Five different lawsuits, from owners of Apple, Dell and HP laptops have combined their lawsuits against NVIDIA over defective GPUs that were shipped in possibly millions of computers.

In some cases, OEMs have modified the BIOS in an attempt to keep the GPUs from overheating, but the change reduces battery life and performance.

The internet is a pretty scary place, or it can be if you don't have the right protection. Viruses, spam, pop ups, phishers, scammers, intruders, spywarethe list goes on and on. So, one thing is for sure - don't surf without the right amount of protection. You want something that gives you peace of mind and works. It's these things that the Yoggie Pico Security Appliance claims to provide. In this review, we'll discuss how well this unit actually provided protection.

The ASUS K50IJ series is one of the latest budget notebooks designed to provide better performance than a netbook and a larger screen for only a modest price increase. Every laptop manufacturer on the market offers a multimedia family PC with a 15-inch screen because these laptops make excellent desktop replacements. The real question is, does the ASUS K50IJ offer enough performance and features at its bargain price of $699? Keep reading to find out.

As promised, MSI has kicked off the new year with some hot new releases, and among them, the MSi Wind U115 hybird laptop Touted as the "world's first hybrid storage netbook" the Wind U115 laptop is capable of operating both SSD and HDD drives simultaneously, delivering the best of both worlds in one cool, compact laptop. The Wind U115 laptop is powered by the new Intel Menlow Platform with an Atom Processor, and comes with up to 2GB DDR2 memory, and a 120 or 160GB HDD complemented by an 8 or 16GB SSD. The advantages of SSD include low power consumption, shock resistance and faster speeds, while the HDD comes in handy for mass storage. The Wind U115 hybrid laptop sports a 10-inch 1,024-by-600-pixel LCD display, and a large keyboard and touchpad for easy use. Added features include a 1.3- or 2-megapixel webcam, built-in high-performance two-channel stereo speakers and microphone, and 802.11b / g / n Wireless LAN with Bluetooth. MSI

Good things come in three’s, and such is the case with Lenovo's latest release, the Lenovo IdeaPad Y650, Y550 and Y450 laptops. Starting with the IdeaPad Y650 laptop (pictured), this desktop replacement laptop measures in at 16 inches and sports an Intel Core Duo processor (6MB cache), a N1M-GE1/256MB graphics chip from Nvidia, 4GB DDR3, up to 500GB of storage, and optional Blu-ray. The IdeaPad Y650 laptop starts from $1,199.

The IdeaPad Y550 laptop and IdeaPad Y450 laptop are the mini equivalent to the Y650, measuring in at 15.4 and 14 inches respectively. Under the hood these laptops sport Nvidia NB10P-GE1 GPU, and taking a cue from their Y650 big brother, they sport many of the same design features including 4GB DDR3 and up to 500GB storage. The IdeaPad Y550 and Y450 laptops start from $829. Lenovo

Well, it looks like Apple has done it again, expanding its success with the latest and greatest Apple MacBook pro laptop. The 17-inch MacBook Pro is being called the thinnest and lightest 17-incher, and though light, it’s certainly heavy on cool features. The new MacBook Pro laptop sports a powerful 2.66GHz Intel Core 2 Duo processor (6MB L2 cache), Nvidia GeForce 9400M, Nvidia GeForce 9600M GT / 512MB, 4GB 1066MHz DDR3 memory, a 320GB HDD, and a slot-loading Super-Drive. All this and more comes wrapped in a durable and beautiful precision aluminum unibody chassis, with an innovative new built-in battery for up to eight hours of operation and up to 1,000 recharges – which is more than thrice the lifespan of the standard laptop battery, for those who are counting. The 17-inch MacBook Pro laptop will start at a price of $2,799. Apple.

