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• The Difference Between .com, .net, .org and Why We’re About To See Many More Top-Level Domains

  - by Chris Hoffman

  .com, .net, .org and other website suffixes are known as “top-level domains” (TLDs). While we normally see only a few of these, there are hundreds of them – and there may be thousands more soon. Top-level domains are managed by the Internet Assigned Numbers Authority (IANA), which is run by the Internet Corporation for Assigned Names and Numbers (ICANN). HTG Explains: What is the Windows Page File and Should You Disable It? How To Get a Better Wireless Signal and Reduce Wireless Network Interference How To Troubleshoot Internet Connection Problems

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• Electric Dreams: Picking Out a Vintage 1980s Computer [Video]

  - by Jason Fitzpatrick

  What if you had to pick out a 1980s era computer for use in your home today? BBC show Electric Dreams walks us through the history with a “time traveling” family. Electric Dreams is a show based on the novel premise that an average British family is starting, technologically speaking, in the 1970s and progressing over a month to the year 2000–restricted each step of the way to using technology available only in the era they are emulating. In the above video clip they’ve reached 1982 and visit the National Museum of Computing to pick out a vintage computer. It’s interesting to see the kids interact with the computer and experience programming for, presumably, the first time. Have a vintage computer memory (mine is programming on a Timex Sinclair); let’s hear about it in the comments. Electric Dreams – The 1980s ‘The Micro Home Computer Of 1982′ [via O'Reilly Radar] How To Encrypt Your Cloud-Based Drive with BoxcryptorHTG Explains: Photography with Film-Based CamerasHow to Clean Your Dirty Smartphone (Without Breaking Something)

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• Desktop Fun: Halloween 2013 Wallpaper Collection [Bonus Edition]

  - by Akemi Iwaya

  Halloween is quickly approaching, so why not get your favorite system ready for the holiday? Make your desktop the spookiest one of all with our Halloween 2013 Wallpaper collection. Halloween 2013 Note: Click on the picture to see the full-size image—these wallpapers vary in size so you may need to crop, stretch, or place them on a colored background in order to best match them to your screen’s resolution.                     More Halloween Goodness for Your Desktop Desktop Fun: Halloween 2012 Wallpaper Collection [Bonus Edition] Desktop Fun: Halloween 2011 Wallpaper Collection [Bonus Edition] Desktop Fun: Halloween Wallpaper Collection [Bonus Edition] Desktop Fun: Halloween 2011 Icon Packs Desktop Fun: Halloween Icon Packs Desktop Fun: Halloween 2011 Fonts Desktop Fun: Halloween Fonts Awesome Desktop Wallpapers: Halloween Edition For more great wallpapers make sure to look through our terrific collections in the Desktop Fun section.     

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• The Best Websites for Free Online Courses, Certificates, Degrees, and Educational Resources

  - by Lori Kaufman

  Have you thought about expanding your knowledge by taking some courses? There are several colleges and other sites that offer free online courses, certificate programs, some degree programs, and education resources for teachers and professors. How to Banish Duplicate Photos with VisiPic How to Make Your Laptop Choose a Wired Connection Instead of Wireless HTG Explains: What Is Two-Factor Authentication and Should I Be Using It?

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• Enjoy Playing Dozens of Classic Atari, Adventure, and Other Types of Games Directly in Your Browser

  - by Akemi Iwaya

  Would you love to play classic Atari games, journey once again with Bilbo Baggins in The Hobbit v1.0, or even try out WordStar 2.26? Then we have the perfect way to indulge in hours of browser-based fun to share with you. The Internet Archive has worked hard to put together a JavaScript port of the MESS computer software emulator and create an awesome online Historical Software Collection of classic games and software from yesteryear! When you visit the homepage, you will be able to scroll down through it for a ‘guided tour’ of the games and software currently available in the initial collection. This is what the individual homepages for each game or bit of software looks like. Keep in mind that none of the ‘Download item’ links we checked were working for us even though they are ‘shown’… Browse on over to the Internet Archive’s Historical Software Collection homepage to start having fun with all the classic games and programs. Historical Software Collection Homepage If you would like to visit the homepage for The Hobbit v1.0 directly, then use the link below. Play The Hobbit v1.0 [via The Verge]     

