XP (2001) 

With the release of Windows XP in October 2001, Microsoft merged its two Windows operating system lines for consumers and businesses, uniting them around the Windows 2000 code base. 

With Windows XP, home users can work with and enjoy music, movies, messaging, and photos with their computer, while business users can work smarter and faster, thanks to new technical-support technology, a fresh user interface, and many other improvements that make it easier to use for a wide range of tasks 

Windows VISTA 

Windows Vista is a line of operating systems developed by Microsoft for use on personal computers, including home and business desktops, laptops, Tablet PCs, and media centers. 

Windows Vista contains many changes and new features, including an updated graphical user interface and visual style dubbed Windows Aero, improved searching features, new multimedia creation tools such as Windows DVD Maker, and redesigned networking, audio, print, and display sub-systems

Clean your keyboard-part 2

When it comes to cleaning your keyboard there are many methods that can be used, some harder and more effective than others. 

The easiest method is the Shake Method. It is so easy that you can do it right now. Pick up your keyboard, turn it over being careful not to press any keys, and shake it. See all of that stuff fall out? It is dirtier than you thought, isn't it? You can use one of the following methods to clean it further. 

The Blow Method - You can buy cans of pressurized air at the computer department or computer store which are made especially for cleaning your computer. They usually have either a hose and nozzle or a tube extending from the nozzle. Hold the keyboard up vertically (that means that end of the keyboard is up and the other end is down), aim towards the keys and press the button. Keep blowing until all of the debris is blown out. Be sure to get around and in between all of the keys. This can be done with the computer on, but it is better if it is off so that you do not have to worry about pressing the keys and coming up with a page of aaaaaaaaaaaaaaaaaaaaa's. 

The Vacuum Method - This is just like the Blow Method except that a vacuum is used instead of a can of pressurized air. It is quite simple. Just turn the vacuum on, pull out the hose, and run the nozzle over the keys. Before doing this make sure your keyboard does not have any loose pop off keys that could be sucked into the vacuum. 

The Cotton Ball Method - This can be done in addition to the above methods and in lieu of the following methods. Take a cotton ball or cloth and wet it with rubbing alcohol. It should not be so wet that the alcohol runs down into the cracks of the keyboard. Wipe the tops and sides of the keys. 

The Dishwasher Method - I hesitate to tell about this method because there is the possibility that it could fry your keyboard. When I had less experience with computers, I dunked my keyboard in a sink full of water to clean it. It did work afterwards, so I don't doubt those who say this method will not mess up your keyboard, but if it does, don't complain to me. I warned you. If your keyboard is not the standard membrane type of keyboard or if it is on a laptop, do not even think of trying this. 

This is how you do it. Unplug the keyboard and place it face down in an empty dishwasher. Do not disassemble the keyboard and do not put it in a dishwasher that has dirty dishes in it. Some say to add soap, some say not to. Run the dishwasher through a regular cycle. Take the keyboard out, shake the water out, and stand it on end until it is completely dry (this may take several days). If it does not work after doing this, it may not be dry. Let it stand another week and try it again. If it still does not work, I warned you. 

The Disassembly Method - This is the most thorough method, but it should not be done on laptop keyboards or non-standard non-membrane keyboards. 

Turn off the computer and unplug the keyboard. Turn the keyboard upside down. You may want to get two books or short boards to place the keyboard on. Position them so that they hold up the keyboard on the edges when it is turned over. This should leave the keys dangling and not touching the books or the floor. This is especially needed when the keyboard's back is off; otherwise the keys will be lifted out of their position by the floor (or whatever surface it is laying on). 

Get a screwdriver and remove all of the screws from the back of the keyboard. Lay the keyboard down on the books and carefully remove the back. 

Take everything apart and clean thoroughly. It is better to take the keys out one at a time and clean them so that you do not put them back in the wrong place. Wipe each one down with a wet cloth and then with a dry cloth. Any keys that may be hard to put back in, can be cleaned in place without removing them. Wipe around the keys as they sit in place and blow any debris out with your lungs (using compressed air or a vacuum may upset the keys). If you are really brave, you can remove all of the keys at once and give the frame a good wipe down too. 