DELL

Dell is kicking 2009 off right by wrapping smart style, solid performance and value-packed pricing into its latest release, the new Dell inspiron 1.5 laptop . Currently available in select configurations at Best Buy, and set to hit Dell online later this month, the Inspiron 15 laptop is replete with customizable features and options aplenty, so the laptop truly is made for you. “Building on the Inspiron platform of mainstream solutions, Inspiron 15 expands laptop personalization through attractive design, an array of optional features and an affordable price,” says Glen Robson, General Manager of consumer notebooks. “By listening to customers we’ve created an ideal multi-purpose system with a range of choices that help them create a custom match for their specific needs and deeds.” The Inspiron 15 laptop features a 15.6-inch LCD display with 16:9 aspect ratio, up to 4GB memory and up to 320GB storage. Options include a choice of Intel Core 2 Duo processors, a built-in webcam, Blu-ray, Bluetooth and facial recognition software. The Inspiron 15 laptop starts from $600. Dell

layer f the thought of a Nissan X-Trail sets your heart aflutter, the NEC lavie G type JX-Trail laptop is the one for you. Inspired by the popular rugged Japanese SUV, the Lavie G Type J X-Trail laptop features an exterior clad in the same fire-engine-red colored panels that grace the vehicle, a waterproof nylon case fashioned from the same material as the Nissan X-Trail’s seats, and it’s dotted with X-Trail logos. The 12.1-inch laptop features a U7500 Core 2 Duo, Vista Home Premium, and a dual-burner. This limited-edition laptop retails for approximately $2,115. NEC

In my continuous effort to educate you in buying only as much laptop as you really need, I'd like to start with the cheap laptop buy series. Dell cheap laptops would be my first choice. Consider the low-end one of Dell's most recent additions... Inspiron 1300 would be an ideal laptop choice for basic computing needs. Let me explain why...

First, please note that I suggest you buy 1300's version with the Intel Pentium M Processor 745 that starts from $649, as of May 2006. The intention is to stay within $649 as this standard setup has everything you need to perform your every day basic computing tasks like sending emails, Internet browsing, may be doing some Excel spreadsheets or Word processing, some amateur photo editing or website developing. Here's how you should choose your options...

Windows XP Home Edition or Professional?
It comes with Genuine Windows XP Home Edition, perfect for the home office laptop. You would only need Genuine Windows XP Professional if you're planning to use your PC as a Web server or a Database server. But you most certainly won't use your laptop as server. You'll definitely need the Operating System Re-Installation CD, so order that one for $10.

Selecting laptop processor
Intel Pentium M Processor 745 (1.80GHz/2MB Cache/400MHz FSB) comes standard for the price above. This gives you plenty of speed, more that you ever need. The speed of 1.80GHz on Pentium M Processor is equivalent to about 2.7GHz on just Pentium Processor. The 2MB Cache is a huge cache size to perform all your Word processing with ease.

Display Size
The 15.4in WXGA Display is included in Price. Perfect. The most common screen size these days. The 17" screen would have added some unnecessary weight to your laptop, and the 14" is too small.

How much Memory do you need in laptop?
256MB DDR2 SDRAM 1 Dimm is included in price. Plenty. Are you tempted to upgrade to 512MB for an additional $50? Why? Just because it's offered? Are you planning to play games or do some video editing? No... Then no need more than 256MB memory. When you fill like your laptop is locking performance then you'll upgrade your memory. 1 Dimm means that there's a second memory slot empty so you can purchase an additional 256MB or two 512MB to upgrade up to 1GB.

Choosing hard drive size
40GB 5400rpm Hard Drive is included in price. Again, if you aren't going to store games or MP3 music file on your laptop, 40GB is already way too much. With games and MP3, you'll fill it quickly though. And by the way, you're not supposed to store backup files on your main laptop hard drive. So stick with 40GB. I only use mine to 30%.

CD/DVD Burner
Here's one case where upgrading to 8x CD/DVD burner (DVD+/-RW) with double-layer DVD+R write capability would be a good idea. If you'd like to create multiple copies of the wedding you'll be able to. So, now we get it up to $719. Still very inexpensive for a great basic laptop.

