An optical mouse uses a light-emitting diode and photodiodes to detect movement relative to the underlying surface, unlike wheeled mice which use a set of one rolling ball and two chopper wheels for motion detection.

Early optical Mice

Early optical mice, first demonstrated by two independent inventors in 1980, came in two different varieties:

Some, such as those invented by Steve Kirsch of MIT and Mouse Systems Corporation, used an infrared LED and a four-quadrant infrared sensor to detect grid lines printed with infrared absorbing ink on a special metallic surface. Predictive algorithms in the CPU of the mouse calculated the speed and direction over the grid.

Others, invented by Richard F. Lyon and sold by Xerox, used a 16-pixel visible-light image sensor with integrated motion detection on the same chip and tracked the motion of light dots in a dark field of a printed paper or similar mouse pad.

These two mouse types had very different behaviors, as the Kirsch mouse used an x-y coordinate system embedded in the pad, and would not work correctly when the pad was rotated, while the Lyon mouse used the x-y coordinate system of the mouse body, as mechanical mice do.
Modern Optical Mice

Modern surface-independent optical mice work by using an optoelectronic sensor (essentially, a tiny low-resolution video camera) to take successive images of the surface on which the mouse operates. As computing power grew cheaper, it became possible to embed more powerful special-purpose image-processing chips in the mouse itself. This advance enabled the mouse to detect relative motion on a wide variety of surfaces, translating the movement of the mouse into the movement of the cursor and eliminating the need for a special mouse-pad.

The first commercially successful optical computer mouse was the Microsoft IntelliMouse® with IntelliEye™, introduced in 1999 using technology developed by Hewlett-Packard. It worked on almost any surface, and represented a welcome improvement over mechanical mice, which would pick up dirt, track capriciously, invite rough handling, and need to be taken apart and cleaned. Instead the reliable performance of the IntelliMouse® allowed relaxed grips which also were less likely to cause repetitive strain injury. Other manufacturers soon followed Microsoft’s lead using components manufactured by the HP spin-off Agilent Technologies, and over the next several years mechanical mice became obsolete.

The technology underlying the modern optical computer mouse is known as digital image correlation, a technology pioneered by the defense industry for tracking military targets. Optical mice use image sensors to image naturally occurring texture in materials such as wood, cloth, mouse pads and Formica. These surfaces, when lit at a grazing angle by a light emitting diode, cast distinct shadows that resemble a hilly terrain lit at sunset. Images of these surfaces are captured in continuous succession and compared with each other to determine how far the mouse has moved.

To understand how optical mice work, imagine two photographs of the same object except slightly offset from each other. Place both photographs on a light table to make them transparent, and slide one across the other until their images line up. The amount that the edges of one photograph overhang the other represents the offset between the images, and in the case of an optical computer mouse the distance it has moved.

Optical mice capture one thousand successive images or more per second. Depending on how fast the mouse is moving, each image will be offset from the previous one by a fraction of a pixel or as many as several pixels. Optical mice mathematically process these images using cross correlation to calculate how much each successive image is offset from the previous one.

An optical mouse might use an image sensor having an 18 x 18 pixel array of monochromatic pixels. Its sensor would normally share the same ASIC as that used for storing and processing the images. One refinement would be accelerating the correlation process by using information from previous motions, and another refinement would be preventing deadbands when moving slowly by adding interpolation or frame-skipping.

The invention of the modern optical mouse at HP was made more likely by a succession of related projects during the 1990s at its central research laboratory. In 1992 John Ertel, William Holland, Kent Vincent, Rueiming Jamp and Richard Baldwin were awarded US Patent 5,149,980 for measuring paper advance in a printer by correlating images of paper fibers. In 1998 Travis N. Blalock, Richard A. Baumgartner, Thomas Hornak, and Mark T. Smith were awarded US Patent 5,729,008 for tracking motion in a hand-held scanner by correlating images of paper fibers and document features, a technology commercialized in 1998 with the HP 920 Capshare handheld scanner. In 2002 Gary Gordon, Derek Knee, Rajeev Badyal and Jason Hartlove were awarded US Patent 6,433,780 for the modern optical computer mouse using image correlation.
Laser Mice

The laser mouse uses an infrared laser diode instead of a LED to illuminate the surface beneath their sensor. As early as 1998, Sun Microsystems provided a laser mouse with their Sun SPARCstation servers and workstations. However, laser mice did not enter the mainstream market until 2004, when Paul Machin at Logitech, in partnership with Agilent Technologies, introduced its MX 1000 laser mouse. This mouse uses a small infrared laser instead of an LED and has significantly increased the resolution of the image taken by the mouse. The laser enables around 20 times more surface tracking power to the surface features used for navigation compared to conventional optical mice, via interference effects.