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• Here’s 6 Great Tricks for Windows 8 that You Probably Don’t Know

  - by Chris Hoffman

  We’ve covered a lot of tips, tricks, and tweaks for Windows 8, but there are still a few more. From bypassing the lock screen to instantly taking and saving screenshots, here are a few more hidden options and keyboard shortcuts. Whether you love Windows 8, hate it, or just wish Metro would go away, these options will help you make Windows 8 work the way you want it to. How to Own Your Own Website (Even If You Can’t Build One) Pt 2 How to Own Your Own Website (Even If You Can’t Build One) Pt 1 What’s the Difference Between Sleep and Hibernate in Windows?

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• Tiny DSLR Intervalometer Snaps Pics On User-Defined Schedule

  - by Jason Fitzpatrick

  If you’re interested in time-lapse photography but underwhelmed by the in-camera options (or lack there of) or don’t want to shell out money for an expensive commercial intervalometer, this DIY option is pretty slick solution. Achim Sack, a fan of hardware hacking and time lapse photography, created a super tiny interval timer that works with Nikon, Canon, and Pentax DSLRs. Plug it in, snap a shot between 0.4 seconds and 18 minutes to set the interval and then leave it be. As long as you have space on the memory card and power left in the battery the camera will keep snapping pictures. Hit up the link below to see his schematics, parts list, and more photos of the build. Interval Timer v2 [via Hack A Day] How To Encrypt Your Cloud-Based Drive with BoxcryptorHTG Explains: Photography with Film-Based CamerasHow to Clean Your Dirty Smartphone (Without Breaking Something)

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• How To Disable the Amazon Search Ads in Ubuntu’s Unity Dash

  - by Chris Hoffman

  Upgrade to Ubuntu 12.10 (Quantal Quetzal) and you’ll run into a surprise – Ubuntu now shows you advertisements for Amazon products when you search in your dash. There’s also an Amazon shortcut pinned to Unity’s launcher. There are several ways to disable these ads, and they aren’t immediately obvious. However, you can easily disable the Amazon search results if you don’t want to see them, or if you’re concerned about the privacy implications. What To Do If You Get a Virus on Your Computer Why Enabling “Do Not Track” Doesn’t Stop You From Being Tracked HTG Explains: What is the Windows Page File and Should You Disable It?

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• How to Get All the Windows 8 Editions on One Install Disk