Video Graphics Card
With this setup you don't get one. Instead you get the standard graphics chip for Pentium M laptop - Integrated Intel Media Accelerator 900 Graphics chip. And it's all you want for your basic laptop computer that you aren't buying for heavy-duty graphics or video editing or gaming. You can still play some not graphics intense video games on this chip.

Laptop battery
The standard option is 4-cell Lithium Ion Primary Battery (29 WHr). This will provide you with up to 2 hours of battery life. This is enough to watch one movie. Not as great but is good enough for many people.

Wireless Networking Card
Intel PRO 2200 Internal Wireless (802.11 b/g, 54Mbps) miniPCI Card is included in price. This card is just fine. 54Mbps is the most common transfer speed on wireless networks today, and the 802.11 b/g are the two most common wireless protocols supported today. You'll be able to connect at any WiFi spot or to your home wireless router.

That's it. We're done with buying Dell Inspiron 1300 laptop for $719. Go with the standard setup for the rest of the options and with the standard 1-year warranty plan. I tend not to buy laptop warranty in access of 1 year. From my experience with laptops, most hardware problems show up within one year from purchase.

With Dell Inspiron 1300 laptop, you'll be online and browsing the Web within minutes. It'll connect to your wireless router automatically. I recommend that you purchase it along with laptop, for best hardware comparability.

Computer Peripherals

Computer peripherals are any electronic devices that can be hooked up to a computer other than the standard input-output devices (monitor, keyboard,mouse). Peripheral devices include speakers, microphones, printers, scanners, digital cameras, plotters, and modems. Peripherals often require special software packages called "drivers". These drivers are usually included with the peripheral at purchase time.

The CD-ROM Drive

This modern miracle gained prominence in the late 1980's and has become the primary distribution medium for software to consumers. The Compact Disk-Read Only Memory (CD-ROM) disk itself is a collection of concentric circles containing millions of pits and plateaus which correspond to on/off bits of data. The disk is read with an optical laser similar to the one used to scan your groceries at the supermarket. Most disks of this kind are "Read Only" meaning that the computer can retrieve information from the disk, but cannot place information on it. New developments have improved this technology to allow writing and rewriting data to the disk. A different kind of hardware mechanism is needed to employ this innovation.

The Floppy Diskette Drive

Once the most advanced of storage devices, floppy diskettes are normally used a temporary storage containers or transportation media for data. A standard floppy diskette can hold 1.44 MB of computer data. This amounts to a rather large number of pages if translated to the paper standard for textual information. Computer diskettes are not as reliable or fast as the internal storage drives on the computer. They are also the primary vector of virus infection in the computer world.

The Mouse

Named for the resemblance of the wire coming out of it and a mouse's tail, the mouse was introduced to computing in the early 1980's when Macintosh created its graphical user interface (GUI). The mouse is another input device used to point at objects on the computer monitor and select them. Using the mouse and keyboard in combination allows the computer user substantial latitude in how to accomplish a wide variety of tasks.

The Keyboard

The Keyboard is the primary input device used to communicate with the computer. A computer keyboard closely resembles a conventional typewriter keyboard with the addition of numerous keys that are used specifically for computing functions.

The Monitor

The Computer Monitor is the computer user's window into the workings of the computer. It consists of a television picture tube that had been modified to accept the type of video signal created by the computer's electronics. Conventional televisions can be used as computer monitors if a tranlation device is used to connect them. The picture quality leaves something to be desired.

The Actual Computer

Your "computer" is a collection of devices that function as a unit. The most basic collection includes a Computer CPU, a Monitor, a Keyboard, and a Mouse. The Computer CPU is normally a rectangular box that sits on your desktop (called a "Desktop Case") or next to your knee under the desk (called a "Tower Case"). The computer's CPU is actually a small electronic device inside the case but the term is often used to refer to the whole collection of electronics inside the box.

