Wikipedia:Reference desk/Computing

Welcome to the computing section
of the Wikipedia reference desk.

skip to bottom

Select a section:

• Computing
• Entertainment
• Humanities
• Language
• Mathematics
• Science
• Miscellaneous
• Archives

Want a faster answer?

Main page: Help searching Wikipedia

   

How can I get my question answered?

• Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
• Post your question to only one section, providing a short header that gives the topic of your question.
• Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
• Don't post personal contact information – it will be removed. Any answers will be provided here.
• Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
• Note:
  • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
  • We don't answer requests for opinions, predictions or debate.
  • We don't do your homework for you, though we'll help you past the stuck point.
  • We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

• The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

See also:

• Teahouse
• Help desk
• Village pump
• Help manual

January 7

Compiling applications for NT4 MIPS?

So, I have Windows NT 4.0 running on a MIPS Magnum R4000. Now as you might know (and as the article says), there are very few applications for NT4 MIPS, so I have internet connectivity but no web browser to begin with (except IE2, which doesn't really work). Now, I do have Visual C++ 4.0 - I wonder if that could become any useful in compiling applications? Or is it not worth bothering? -- Prince Kassad (talk) 02:49, 7 January 2011 (UTC)

What is your objective? C and C++ code will compile for MIPS, but the architecture is sufficiently different that any reasonable application (like anything with a GUI) will be non-trivial to port. *nix has great support for MIPS, and your workstation in particular can run BSD and Linux. But what is your objective? A low-end $25 consumer digital camera has a more powerful MIPS core, probably with more RAM, higher-resolution LCD, and more modern peripheral buses than your Magnum; so if you're looking at hacking up some MIPS code, you might refocus your effort. If your goal is hobbyist recreation of the historical platform, it'd be a bit out of place to port modern software to the Magnum. Maybe you could port Android to it - there's a free documentary/webinar available through the MIPS website to train you up on that. Nimur (talk) 03:56, 7 January 2011 (UTC)

I'm not sure if Visual C++ had cross-compilers. Do you have a native MIPS version? The Windows APIs have changed a lot since NT 4.0... Lots of GUI apps indeed will be hard to recompile even if you have a working cross-compiler, so I generally agree with Nimur's recommendation to drop NT and try out something more modern (NetBSD in particular is a great OS that supports a dizzying array of platforms). But if you insist, the usual route I've gone when working with odd platforms is to first get a modern compiler and toolchain (e.g. gcc and friends) running, then from there try to build apps. Assuming that can get a MIPS cross-compiler, you should be able to cross-compile a small compiler, then use that to bootstrap gcc (which might require a couple other things like a shell, lex/yacc, etc. See the MinGW project for a ready-made set of packages you can start fiddling with. The MinGW folks might still have some people around with some knowledge about cross-compiling for MIPS, so their user groups may be a good help. Once you have the basic MinGW pieces in place, you can start compiling bigger packages like X11, and from there, Firefox and other tools that you're accustomed to using. If just using the machine is your goal, though, it's probably easier to use something like NetBSD where they've already gone through all the trouble of building you a userland. Then all you need to do is download and build the things you need. —Preceding unsigned comment added by 128.12.174.253 (talk) 03:44, 8 January 2011 (UTC)

Is this spam/a virus?

I got an email without a heading from someone I trust. I don't think she ever sends emails without a heading, and even more puzzling is that all it contains is a URL. Apparently the website is from France; I can provide the URL if needed. I don't see why someone would send and email with nothing but a URL; is it some kind of spam or is it a website with a virus/worm/whatever? Kayau Voting IS evil HI AGAIN 05:49, 7 January 2011 (UTC)

Yes, it is. I get such emails, too. I suggest you reply back to them to let them know their computer is infected, and likely everyone in their address book is now getting SPAM. StuRat (talk) 05:56, 7 January 2011 (UTC)

Thanks, I have. Kayau Voting IS evil HI AGAIN 06:20, 7 January 2011 (UTC)

Note that it is incredibly easy to forge the From: address of an email. This is rather common with spam messages. There is a possibility that the email did not come from her computer at all, but was instead sent from some other computer with a forged from: address. -- 174.21.250.227 (talk) 16:54, 7 January 2011 (UTC)

It could also have been that her email was hacked, so in that case you might want her to get her to change her password after disinfecting/removing the malware or virus. Chevymontecarlo 19:47, 7 January 2011 (UTC)

Sorry if I'm pointing out the obvious, but the advice from 174.21.250.227 implies that it is important to write a separate email to your friend, and not to reply to the email directly. That reply might go to the originator of the spamming scheme, and provide them with your email address. A follow-up question to the other refdeskers: might there be additional damage done by replying to such an email, like malware installation on your computer? --NorwegianBlue ^talk 10:23, 8 January 2011 (UTC)

Phew... I replied the email, and she said she did not send it. So (fortunately) it was not what 174 said. Thanks, everyone. Kayau Voting IS evil HI AGAIN 13:39, 8 January 2011 (UTC)

I don't think you understood what I wrote. The From: address on an email is exactly like a return address on a letter. Although most are labeled with the address of the person who sent it, there's not physical or technical prohibition that it *has* to be that way. If you know how to do it, you can substitute any address and any name, and the mail system will accept it without question. If her address was forged by a third party, your friend *wouldn't* have sent it.

The email system works like this: Your friend uses the email program on her computer to send a message through her email provider (ISP/Gmail/Hotmail/etc.), which then passes it through the internet, where it is accepted by your email provider, which sends it to the email program on your computer, where you read it. There's only a limited amount of security at any point in that path. At any point in that system, a third party spammer could break in an send a spam message. (1) They could install malware on her machine which sends the message without her. (2) They could hack into her email account, and send the message without her or any of her computers being involved. (3) They could spoof the from: address ("Hi Kayau's email provider, I have a message for Kayau from (friend)" "Okay, stranger who I have never seen before, I will trust that it's from (friend), even though you have no proof it is."), and send the message without her, her computers or her email provider being involved in any way shape or form. Due to the way the email system is set up, this can happen even if you use the same email provider. Mail systems will accept internet-originated messages even if the from: address indicates they should have originated internally. (4) Technically they could do something with your email provider/account/computer, but that's very unlikely. Most spam messages happen by (3). The spammer just inserts a random from: address so people can't track who's really sending the message, and doesn't have anything to do with the person who is supposedly "sending" the message. As you know her, it's likely the spammer is aware of the fact you email each other, so probably has her address book, which means (1) or (2) are more likely than (3) (but (3) is still possible).

Finally, the point of forging the From: address is that it hides who sends it. There isn't any secretly encoded "real sender" information, so if you do reply to the message, the reply will go to the account it says on the From: line, not the person who actually sent it. (Caveat, there is also a Reply-to: line, and if set, the reply will go to the Reply-to: address, rather than the From: address. This could be the real sender, but it would somewhat defeat the purpose of forging the From: address.) I can think of no practical situation where replying to an email will harm your computer. (If there are executable attachments, and you run them, that may infect/harm your computer, but most email programs shouldn't open attachments just because you reply.) Replying to spam is usually bad because by replying you inform the recipient that your account is active, but your message will only be sent to the addresses on the To: CC: or BCC: lines. If they're all people you know, the spammer has no way of receiving your message. (Unless he's hacked their computers/accounts, in which case he'll get all their messages, replies or new.) That said, composing a new message is not a bad idea, even in situations where replying is perfectly safe. -- 174.21.250.227 (talk) 17:18, 11 January 2011 (UTC)

TLDR of the above; Replying to the email, rather than writing a seperate email is a bad idea. If the reply-to field is set you would just have confirmed that your email account is live, and hence worth more to spammers. This can mean that your email account will receive more spam. Nothing bad actually happens on your computer, but it's not a desirable thing anyway. Taemyr (talk) 08:59, 12 January 2011 (UTC)

What would you learn after you learned how to program?