Glass laser (or glaser) mice have the same capability of a laser mouse but can also be used on top of mirror or transparent glass with few problems.

In August 2009, Logitech introduced mice with two lasers, to track on glass and glossy surfaces better; they dubbed them “dark field” mice.
LED Color

The color of the optical mouse’s light-emitting diodes can vary, but red is most common, as red diodes are inexpensive and silicon is very sensitive to red light. Other colors are sometimes used, such as the blue LED of the V-Mouse VM-101 illustrated at right.
Power

Manufacturers often engineer their optical mice—especially battery-powered wireless models—to save power when possible. In order to do this, the mouse dims or blinks the laser or LED when in standby mode (each mouse has a different standby time). This function may also increase the laser / LED life. Mice designed specifically for gamers, such as the Logitech G5 or the Razer Copperhead, often lack this feature in an attempt to reduce latency and to improve responsiveness.

A typical implementation in Logitech mice has four power states, where the sensor is pulsed at different rates per second:
- 1500: full on condition for accurate response while moving, illumination appears bright.
- 100: fallback active condition while not moving, illumination appears dull.
- 10: standby
- 2: sleep state

Some other mice turn the sensor fully off in the sleep state, requiring a button click to wake.

Optical mice utilizing infrared elements (LEDs or lasers) offer substantial increases in battery life. Some Logitech mice, such as the V450 848 nm laser mouse, are capable of functioning on two AA batteries for a full year, due to the low power requirements of the infrared laser.
Optical Versus Mechanical Mice

Unlike mechanical mice, which can become clogged with lint, optical mice have no rolling parts; therefore, they do not require maintenance other than removing debris that might collect under the light emitter. However, they generally cannot track on glossy and transparent surfaces, including some mouse-pads, sometimes causing the cursor to drift unpredictably during operation. Mice with less image-processing power also have problems tracking fast movement, though high-end mice can track at 2 m/s (80 inches per second) and faster.

Some models of laser mice can track on glossy and transparent surfaces, and have a much higher sensitivity than either their mechanical or optical counterparts but are more expensive than their LED based or mechanical counterparts.

As of 2006, mechanical mice have lower average power demands than their optical counterparts. In practice this is only significant when the mouse is either used with a battery-powered computer, such as a notebook model, or is a battery-powered wireless mouse.

Optical models will outperform mechanical mice on uneven, slick, soft, sticky, or loose surfaces, and generally in mobile situations lacking mouse pads. Because optical mice render movement based on an image which the LED (or infrared diode) illuminates, use with multicolored mouse pads may result in unreliable performance; however, laser mice do not suffer these problems and will track on such surfaces. The advent of affordable high-speed, low-resolution cameras and the integrated logic in optical mice provides an ideal laboratory for experimentation on next-generation input-devices. Experimenters can obtain low-cost components simply by taking apart a working mouse and changing the optics or by writing new software.

LED TV’s and monitors are part of the new High Definition generation. Quite simply, LED (Light Emitting Diode) technology uses individual backlights which in many cases can be tuned on or off in areas to allow for precision control of the lighting emitted from the TV screen or monitor. This differs from traditional backlighting which uses a CCFL (Cathode Fluorescent Lamp) that involves several fluorescent tubes placed horizontally across the screen. The enhanced benefits of LED technology allow for a sleeker screen design plus improved brightness potential, colour reproduction and viewing contrast.

The following guide will help you get to grips with LED technology so you can decide for yourself whether it deserves the must-have hype.

