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

June 7

Graphics card causing reboots?

Hello! I bought an nVidia (evga) GTX 550 Ti card close to the start of May, installed it, and it was working fine. Games played well at 1080p at full frame rate with no problems. Then, about a week and a half ago (so three weeks after installing the card), my computer would start randomly rebooting...at first just one freak occurrence, then once every few days, up to the point it couldn't be up and running for more than 5 minutes. I was using a 500 W PSU, so I replaced it with a 700 W model...same problem. I've now removed the graphics card and have been running smoothly for 3-4 hours so far. The card specs recommend a minimum PSU of 400 W, so the 500 W and current 700 W should be more than enough to support it.

I dualboot to Ubuntu 12.04 and Windows 8 CP...same problem in both. In fact, a reboot was triggered even just being booted in memtest86+, so I doubt this is a driver issue. I was, however, able to run a pass in memtest86+ failsafe mode, but I don't know if that's significant, or just dumb luck that it stayed on for that after rebooting twice in non-failsafe mode of memtest86+ (no memory errors). Besides rebooting, it would occasionally just freeze the display in Ubuntu and Windows, and not reboot by itself. There was no useful information in the Ubuntu logs, which acknowledged the kernel was going through the boot process again but did not log any shutdown. These reboot problems happen even if I'm not doing any CPU- or GPU-taxing operation; simply browsing in firefox or even being away from the keys has triggered a reboot.

The CPU is always in a suitable temp range, and there are no thermal problems logged in Ubuntu. I strongly suspect the graphics card and am about to RMA it, but I figured I'd check here to see if anyone else might offer some other diagnostic advice. Unfortunately, I don't have access to another computer where I can pop this gfx card in and see if the same problem occur, nor do I have an extra graphics card to check if the motherboard pci-express slot is bad (there's only one pcie slot on my board). Looking online, I find most people with defective gfx cards get them dead on arrival or get some obnoxious BSOD that points to the gfx card (I've never gotten a BSOD), and I was surprised that this card worked so well for a few weeks and then suddenly brought on these problems, so I wanted to check here and see if that sounded plausible. Thank you very much for any advice you can give on this matter. I will update you if I have any problems with the card now removed, but so far, this is very much longer than I've been able to go without a reboot.--el Aprel (^facta-_facienda) 00:46, 7 June 2012 (UTC)

Have some paragraph breaks, on me: ¶ ¶ ¶. :-) StuRat (talk) 01:32, 7 June 2012 (UTC)

I agree with the possibilities of a bad slot or bad graphics card. Another possibility is that the card just wasn't seated properly in the slot. Did you put it back in all the way to check this ? StuRat (talk) 01:21, 7 June 2012 (UTC)

Following your advice, I reinstalled the gfx card inside the machine, and made sure it's secure (screwed into the case and mobo pcie latch flipped to hold it in), but still have the same issue. I was able to get a good 2 hours out of it, but it rebooted again. However, as I was messing around with it after its self-provoked reboot, I found I could trigger hangs and reboots manually by applying a bit of force onto the top of the card with the tip of my index finger. To further explain: If I pushed down on the graphics card with my index finger (pushing it in the direction of the mobo), sometimes giving it a gentle shake with just the index finger (as if you're making a smudge on a piece of paper with your finger), this action will often trigger the reboot process, leading me to believe it's a gfx card or pcie slot issue.

Sometimes this action doesn't work, but it seems if the computer is up for about 2-3 minutes and I try this, that little bit of agitation usually acts as a way to trigger this problem. Of course, not doing this, the system eventually reboots on its own anyway. I've checked and checked again, and the gfx card is certainly secure, firmly held in the pcie slot...there's definitely no feeling of looseness when I use this finger tactic. Maybe this can be diagnostically useful. Also, what's the best way to test for a faulty PCIe slot? FWIW none of the components in this build are older than January 1st of this year.--el Aprel (^facta-_facienda) 04:23, 7 June 2012 (UTC)

Well, we seem to have narrowed it down to an intermittant connection, but it's still not clear whether it's on the card, in the slot, or between the two. The best way to test the slot is to try a new card in there. At this point, assuming you can't borrow another card to try, or borrow another computer to test the card, I think you need to bite the bullet and buy a new graphics card. (Keep the receipt just in case that's not the problem, though, and you want to return it.) StuRat (talk) 04:41, 7 June 2012 (UTC)