After you went through your programming 101, learning the syntax, how to use the libraries, etc, what would you learn? I thought that UML is nice (and relatively simple, at its most basic level), but what do programmers how want to improve their skills would need to know? (specially in the field of mathematics). —Preceding unsigned comment added by 77.231.17.82 (talk) 10:33, 7 January 2011 (UTC)

You need to learn about the hardware. If you don't have a firm grasp on the hardware, you will go off and write bad code. As an example, assume you just finished officer school in the military. Now, you're off to war. You could sit in your office and hand out orders without ever taking time to see what kind of troops you are ordering around. It would obviously be better to first find out what the unit is designed to do and what the troops' specialities are. Within a computer, you are ordering around all the components. So, it is a good idea to get to know what those are, how they work, and how to get the best effectiveness out of them. Since you are considering math-related work, you will want to know the ALU very well. I also suggest studying discrete mathematics and computer algorithms (P/NP algorithms) so you don't go off and try to reinvent work others have done over and over and over - such as coming up with yet another radix sort. -- kainaw™ 15:28, 7 January 2011 (UTC)

Well, I think there are a set of things. The single most important thing a programmer needs to learn is how to work together productively with other people, but it's hard to find a class that teaches that. I would say the second thing, beyond even a knowledge of hardware, is a knowledge of project-management tools, including version control systems such as SVN and Git as well as organizational tools such as GNU autotools. In the math realm, numerical methods are very helpful, besides the things that Kainaw mentioned. Looie496 (talk) 17:25, 7 January 2011 (UTC)

It depends very much about what you want to do. But for challenging work, algorithmics and basic complexity theory are very important - the first both to show you what methods are available, but also which techniques have been used to tackle hard stuff before, and the second to understand why you should care about good algorithms and data structures. --Stephan Schulz (talk) 17:35, 7 January 2011 (UTC)

re: "how to work together" classes... Every university that I've taught at has at least 2 semesters of required software project courses. They have different names from campus to campus, but the concept is the same. Start with the waterfall method and go through all the other popular methods of software development. Teach project management tools. Have students work in groups to complete a complex project (usually over the course of two semesters). -- kainaw™ 19:36, 7 January 2011 (UTC)

computer theory is an important next step. Other than that, CS programs in four year colleges are also usually heavy on the math. Calculus and Discrete math are usually covered. A Computer Architecture class and/or an Assembly Language class are probably in there too.

Students at four year schools tend to specialize somewhat within their degree. Students may have the choice of taking a certain number of credits in areas like databases, robotics, computer graphics, human-machine interaction, artificial intelligence, machine learning, etc.

IS all this strictly necessary? No. I'm sure there are people who make a good living having learned everything they needed "on the job", or from a "Learn iPhone programming in 30 days" type book.

One last note, while learning syntax is easy, I don't think that there is an "after you learned how to use the libraries". Any real world programming will require using a lot of different libraries from different vendors. Learning the libraries that "come with" your language of choice is only the beginning. APL (talk) 17:36, 7 January 2011 (UTC)

In most accredited university degree programs in computer science, the basic introductory course involves a class in each of the following areas:

• Computer programming basics:
  • a language primer ("Programming 101")
  • an advanced language course, ("Programming 201")
  • an algorithms and/or data structures course ("Programming 301")
• Computer science basics
  • discrete mathematics and computer-theory course
  • elementary computer architecture
  • Software engineering fundamentals
  • operating systems concepts

Beyond those classes, specialized fields of computer science, computer engineering, or software design can be pursued. Most reputable computer science programs also require extensive math training, in calculus, linear algebra, and often in differential equations. Here's a semester-by-semester breakdown from my undergraduate alma mater, North Carolina State University's computer science core curriculum. You can read a "blurb" / paragraph course overview for each of the required classes. These requirements are comparable to almost any other major university program for a Bachelor of Science in Computer Science. But you don't have to pursue "computer science" - maybe you learned to program so that you could become a mathematician, a physicist, an engineer, an economist, or any other type of career or academic track, you might follow a different route. If you like applied math, I highly recommend at least one or two solid classes in numerical methods, in addition to basic algorithms. Bear in mind that you will need to know some fairly advanced calculus in order to program a computer to compute even simple calculus correctly; the same goes for all other disciplines of mathematics. As a rule, programmers must be better at the mathematics than the machine, because they are giving instructions to the machine. Nimur (talk) 19:45, 7 January 2011 (UTC)

May I recommend Knuth's The Art of Computer Programming? It taught me all sorts of useful and interesting things, especially mathematical stuff, that my BSc in CS missed out. Marnanel (talk) 15:20, 8 January 2011 (UTC)

Task manager

If I go to the task manager on my computer, it gives to bar graphs, one for CPU usage, in percent, and the other is "PF Usage", measured in megabytes. anyone know what "PF" is? Something to do with RAM? --T H F S W (T · C · E) 19:44, 7 January 2011 (UTC)

Page file. Nimur (talk) 19:47, 7 January 2011 (UTC)

Thanks. How do I tell how much RAM my computer is using? --T H F S W (T · C · E) 19:57, 7 January 2011 (UTC)

Due to caching, the answer to that will likely be "all that is available". There is no benefit in having unused RAM. So, modern operating systems keep as much stuff in RAM as possible to avoid pulling it off the hard drive or recalculating it again in the future. -- kainaw™ 20:01, 7 January 2011 (UTC)

So in other words, almost all your RAM is being used at once, and the "overflow" is put on the page file? --T H F S W (T · C · E) 21:37, 7 January 2011 (UTC)

Yep. Of course, if your computer isn't doing much, the RAM may not be 100% in use, and the paging space will be empty. StuRat (talk) 22:17, 7 January 2011 (UTC)

On Windows, there is a special operating system file on disk, pagefile.sys, which is usually invisible. Certain portions of that file are mapped to RAM; the job of the Windows operating system's memory manager is to decide which portions, and when to swap them out. The value reported in Task Manager for "size" of the page file is not necessarily the size of the file-on-disk. (That's managed dynamically by this system setting, and varies between a minimum and maximum file-size). Task Manager is really reporting the total number of bytes that user-space programs have allocated. Those bytes may reside in RAM or on the disk in the pagefile.sys file; or in both places, with a caching policy managed by Windows. This Microsoft TechNet blog gives a good overview of the whole process. Nimur (talk) 22:36, 7 January 2011 (UTC)

January 8

Restoring a Windows XP user profile

I have a problem with a computer (running Windows XP), which is a member of a domain. After a system restore following by an undo of the restore, the user's profile is "lost". Actually it's not lost, it's still in the file system, but Windows has created a new profile for the user. When the user logs onto the domain, the user's settings are loaded from the new profile folder, not the previous one. It is in principle possible to copy the user's files from the old profile folder to the new one, but the pathname references in the user's application settings (whether in config files or in the HKEY_CURRENT_USER branch of the registry) will become invalid. What is a good way to restore the previous user profile folder for the user? —Preceding unsigned comment added by 173.49.14.169 (talk) 00:39, 8 January 2011 (UTC)

If you log in as an admin, you can use advanced system properties to copy user profiles from one user to another. This may do what you want.--Phil Holmes (talk) 11:27, 8 January 2011 (UTC)

3G

Is 3g as insecure as wifi? 62.255.129.19 (talk) 01:07, 8 January 2011 (UTC)

3G#Security; by default, probably not, but they both have the same potential security. ¦ Reisio (talk) 02:12, 8 January 2011 (UTC)

Eh, where am I?