Types of LED Lighting

The first thing to understand is that there are two distinct types of LED TV screens or monitors based on how the LED backlighting is arranged:

Edge-lit screens

This type of TV screen or monitor has a row of LED backlights placed around the edges of the screen panel, which shine into a multi-layered diffuser panel creating a uniform view. Because the lights surround the perimeter of the screen instead of being behind it, edge-lit models allow for an ultra sleek design.

Full-matrix screens

These models have their LED lights arranged across the back of the display, which then feed through a diffuser panel to make the backlighting even. The most effective LED TV’s or monitors of this range have a feature called ‘local dimming’ or ‘smart dimming’ – this allows you to dim or switch off particular sections of the lighting elements while leaving other areas at full brightness. The result is enhanced picture contrast of black levels and other colours. It must be said that without this ability to fine tune the LED lighting to your tastes, LED TV’s are generally very similar to traditional LCD TV’s.

LED Viewing Quality

Colours

For on-point colour accuracy, LED TV’s and monitors with coloured backlighting are the best option. The display is still impressive however with the other type of LED lights which are white.

Definition & Contrast

As explained above, LED TV and monitors with the ‘local dimming’ feature gives you the power to control the backlighting arrangement for an improved picture quality in terms of definition and colour contrast. The result of being able to dim or switch off certain sections of the LED lights allows for darker blacks and enhanced definition while viewing dark-lit images. The other models that don’t have this feature are still high in viewing quality to the eye of the average person, but a true visual connoisseur will notice that uniform LED backlighting causes some areas of the screen to be better lit than others.

Angle of View

Because of the flat screen used by LED technology, it must be noted that this design suffers slightly from contrast degradation when the screen or monitor is viewed at angles of more than approximately 30 degrees from the centre. This issue has been significantly improved on over the past few years and has now advanced sufficiently to offer better viewing quality than plasma screens.

Size and Cost of LED TV’s

Televisions with LED backlights are currently on offer in sizes that range from 46 to 70 inches. While they generally cost a fair amount more than their traditional LCD television counterparts, many people are happy to pay the extra cost to have the best picture quality possible.

Life Expectation

As a general rule of thumb, TV manufacturers say their products have the longevity of approximately 100 000 hours. Since LED TV’s are quite new to the marketplace, this life expectation has not been fully confirmed as yet, however LED lights are known to last for a reasonably long period of time. LED backlighting technology is also said to suffer less degradation in colour over time than LCD models.

Power Usage

LED backlights offer better energy efficiency than CCFL-based backlights. It must be said however that a LED TV with the local dimming feature will use more electrical power than a traditional or edge-lit LCD TV that has the same screen size.
Whether you’re looking to buy a LED TV or LED monitor, the above information gives you the key facts about this new technology so you can make the right choice when shopping around for your viewing needs. As there are now an increasing amount of models available from different manufacturers, it’s crucial to do your research so you can be sure of finding the manufacturer and model that offers the best quality for your money.

See the original article here>>

The Internet is vast and filled with many different dangers for people of all ages. There is really no set age where someone can be completely safe from online dangers. There are several ways to protect children, adults, and the elderly from falling victim to dangers online.

How to Keep Kids Safe on the Internet

Children who have access to the Internet must be monitored at all times. There are several different things that children can be exposed to online (sometimes from simply misspelling a domain name).

Children can be exposed to:

Adult Content Websites (pornography)
Racism/Prejudice (hate crime, violence, etc.)
Drugs (paraphernalia, alternatives)
Gambling (other addictive online practices)
Alternative Lifestyle Choice Information (homosexuality, other religions)
Pedophiles (other ill-intentioned individuals as well)
Children who hear new words are likely to use the Internet to look them up. Search engines without the proper filters (and sometimes with the filter on) may display large amounts of risky and adult oriented material. For example, searching a generic female name in Google Images results in a large amount of pornographic material being displayed. Even websites that are designed for children, offer website membership, and allow members to interact with each other may be used by pedophiles and others who intend to hurt children.

Of course there is no set solution for keeping children safe online. It is important that parents teach children what is proper to view online, what is out of bounds, and what behavior is risky/dangerous. Children must be taught to never divulge personal information, especially their real names or contact information to anyone. They should understand that anyone delving into their personal information may be doing so with the intention of hurting them and that they should tell their parents as soon as this occurs.