Computer Components

Computers come in all types and sizes. There are primarily two main sizes of computers. They are:

• Portable
• Desktop

The portable computer comes in various sizes and are referred to as laptops, notebooks, and hand-held computers. These generally denote different sizes, the laptop being the largest, and the hand-held is the smallest size. This document will mainly talk about the desktop computer although portable computer issues are also discussed in various areas.

Computer Components:

Computers are made of the following basic components:

1. Case with hardware inside:
   
   
   1. Power Supply - The power supply comes with the case, but this component is mentioned separately since there are various types of power supplies. The one you should get depends on the requirements of your system. This will be discussed in more detail later
      
      
   2. Motherboard - This is where the core components of your computer reside which are listed below. Also the support cards for video, sound, networking and more are mounted into this board.
      
      
      1. Microprocessor - This is the brain of your computer. It performs commands and instructions and controls the operation of the computer.
      2. Memory - The RAM in your system is mounted on the motherboard. This is memory that must be powered on to retain its contents.
      3. Drive controllers - The drive controllers control the interface of your system to your hard drives. The controllers let your hard drives work by controlling their operation. On most systems, they are included on the motherboard, however you may add additional controllers for faster or other types of drives.
      
      
   3. Hard disk drive(s) - This is where your files are permanently stored on your computer. Also, normally, your operating system is installed here.
      
      
   4. CD-ROM drive(s) - This is normally a read only drive where files are permanently stored. There are now read/write CD-ROM drives that use special software to allow users to read from and write to these drives.
      
      
   5. Floppy drive(s) - A floppy is a small disk storage device that today typically has about 1.4 Megabytes of memory capacity.
      
      
   6. Other possible file storage devices include DVD devices, Tape backup devices, and some others.
   
   
2. Monitor - This device which operates like a TV set lets the user see how the computer is responding to their commands.
   
   
3. Keyboard - This is where the user enters text commands into the computer.
   
   
4. Mouse - A point and click interface for entering commands which works well in graphical environments.

These various parts will be discussed in the following sections.

The parts of your computer

Computers are made up of many parts. These different parts perform one or more functions including input, output, processing, or storage.

OUTPUT DEVICES

Output devices send information from your computer to you. This information is usually in the form of sound and sight, but some devices can send information as touch and even as smell! Some common output devices are monitors, printers, and speakers.

INPUT DEVICES

Input devices are the parts that let you enter and manipulate information on a computer. These devices range from the standard keyboard and mouse, to scanners, microphones, joysticks, and light pens.

There are some devices that can input and output. Some examples would touch screen monitors (input by touch, output by sight) and force feedback joysticks.

ON THE INSIDE

The inside of your computer has many parts that all work together. These parts are generally found within your computer case - this is usually the big "box" that probably sits under your desk or below your monitor. If you're using an iMac, many of the computer parts are built into the monitor case.

The motherboard [shown at right], or mainboard, is the backbone of the computer. All the individual pieces connect to the motherboard in some way. The motherboard is home the processor chip, pci slots, and memory.

Processor - This is the chip that does the "thinking" of the computer. These are the "Pentium" and "AMD" chips you hear about. Processor speed is measured in MegaHertz(Mhz) and GigaHertz(Ghz). 1 Ghz = 1000 Mhz

Memory - This is where information is temporarily stored for the processor to use and manipulate before storing on the HARD DRIVE. Also known as RAM (Random access memory). Information is stored in memory only when the computer is turned on. Ram is measured in Megabytes(Mb), which is storage capacity, not to be confused with MegaHertz, which is speed.

PCI Slot - These are outlets in the motherboard that allow you to install extra components like sound cards, modems, video cards, and other devices. The images below show different PCI card components.