I also added paragraph breaks to both my posts above to make them more readable.--el Aprel (^facta-_facienda) 04:28, 7 June 2012 (UTC)

Update: After removing the graphics card, I noticed that giving the whole computer case a gentle shake also triggers this problem, so it must be a loose connection somewhere, but I'll be damned if I can find it. The obvious point of interest was the PSU connection to the motherboard, but I've checked that and it's secure. Again, I've tried two different PSUs, so it's not a problem with the connecting wires themselves. I'll probably have to resort to taking it apart and reassembling it, since no loose connection is visually obvious. If that doesn't work, though, what are some diagnostics I can do to see if the problem is embedded in the motherboard itself? Thank you.--el Aprel (^facta-_facienda) 18:48, 7 June 2012 (UTC)

Have you got automatic restart disabled in windows? This will tell you if the computer is 'crashing'(blue screening) or actually rebooting. If it is actualy rebooting, my guess is it's most likely a RAM issu. How many ram chips are you using? If it is more then 1, simply try taking each out one by one and seeing if your problem stops.(source: ten years in IT support). Vespine (talk) 01:47, 8 June 2012 (UTC)

If you get the problem only when using the graphics card (it disappears completely using the built-in graphics), then I don't see how it could be the motherboard or ram chips. It's the graphics card, the slot, or the connection between the two. StuRat (talk) 04:49, 8 June 2012 (UTC)

The post from the OP directly above mine says they tried to remove the card but still got the problem.. Unless i'm misunderstanding something. Vespine (talk) 04:28, 12 June 2012 (UTC)

OK, I was reading "after removing the graphics card" to mean "after removing and then reseating it", which would be more consistent with what they reported earlier. But, you may well be right. StuRat (talk) 19:32, 12 June 2012 (UTC)

PHP Function.

I'm learning php, so I did a "proxy" to test my 'skills', I showed it to someone experienced in netwroking. He managed to acess my computer files (He even downloaded some files, and pasted them as a proof) and access my network.. I asked him several times how he did it but he didn't show me..

Anyway here Is the function that get's the files, as you can see, the function that gets everything is file_get_contents, how he managed to do it?

 

$url = $_POST['pageurl'];
$opts = array(
  'http'=>array(
    'method'=>"GET",
    'header'=>"Accept-language: en\r\n" .
              "User-Agent:php"
  )
);
$context = stream_context_create($opts);
$contents = file_get_contents($url,false,$context); 

Thanks for reading 190.158.212.204 (talk) 01:52, 7 June 2012 (UTC)

I discovered how the vulnerability works. how can I filter it? 190.158.212.204 (talk) 04:39, 7 June 2012 (UTC)

The vulnerability (as you have probably figured out) is that the URL doesn't have to be a real URL — it can also be a file path on the server, and you haven't filtered it at all, so unless you are really careful with how your PHP's permissions are set, you can put in all sorts of nefarious paths like "../../../Users/YourUserName/Desktop/SecretFiles.txt" and so on. The base lesson here is "be careful when you take user input and use that in a function like file_get_contents which can access local files." How to fix it? Sanitize the user input — if you only want it to refer to URLs, make sure that the string starts with "http://" or "https://", and if not, add it to the front of it (http://../../../etc would not resolve to a valid URL, but it won't access your server filesystem, either). If you need it to access local files (or relative paths), reject any paths that include double periods (..). --Mr.98 (talk) 00:36, 8 June 2012 (UTC)

What is the price to put video ad on youtube (the video ads that plays before the video start)?