A free tool that may help keep children safe while they use the Internet is K9 Web Protection, which is available at http://www.k9webprotection.com/. K9 Web Protection is like a watch dog for online practices. It is simple to use and has customizable features that can help children stay safe online. It blocks images and websites that are known to be inappropriate for child audiences. The only thing that the K9 Web Protection service does not do is teach children safe Internet practices, which is the parent/guardian’s responsibility. K9 Web Protection may even prevent adults from falling prey to malicious sites as well.

How to keep personal information safe on the Internet

It is really important to safeguard personal information online. Personal information can be used for a variety of things such as opening accounts with financial institutions and website services, which puts Internet users at risk for identity theft.

Identity theft often happens through means that users ignore because they seem authentic:

Email – Email advertising, offers, and notifications can be sent from anyone online and they may ask for personal information. The general rule of thumb is to never give out personal information over email to any organization no matter how authentic the service looks. If the email was sent from a company that the user has had a past relationship with, the user should contact the company directly via phone to verify authenticity.

Fake Websites – Many emails, websites, or malicious users link innocent people to websites that seem to be legitimate. These websites are designed to collect login or other personal information, which may be used for identity theft or compromising an account.

Scams – Scams are popping up throughout the Internet. These include pyramid schemes for easy money, claiming an inheritance from a relative overseas, and even a foreign lottery that users may or may not have entered. If the offer is too good to be true then it more than likely is and someone else is trying to profit from the Internet users’ gullibility.

It is so easy to give away personal information that many people do not realize that they have, especially on social networking websites such as Facebook, Myspace, and Twitter. The following is a list of personal information that is most commonly used for ill:

Full Real Name
Birthday
Birthplace
Current Address
Social Security
National Identification Number (If Outside the US)
Vehicle Registration or License Plate Number
Driver’s License Number
Handwriting samples
Credit/Debit/Charge Card Numbers
Bank Routing Numbers
Online Account IDs or Passwords
It is very important to only divulge such information when it is necessary so that it is not used to harm the user physically or financially.

Only make purchases online through highly trusted websites. Check websites directly through a trusted service such as the Better Business Bureau, which is available in the United States and Canada at www.bbb.org.

How to Spot Scams on the Internet

Scamming Internet users is a way of life for many people online. Scams come in a variety of forms that can cause financial harm to anyone who falls victim to them. Here is a list of common scams that most people are exposed to through email or other forms of online contact:

Online Dating – Many online dating websites are full of fake accounts. The owners of these accounts often contact other users pretending to be interested in them. Online dating sites charge a premium for their service and give many people who are willing to pay false hope.

Phishing – Contact that is designed to collect information for site logins and can come from a variety of sources that may even seem authentic.

Nigerian 419 Letter – Any email in a format that is designed to try and convince the recipient that they can embezzle money for a profit.

Post Forwarding or Reshipping – Emails asking to reship documents to another address. Usually involves cashing checks, taking a small commission from the funds (sometimes in excess of $5000), and creating a money order to resend to another person.

Winning Notifications – Notification of winning electronics, a lottery, or other types of prizes that require a deposit, shipping cost coverage, or anything else. The company will ask for a credit card or bank information before dispensing the prize but will charge large amounts later on.

Travel Vacation – Vacation offers to locations that seem cheap. They will ask for payment through an unconventional method (such as a wire transfer through a service that does not require an ID) and will send fake tickets.

Auction Fraud – Purchasing anything online from new auction websites can be very dangerous. Even popular auction sites like eBay, for example, are not completely immune to fraud. Be cautious when dealing with auction websites, especially if payment involves mailing funds, doing a wire transfer, etc. If something of high quality is being sold very cheaply, it may not be authentic.

source: http://www.tech-faq.com/internet-safety.html

You have to know the different parts of your computer particulaly the computer hardware. Rarely do you find a home with no computer nowadays. Some people call it the computer age and it is true because computers have already become a very important part of our lives such that we can no longer do away with computers. We bring these gadgets wherever we are. You can see people, adult and young people alike, bringing their notebooks in restaurants and cafeterias. They are taking advantage of the WiFi zone. Children cannot study without computers because all the data that they need are stored in the World Wide Web. It is always easy to browse through the internet. Just type the data that you want in the search bar and click enter. All the relevant information regarding that topic will immediately pop out on your screen. There is no need to go to the library and read all the thick books piled on the cabinet. All the data you need can be accessed through the computer.