Hard Drive - This is the part of your computer where information is stored for later retrieval. All the information you access on your computer, all your documents, pictures, email messages, and programs are here. Unlike memory, the hard drive stores information even after the power is turned off. The image to the right shows the inside of a hard drive.

Floppy Drive - This is the slot in the front of your computer where you insert a disk to store data and move it to another computer. If your computer is an iMac, you will not have a Floppy Drive. Floppy disks are 3¼ inches in size, and hold 1.44Mb of data. The images below show a floppy drive, and some floppy disks.

CD ROM or DVD ROM Drives - This plays your music and data cd's, or if you have a DVD drive, it will also play DVD movies. Data CD's hold up to 700Mb of information. If you have a CD-R or CD-RW drive, you can store your own information on CDs.

• Complete Computer Builds

  Customer specified system builds. Complete ground up builds and configurations. Call for more information.

  $ 15.00 / Each hour of service

  + the cost of computer parts and components.

• Hardware Upgrades and Installation

  Complete installs of new or additional hardware, including adaptor seating, setting jumpers, and driver configuration.

  $ 12.00 / Each hour of service

  + the cost of computer parts and components.

• Printer Set-Up, and or Configuration

  New printer installation, including connection of proper cables, driver installs, and software configuration.

  $ 15.00 / Each hour of service

• Networking Configuration

  Home networking solutions, such as Peer-to-Peer networking set-up, and Internet configuration and troubleshooting. All types of internet services are covered, Dial-Up, Wireless, High-Speed, and Cable Modem. Call for more information.

  $ 12.00 / Each hour of service.

• PC Operating System ( Windows, Linux ) Installation

  This service is for novice PC users. I walk the end user through the process, and configure the install to the users request.

  $ 12.00 / Each hour of service.

• PC System Tune-Up

  Service includes all of the following:

  Clean-up hard disk

  Defragment main drive

  Check registry for conflicts

  Check and up-date drivers

  Add new service packs ( If applicable )

  Update anti-virus software

  Dust inside of PC with canned air

  Check seating of adaptor cards

  Manage and organize computer connection cables

  Test and replenish printer ( If applicable )

  $ 15.00 / Each hour of Service

We are a new experimental brand, designed to provide an On-Line Ordering service for Computer parts and components.

As this service is in its trial period, there are a couple of restrictions:

Firstly , you will only be able to buy items via the Paypal System, if it is successful you will be able to pay via Debit/Credit Card at a later stage.

Secondly, we regret that you will not be able to purchase items 'over the counter' at present. This is so we don't have too much in stock, therefore increasing our over-heads, and cost to you - our Customer. However, if we don't have listed the item you require, let us know, and we can order it for you!

Enjoy browsing Alanath: Dartford On-Line Distribution, and we look forward to receiving your orders!

Building your own PC? Need computer parts? Ambassador Computers stocks most of the basic parts and supplies you need to keep your desktop or laptop PC going:

• Mother Boards
• Cooling & Case Fans
• Power Supplies
• CD/DVD Drives

• Hard Drives
• Memory
• Cases
• Modems
• Routers
• Switches
• Sound Cards
• Graphics Cards
• NIC Cards
• Cables

Ambassador Computers strives to be your complete source for computer parts and supplies. If you don’t see what you need, contact us and if we don’t have it in stock we can order for you. Need it fast? We can expedite your special order 2nd day or overnight.

CPU – Most of the mathematical manipulations that make computers operate are done by the CPU. Other components like high performance graphic cards, may also have their own processors, but their results still have to be passed through the CPU. The speed of the computer is usually measured by the speed of the CPU. Even though other factors also affect overall speed, the CPU rating is generally seen as the single most important measure of performance. For instance, 3-D computer games would run better on a computer with a higher CPU rating than a computer used mostly for office applications that have a lower CPU rating. CPU in most computers today, are usually rated between 2.0 GHz and 3.0 GHz allowing for a wider range of computer programs from computer games to movies. This measurement refer to the number of calculations the processor can make in 1 second. The higher the number, the faster (better) the computer. CPUs generate a lot of heat doing this work, so they need a heat sink and fan attached to them

The motherboard is like the engine of an automobile. It provides support for the internal components and also passes information between the computer parts. Just like an engine in a car which interacts with the spark plugs, pistons and fuel, the motherboard is the block that the other components plug into. If the motherboard is the engine, and like most modern cars today there is a brain. On a computer you could say the CPU is the brain.