What is the price to put video ad on youtube (the video ads that plays before the video start)? — Preceding unsigned comment added by 201.78.132.208 (talk) 05:35, 7 June 2012 (UTC)

http://google.com/search?q=youtube%20advertising ¦ Reisio (talk) 07:09, 7 June 2012 (UTC)

Memory Space

Whenever I but a pendrive or a portable hard drive - say 1000 GB portable hard drive, I dont get to use the entire space in it. In the case of the 1000 GB hard drive, I am able to use only 930 GB. So is the case with pen drive - around 95 % of the space is only usable. Why is it so ? — Preceding unsigned comment added by 117.193.139.99 (talk) 08:09, 7 June 2012 (UTC)

It's likely you are in fact using all (or at least most) of the space, but that the capacity as printed on the device and the capacity as given by your operating system are arrived at by using different measurements, specifically: the device manufacturer has measured in base 10, and the OS (for historic reasons) has measured in base 2. ¦ Reisio (talk) 09:09, 7 June 2012 (UTC)

In addition to base-10 vs base-2, a file system reserves space for metadata - file names, modification time, ownership, permissions, and such. This space will be unavailable for file contents. 88.114.124.228 (talk) 16:34, 7 June 2012 (UTC)

Wikipedia article Binary_prefix#Consumer_confusion... -- AnonMoos (talk) 02:01, 13 June 2012 (UTC)

gmail

Resolved

How do i delete a pre-existing email address which is remembered by gmail "compose"? Kittybrewster ☎ 10:06, 7 June 2012 (UTC)

I think you have to delete the email from your "contacts" list. Heck froze over (talk) 13:26, 7 June 2012 (UTC)

it isnt on it. Kittybrewster ☎ 13:37, 7 June 2012 (UTC)

You probably have multiple contacts lists. Click on the red "Gmail" top left of screen, and select Contacts. If you see multiple contacts lists, you will need to work through each of them to find the one you want to remove. Also turn off "Create contacts for auto-complete" in your general settings options.--Shantavira|^{feed me} 15:02, 7 June 2012 (UTC)

Many thanks Kittybrewster ☎ 15:16, 7 June 2012 (UTC)

Email SMS alerts.

Does anyone know of such a service reminding a user that he/she has email via a text message. I know there is one, but it's only available for subscribers in India, Pakistan and elsewhere, but not in the Philippines. Blake Gripling (talk) 10:26, 7 June 2012 (UTC)

All implementations of such service (which i have used), consisted of email to SMS gateway (email address which forwards received emails as text messages to specific phone) and ordinary email forwarding (which is set up at mail server). First part (SMS gateway) depends on cellphone operator (they owns it), second part (email forwarding), depends on email server. -Yyy (talk) 09:17, 8 June 2012 (UTC)

Scorewriter licensed under BSD License or similar licenses

Are there general-purpose scorewriters with extensive functionality and licensed under BSD License or other copyfree licenses? 117.5.13.6 (talk) 11:01, 7 June 2012 (UTC)

Wikipedia has a list of scorewriters that should answer your question.--Phil Holmes (talk) 08:25, 8 June 2012 (UTC)

If Comparison of scorewriters is to be believed, the answer is no, unless the one LGPLed program counts. I'm not sure I know what copyfree means. -- BenRG (talk) 06:27, 9 June 2012 (UTC)

Computer security

Hi all, I remember back in the 90s people used to tell me you couldn't catch a virus just from being connected to the internet, and you couldn't catch anything from a webpage unless the owner of the page had put one there (or, say, unless a virus on his computer had put one there). Nowadays all you hear is that a (Windows) computer only has to be connected to the Internet for a few minutes to catch its death of cold. What has changed in the meantime? Is it that I used to listen to people who didn't know what they were talking about? What is the situation for Mac and Linux? It all seems rather strange to me, and it sounds like a rather basic thing to be able to prevent a computer from catching a virus except in the case of downloading and running software. Note that by "downloading" I mean in the sense of being able to run downloaded software from the start button, rather than in the controlled environment of a webpage, as happens with javascript. IBE (talk) 13:29, 7 June 2012 (UTC)