This may be a supremely stupid question, but can the internets tell me where I am exactly? I am on a train and have absolutely no idea. Is there some service for triangulation of signals or some shit? 78.40.152.129 (talk) 09:00, 8 January 2011 (UTC)

Is Google Latitude what you had in mind? Dismas|^(talk) 09:04, 8 January 2011 (UTC)

Possibly, but seems to only work for mobiles? I'm working off a laptop... 78.40.152.129 (talk) 09:18, 8 January 2011 (UTC)

If you're using your laptop on a train, then it's using a mobile phone signal which can be triangulated. Another option would be to get a cheap GPS navigation device which is not dependent on a mobile phone signal.--Shantavira|^{feed me} 10:16, 8 January 2011 (UTC)

Most trains offer WiFi nowadays. Presumably the train gets it from a satellite connection or something, but I'm not sure you'd be able to geo-locate that.

Surely the best way to pin-point your position would be to estimate your speed and the time since you left the last station? APL (talk) 22:08, 8 January 2011 (UTC)

Congratulations, you made it to the UK in less than 4 months. -- 78.43.71.225 (talk) 22:09, 8 January 2011 (UTC)

What is Binary Package?

In many of the Linux distros, there are Binay Packages available to be downloaded. What are these Binary Packages? How can they be used? —Preceding unsigned comment added by 122.164.51.244 (talk) 09:32, 8 January 2011 (UTC)

Computer programs exist in at least two forms. They are generally written by humans in various specialised languages. This form is called "source code". It cannot generally be used directly by a computer. Then they are passed through another program called a "compiler" to produce code which can be used by a computer. This form is called "binary" (for historical reasons; it has little to do with the number base). Linux distributions are free software, which some call open source, and are therefore required to offer you not just the binary forms of the programs but also the source code. This is useful for programmers because they can modify the program to do what they want more exactly. If you are not a programmer, the binary packages are the only packages you are likely to need. Marnanel (talk) 15:12, 8 January 2011 (UTC)

You could be talking about a few different things.

There are distributionss whose package management systems are aimed at building of source directly to make the compiled, binary files for a computer to run (these typically exclude programs written in interpreted languages, but often not the interpreters themselves); source code is often distributed in some form of tarball, or copied directly from a VCS. This approach gives an advantage in the ability to customize, and availability of current code.

For most distros, however, the bulk of binaries are built by developers to ensure a certain quality/continuity, and then distributed to end users — they basically end up merely copying a program to where it should be on a system, and it's ready to run. This has the obvious advantages of being fast and reliable, particularly for those unfamiliar with compiling source code (which is most people).

Distros following either approach can utilize the other approach also, but usually only one is preferred.

There are also .bin files and the like, which are usually built and distributed by upstream and not by distribution maintainers, usually for the purpose of protecting a certain quality in their product, or because the package contains non-"free" parts, or for a perceived "ease" of installation, or any of the above, etc..

¦ Reisio (talk) 15:14, 8 January 2011 (UTC)

The binary packages are the packages that contain the program's executable file, as opposed to containing the source code. If a package in the repository is not identified as a source package in its description, then it is a binary package. Unless you are a programmer, binary packages are the only packages you should worry about. --Nat682 (talk) 18:54, 11 January 2011 (UTC)

Video

I have a video encoded in h264 at 5fps. I need the video to be 25fps, but I want it to remain the same speed and duration. What Windows programs (preferably free) can do this? 82.44.55.25 (talk) 14:51, 8 January 2011 (UTC)

It sounds like you want to do tweening to fill in the missing frames. I can tell you right now that this isn't going to look very good, with 80% of the frames being made to fill in the gaps, because there's just not enough "information" to start with. I think 50% or fewer frames "tweened" in this way might look OK. StuRat (talk) 15:03, 8 January 2011 (UTC)

Yes, that's exactly what I want. I'm not too worried about quality 82.44.55.25 (talk) 16:15, 8 January 2011 (UTC)

FFmpeg can do this sort of video conversion. Graeme Bartlett (talk) 20:45, 8 January 2011 (UTC)

ffmpeg can adjust the frame rate of a video, but only by duplicating or dropping frames, not interpolating. In this case each frame would be followed by 4 exact copies of itself, so the result played at 25fps would exactly like the original at 5fps, not smoother. ffmpeg is too simple for such a complex job. 67.162.90.113 (talk) 22:28, 8 January 2011 (UTC)

You could use FFmpeg to dump to JPEGs (ffmpeg -i foo.h264 %d.jpg), then use ImageMagick (and a for loop) to make filler frames morphed from adjacent ones, then FFmpeg again to go from JPEG to <insert video format of choice>. ¦ Reisio (talk) 03:47, 9 January 2011 (UTC)

How to make a "clean link" to a video on youtube.com ?

Resolved

When I have found a really nice video at youtube.com, that I want my friend to see, how do I link to it in a "clean" way?

I want to send my friend a link to a webpage where the video may be seen, but I do NOT WANT want ANY of the "suggested further viewing"-links that youtube.com automatically adds around, below and following all the videos.
(What I have got is a URL looking like this:
http://www.youtube.com/watch?v=STRING
What I want is some "clean" URL based on the same STRING ).

The reason why I don't want it, is that I have no control over those suggestions and they will often totally destroy an otherwise pleasant viewing experience.
Or they may slightly frame the video in such a way that it distorts or adds a subconsciously perceived intention behind my sending of the link.
Is there any way out of this problem? --178.232.73.66 (talk) 18:22, 8 January 2011 (UTC)

There's an icon third from the right that looks like the traditional maximize window icon, if you hover over it, it says 'Pop out'. Also if you hit the 'Embed' button underneath the video, the value of the src attribute of the embed element or the value of the value attribute of the param element with name attribute with value 'movie' (they are the same/redundant) will work as a fullscreen link of the Flash player with video only. You will of course still get suggestions when playback finishes. ¦ Reisio (talk) 18:28, 8 January 2011 (UTC)

Like this http://www.youtube.com/v/QQrWTQBZPo4 Replace "QQrWTQBZPo4" with the video id of your choice 82.44.55.25 (talk) 18:30, 8 January 2011 (UTC)

Yes, (thank you!) a link on the form: http://www.youtube.com/v/STRING is very close to what I wanted, but I really want to avoid ALL the suggestions about further viewing that, now, still pops up below my video after it is finished runnig through the first time.--178.232.73.66 (talk) 19:11, 8 January 2011 (UTC)

I found a way; append &rel=0 to the end of the url, eg: http://www.youtube.com/v/STRING&rel=0 82.44.55.25 (talk) 19:20, 8 January 2011 (UTC)

Perfect! Thank you! :-) --178.232.73.66 (talk) 20:41, 8 January 2011 (UTC)

Restoring iPod touch Firmware without iTunes

Is there any way that I can restore my iPod touch's firmware to an arbitrary version, bypassing the SHSH signing process—in other words setting my iPod touch to any firmware version in such a way that iTunes is not used? --Melab±1 ☎ 19:31, 8 January 2011 (UTC)

QIF to CSV conversion

Is there any free straightforward offline (not online) no-hidden-catch way of converting the QIF format to comma separated values please? OpenOffice cannot do it. Thanks. 92.15.7.205 (talk) 20:37, 8 January 2011 (UTC)

Other than checking the obligatory http://www.google.com/search?q=%22qif2csv%22, this looks half promising (sorry if you don't Perl, you should! :p). ¦ Reisio (talk) 04:31, 9 January 2011 (UTC)

BBC

According to this one needs a tv license to watch live programs on the iplayer, per "Anyone in the UK watching or recording television as it's being broadcast or simulcast on any device - including mobiles, laptops and PCs - must, by law, be covered by a valid TV licence." That seems pretty clear, and the iplayer site warns you when you start to watch. However, what is the policy concerning the news section of the bbc site offering a live broadcast of breaking news, for example the live BBC News coverage of the US Congresswoman shooting? There is no mention on that page that one needs a license, nor is it part of the iplayer section. They're also enticing people to watch it with big banners across the news section saying "Watch live!". —Preceding unsigned comment added by 91.146.188.190 (talk) 22:30, 8 January 2011 (UTC)