COMPUTER PART

Find computer parts, you can see some interesting places. If you are lucky, you can simply take the phone calls and payment to someone who already has the legs, but not if you have, do it yourself.

You do not just love the Legislature, Do-it-yourself. Purchase of old computers is a way of the computer you need parts, but there is no guarantee that the part you are looking for is in the best condition, or that is not obsolete. For contempt of an injury of the party can not be, although sometimes you find a computer in good condition, a great source for computer entertainment.

Combs of the economy is another way to find computer parts. Much of the computer models older but in good condition.

What is really old depends on what you want. If you are in a state of the art devices such parties will not be for you all. How strange, because as it may seem, if you have a Saturday afternoon to lead you to be surprised, like many people who are simply sitting in the control of after all that you do Lookingfor parties.

But this is the sweater of your own talk Bootstrap .. Your company is used, and you need a reliable computer parts to the source, and is being, and you must configure your computer for parts reliably.

TCP/IP
One very important set of protocols is called TCP/IP. It is important because it is what the creators of the Internet decided would be used for that particular network, which means that any computer that wants to connect to the Internet must also use TCP/IP. TCP/IP stands for Transmission Control Protocol / Internet Protocol.
TCP/IP is actually in two parts. The TCP portion covers the agreements between systems about how they will carry on their ‘conversation’, and the IP portion deals with addressing the packets and routing them.
The TCP part all happens in the background and we don’t really need to concern ourselves with it under normal circumstances. However, in a network that uses TCP/IP, every system must have a unique IP address, and that is something that requires human intervention in one way or another.