Do a once over and make sure that you have cleaned everything. Then reassemble it all. 

Don't forget the keyboard's cable. Wrap a wet cloth around it and wipe it down. It may have an accumulation of grime that needs to be scrubbed off. Also if any of the letters on the keys have rubbed off, you can use a fine point permanent marker to draw the letter back on the key. 

Use these cleaning methods and your keyboard will last a long time and be something you can be proud of.

Clean your keyboard

       I know most of you will not need this advice, but KEYBOARDS CAN MAKE YOU SICK (how's that for tactfulness?). Germs live on your hands and fingers. When you type, many of them jump on to the keyboard. When someone else types on your keyboard, those germs transfer to their fingers. Or when you later type on the same keyboard, those germs reconquer your fingers. Regularly disinfecting the keyboard can prevent this. 

        To disinfect the keyboard, turn off the computer. Then spray disinfectant on a cloth. Be sure to use disinfectant and not just any type of cleaner because not all cleaners disinfect. Also do not spray the disinfectent directly on the keys. Spray it on the cloth. Wipe down the top and sides of the keys. Give the keys a few minutes to dry off before turning the computer back on. 

        Now that you know how to do it, you should make it a regular practice to disinfect the keyboard. It's one step towards a healthier you. 

        you have your keyboard disinfected and life is great. Then your child spills koolaide all over it. What do you do? There are certain steps that you should take when something, like pop, beer, wine, coffee, milk, or kool-aide, is spilled on the keyboard. 

        The first thing to do is immediately unplug the keyboard from the back of the computer and turn the keyboard over so that its keys are down. This will allow the liquid to drain out. You will probably want to put a cloth under the keyboard or at least make sure that the surface you have put it on is washable. 

        Then use the mouse to shut down Windows and turn off the computer (this is important because later you will have to plug the keyboard back into the computer and you should never plug any device into a computer while it is on). 

        While the keyboard is upside down use a cloth to dry as much of the liquid off as you can. If you have a can of compressed air or a vacuum, while the keyboard is upside down blow or vacuum it out. Then let the keyboard set upside down for at least a night so that it can adequately dry out. 

        Liquid spilled on a laptop keyboard can easily reach the hard drive, so turn it over immediately and leave it in that position until it dries. 

        Keyboards are quite resilient and so it should work when you turn it on again. But if not, another attribute of keyboards is that they are cheap and so it won't cost too much to buy another one. 

        With these pointers in mind and a quick reaction, you just may save your keyboard from total destruction the next time it gets coated with coffee.

How to make an LED work

An LED (Light Emitting Diode) is a semiconductor that emits light energy when a current flows through it. Current will only flow one direction, just like a regular diode. There are a few things you need to know about an LED before you use one. First, and most importantly, is that an LED has very low internal resistance. This means that left to itself, an LED will pass so much current that it will burn up. They require an external resistor to limit the current.

Most LED's have a current rating, which determines the size of the resistor you will need. The current rating tells you what the maximum allowable current for the part is. In general, the higher the current, the brighter the LED.

Most LED's seem to handle at least 15mA. If you are using a 5 volt circuit, then Ohms law tells you what resistor value to use. R = V / I, so R = 5v / .015A = 333 ohms.

BJT configurations

BJT Configurations

There are plenty of texts around on basic electronics, so this is a very brief look at the three basic ways in which a bipolar junction transistor (BJT) can be used. In each case, one terminal is common to both the input and output signal. All the circuits shown here are without bias circuits and power supplies for clarity.

Common Emitter Configuration

Here the emitter terminal is common to both the input and output signal. The arrangement is the same for a PNP transistor. Used in this way the transistor has the advantages of a medium input impedance, medium output impedance, high voltage gain and high current gain.

Common Base Configuration

Here the base is the common terminal. Used frequently for RF applications, this stage has the following properties. Low input impedance, high output impedance, unity (or less) current gain and high voltage gain.

Common Collector Configuration

This last configuration is also more commonly  known as the emitter follower. This is because the input signal applied at the base is "followed" quite closely at the emitter with a voltage gain close to unity. The properties are a high input impedance, a very low output impedance, a unity (or less) voltage gain and a high current gain. This circuit is also used extensively as a "buffer" converting impedances or for feeding or driving long cables or low impedance loads.