Are you interested in knowing the policy, or viewing the programs? If the latter, there are so many ways to do so from anywhere, you need only seek out the solutions. ¦ Reisio (talk) 04:32, 9 January 2011 (UTC)

And if the former, we don't give legal advice... AndyTheGrump (talk) 06:51, 9 January 2011 (UTC)

It's not legal advice to ask why some policies look inconsistent, or to ask about the relative application of laws. There is no request for legal advice in the above whatsoever. --Mr.98 (talk) 14:46, 9 January 2011 (UTC)

I would imagine its because the iPlayer is available to UK users and people who pay a subscription outside the UK only, whereas the news site is available for free internationally. This requires different T&Cs. -- Q Chris (talk) 09:58, 10 January 2011 (UTC)

radiant

ben bu bılgısayar sıstemınızden sipariş vermek istiyorum ş yerım ıcın bana bu konuda yardımcı olur musunuz —Preceding unsigned comment added by 88.226.180.103 (talk) 22:53, 8 January 2011 (UTC)

Google translate (from Turkish): "Job I'd like to place an order for the location of this computer system helps me to do about it". Not very helpful... AndyTheGrump (talk) 23:00, 8 January 2011 (UTC)

http://tr.wikipedia.org/wiki/Ana_Sayfa. AndyTheGrump (talk) 23:03, 8 January 2011 (UTC)

Radiant Systems? 213.122.40.179 (talk) 01:44, 9 January 2011 (UTC)

January 9

Could intermediate networks alter my data?

If I do a traceroute to Wikipedia I see that the connection goes through several seemingly unrelated networks before reaching "ge-2-2.br1-knams.wikimedia.org". To simplify things for my question, lets assume it's just;

- myisp.org
- somenetwork.net
- wikimedia.org

I assume my http requests, ip address, and other info are sent to each link along the connection? What verification checks are in place (if any) to ensure that one of the links doesn't corrupt or alter the info either by accident or on purpose for some nefarious reason? For example, "somenetwork.net" receives my ip as 82.44.55.25 but sends my ip as 12.34.56.78 to wikimedia.org. Is such a thing possible? Would wikimedia.org see 12.34.56.78? 82.44.55.25 (talk) 22:05, 9 January 2011 (UTC)

Unless you use the https link to wikipedia there is no such guarantee. Dmcq (talk) 22:16, 9 January 2011 (UTC)

So if I owned "somenetwork.net" I could make it appear as though I had any ip address I wanted? 82.44.55.25 (talk) 22:28, 9 January 2011 (UTC)

You are making the assumption that your request and the response are all in one packet. See TCP/IP model for a better idea how internet traffic works. -- kainaw™ 22:31, 9 January 2011 (UTC)

Also see man-in-the-middle attack, which is what it's called when there's an attacker controlling some part of the path between you and the entity you're trying to communicate with. 67.162.90.113 (talk) 23:41, 9 January 2011 (UTC)

They could mess with your data just like food distribution companies could mess with your groceries. Your ISP pays a bigger ISP for bandwidth which it subdivides among its customers, that ISP gets its connection from an even bigger ISP, and so on. Eventually (usually very quickly) this tops out at the tier 1 network providers, which own the physical world-spanning cables. Your route to Wikipedia goes up your ISP chain to the tier 1 providers, then down Wikipedia's ISP chain to their datacenter. These big ISPs don't want to corrupt your data packets because that wouldn't maximize shareholder value. Whether somebody is eavesdropping on the connection is another matter; probably many governments have arrangements with the tier 1 providers to give them access to the traffic. -- BenRG (talk) 09:40, 10 January 2011 (UTC)

Actually, forget the grocery analogy. A much better analogy is UPS or FedEx. If you track your package through their system you'll see it percolate up to a major hub, then possibly to a different one, then back down the hierarchy. They have internal measures in place to prevent damage/tampering because it would undermine their business. And governments inspect the mail of people they've placed under observation.

On the other hand, if you use Tor then your traffic can be sniffed and modified by the random unaccountable people who run Tor exit nodes, and apparently some of them do try to conduct MITM attacks on SSL (HTTPS) connections. (You're safe from this attack as long as your browser validates site certificates, which the major ones all do.) -- BenRG (talk) 01:52, 11 January 2011 (UTC)

It is technically very possible for someone in the middle to alter the data without the endpoints noticing. The only protection against that is an authentication scheme. Https, IPSEC, and similar protocols provide some protection against this if done correctly. Note that authentication here is different than encryption, although a good encryption system will almost certainly have authentication (the opposite doesn't have to). Shadowjams (talk) 00:30, 11 January 2011 (UTC)

What OP are describing is routinely being done. See Network address translation. It's beeing done in order to use local adresses on your LAN and only have a single public IP adress. This is needed because there are too few IPv4 adresses. But you can't use it to show any IP adress, because you need to use IP adresses that actually gets routed to your network. Taemyr (talk) 08:54, 12 January 2011 (UTC)

January 10

3g video calling architechre

hi,

i need to know about the 3g video calling with the call routing architecture. please let me know at the earliest. —Preceding unsigned comment added by 182.71.230.217 (talk) 08:18, 10 January 2011 (UTC)

how to Assign Structure Address

Hi,

I have doubt in C structure. That is how to assign structure address manually not default. Just i write one example structure,

struct ADC
{
 int A;
 int B;
}REG1,REG2;

when i compile the above structure defualt address in assigned like 8100,8101.. somethinglike that. I am using 16-bit processor. so that same code i want to use my address like 8000,8001,8002,8003... I know very well structure memory is stored in contiguous memory location. so that how to assign structure(ADC)starting address is 8000. Can anyone help me to solve this issue?

THANKS & REGARDS, M.ANTONY PRABHU

Try this:

struct ADC
{
 int A;
 int B;
} *REG1 = (struct ADC *) 0x8000;

-- BenRG (talk) 14:01, 10 January 2011 (UTC)

Is it possible to do without pointer? Is possible to use preprocessor to assign address? —Preceding unsigned comment added by 192.8.222.82 (talk) 06:40, 11 January 2011 (UTC)

Your compiler may have a special syntax to do what you want. Check the documentation. Here's an example. -- BenRG (talk) 09:58, 11 January 2011 (UTC)

cmd capture

Is there an easy way to capture and save an image from a webcam via the command prompt in Windows? 82.44.55.25 (talk) 15:28, 10 January 2011 (UTC)

Number of unique colours in a digital photograph

I would like to identify which of these images http://www.google.co.uk/images?hl=en&expIds=0&xhr=t&q=flowers+spring+road&cp=18&um=1&ie=UTF-8&source=og&sa=N&tab=wi&biw=1024&bih=609 is closest to the original photograph. Inspecting them with Irfanview, they differ in their number of unique colours. Am I right in thinking that the image with the highest number of unique colours is most likely to be closest the original photo? I expect that when they are reduced in file size as preperation for including them on a website, the reduction in file size includes reducing the number of unique colours. Thanks 92.15.21.144 (talk) 15:35, 10 January 2011 (UTC)

Reducing the dimensions of a picture nicely (i.e. not using nearest-neighbour sampling) will potentially increase the number of unique colours, since nearby pixels are averaged, although it will also potentially decrease the number of unique colours simply because there are fewer pixels available to be any colour at all. Scaling a picture up nicely will likewise increase the unique colours, though it will be more blurry. These images are jpegs, and the way to reduce the file size of a jpeg is to increase the compression. In a palette-indexed image such a GIF or certain kinds of PNG, the number of colours can be reduced directly to make the file smaller. Jpegs don't work that way. They produce small file sizes for images containing smooth gradients, for instance. Their compression is achieved by reducing the level of detail (frequency) of the image. It might incidentally be the case that a more compressed jpeg contains fewer unique colours than a less compressed one, due to the loss of colours contained in some small details, but I wouldn't rely on it. 81.131.24.192 (talk) 16:02, 10 January 2011 (UTC)