IP Addresses
An IP address is made up of four sets of numbers separated by periods. An example is:
192.168.42.122
Each of these sets of numbers is called an octet, because they started out as 8-digit binary numbers. By changing them into 3-digit decimal numbers, the whole address is shorter and easier to remember. The highest value for any octet is 255, because the highest number you can make with eight binary digits is equal to 255 in decimal.
In most networks, the first three octets are the same for all systems, and the last octet is different for every machine. If there are more than 255 computers in a network, it is usually divided into smaller subnets.
Static or Dynamic?
There are two ways to associate a unique IP address to a specific computer. One way is for the administrator to assign a number, which stays the same unless somebody decides to change it some day. That number is then a static IP address.
The other way is to assign a group of addresses to a server, and let the server hand them out as needed to any system that wants to communicate on the network. This produces a dynamic IP address. It is sometimes important to know which method is in use on a network, because with dynamic addressing, the IP address of a machine may be different each time you try to communicate with it.
Computer Names
The example address 192.168.42.122 is only one digit longer than a phone number with area code, but that’s plenty long enough to give most of us a hard time. It’s much easier for people to remember a name instead of a number, and for this reason computers in a network are also given a unique name. It may be something mundane like Sales14, but at least it’s a name and not a number.
This is not only easier to remember, but it solves the problem of a dynamic address that changes all the time, because the computer name doesn’t normally change. It does create another problem though, because the computers use only the addresses and not the names to keep track of each other. Fortunately there is a part of the TCP/IP protocol called address resolution, and it matches up the names and addresses so things keep rolling smoothly along.
Security
The problem with connecting computers to the Internet is that they are then sharing a network with many other computers from all over the world, and the users of some of those other computers are not such nice folks. Protecting the network and the information on it is one of the most important parts of a network administrator’s job.
Encryption
One way to protect information is to scramble it so that it appears to be gibberish unless someone has the right ‘key’ to unscramble it. Scrambling it is called encryption, and unscrambling it is called decryption. There are many ways to encrypt information, and of course just as many keys to decrypt it.
Encrypting and decrypting information slows things down a bit, so a decision must be made about when to use it. For packets going around the LAN, it depends on how likely it is that someone will gain unauthorized access to the LAN, called hacking. It also depends on how much damage would be done if that happened. If the threat is severe, encryption can be done not only on the transmitted packets but also to information stored on the disk drive.
For information going over the Internet, encryption is much more important unless it’s all right for the whole world to see the information. If you send your credit card number to a vendor, you must trust that vendor to encrypt and safeguard the information.
Virus Software
A computer virus is a little program that makes copies of itself to send to other computers. It’s very similar in some ways to contagious germs spreading a disease from one person to the next. And like diseases, some of these computer viruses have some really nasty side effects, like wiping out important files in the operating system or filling up the hard drive with garbage data.
As we will discuss a little later, there are ways to keep these virus programs from getting to your computer, but they are not foolproof. A lot of viruses come in attached to e-mail, and then they will mail copies of themselves to everyone in your e-mail address folder. You can’t completely block them without blocking e-mail, and most of us like to get e-mail from our friends and coworkers.
The most important prevention for viruses is to have a good anti-virus program installed on your computer. Norton, McCaffey and Panda are probably the most popular. The next most important thing is to keep the anti-virus software up-to-date, because the delinquents who write virus software are always coming up with new tricks, and the anti-virus companies are just as quickly coming up with new versions to stop them.
Access Control
If you have ever had a computer that was connected to a local area network, you almost certainly had to type in a user name and password to get network access. It’s two forms of ID, just like when you cash a check at department store.
The network administrator used that identification information to determine what you could and couldn’t do on the network. And there may have been additional passwords to access the company’ customer database, employee payroll records, or files stored on someone else’s computer.
Here are a few tips about passwords:
First, if you share files on your computer, use password protection for them even if they are available to everyone in the network. That way they can’t be tampered with if a hacker breaks in.
In choosing a password, never use your name, your birthday or other obvious personal information. The best is a random combination of letters and numbers.
Commit the password to memory, and if you must write it down, hide it. A password written on a post-it note stuck to your monitor is probably worse than no password at all.
Don’t give your password to someone you don’t know personally just because they claim to be tech support, the phone company, the police or your long-lost Aunt Matilda. Refer them to the network administrator, or better yet, get their phone number and have the network administrator call them back.
Firewalls
In a building, a firewall is a wall to keep fire from spreading from one area to another. In a computer network, a firewall is a boundary that can block unwanted data packets. The firewall may be program running on the server or router, or it may be a separate piece of hardware or even a complete computer system just for that purpose. In any case, its purpose is to look at all of the packets coming through, and decide which ones can pass and which ones get blocked.
Ports – Several pages ago, we defined a port as the place in a hub that a cable plugs into. There is another completely different kind of thing called a port, and that is a location in a computer’s memory that is used by a device or application to send and receive data. Each application will have one (or more) of these locations for its own use.
For instance, there is a common e-mail program that has port # 110, which means that the program exchanges information with the rest of the system at memory location 110. The popular game called Doom uses port # 666.
When a packet is sent over a network, it will contain not only the destination address, but also the port number of the application that will use it at that destination. One of the ways a firewall controls the packets is by looking at the port number, and only passing packets with ports that are appropriate for the destination. If nobody should be playing Doom on the network’s computers, then it would make sense to block port 666.
Another way a firewall can control traffic is to look at the source of the packet. It can have a ‘prohibited’ list that keeps out packets from certain IP addresses, or it can have an ‘allowed’ list and block everyone who isn’t on it. Ports can be done the same way, with a ‘prohibited’ or ‘allowed’ list of ports.
Conclusion
There is much more to know about security, and about networks in general, if one is to be involved in managing them. The purpose of this paper is to present just enough information to enable you talk with network administrators and to understand their concerns when presenting network products to them. For additional training in this subject, we recommend the Micro2000 A+ and Network+ courses.