Hi. Nowadays, hackers (I shall refer to them as crackers from now on, and crack instead of hack), and they also crack for very different reasons. It was technically possible for a cracker to spread viruses just because you were connected to the internet in the 90s. However, most crackers then cracked due to their own mischief, they do not expect to earn money out of it, they only want to see people's computer crash and the feeling of invincibility. Because of this, they mostly did not bother making their virus spread in such a way that even those connected to the internet without doing anything else would also get infected. Therefore, people just ASSUMED that virus cannot spread just because you are connected to the internet. Unfortunately, times have changed. Crackers now crack because of economic reasons, that is, they want to earn money. They code viruses that stays rather dormant in your computer, slowly logging your personal details such as credit card numbers and sending them back. Since it is credit card numbers and other personal details they want, it means that the more they have, the merrier. Therefore, more energy is spent on making sure that every, or at least, nearly every, channel for the virus to spread is exhausted. Therefore, we have viruses that can spread, for example, to all computers in a LAN from just one computer connected to it. Thus, we come to assume that viruses now can spread just by being connected to the internet. Cheers! ★ Oliverlyc ★ ✈✈✈ Pop me a message! 14:29, 7 June 2012 (UTC)

Well technically you can't get a computer virus just by being connected. You may get a computer worm. More seriously, what you're saying is only really true for a preSP2 Windows XP that isn't behing a NAT or firewall. PostSP2, the firewall does a decent job provided it's properly configured (and of course enabled). Also, I don't know what people you listined to, but the risk of services open to the internet was well recognised even before Windows 95 let alone Blaster (computer worm). (There were of course a number of Internet Information Services vunerabilities that predated blaster and were fairly widespread like Code Red (computer worm) although most Windows users didn't/don't run IIS.) Think of OpenBSD's mantra for example (which wasn't before Windows 95, but you get the idea). 2001:0:5EF5:79FD:20CB:1C04:833A:FA41 (talk) 15:29, 7 June 2012 (UTC)

You can't get a virus just by being connected, but a Windows computer that detects an internet connection will do some things automatically. For example, it will automatically download updates. Looie496 (talk) 03:09, 8 June 2012 (UTC)

The auto updates can be turned off (and updates done manually), but it can be quite tricky to ensure that they are all disabled. Dbfirs 21:04, 8 June 2012 (UTC)

Auto updates, at least those from Microsoft, are safe. They have a digital signature which is verified locally. Yes, there was just a story in the news about Microsoft revoking some bogus keys which could apparently be used to sign updates, but that's an extraordinary circumstance. Your average Joe villain doesn't have access to that kind of thing. Disabling auto updates is very unsafe since your system will accumulate vulnerabilities which are known to everybody (since the updates themselves represent a public disclosure). It's important to install security updates as soon as they are made public. Many, even most, real-world attacks exploit vulnerabilities that have already been patched and so affect only people who don't update (which is a lot of people, unfortunately). -- BenRG (talk) 22:08, 8 June 2012 (UTC)

Interesting answers - thankyou. So does that mean the only true vulnerability with Windows is the checking for updates? If you configured it so as not to check for updates, would it be safe, at least until you visited a dodgy porn website? It just strikes me that it should be simplicity itself to protect a computer from unsolicited code. Stuff you download and run can obviously be malicious, as with anything (even offline) that asks for your private information, but stuff just jumping onto your system looks preventable. Does anyone know the situation with Macs? IBE (talk) 05:42, 8 June 2012 (UTC)

The chief thing that has changed since the 90's is that programs are expected to interact with each other in to a much larger extent today than what was the case 15 years ago.

Is update checking the only vulnerability? No, definitly not, any program that downloads code or content that can contain code can be a vulnerability. So the updates are necesarry in order to plug those holes.

In principle it is possible to prevent attacks by blocking anything that could contain code. However the current trend is that content and presentation should be synchronized with the cloud and with a users several devices (Phones, pads, other PC's). So content will be downloaded from outside of the computer, and this will reach (or have reached) a volume that means that direct user inspection would be annoying. Also content is becoming more complex and thus the need for content that can contain code is increasing.

Mac is currently somewhat safer than Windows, arguably because Mac is a less atractive target (they still have a smaller userbase). Wether this will hold as mobile devices gets more important remains to be seen. Mac might have an advantage over Windows because of tighter control on third parties. OTOH Windows might have an advantage because there are several compaines developing antimalware for the platform. Taemyr (talk) 11:49, 8 June 2012 (UTC)

As I said above, disabling auto updates makes your computer much less secure. Please don't do it. -- BenRG (talk) 22:08, 8 June 2012 (UTC)

Yes, apologies for mentioning this. I agree with Ben that Windows updates are important. I have auto-updates disabled on my computers for local reasons, but I do update regularly.Dbfirs 07:17, 9 June 2012 (UTC)