  - by Taylor Gibb

  There are a lot of different versions of Windows, but you probably didn’t know that short of the Enterprise edition, the disc or image that you own contains all versions for that architecture. Read on to see how we can use them to make a universal Windows 8 install disc. Things You Will Need A x86 Version of Windows 8 A x64 Version of Windows 8 A x86 Version of Windows 8 Enterprise A x64 Version of Windows 8 Enterprise A Windows 8 PC Note: While we will use all the images above you don’t really need the Enterprise Edition. You could always leave out parts of the tutorial if you know what you are doing, if you are not comfortable with that and still want to follow through you could always grab the Enterprise evaluation images that are available for free to the public, on MSDN. Getting Started To get started you will need to Download the Windows 8 ADK from Microsoft. Once downloaded go ahead and install it, you will only need the Deployment tools so be sure to uncheck the rest of the options. Lastly you will also need to create the following folder structure on the root of your C:\ drive to make things a bit easier. C:\Windows8Root C:\Windows8Root\x86 C:\Windows8Root\x64 C:\Windows8Root\Enterprisex86 C:\Windows8Root\Enterprisex64 C:\Windows8Root\Temp C:\Windows8Root\Final OK lets get started. Making The Image The first thing we need to do is create a base image, so mount the x86 version of Windows 8 and copy its files to: C:\Windows8Root\Final Now move the install.wim file from: C:\Windows8Root\Final\sources To: C:\Windows8Root\x86 Next go ahead and copy the install.wim file from the other 3 images, Windows 8 x64, Windows 8 Enterprise x86 and Windows 8 Enterprise x64 to the respective folders in Windows8Root, the install.wim file can be located at: D:\sources\install.wim Note: The above assumes that the images are always mounted at drive D. Remember that each install.wim is different so don’t copy them to the wrong directories or the rest of the tutorial wont work. Next switch to the Metro Start Screen and open the Deployment and Imaging Tools Environment. Note: If you are not a local administrator on your PC, you will need to right-click on it and choose to run it as an administrator. Now run the following commands: Dism /Export-Image /SourceImageFile:c:\Windows8Root\x86\install.wim /SourceIndex:2 /DestinationImageFile:c:\Windows8Root\Final\sources\install.wim /DestinationName:”Windows 8″ /compress:maximum Dism /Export-Image /SourceImageFile:c:\Windows8Root\x86\install.wim /SourceIndex:1 /DestinationImageFile:c:\Windows8Root\Final\sources\install.wim /DestinationName:”Windows 8 Pro” /compress:maximum Dism /Export-Image /SourceImageFile:c:\Windows8Root\x86\install.wim /SourceIndex:1 /DestinationImageFile:c:\Windows8Root\Final\sources\install.wim /DestinationName:”Windows 8 Pro with Media Center” /compress:maximum Dism /Export-Image /SourceImageFile:c:\Windows8Root\Enterprisex86\install.wim /SourceIndex:1 /DestinationImageFile:c:\Windows8Root\Final\sources\install.wim /DestinationName:”Windows 8 Enterprise” /compress:maximum Dism /Export-Image /SourceImageFile:c:\Windows8Root\x64\install.wim /SourceIndex:2 /DestinationImageFile:c:\Windows8Root\Final\sources\install.wim /DestinationName:”Windows 8″ /compress:maximum Dism /Export-Image /SourceImageFile:c:\Windows8Root\x64\install.wim /SourceIndex:1 /DestinationImageFile:c:\Windows8Root\Final\sources\install.wim /DestinationName:”Windows 8 Pro” /compress:maximum Dism /Export-Image /SourceImageFile:c:\Windows8Root\x64\install.wim /SourceIndex:1 /DestinationImageFile:c:\Windows8Root\Final\sources\install.wim /DestinationName:”Windows 8 Pro with Media Center” /compress:maximum Dism /Export-Image /SourceImageFile:c:\Windows8Root\Enterprisex64\install.wim /SourceIndex:1 /DestinationImageFile:c:\Windows8Root\Final\sources\install.wim /DestinationName:”Windows 8 Enterprise” /compress:maximum Next navigate to: C:\Windows8Root\sources\ And create a new text file. You will need to call it: EI.cfg Then edit it to look like the following: The last thing we need to do is work some magic to get Windows Media Center added to the WMC editions of Windows 8. For that I have written a little script to make it easier for everybody, you can grab it here. Once you have downloaded it extract it. In order to use it right-click in the bottom left hand corner of the screen, and open an elevated command prompt. Then go ahead and paste the following into the command prompt window. powershell.exe -ExecutionPolicy Unrestricted -File C:\Users\Taylor\Documents\HTGWindows8Converter.ps1 Note: You will need to replace the path to the script, another thing to note is that if the path you replace it with has spaces you will need to enclose the path in quotes. The script should kick off straight away and has some progress bars you can watch while it does its thing. Half way through another Window will pop open, which will start creating your final ISO image. When its complete, close the command prompt and you should have an ISO image on the root of your C drive called: HTGWindows8.iso That’s all there is to it. 7 Ways To Free Up Hard Disk Space On Windows HTG Explains: How System Restore Works in Windows HTG Explains: How Antivirus Software Works

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• Desktop Fun: Dreams of Spring Wallpaper Collection

  - by Asian Angel

  For those living in the northern hemisphere Spring is almost here. But until those lovely warm temperatures and bursts of color arrive, let our Dreams of Spring Wallpaper collection fill your desktop with the beauty of the upcoming season. Note: Click on the picture to see the full-size image—these wallpapers vary in size so you may need to crop, stretch, or place them on a colored background in order to best match them to your screen’s resolution. HTG Explains: What’s the Difference Between the Windows 7 HomeGroups and XP-style Networking?Internet Explorer 9 Released: Here’s What You Need To KnowHTG Explains: How Does Email Work?