There are different types of computer, from the desktop and laptop to the mini notebook that most people always carry with them. If you are a writer, you will definitely treat your personal computer as your partner. You need the computer in your daily activities. You simply cannot live without it because all your articles and files are stored in the computer. There is no need for you to bring thick notes anymore. This generation is indeed very lucky to have such a powerful technology. That is the reason why you should take good care of your computer hardware. There are two major components of the computer which are the hardware and the software. The hardware is everything that you see on the outside, we have the keyboard, screen or what others call monitor, mouse, speaker and the system unit or the tower. You might be wondering why do need to know all these components. The answer is quite simple and that is so you will know how to take good care of your computer.

Most cases of hardware failure are due to lack of proper maintenance. You cannot ignore the fact that your computer needs to be cleaned also especially if you bring it outside your home. Dust particles can easily accumulate. The time will come when you might be wondering why your computer does not turn on and you will later find out through the technician that dust has already made its way through the small holes and that is what’s causing the problem. It is very important that you have a small soft brush so you could clean the unit every now and then. It is even advisable to clean it after using. Take good care of your computer because if it will be destroyed, the repairs will not only cost you lots of dollars, you will also lose relevant time that should have been used in working. The worst thing that could happen if you continue to ignore computer maintenance is that the unit might be totally destroyed and you have to purchase a new computer.

source: http://ezinearticles.com/?Computer-Hardware&id=6005669

Computing and the Internet is full of terms that novices of the web may find confusing. This is a glossary with a basic description of some terms relating to the computer and internet world.

Bandwidth

Bandwidth is measured in bits per second and is the amount of data that can be sent through a network or modem connection. The higher than bandwidth, the more data that can be transferred. If the bandwidth is high it can cope with more visitors and more downloads. It also affects the speed at which the site loads.

Dashboard

A dashboard is a user interface used on many different types of software. From the dashboard you may get the options and see basic information about your account. The word is taken from a dashboard on a car, where you will see basic information like speed and mileage and reach option such as the gears and radio.

Desktop Publishing

Desktop publishing is where a computer is used to create a document. If words and images are created and combined in designing something, it is called desktop publishing. The creation of a poster using a computer is a good example of desktop publishing.

Encryption

When data is scrambled so it can only be decoded and understood by someone who it should be, it is called encryption. It is effectively a way of enhancing the security of confidential information so if someone who shouldn’t manages to access it, they won’t be able to understand it.

Facebook

Facebook is the name of a social networking website (see below for social networking) where users can create a profile of themselves and share information and photographs with other users who they have specified as a friend. Friends being able to post messages to each other is a popular feature of Facebook.

Firewall

This is software that prevents viruses (see below for virus) and other malicious programs from accessing a computer system. Its job is to spot programs and websites that could be dangerous, and they can prevent traffic from certain IP addresses.

Hard Disk

A hard disk is the internal memory (see below for memory) of a computer and somewhere you can save documents and other files to.

JavaScript

This is a programming language. It is used in the creation of web pages and is used for the dynamic and interactive parts of sites, such as rollovers and image rotation.

LAN

LAN stands for local area network, a computer network that is limited to a small area, such as an office or school. With a LAN, users (who will usually have a user name and password) will be able to access the same files and information from shared areas of the network. It also means users can access the same files from different computers.

Memory

Computers need memory to store data. A hard drive is an example. Memory can also come in the form of external devices plugged into a computer, such as the almost obsolete floppy disk, CD’s and USB drives.

Open Source

If a piece of software’s code is open for the use of any member of the public, it is called open source software. The code can be modified where necessary, so users are effectively taking a program created by someone else and modifying it how they please. Examples include some web development software. This can be used by different web development companies who can modify it to suit their needs.