A note about Phase Shifts

In both the the common base and emitter follower configurations, the input and output signals are in phase, but with the common emitter configuration only, the input and output signals are phase inverted, a positive input resulting in a negative output and vice versa. This is also known as  phase displacement.bbjt

Estimating Transmitter Distance

Here is a much simplified equation for analysing low power radio transmitters, for line of sight. It does not take into account probagation conditions or other limiting factors, but does include a variable for the losses in the antenna and tank circuit of a transmitter. It may be applied to low power transmitter circuits such as the circuits on this site. In deriving this equation, I have had to estimate two unknowns, the loss and inefficiency of a telescopic whip antenna, and the small signal high frequency collector current of the transistor in this circuit. Here is an example circuit:



The general equation for estimating transmitter field strength is calculated from the equation below:



Where d is distance in meters, E is the field strength in V/m and Pt is the total power from the transmitter. By finding your radio receivers field strength,(usually in the manual) then the equation can be transposed to solve distance:



The next step is to work out the power from the transmitter. The 2 stage circuit above works from a 9 volt battery, its output frequency was measured to be 107.2MHz. The final common emitter stage of this circuit, develops power in the tank circuit, which is transferred to the antenna, in this case a 30cm telescopic whip. Most of the power is developed in the coil, there are three ways to calculate this:



At resonance the voltage and current in the oscillator tank circuit will be in phase. Therefore all that is needed is to find the impedance of the tank circuit and either the voltage across it or the current flowing through it. The problem in measuring the ac voltage across the tank circuit is that most meters will not give accurate results at high frequencies. This is the same for high frequency currents. To estimate the ac collector current in the tank circuit, I have worked out the dc collector current. The two values will be slightly different, but as this is only an approximation, the error will not be significant. To find the dc collector current, measure the dc voltage across the emitter resistor and use ohm's law. In my circuit, this measured 2.99V across the 470 ohm emitter resistor, the dc collector current is therefore :

2.99 / 470 = 6.362mA

This value will be substituted for the ac collector current. The impedance of the tank circuit at resonance is given by the following equation: =100K

The R is the dc resistance of the coil in the tank circuit. At VHF, this is small as coils have only a few turns. In this circuit the dc resistance was measured at 0.1 ohm.

Small signal Analysis:
The equivalent output circuit for the transmitter is now worked out and drawn as below. The impedance of the tank circuit (100K) is in parallel with the output impedance of the transistor. This value, around 40k can generally be ignored, but in this case it is in parallel with the output circuit and makes an appreciable difference. Also the 3.3pf capacitor is in series with the 470 ohm resistor. This is also considered at short circuit as the power supply is decoupled with a capacitor. The capacitive reactance of the 22nF capacitor is a short circuit. The effective load or impedance of the output will be as below:



The overall output circuit is the parallel combination of these components. The 3.3p capacitor has an impedance of around 450 ohms at 107.2 MHz. The combined impedance is therefore:-
40k // 100k // (450+470) = 891.3 ohms

Having now found the impedance, the approximate power in the tank circuit can be calculated:-



Having now found a value for total transmitter power,Pt and using a radio receiver with a known sensitivity of 20uV/meter the distance the signal would be received is worked out:



This equation assumes that all the power in the tank circuit, 36mW is transferred without loss to the antenna and that the antenna has a gain of unity. The result also assumes there are no losses incurred from transmitter to receiver due to probagation effects as well. Using a 30 cm length of telescopic antenna , I have modified the equation to compensate for losses in the antenna and coupling circuit . I have assisgned a variable called A_L into the equation and estimated its value at 1%. The modified equation is then:



The new result calculates effective distance from transmitter to a radio receiver with 20uV/m sensitivity. This is clearly a vast reduction in distance from the first result. To test this result, i went to a large field. Holding the transmitter at roughly 1 meter high from the ground, i walked away carrying the receiver. The signal was clearly audible 300 meters from the transmitter giving a strong reading on the signal strength meter of the receiver. This was about the length of the field. I must stress again that the above calculations are ONLY approximate, but if anyone repeats this experiment, i would like to hear from you.