I know this is nitpicking, but I believe the word you want is "distinct" or "different," not "unique." The word "unique" means "one-of-a-kind." —Bkell (talk) 16:47, 10 January 2011 (UTC)

You're absolutely right - that is nitpicking. :D Seriously, "unique" gets used that way all the time, and the OP is just quoting from a dialog box displayed in Irfanview. The colours are one-of-a-kind if we limit the context to the image. The opening words of Unique identifier are "With reference to a given (possibly implicit) set of objects ..." 81.131.33.9 (talk) 18:04, 10 January 2011 (UTC)

Yes, I know that the word "unique" is used that way all the time, but "unique" doesn't mean "distinct." :-) The colors in an image aren't unique—each one is probably assigned to many different pixels. A unique identifier is assigned to one and only one object. That's what makes it a unique identifier. —Bkell (talk) 06:06, 11 January 2011 (UTC)

Oh, fair point. *Strokes chin* 81.131.69.118 (talk) 06:36, 11 January 2011 (UTC)

Possibly depends upon if you mean "unique pixels" or "unique colours" for the set of pixels. 92.24.181.78 (talk) 15:07, 11 January 2011 (UTC)

So the "number of unique colors" to quote Irfanview, not my choice of words, is not any use in trying to guess which jpg image has been the least mucked around with? I was thinking of suggesting the ratio number-of-different-colours divided by number-of-pixels as an approximate metric or proxy for the quality of an image, but that's out.

Is there any way of deciding objectively which is the least-blurred best quality image? Thanks 92.15.3.168 (talk) 20:27, 10 January 2011 (UTC)

The "less blurred" image will have more high frequency data. You can perform a 2-D fourier transform, using free software like GNU Octave, to analyze that. However, you should know that digital image manipulation can be very complicated. It could add or remove unique colors, high frequencies, and so on. So strictly from these metrics, it's not really possible to say which image is closer to the "source." If we had a known, canonical source image, we could estimate which of the other images are more processed than others by comparing to the original; but it's not generally possible to directly conclude which image is the original based solely on statistical analysis of image characteristics. Nimur (talk) 22:40, 10 January 2011 (UTC)

The largest image you find has the best chance of most accurately matching the original. In an ideal case, an image would have EXIF metadata attached to it that would tell you how it was created, but none of the ones there that I looked at have any. Looie496 (talk) 22:56, 10 January 2011 (UTC)

Not really, people often increase the size and you just get a large but blurry image. 92.15.3.168 (talk) 00:47, 11 January 2011 (UTC)

I will have to try an experiment with increasing and decreasing the size of a test image to see what effect that has on the number of different colours and also the ratio described above. 92.24.190.219 (talk) 00:11, 12 January 2011 (UTC)

Non-English glyphs in programming

Do they get any use? Plenty of common keywords (e.g. continue) are English, but does that mean the convention is to write in English throughout, even if you come from, say, Sweden, or would it be normal for such a programmer to name a function " räkna() " ? (I particularly want to know about the use of glyphs with diacritics, like ä, not the use of non-English words.) 81.131.33.9 (talk) 18:15, 10 January 2011 (UTC)

Either the compiler/interpreter can parse them or it can't. Easy to find out on your own. ¦ Reisio (talk) 18:16, 10 January 2011 (UTC)

That's not really my question - I'm asking about common usage. It's because I'm designing a font, and want to know whether to bother putting them in or not. Edit: actually I know what to do - of course they must go in, because even if they're not used in identifiers, they'll still appear in various string literals. (Mind you, I'm still kind of curious about the original question.) 81.131.33.9 (talk) 18:20, 10 January 2011 (UTC)

Yes, the convention is to write in English throughout, except in a few rare non-English-based programming languages. Marnanel (talk) 18:38, 10 January 2011 (UTC)

Actually, in my (admittedly rather limited) experience, programmers won't hesitate to write identifiers (and comments) in their native language, though they will omit the diacritics (because usually these are not allowed by the language specification). Source code intended to be publicly released to the wider world is generally an exception.—Emil J. 19:05, 10 January 2011 (UTC)

Fantastic find :) 81.131.33.9 (talk) 19:32, 10 January 2011 (UTC)

Recently-designed languages like Java explicitly allow non-ASCII characters in identifiers and string literals (and of course in comments). Modern compilers for older languages like C understand non-ASCII encodings, but people tend to avoid them for portability reasons. Comments are likely to contain non-ASCII characters in any case because compilers that don't understand character encodings will usually skip over unknown bytes in comments. I've seen a fair amount of code with Japanese (Shift-JIS) comments and everything else in ASCII. -- BenRG (talk) 21:33, 10 January 2011 (UTC)

I'm not a programmer, but I do write some code occasionally, and I sometimes (but not too often) use my native language - for one thing, it is less likely that a given word I want to use have a reserved meaning in the programming language I use (which I tend not to be perfectly fluent in). But I never ever use native letters - I think most computer users from Scandinavia at least get used to replace the native letters (jørgen --> jorgen) because it leads to far less problems, even if the language / operating system supposedly supports them. There's always a complication someone hasn't thought of. For programming languages, it could for example be the encoding of the relevant text file. Jørgen (talk) 19:31, 10 January 2011 (UTC)

That's valuable anecdotal information, thank you. 81.131.33.9 (talk) 19:39, 10 January 2011 (UTC)

Java allows arbitrary Unicode as its input, though it also provides an escape sequence mechanism to represent arbitrary Unicode characters without having to actually include them in the source (where they might cause grief for text editors, printers, etc.). C99 allows similar escapes (that it calls "universal character names"), and allows implementations to interpret identifiers and strings with whatever encoding they like. Python requires its input to be ASCII but allows a "coding declaration" to affect the interpretation of string literals only. So whether non-ASCII characters are common in source code (literally rather than by escape sequences) surely depends on which programming community you mean. It is also undoubtedly true that programmers concerned about the confusion that can arise when non-ASCII code is shared between different systems (some of which might not be 8-bit clean, or might assume different encodings) will prefer ASCII even when writing in other languages. --Tardis (talk) 21:18, 10 January 2011 (UTC)

Haskell users seem to be considerably more willing to stray far from ASCII than do programmers in other languages (its native input is, like Java's, natively unicode - I think utf8). In particular, it's fairly common to define operators using characters from the greater mathematical alphabet - so e.g. you get code like test "-a+b*c≡d⊕!(c∧d)" (source). Equally, as a purely functional language beloved of academics, it's often written as if its code really was mathematical notation, so one often sees non-ascii character (particularly Greek) used, much as they are in math in general. 87.115.125.162 (talk) 21:37, 10 January 2011 (UTC)

Same for Racket (I think there are probably other Schemes that support Unicode). I recently discovered the tex input-mode in Emacs and went a little crazy in my last project. Paul (Stansifer) 22:50, 10 January 2011 (UTC)

What is the efficiency of human sorting?

...or phrased slightly differently, what sorting algorithms do humans tend to use, and what are their efficiencies? I suspect the answer will depend a lot on the items that are to be sorted, so I'll present the example I'm particularly interested in, the sorting of sample tubes at a laboratory. The tubes are numbered (long numbers, say 9 digits). The numbers come in different series with the same three leading digits (six series, say), and may or may not arrive partially sorted. Sometimes they arrive in racks where each rack is partially sorted. I read the article Sorting algorithm, which states that a good algorithm has a complexity of ${\mathcal {O}}\left(n\log n\right)$ and a bad algoritm is ${\mathcal {O}}\left(n^{2}\right)$.