Page Views

The number of times a webpage has been viewed is called the number of page views. It is a statistic that is regularly used by website owners to see how many times each page has been viewed. This can help them to establish visitor behaviour, and is one metric of measuring the success or failure of a webpage, and a website in general.

Screenshot

A screenshot is effectively an image taken of what is seen on a computer screen, using the computer. It is also sometimes called a screen grab.

Script

A computer script is a set of commands. These are instructions to a computer. They are used to run processes on computers and computer systems.

SEO

SEO stands for Search Engine Optimisation and refers to optimising a website for the search engines to give it the best chance possible of appearing towards the top of the search engines. On-page and off-page techniques can be used. On-page SEO are things carried out on the website itself. Off-page SEO is generating links from other websites to yours.

Social Networking

Social networking websites are sites where people can share information about themselves with others. Basically, they are online networks of people or online communities.

WAN

WAN stands for Wide Area Network, as opposed to a local area network (see above). It essentially does the same thing but over a larger distance. Whereas a LAN may be only within an office, a WAN can connect people from different towns, or even different countries.

Web Host

For a website to be viewed by others, it needs to be hosted on a server. Web hosts (or web hosting companies) lease servers to website owners, where their sites can be uploaded for the world to see.

Virus

A computer virus is a malicious script or piece of software that can infect a computer. This can cause havoc by destroying the computer. Some viruses will allow the virus’s creator to view confidential information contained on a computer.

source: http://ezinearticles.com/?Computer-and-Internet-Glossary&id=5903819

A computer has become a necessity in everyday life. The popularity of the internet and the ease of communicating through it have increased the use of computers for professional as well as personal needs. From filling online forms for a school/ college admission to applying for a job, a computer is must have for all. A branded desktop fitted with the latest and genuine software is the first choice of consumers. However, it is very important to know about the parts and configuration of the computer that distinguishes an average computer from a high performance device.

The brain of a computer is the CPU or central processing unit. It controls the processes and information stored in the computer. Each part of the computer is controlled by the CPU. Computer CPU parts consist of motherboards, processors, printed circuit boards (PCBs), hard disk and random access memory (RAM). All these components have different functions that determine the speed, precision of operation, quality and reliability of a computer. There is a wide range of assembled computers available with Intel and AMD leading the market in processors. The price of CPU varies according to the specifications of the processor and the kind of computer hardware fitted in the cabinet.

Computer hardware accessories like sound cards or graphics card enhance the audio visual performance of the computer. One can even attach external speakers and web cameras in the computer and enjoy movies theatre style or chat endlessly with loved ones. TV Tuner / FM cards add to the pleasure of working on a computer. CD ROM/writers and DVD ROM /writers are generally in built in the desktop and wireless networking devices like Wi-Fi and bluetooth are standard with laptops. External drives can also be used to increase the storage capacity of the desktop or laptop PCs.

Computer accessories like keyboards, mouse and monitors are very essential without which a computer can not be operated. The variety and range of these products is immense and one can buy according to the need and budget. UPS is very helpful in case of an erratic power supply and is easily available. Memory cards, pen drives and all-in-one printer are the other accessories that can be fitted in a computer. Computer parts list is endless and one can go for the choicest brands and manufacturers.

The knowledge for computer parts is handy if one is getting the computer customised or while upgrading the old system. The demand for computer parts is so much that old parts can be sold or exchanged also. It is very easy to sell computer parts through the internet while sitting at home. If one has to buy computer accessories, then also an internet connection is helpful. All the leading brands have online stores where one can buy the required accessories and get them delivered at the doorstep.

source: http://ezinearticles.com/?Computer-Parts-and-Accessories—The-Lifeline-of-a-Computer&id=5633587

The personal computer consists of multiple computer hardware or multiple devices linked together to create a whole working machine. Some of the hardware are external such as keyboards, printers and mouse that is connected via cable or other methods. These hardware need to be installed via a software program before it can run. They increase the efficiency of the personal computer, and do tasks such as business, design, entertainment and more. Here are the main types of computer hardware that you can buy for your PC.

1. Hard drive – also called hard disk, it is the permanent storage space that stores all information and applications of the computer, retaining the space even when it is turned off.