Thanks again - so if the problem isn't auto updating, is it just what Taemyr says, that user expectations for interactivity are high? Because this still seems inherently fixable. Again, I still find it very strange that a remote blackhat can get a computer to download and run some software when all I was doing was registering a connection. Cloud computing is a very small thing to me, and seems a small thing to gain for an insecure computer. Why should the threats be so blatant? IBE (talk) 12:04, 10 June 2012 (UTC)

This is a very complicated problem, but I don't think what Taemyr said is accurate. Generally computers are much more secure now than they used to be. Consumer versions of Windows didn't even attempt to provide a real security model until XP, and Mac OS didn't even attempt it until X. Early Linux distributions, like the Unices before it, shipped with a lot of remotely-exploitable Internet services enabled by default. The Morris worm exploited bugs that had, I think, been known for years, yet remained unpatched on professionally maintained systems. That's unthinkable now. I don't think there's been an increase in "interactivity". People have always run software on their computers. Microsoft Office has had a full-fledged programming language built in for 20+ years. When you hear stories about malware that escapes the Javascript sandbox, just remember that the very existence of the sandbox is a step up from the traditional Unix/Windows model of always giving all of your privileges to all of the software you run.

To the extent that the situation is worse than it used to be, it's because malware is now mostly written for profit instead of fun and because most computers are connected to the Internet a lot of the time now, which makes it possible (or at least much easier) for malware to phone home. But fearmongering around this issue is nothing new. Don't be afraid just because someone says you should be. They're probably trying to sell you a magazine, an antivirus product, or a government agency. -- BenRG (talk) 16:47, 11 June 2012 (UTC)

Yes, MS office has had an inbuilt programming language for a long time. But when email started becomming common that fact was a mark against the suite, in that it was an uncessary risk that you could avoid by using other software. Today it's far less of a mark against MS, mostly because safeguards are far better, but also because it's getting much harder to avoid. Taemyr (talk) 09:26, 12 June 2012 (UTC)

Also to OP, no it's not just cloud computing. It's not just any single thing. It's all things at that same time, most serious threats today (Ie. threats that have consequences that the user will notice) will use several weaknesses in order to have an effect. Opening a connection means that you expect to get data in return. That means that your firewall will need to allow data from what it thinks is the source. And so creating a connection will open an avenue of attack. Also see BenRG's comment re security of computers. Computers today are, provided the software is kept up to date, reasonably secure.Taemyr (talk) 09:33, 12 June 2012 (UTC)

iPhone charger

I think that I have asked this before but mislaid the answer. Can I charge my iPhone with my iPad charger please?85.211.222.224 (talk) 14:07, 7 June 2012 (UTC)

I suggest you try searching the archives (there's a box at the top) but AFAIK you shouldn't have a problem. Charging your iPad with an older iPhone charger may not work however. 2001:0:5EF5:79FD:20CB:1C04:833A:FA41 (talk) 15:15, 7 June 2012 (UTC)

Thanks for this, found my earlier post and links, and the answers seems to be 'Yes'. Thanks again.--85.211.222.224 (talk) 15:49, 7 June 2012 (UTC)

wow, that's the first ipv6 I've seen here 190.158.212.204 (talk) 22:17, 7 June 2012 (UTC)

What is an ipv6? — Preceding unsigned comment added by 85.211.222.224 (talk) 06:08, 9 June 2012 (UTC)

We have an article about it. →Στc. 06:12, 9 June 2012 (UTC)

Java compiler

Can you suggest me some good compilers to make Java software? Cambalachero (talk) 15:37, 7 June 2012 (UTC)

The Java Development Kit, which you get from Oracle, comes with javac, the standard Java compiler. For a general developer, this is the first and most obvious choice. -- Finlay McWalterჷTalk 15:54, 7 June 2012 (UTC)

And if you are more into a GUI environment, Eclipse (software) is a popular free choice, though not the only one; there are links to others in the Eclipse article. A common answer to this is to play with javac first, then graduate to a GUI, in the spirit of "learn to walk before you run". 88.114.124.228 (talk) 16:18, 7 June 2012 (UTC)