How will a human perform, in the setting I described? Guesstimates are welcome, pointers to relevant empirical studies even better.

Thanks, --109.189.66.11 (talk) 19:59, 10 January 2011 (UTC)

When I've taught algorithms class, I task 3 to 4 students with sorting short, medium, and long lists of items (sometimes numbers, sometimes words, sometimes sort on height or size). My experience is that humans use an insertion sort or bubble sort for short lists. When the list gets long, they tend to use a bucket sort to get it partially sorted and then an insertion sort on the shorter lists. There is a problem with identifying efficiency in computer standards. A human is capable of viewing more than one item at a time. So, insertion sort on small lists is O(n). For example, sort 4, 9, 2. You can see all three numbers at once and instantly note that 2 is the smallest. Then, you can see both 4 and 9 at the same time and note that 4 is the smallest. That leaves 9. A computer would have to look at each number, one at a time, to see that 2 is the smallest. Then, it need to look at the 4 and 9 separately to note that 4 is the smallest. If a computer was capable of looking at more than one number at once and perform a comparison on all numbers against all other numbers all at the same time (the way humans do), sorting would be much faster in computers. -- kainaw™ 20:23, 10 January 2011 (UTC)

(EC) Maybe it's obvious, but I'll point out that many of the linked sorting algorithms are useful for humans sorting physical objects too. For instance, I've used a truncated merge sort for sorting student assignments. I imagine it would work well for your tubes, provided you have plenty of cache space. SemanticMantis (talk) 20:30, 10 January 2011 (UTC)

Thanks! Bubble sort and insertion sort are O(n²), merge sort is O(n log n). If the number of samples is doubled, is it safe to assume that the number of man-hours needed to do the job should be somewhat less than the square of what it was before the number of samples was doubled? --109.189.66.11 (talk) 20:44, 10 January 2011 (UTC)

As Tardis said below, those big-O times are based on assumptions about the speed of the primitive operations that don't necessarily apply to sorting of physical objects. -- BenRG (talk) 22:48, 10 January 2011 (UTC)

(edit conflict) If you know that there are only a small number of "series" (six, you suggested), you'll use bucket sort or one of its many variants (MSD radix sort or postal sort or so). If sorting something like a deck of cards where the total is known and every card's position in the result is known, you can use a trivial tally sort that barely counts as a sort at all. These are not comparison sorts and so the usual ${\mathcal {O}}\left(n\log n\right)$ rule (namely, that all good sorts have that complexity) doesn't apply.

One trick that humans can often use is that shifting physical objects can be much more efficient than shifting data: you can shove a line of books down a shelf to make room for another in their midst, and if you're strong enough it doesn't take any longer no matter how many you're moving. This makes insertion sort pretty efficient in the physical world even though it's a "bad" algorithm in the standard sense. Heuristics allow that to be applied even when there are multiple shelves each of a fixed size: "allocate" more shelves than will be needed in the end, and then almost all of them will retain some empty space throughout so that you can do the shove-insert trick. Then you can pack the shelves (if desired) at the end in linear time.

Anecdotally, I recently wanted to sort about 200 CDs into racks that had discrete slots (so that I really had to treat them like a computer would); I very consciously used merge sort between various piles of CDs on the floor (with the last merge "writing" into the racks). Of course, since I know the standard sort algorithms, perhaps I'm not useful evidence for what "humans tend to use".

You might also be interested in physical computation (which is unfortunately a redlink): algorithms that rely on physical processes other than the usual read/write/address of the Turing machine. Quantum computing gets lots of attention, but there are surprisingly efficient ways to use even the classical world to do what you might call computation: spaghetti sort, for instance. Unfortunately, I'm having trouble finding other good references on physical computation (variously called {physical|analog} {computation|algorithms}). --Tardis (talk) 21:00, 10 January 2011 (UTC)

Another factor to consider is whether a single human or more will be doing the sorting. The multiple human case mimics parallel processing in computers. For example, one person could do a bucket sort, as Tardis said, where they divide the pipes up into, say, 6 series of pipes. Others could then sort those buckets, by using an insertion sort, and wouldn't need to wait until the first person finished his sorting. If there's just one human doing the sorting, though, perhaps an insertion sort right away makes sense (although there may still be 6 lines ("buckets") of pipes laid out, but he would put each in it's proper position in each "bucket", immediately, and not just pile them up for later sub-sorting). StuRat (talk) 21:47, 10 January 2011 (UTC)

I remember reading somewhere that most humans did insertion sort methods on lists up to a certain size, and then switched to various divide and conquer style sorts. This book (ISBN 0596155891 page 208) says "Humans naturally resort to a divide-and-conqueror algorithm" but it's referring to a specific kind of problem. I'm having trouble finding papers on that, but I'm sure someone's researched that question. Shadowjams (talk) 00:27, 11 January 2011 (UTC)

Thanks, everyone! --91.186.78.4 (talk) 09:24, 11 January 2011 (UTC) (OP from different PC)

LC220EM1 emerson does not turn on

We have an Emerson LC220EM1 from Walmart. It was working fine until last night. This morning, it just quit working. The power button does nothing and I just don't see any signs of life in it. Any ideas on what I can do for troubleshooting? Thank you much. Kushal (talk) 21:04, 10 January 2011 (UTC)

For anybody else who is wondering, that model is a '22" Class LCD 720p 60Hz HDTV'. --LarryMac | Talk 21:12, 10 January 2011 (UTC)

Thank you, LarryMac. I can't find the receipt although it has only been a few months since we bought it. Kushal (talk) 21:23, 10 January 2011 (UTC)

The Emerson website links to the Funai website, which offers this handy tip - "Try unplugging the unit for about 5-10 minutes, then plugging it back in. You may also want to try a new outlet. " and now I feel like part of The IT Crowd --LarryMac | Talk 21:26, 10 January 2011 (UTC)

Thank you. I tried it with no success. Any other ideas? Kushal (talk) 23:50, 10 January 2011 (UTC)

No receipt at all? Even so, it should still be covered by the manufacturer's warranty (usually a year for things like TVs). Try talking to the store first, but failing that contact the manufacturer (or their representative in your country). That said, if you can definitely diagnose the problem as being with the on/off switch and not somewhere else in the power supply chain, they are quite easy to replace yourself, if you can get the part and are handy with a soldering iron. Astronaut (talk) 12:30, 11 January 2011 (UTC)

I'll try talking to Walmart tomorrow. I didn't get the tv myself. It was a rather impulse buy (and I should probably stop there). Any ideas how I can contact Emerson's representative for the US? Thanks Kushal (talk) 02:53, 12 January 2011 (UTC)

Comprehensive Scrabble word list needed

I would like an official Scrabble word list I can download. I did a Google search, but only found partial dictionaries, such as those excluding naughty or long words. My requirements:

1) Should be the North American version of English word spellings.

2) Should be free.

3) Should ideally be sorted alphabetically, but I can sort them myself, if I must.

4) Should be a readable text file, ideally, with one word per line (I don't want various forms of the word on the same line, for example).

5) I would think it would all fit in one large file, but I could also take, say, 26 files (for words starting with each letter).

I would like to write my own Scrabble solver, and need this to get started. Also, there's a game similar to Scrabble called QWERTY (Pogo has it), and I'd like the same thing for that, since they use a slightly different dictionary. Thanks for your help ! StuRat (talk) 21:30, 10 January 2011 (UTC)

How about this one? [1] - it's not a raw text file with one word per line, but turning it into one shouldn't be very hard. (I found this via the search string "aardvark aback abacus abaft abalone abandon abandoned abase abash abate abatement abatis abattoir abbacy abbe abbess abbey abbot abbreviate abbreviation abdicate abdomen abduct abeam abecedarian".) 213.122.53.182 (talk) 22:31, 10 January 2011 (UTC)

As for point 1, British spellings are allowed even in North American Scrabble. If you intend to disallow "COLOUR", you're more strict than any official rule set.