2. Motherboard – Considered as the most important types of computer hardware. The motherboard houses the microprocessor, providing the necessary sockets and slots that connect to all other types of computer hardware. Thus the motherboard serves as the ‘mediator’, a channel that allows the components to work together and walk to each other, making it a whole and completely working unit.

3. RAM – short for Random Access Memory. It is the memory used to process applications. RAM is lost when the computer is turned off.

4. ROM – short for Read Only Memory. It serves as memory for storage of programs.

5. Storage Devices – External storage devices like CDs, DVDs, USB flash drives are important as removable storage devices that you can take from one personal computer to another.

6. Power Supply Unit (PSU) – this converts the AC power to low voltage DC power, integral for the internal components of the PC.

7. Sound Card – responsible for the PC’s audio input and output, necessary for games, music and other multimedia programs.

8. Keyboard – an input device used to input text & characters by pressing the keys.

9. Mouse – pointing device that detects two-dimensional motion to the surface. Other pointing devices include the track ball, the touch pad and the touch screen.

10. Joystick – a gaming device with a handheld stick that pivots from left to right and up to down, detecting angles in two and three dimensions.

11. Image input devices – includes scanners and web cams, these devices are used to provide input of images, written text, handwriting, etc for digital use.

12. Image output devices – the printer, used to produce a physical and permanent text or graphic document.

13. Audio input devices – the microphone is used to record or provide input through sound conversion to electrical signals.

14. Audio output devices – headphones and speakers that allows you to hear the audio coming from the computer.

15. Monitor – the monitor is an electronic visual display that shows the graphical and textual information of the computer. There are may types of monitors, such as the CRT (Cathode Ray Tube), which is almost obsolete, the LCD (Liquid Crystal Display) which is the most common monitor used nowadays, and the touch screen display.

All these types of computer hardware can contribute to the overall experience of your computer. It can make your computer faster, brighter and more entertaining. Some of the computer hardware are necessary for your PC to work, while others amplifies the whole experience.

source: http://ezinearticles.com/?Types-Of-Computer-Hardware:-Basics-101&id=5551197

It is a default private IP for various NAT/network devices such as routers. In order to resolve the issue of shortage of IP to be used on the Internet, these IP addresses were devised. RFC 1918 defines the ranges of the private IP.

An IP, where IP stands for Internet Protocol, is a numeric identification that is assigned to all the devices or machines, which are a part of any computer network. All the devices, which are connected to a network, have a unique IP. As we have said earlier, these addresses are numeric representations, which are divided into four parts, and each part is separated by a period (dot) between them. For instance, an IP normally looks like 192.168.1.1.

One series of these numbers is classified as private IP. Generally, this set of numbers range from 192.168.0.0 to 192.168.255.255. Each of these numbers is retained and unique as compared to other IP addresses. The word unique here is used in the sense that these numbers are unique within the network they belong. To make this clear let us take an example of your college or office computer, which is assigned an IP 192.168.1.1 in network and you, will have the same IP address in your home network as well and it won’t create any conflicting issue.

NAT (Network Address Translation) and Private Address Space

With the evolution of Internet, there started to be a shortage of IP addresses simply due to the way through which these are allocated. For a quick fix of this problem, NAT devices are used. For instance, if you have more than one computer in your home and all of them are connected to a NAT device say router, that router assigned a unique private Ip to each computer.

The NAT devices, such as router or firewall, modify the information that your computer send to the Internet, hence in turn they get a normal address that can be used on the web. Another important feature of the NAT device is that they are accountable to route the information entering the network to the right computer in your network.

Default IP

192.168.1.1 is a default IP address used by various NAT devices in private networks such as routers. Some other default IP addresses include 192.168.2.1 and 192.168.0.1. As we have said in the beginning that the ranges of these IP is defined by RFC 1918. The Internet Assigned Numbers Authority (IANA) is responsible for keeping these and other numbers reserved within their particular ranges for private network use.

There are so many Nat devices or network devices, which use 192.168.1.1 as default private IP. But the two most popular NAT devices brands, Linksys and Speedtouch use this and other numbers as their default IP.

source: http://ezinearticles.com/?What-Is-an-IP-Address?&id=5235745