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• Bar Table Modded Into Standing Desk

  - by Jason Fitzpatrick

  This polished looking standing desk combines a stand alone bar-height counter with extra storage, cable management, and monitor riser. The end result looks like a $$$$ standing desk at a fraction of the price. Courtesy of IKEA hacker Marc Marton, the build combines the Billsta Bar Table, the Ekby Alex Shelf, and Besta legs to raise the shelf up off the desk and create a keyboard storage area. For more information about the build hit up the link below. Billsta Bar Table into Standing Work Station [IKEAHacker] 8 Deadly Commands You Should Never Run on Linux 14 Special Google Searches That Show Instant Answers How To Create a Customized Windows 7 Installation Disc With Integrated Updates

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• Mario and Luigi’s Pick-up Game of Baseball – Choosing Teams [Video]

  - by Asian Angel

  Mario and Luigi are choosing players for a pick-up game of baseball and Chargin’ Chuck is ready to go. Will Mario or Luigi pick him for their teams early on or will poor Chuck be the last one chosen? Note: Contains slightly inappropriate language. Dorkly Bits: Chargin’ Chuck Gets Picked Last [via Geeks are Sexy] HTG Explains: What’s the Difference Between the Windows 7 HomeGroups and XP-style Networking?Internet Explorer 9 Released: Here’s What You Need To KnowHTG Explains: How Does Email Work?

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• Tolkien’s Rivendell Rendered in LEGO

  - by Jason Fitzpatrick

  If you’re a fan of all things geeky rendered in LEGO–and we certainly are–you’ll want to take a moment to appreciate this incredible model of the mythical Rivendell from the Lord of the Rings universe. Courtesy of builders Blake Baer and Jake Bittner, the behemoth model measures nearly 4×3 ft. in size, weighs 120 pounds, and required over 50,000 LEGO bricks. Hit up the link below to check out the full set of photos. Rivendell in LEGO [via Geeks Are Sexy] How To Switch Webmail Providers Without Losing All Your Email How To Force Windows Applications to Use a Specific CPU HTG Explains: Is UPnP a Security Risk?

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• This Computer Slices, Dices, and Does it ‘All’ [Humorous Retro Video]

  - by Asian Angel

  Sit back and enjoy this entertaining retro computer ad as Rich DuLaney from the OS/2 Multimedia Presentation Manager/2 team jumps into ‘super salesman mode’ to sell you the Ultimedia M57SLC computer for only $3,395! It slices, It dices [via MUO] 6 Ways Windows 8 Is More Secure Than Windows 7 HTG Explains: Why It’s Good That Your Computer’s RAM Is Full 10 Awesome Improvements For Desktop Users in Windows 8

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• Inside Sweden’s Nuclear Bunker Turned Data Center

  - by Jason Fitzpatrick

  A data center inside a decommissioned nuclear bunker is interesting enough, but one that looks as futuristic and awesome as the center under Stockholm begs to be seen. A hundred feet under the city of Stockholm is a decommissioned nuclear bunker that the government had previously leased out intermittently for various events, but it was never put to serious or extended use. Not until, that is,  Jon Karlung discovered the location and brought his vision of an ultra-modern, stylish, and secure data center to life. The passage from Wired’s write up of their photo tour that best encapsulates the feel of the bunker is: Most often data centers are built in boxy warehouses, so Bahnhof stands out as perhaps the world’s most stylish. In fact, it inspired Cisco IT Architect Douglas Alger to write a book on the world’s best-looking data centers. ”The idea that people were sitting in a design meeting and said, ‘what we need for our data center is waterfalls,’ that must have been a very fascinating discussion,” Alger says. Hit up the link below for the full photo tour. Deep Inside the James Bond Villain Lair That Actually Exists [Wired] Why Does 64-Bit Windows Need a Separate “Program Files (x86)” Folder? Why Your Android Phone Isn’t Getting Operating System Updates and What You Can Do About It How To Delete, Move, or Rename Locked Files in Windows