If you google "TWL06", you should get what you need, including a link to the wikipedia article Official Tournament and Club Word List which is another way to find it. 67.162.90.113 (talk) 22:35, 10 January 2011 (UTC)

Yes, that worked. I found this, which seems to be just what I need. Thanks. StuRat (talk) 23:27, 10 January 2011 (UTC)

http://www.hasbro.com/scrabble/en_US/search.cfm ¦ Reisio (talk) 01:41, 11 January 2011 (UTC)

That is a rather basic Scrabble solver, where you enter your letters and it returns all words that can be made from them. I'd like to add more capability:

A) Allow blanks to be specified.

B) Allow some letters to be anchored, so they must be in a given position, such as the first or last letter in the word.

C) Calculate points for each word, and sort them from most points to fewest. This requires adding both point info for letters and special squares on the board.

D) Eventually add capability to input current state of the board and find the best move.

Of course, such programs already exist, but I'd like to write my own as a coding exercise. StuRat (talk) 18:20, 11 January 2011 (UTC)

Now, how about the same, for the game of QWERTY ? StuRat (talk) 23:28, 10 January 2011 (UTC)

Isn't it just Scrabble without Hasbro's intellectual property (the name 'Scrabble')? Don't waste your time. Anyone playing QWERTY would rather be playing Scrabble. ¦ Reisio (talk) 01:41, 11 January 2011 (UTC)

It seems to use a different dictionary, and the rules are quite a bit different, too. StuRat (talk) 18:13, 11 January 2011 (UTC)

January 11

PPT keyboard shortcuts

Much like I've made my own keyboard shortcuts in Word, I'd like to do the same with PPT 2003, but I can't find that option. Is there an option? Or perhaps there's a list -- like Cntl-[ makes things larger, I just know that but I don't know from where. My specific trouble is that I'd like to center and middle align photos but going into DRAW and then ALIGN and then MIDDLE is way too time consuming. There is an underlined M in MIDDLE, but I can't seem to activate that, either. Or maybe I can drag out those aligning buttons to a new taskbar? DRosenbach ^{(Talk | Contribs)} 03:37, 11 January 2011 (UTC)

Ok -- I've found out how to use the underlined shortcut keys, but is there a way to make it with only one key instead of Alt+RAM? DRosenbach ^{(Talk | Contribs)} 03:57, 11 January 2011 (UTC)

Handwritn recognition software for tablet

I am a real estate appraiser. In my business I use a computer and purchase specialzed soft ware from Appraisers Choice, ACI. My questions is there software writing recognition for a tablet that as I have the appraisal from in tablet and complete the form in the field using cursive writing to have the writing converted to typed text. [email deleted] Thanks, Fred Javer —Preceding unsigned comment added by 24.0.222.23 (talk) 04:17, 11 January 2011 (UTC)

Deleted the email address. --Phil Holmes (talk) 09:59, 11 January 2011 (UTC)

Does your tablet run Windows? Here is "Handwriting 101" from Microsoft, and here are detailed technical instructions for setting up handwriting text input on Windows; you can "train" the system with your handwriting, but I suspect that if your letters are very curly or otherwise different from what the system expects, that your computer will have a hard time converting it to text. Microsoft's website actually claims that cursive is easier to recognize than print. Nimur (talk) 15:56, 11 January 2011 (UTC)

Turning the menu bar back on in Firefox

The option to turn the menu bar on is within the menu bar, or would be, if it was already on (somebody didn't think that through very well). So, is there another way to turn it back on ? StuRat (talk) 18:10, 11 January 2011 (UTC)

I don't see any such option. Do you use some extension, such as [2][3][4][5][6]?—Emil J. 18:23, 11 January 2011 (UTC)

The only way I know to turn it off is with Full Screen, in which case direct the focus to the page (not the location field) and type F11. --Tardis (talk) 18:25, 11 January 2011 (UTC)

If you right click on the menu bar, you see a set of checkboxes, one of which allows you to turn off the menu bar. It is indeed not obvious how to turn it back on again afterward -- but in fact there is a narrow zone at the top where you can rightclick and get back those checkboxes. (At least, all this holds for my version, 3.6.13.) Looie496 (talk) 20:25, 11 January 2011 (UTC)

Nope. That narrow zone is part of the navigation bar. So if both navigation bar and menu bar is disabled I don't see how to reenable. Taemyr (talk) 09:57, 12 January 2011 (UTC)

Pressing alt+v brings up the menu bar with the 'vis' menu open on my Norwegian version. It's probably not v in english, but alt+some letter should work, any letter that brings up the bar allows you to fix the problem. Taemyr (talk) 10:03, 12 January 2011 (UTC)

operating system from 'scratch'

I want to build one. There is a basic idea I am simulating with WINDOWS.

First, I want to reduce an operating system to most the most basic components, while formulating 'OpenSource' educational materials for alternatively-schooled children of all ages. Basically learning and teaching my kid about computers. The system design is intended for a universal, primarily economic and 'third-world' centred application.

Can Wiki point me to similar projects. My existing plan is to explore Ubuntu for starters. Any better ideas? 18:16, 11 January 2011 (UTC)

Take a look at Damn Small Linux. StuRat (talk) 18:24, 11 January 2011 (UTC)

You are attempting to recreate Linux. Unlike Windows, Linux is very modular. Learn about compiling the kernel. Then, you can compile it with just the minimum functionality that you want. -- kainaw™ 18:25, 11 January 2011 (UTC)

Note: Ubuntu is just a friendly version of Debian, which is just a distribution of Linux. -- kainaw™ 18:27, 11 January 2011 (UTC)

The classical teaching OS for teaching OS design is Minix, explicitly build for that purpose, and handy to use with Operating Systems: Design and Implementation by Andrew S. Tanenbaum. --Stephan Schulz (talk) 18:28, 11 January 2011 (UTC)

You may want to take a look at Linux From Scratch --Nat682 (talk) 18:43, 11 January 2011 (UTC)

Pick your computer carefully before you try to design a "simple" operating system. A modern "Personal Computer" (like the one you are probably reading this webpage on) is extraordinarily complex. These complex systems are the result of many many many years of design and engineering; not every part of a modern personal computer is straightforward, and much of it will require extremely detailed understanding of specific, sophisticated, and often proprietary computer architecture designs. For example, booting an Intel i7 core CPU is not as simple as powering it up and starting to run code. Here are the technical design documents for Intel i7. They are many tens of thousands of pages and are not intended for the casual hobbyist. For this reason, millions of lines of free and open-source software, such as the Linux Kernel (hosted at http://kernel.org) have already been written to manage the complexity of this and similar CPUs (as well as the standard peripheral hardware, like main memory, video output, and nonvolatile storage). If you want to design an operating system from scratch, it's advisable to start with a smaller, simpler controller: how about a simple 8-bit PIC controller from microchip.com? These are cheap, easy, and fun; small microcontrollers don't have the same power or capabilities as a full-blown Intel or AMD system, but it is much easier to design low-level operating system software for a PIC than a PC. You can write a simple round robin scheduler operating system in PIC assembler or in C code, and have yourself a straightforward operating system that you can start adding features to as you decide they are necessary. Nimur (talk) 19:45, 11 January 2011 (UTC)

The external links at the end of the Stack machine article appears to describe home-brewed OS and a home-brew hardware computer. I'm skating on very thin ice here but perhaps Forth (programming language) may do the low-level things you want. 92.24.190.219 (talk) 20:19, 11 January 2011 (UTC)

Internet

On Windows 7 I need a way to limit the amount of internet bandwidth specific programs can use, independent of the programs themselves (ie not setting limits in each programs settings which would be tedious and in some cases impossible). Does Windows 7 contain some feature for doing this? 82.44.55.25 (talk) 19:16, 11 January 2011 (UTC)

Not that I know of, but there are third party apps. netlimiter pro? Might also check sysinternals. ¦ Reisio (talk) 22:02, 11 January 2011 (UTC)

Free vs. Open Content

Hi, I searched the archive but I did not find something that matches my question appropriately. Trying to figure out the difference between free content and open content I would figure that cc-by-nc-sa qualifies as an open, yet not free license. Is that correct? Would Wikipedia (well lets restrict to text only for simplicity, as I am not that much into the discussion about images) qualify as free content or "only" as open content? (I would guess it could be characterized as free?) Also, if my above example of cc-by-nc-sa does not fit, can you give a simple example of open but not free content with a short explanation? Frankly said, I did not understand why the given example Open Directory Project is not free.