There is also no rule that says a server must serve the entire network. It is usually convenient to have a separate network server for each subnet. There are other divisions that can occur even within a subnet. Computers that need to share the same resources can be organized into workgroups. With the Windows NT operating system, the LAN can be divided into sections called domains, and each domain needs its own server called a domain controller.
Protocols
A protocol is an agreed-upon standard for how something will be done. When your mother taught you to chew with your mouth closed and keep your elbows off the table, that was a protocol for proper dining. Computer protocols are the rules for connecting with other computers and exchanging information with them.
Ethernet is a protocol. Earlier we called it a technology, but it is also a set of rules for how that technology is used. If each piece of hardware and software complies with the rules, then information can be correctly transferred from one from one system to another in a LAN.
There are many protocols used in networking. There are some protocols that are used together with other protocols, where each one takes care of different aspects of networking. Sometimes two protocols do the same thing in different ways, and it is necessary to choose one or the other. The important thing is that both systems trying to communicate with each other have matching protocols that they can use.

One place where routers are used in a big way is the Internet. If you send a message on the Internet, it might go through many routers before it reaches its destination. And when you surf to a website, all of the graphics and text showing up on your screen had to go through routers to find their way from the web site to your computer.
By the way, every LAN that connects to the Internet becomes a subnet of the Internet, even if it has its own internal subnets.
Clients and Servers
In addition to the various ways networked systems can be physically connected, there are two basic ways that network activities can be arranged. In one, all of the computers have equal status. This is called peer-to-peer, because a peer means someone (or something) that is the equal of another. Peer-to-peer is used mostly in very small networks of less than a dozen systems.
The more common arrangement is called client-server. One system, called the server, is responsible for a particular activity or resource. The other systems are called clients, and they go through the server when they want to use the function or resource that the server is responsible for.
Some of the things servers are commonly used for include network administration, e-mail, printers, file storage, and Internet access. Often several of these functions will be combined into one machine. There is no rule that says a network server and a print server can’t be the same system.

To create larger networks, hubs can use one or more of their connections to connect to other hubs. This is called a star network, but as far as the electrical signals are concerned, they go from one computer to every other computer, no different than the bus network.







When networks get really big, with 100s of systems or more, it’s no longer such a good idea to have each computer look at every packet, because almost none of the packets will be for that computer. The large network can be broken up into smaller groups called subnets, and these are connected with a device called a data switch, or just a switch.
Within each subnet, all of the computers still see every packet, and so does the switch. Normally the switch won’t pass those packets on to the other subnets, but if the packet has an address for a destination in another subnet, the switch will pass the packet to the port for that subnet. All of the systems in that subnet will then see the packet, including the system it is actually addressed to. In order to know where to send a packet, the switch must have a table of addresses for each subnet.

Bus Network
A bus network is the simplest to explain and draw, but it’s not often the simplest one to use, especially if computers are distributed around various offices in a building, and then get added, taken away, moved around and so forth.
A much more practical way to connect more than a couple of systems is to connect each one to a device called a hub. Each system has a cable that goes from it to the hub, and inside the hub an electrical connection is made between all of the cables. Each place where a cable plugs into the hub is called a port.

Packet diagram
Then, each computer looks at the address on each packet that comes by on the network cable, and copies the ones that have the right address. The computer that sent the packet is called the source, and the one that is supposed to receive it is called the destination.
Network Connections
When a packet comes out of the computer that originated it, that packet must have a complete electrical path to every other computer. The simplest way to do this is to have a cable that goes from one computer to the next until it has connected to each one. This is called a bus network.