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• HTG Explains: Why You Shouldn’t Log Into Your Linux System As Root

  - by Chris Hoffman

  On Linux, the Root user is equivalent to the Administrator user on Windows. However, while Windows has long had a culture of average users logging in as Administrator, you shouldn’t log in as root on Linux. Microsoft tried to improve Windows security practices with UAC – you shouldn’t log in as root on Linux for the same reason you shouldn’t disable UAC on Windows. How To Create a Customized Windows 7 Installation Disc With Integrated Updates How to Get Pro Features in Windows Home Versions with Third Party Tools HTG Explains: Is ReadyBoost Worth Using?

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• Cracking Websites with Cross Site Scripting

  - by Akemi Iwaya

  You may have heard the term ‘cross site scripting’ before, but what exactly is ‘it’ and why is it dangerous for a website? YouTube channel Computerphile presents a nice primer on the ‘how and why’ of cross site scripting and the dangers it presents in their latest video. Cracking Websites with Cross Site Scripting – Computerphile [YouTube]     

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• What You Said: What’s Powering Your Media Center

  - by Jason Fitzpatrick

  Earlier this week we asked you to share your media center setups, tips, and tricks. Now we’re back to share of the great comments you left. The range of techniques you all use for getting access to your media is impressive. Some readers had setups as simple as tamasksz’s setup: WDTV Live with an external HDD… So simple, but works. Others started with simple setups, like a WDTV Live, and worked their way up, like Dave: How to Own Your Own Website (Even If You Can’t Build One) Pt 1 What’s the Difference Between Sleep and Hibernate in Windows? Screenshot Tour: XBMC 11 Eden Rocks Improved iOS Support, AirPlay, and Even a Custom XBMC OS

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• Add 33 Unique Biomes to Minecraft with the Biomes O’ Plenty Mod Pack

  - by Asian Angel

  Are you tired of looking at the same old biomes in Minecraft? Then add some fresh scenery with the Biomes O’ Plenty mod pack and enjoy a whole new Minecraft world! Biomes included in the mod pack: Birch Forest, Bog, Cherry Blossom Grove, Crag, Deadlands, Dense Forest, Field, Frost Forest, Garden, Glacier, Highland, Mangrove, Marsh, Meadow, Mesa, Mountain, Mystic Grove, Oasis, Ominous Woods, Orchard, Prairie, Quagmire, Rainforest, Savanna, Scrubland, Seasonal Forest, Shrubland, Spruce Forest, Tropics, Tundra, Wasteland, Wetlands, and Woodlands. You can download the mod pack, view the setup instructions, see images of each biome type, and more by visiting the link below. [1.3.2] [MODLOADERMP] Biomes O’ Plenty – Adds 33 Unique Biomes! (SSP/SMP) [via BoingBoing] 8 Deadly Commands You Should Never Run on Linux 14 Special Google Searches That Show Instant Answers How To Create a Customized Windows 7 Installation Disc With Integrated Updates

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• The Best Ways to Lock Down Your Multi-User Computer

  - by Lori Kaufman

  Whether you’re sharing a computer with other family members or friends at home, or securing computers in a corporate environment, there may be many reasons why you need to protect the programs, data, and settings on the computers. This article presents multiple ways of locking down a Windows 7 computer, depending on the type of usage being employed by the users. You may need to use a combination of several of the following methods to protect your programs, data, and settings. How to Stress Test the Hard Drives in Your PC or Server How To Customize Your Android Lock Screen with WidgetLocker The Best Free Portable Apps for Your Flash Drive Toolkit

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• From the Tips Box: Pre-installation Prep Work Makes Service Pack Upgrades Smoother