Also, how is the relation between free content and the right to fork: If e.g. a website publishes under cc-by-sa, implying a right to fork, does it still make the content "unfree" if the website itself e.g. blocks part of its content for modification by certain groups of users (yes, I am implicitely also referring to Wikipedia here)? -- 92.206.140.12 (talk) 23:43, 11 January 2011 (UTC)

Different people use the terms "free" or "open" to refer to divergent things. The easiest way to be sure you're in the clear is to read the license: our terms of use are linked from every page on Wikipedia. Our content is licensed under the GNU Free Documentation License and the Creative Commons License, "Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)", requiring attribution to the original authors and re-sharing under a similar license. Whether this means our content is "open" or "free" is a moot, semantic argument that requires a definition of "free" or "open."

Regarding Open Directory Project, their ODP license is different from the GFDL. The GNU project does not call it a "free documentation license" - in their estimation, it is not free because "your right to redistribute any given version is not permanent and that it requires the user to keep checking back at that site, which is too restrictive of the user's freedom." Though I am generally in accordance with the ideology of the Free Software Foundation, I will point out that neither FSF nor Richard Stallman are the authoritative definition-provider for the words "free" or "open." If you need advice on whether ODP license is legally compatible with GFDL, you should consult an attorney.

Finally, you should note the important distinction between "our content is freely licensed" (which is a valid reading of Wikipedia's content license), and "you may do whatever you like with Wikipedia's servers" (which is not ever offered by any terms of use on Wikipedia). So, Wikimedia Foundation or its agents reserve the right to block access to the servers (not the content). Nimur (talk) 00:07, 12 January 2011 (UTC)

blurred (censored) image appearing un-blurred, personal information

I've come across an image on commons, it's basically a form of photo identification with a persons face and numbers on it, both of which have been blurred out, but when I opened it in GIMP I noticed that the image had been restored in the image preview (i.e. no blurring, so I could see clearly the face of the person, though it was too small to make out the text). Having opened the image the blurred parts once again looked blurred, but there is no indication of any layers other than the background, and this is a .jpg file so I wouldn't expect any. It's apparent though that GIMP has access to some extra data that was left over? before the image was saved, and anybody that wanted to could probably get at the info, so my question is two fold; how could the image layer behind the blurring possibly remain in a .jpg image, and why does this get through? This is just one example (albeit a dangerous example) of information being stored behind a layer in a .jpg but there could be hundreds more images that have the same loophole, if it's just as simple as saving a layered image as a .jpg. Forgive me for not wanting to specify the exact image, but I'd rather not give everyone access to this guys identity. 64.180.84.184 (talk) 02:01, 12 January 2011 (UTC)

First you should have an admin remove the file (but keep a copy so someone can figure this out). After that you could try to alter the image so the personal parts are indeed censored (on top of the blurring being applied), if you can; then we could all figure out what's going on. Otherwise I suppose you'd want to find and admin or three to take care of it; WP:RFAA. ¦ Reisio (talk) 02:06, 12 January 2011 (UTC)

What's going on is that a preview image is saved within the image as metadata, and it was made from an earlier (uncensored) version. This is a known flaw with a lot of image programs and has resulted in lots of information getting leaked out when people thought they were being clever and censoring it. It's easy enough to fix (open the image, select all, create new, copy and paste, save over the old file). But I agree that the file needs to be deleted entirely from Commons as well, because the preview is saved in the history as well. --Mr.98 (talk) 03:08, 12 January 2011 (UTC)

OK so it's just his picture that has been revealed, as the text is probably too small to see if it's just the preview. Good to know. Are there any commons admins floating around here? I'm not sure how to find one. 64.180.84.184 (talk) 03:34, 12 January 2011 (UTC) NM I found Reiso's link, thanks! 64.180.84.184 (talk) 03:35, 12 January 2011 (UTC)

I'd hit up irc://irc.freenode.net/wikimedia-commons ¦ Reisio (talk) 04:46, 12 January 2011 (UTC)

Also I wonder if there's no easy way to check .jpgs for accurate previews, or to remove them completely. 64.180.84.184 (talk) 03:41, 12 January 2011 (UTC)

That's a problem for https://bugzilla.wikimedia.org/ ¦ Reisio (talk) 04:46, 12 January 2011 (UTC)

skype

is there a way to search for contacts using the old skype search. the new one i cant find anyone. i accidentally deleted a contact yesterday now i cant find him again using the new search. — Preceding unsigned comment added by Tommy35750 (talk • contribs) 04:02, 12 January 2011 (UTC)

Is there such a laptop with a 22 inch screen?

I need a laptop (not at netbook) with a 22-inch screen. I have tried to find it, but without any luck so far.
I will occasionally use this laptop to view TV or Video, but first and foremost I need it as a computer. Therefore I want a higher screen resolution/image quality than the high-definition television 1080p standard.
Other wanted features are:

1. 4 GB RAM or more. (6GB would be nice to avoid most of the disk swapping).
2. At least 500GB harddrive.
3. Optical disc drive capable of reading and writing CD-RW, DVD±RW/DVD+R DL and preferably also Blu-ray Disc and Blu-ray Disc recordable.
4. 5 (or 6) USB 2.0 ports. (USB 3.0 would, of course, also be nice).
5. SDHC Card connection.
6. Integrated stereo speakers.
7. TRS (jack) connection for External speakers, Earphones and Microphone. (An additional 2.5mm jack connection for use with Mobile phone headsets would be a bonus).
8. 2 HDMI connections.
9. Enabled support for Consumer Electronics Control (CEC) (AV.link) through the HDMI. (To talk with set-top boxes, Television sets and PVRs).

Well, I have asked around for this, at local laptop retailers, but none have been able to provide.
Do you know if such a laptop is currently available from somewhere? --46.15.71.199 (talk) 10:22, 12 January 2011 (UTC)

The largest laptop screen size I've seen is 18.4". (I've checked for larger at various online retailers but was unable to find anything bigger) So right off, your exact specifications can't be met. The idea of lugging around a 22" laptop is interesting indeed! As is your linking of basic computing terms like "laptop" and "RAM" on a page which is frequented by people who are already knowledgeable in more advanced topics Dismas|^(talk) 10:53, 12 January 2011 (UTC)

Firefox not saving cookies

Is there anything that would make Firefox not save cookies all of a sudden? This started happening to me a few days ago, and it's getting irritating because it will not allow me to remain logged into Wikipedia at this computer. (And before you ask, Firefox is presently not configured to delete cookies on close here.) —Jeremy ^{(v^_^v Hyper Combo K.O.!)} 11:16, 12 January 2011 (UTC)

tor

i cant get the Flash player to work. Any help?

Like if i were to go on youtube it wont work.