  - by Jason Fitzpatrick

  Last month Microsoft rolled out Windows 7 Service Pack 1 and, like many SP releases, quite a few people are hanging back to see what happens. If you want to update but still error on the side of caution, reader Ron Troy  offers a step-by-step guide. Ron’s cautious approach does an excellent job minimizing the number of issues that could crop up in a Service Pack upgrade by doing a thorough job updating your driver sets and clearing out old junk before you roll out the update. Read on to see how he does it: Just wanted to pass on a suggestion for people worried about installing Service Packs.  I came up with a ‘method’ a couple years back that seems to work well. Run Windows / Microsoft Update to get all updates EXCEPT the Service Pack. Use Secunia PSI to find any other updates you need. Use CCleaner or the Windows disk cleanup tools to get rid of all the old garbage out there.  Make sure that you include old system updates. Obviously, back up anything you really care about.  An image backup can be real nice to have if things go wrong. Download the correct SP version from Microsoft.com; do not use Windows / Microsoft Update to get it.  Make sure you have the 64 bit version if that’s what you have installed on your PC. Make sure that EVERYTHING that affects the OS is up to date.  That includes all sorts of drivers, starting with video and audio.  And if you have an Intel chipset, use the Intel Driver Utility to update those drivers.  It’s very quick and easy.  For the video and audio drivers, some can be updated by Intel, some by utilities on the vendor web sites, and some you just have to figure out yourself.  But don’t be lazy here; old drivers and Windows Service Packs are a poor mix. If you have 3rd party software, check to see if they have any updates for you.  They might not say that they are for the Service Pack but you cut your risk of things not working if you do this. Shut off the Antivirus software (especially if 3rd party). Reboot, hitting F8 to get the SafeMode menu.  Choose SafeMode with Networking. Log into the Administrator account to ensure that you have the right to install the SP. Run the SP.  It won’t be very fancy this way.  Maybe 45 minutes later it will reboot and then finish configuring itself, finally letting you log in. Total installation time on most of my PC’s was about 1 hour but that followed hours of preparation on each. On a separate note, I recently got on the Nvidia web site and their utility told me I had a new driver available for my GeForce 8600M GS.  This laptop had come with Vista, now has Win 7 SP1.  I had a big surprise from this driver update; the Windows Experience Score on the graphics side went way up.  Kudo’s to Nvidia for doing a driver update that actually helps day to day usage.  And unlike ATI’s updates (which I need for my AGP based system), this update was fairly quick and very easy.  Also, Nvidia drivers have never, as I can recall, given me BSOD’s, many of which I’ve gotten from ATI (TDR errors).How to Enable Google Chrome’s Secret Gold IconHTG Explains: What’s the Difference Between the Windows 7 HomeGroups and XP-style Networking?Internet Explorer 9 Released: Here’s What You Need To Know

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• From the Tips Box: Pin Any File to the Windows 7 Taskbar

  - by Jason Fitzpatrick

  Every week we dip into the tip box and share the tips you send in. This week we’re highlighting a great tip and the accompanying tutorial video that shows you how to pin any file to the Windows 7 taskbar. Robert Jasinski writes in with a clever way to pin any file you want to the task bar. By default if you drag a text document to the taskbar it will pin it to the Notepad executable—the same thing happens with any other file that has an association with an executable. What if you want to pin that specific text file to the taskbar and not to the executable (or any other file for that matter)? Robert shares his method:  What is a Histogram, and How Can I Use it to Improve My Photos?How To Easily Access Your Home Network From Anywhere With DDNSHow To Recover After Your Email Password Is Compromised

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• Bring the Lantern Corp to Your Desktop with the Green Lantern Theme for Windows 7

  - by Asian Angel

  Calling all Green Lantern fans! Here is your chance to bring the excitement of the new movie straight to your desktop in a ready to go theme. The theme comes with 31 Hi-Res wallpapers, custom icons, and sounds from the movie for an awesome Lantern Corp desktop experience. View Additional Screenshots of the Theme [VikiTech] Download the Theme [VikiTech] Want additional Green Lantern icons and more for your desktop? Then browse on over to our Desktop Fun: Green Lantern Customization Set post. How To Encrypt Your Cloud-Based Drive with BoxcryptorHTG Explains: Photography with Film-Based CamerasHow to Clean Your Dirty Smartphone (Without Breaking Something)

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• Homebrew LEGO CD Duplicator Copies CDs On The Cheap

  - by Jason Fitzpatrick

  If you’d like to bulk copy CDs/DVDs without the sticker shock of a $500+ commercial duplicator, this DIY LEGO duplicator is a homebrew solution. Paul Rea wanted to rip and copy CDs and DVDs without shelling out for a commercial duplicator and without the hassle of being bound to that commercial duplicator’s propriety software. His homebrew solution–a combination of LEGO, a rotating base, an Arduino controller, and little ingenuity–handles his ripping and copying needs with ease. Watch the video above to see it in action then hit up the link below for the build log and Arduino code. CD Duplicator [PaulRea.net via Make] HTG Explains: Understanding Routers, Switches, and Network Hardware How to Use Offline Files in Windows to Cache Your Networked Files Offline How to See What Web Sites Your Computer is Secretly Connecting To

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• How do NTP Servers Manage to Stay so Accurate?

  - by Akemi Iwaya

  Many of us have had the occasional problem with our computers and other devices retaining accurate time settings, but a quick sync with an NTP server makes all well again. But if our own devices can lose accuracy, how do NTP servers manage to stay so accurate? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. Photo courtesy of LEOL30 (Flickr). The Question SuperUser reader Frank Thornton wants to know how NTP servers are able to remain so accurate: I have noticed that on my servers and other machines, the clocks always drift so that they have to sync up to remain accurate. How do the NTP server clocks keep from drifting and always remain so accurate? How do the NTP servers manage to remain so accurate? The Answer SuperUser contributor Michael Kjorling has the answer for us: NTP servers rely on highly accurate clocks for precision timekeeping. A common time source for central NTP servers are atomic clocks, or GPS receivers (remember that GPS satellites have atomic clocks onboard). These clocks are defined as accurate since they provide a highly exact time reference. There is nothing magical about GPS or atomic clocks that make them tell you exactly what time it is. Because of how atomic clocks work, they are simply very good at, having once been told what time it is, keeping accurate time (since the second is defined in terms of atomic effects). In fact, it is worth noting that GPS time is distinct from the UTC that we are more used to seeing. These atomic clocks are in turn synchronized against International Atomic Time or TAI in order to not only accurately tell the passage of time, but also the time. Once you have an exact time on one system connected to a network like the Internet, it is a matter of protocol engineering enabling transfer of precise times between hosts over an unreliable network. In this regard a Stratum 2 (or farther from the actual time source) NTP server is no different from your desktop system syncing against a set of NTP servers. By the time you have a few accurate times (as obtained from NTP servers or elsewhere) and know the rate of advancement of your local clock (which is easy to determine), you can calculate your local clock’s drift rate relative to the “believed accurate” passage of time. Once locked in, this value can then be used to continuously adjust the local clock to make it report values very close to the accurate passage of time, even if the local real-time clock itself is highly inaccurate. As long as your local clock is not highly erratic, this should allow keeping accurate time for some time even if your upstream time source becomes unavailable for any reason. Some NTP client implementations (probably most ntpd daemon or system service implementations) do this, and others (like ntpd’s companion ntpdate which simply sets the clock once) do not. This is commonly referred to as a drift file because it persistently stores a measure of clock drift, but strictly speaking it does not have to be stored as a specific file on disk. In NTP, Stratum 0 is by definition an accurate time source. Stratum 1 is a system that uses a Stratum 0 time source as its time source (and is thus slightly less accurate than the Stratum 0 time source). Stratum 2 again is slightly less accurate than Stratum 1 because it is syncing its time against the Stratum 1 source and so on. In practice, this loss of accuracy is so small that it is completely negligible in all but the most extreme of cases. Have something to add to the explanation? Sound off in the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.

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