BlueJ is also a very good developing environment for beginners. It's good because it automates a few tasks (like the compiling process) and has basic syntax highlighting, but doesn't have any advanced feautures like auto-completion, thus forcing beginners to get very comfortable with Java and not rely on features that do too much of the work for them. Oracle's javac seems like the way to go.--el Aprel (^facta-_facienda) 18:54, 7 June 2012 (UTC)

We have an article, java compiler. Another well-known one is GNU Compiler for Java. 81.98.43.107 (talk) 23:37, 13 June 2012 (UTC)

June 8

"Gateway timed out"

I keep getting this message in a pop up box in the center of my screen while I try to access Wikipedia and the whole screen behind it darkens. I click on "okay" and it goes away but it's annoying and I want to know what's causing this. Can anyone explain? Thanks.--108.46.98.134 (talk) 01:40, 8 June 2012 (UTC)

Oh, I'm on a iMac 10.6.8, using Firefox, latest version--108.46.98.134 (talk) 01:42, 8 June 2012 (UTC)

I'm getting the same error tonight. Though, I'm on a MacBook with 10.5.8 and using Safari. It's been every time that I click on something on my watchlist. We should probably take this to WP:VPT. Dismas|^(talk) 02:05, 8 June 2012 (UTC)

I see there's already a discussion there. What that confirms for me this that it is NOT ME--this take away my mild worry that it was a problem with my computer. Thanks for responding.--108.46.98.134 (talk) 02:24, 8 June 2012 (UTC)

Need help troubleshooting computer with corrupted HDD

One of my computers has a crashed/corrupted hard drive. Windows fails to boot normally, but can boot into some recovery mode. One of the options is "repair your computer" or some such, but no OS is listed in the dialog. It says that if no OS is listed, I'll have to load some drivers. The computer didn't come with a restoration disc. Not sure if the recovery discs I burned post-install would have the needed drivers. Tried Linux-based SystemRescueCD, but couldn't mount any of the (NTFS) partitions. Tried a diagnostic CD from the HDD manufacturer. It said the HDD failed some important diagnostic test. There was a longer test that identified a screenful of sector read errors (all excerpt one had the same LBA address--it's weird) and offered an option to repair them. Didn't try the repair option for fear that it might make the problem worse. Don't know how many more screenfuls of error the tool would find if I continued.

I'm looking for info on how to troubleshoot/fix the problem. The primary goal is data recovery. Recovery without reinstalling all software would be a plus. My first objective is to determine, without disturbing the HDD content, whether I have a hardware problem or just bad sectors in some critical places. Assuming I don't have a hardware problem with the drive, my next objective is to determine whether the file system can be repaired, and get a sense of how much of the data can be recovered.

I could use some advice on what tools to use, what procedures to try, and in what order. Thanks in advance! --98.114.146.239 (talk) 04:55, 8 June 2012 (UTC)

It sounds like you need to install the O/S and drivers on a different hard disk, first, and make that the boot disk, so you can get the computer up and running. If you don't have the necessary backup disks to do this, you might be able to download them (using another computer), assuming you have the validation codes. Once you get the computer running, you can try to repair the bad hard disk and copy over any data you can still save. There are also places you could take the bad disk, which will attempt to recover the data, for a fee. StuRat (talk) 05:10, 8 June 2012 (UTC)

dd (Unix)#Data_recovery ¦ Reisio (talk) 12:58, 8 June 2012 (UTC)

Phones are smart afterall!!!

Why do smartphones switch themselves on when you switch them off? Difficultly north (talk) 10:21, 8 June 2012 (UTC)

Poor/broken power buttons, probably stemming mostly from the idea that power buttons should be held to be used, as opposed to just pressed/switched. ¦ Reisio (talk) 12:34, 8 June 2012 (UTC)

Mine has the option to turn itself off at a certain time and back on at another time, so, if you have that option set on yours, this might explain it. Also, I only use the clam-shell design, as any design which leaves the buttons exposed while in your pocket is bound to do bad things like this. StuRat (talk) 17:13, 8 June 2012 (UTC)

Yahoo Live Chat

Separately, is there a way to permanently disable Yahoo Live Chat (which is not the same as Yahoo Messenger as it is only located within Yahoo mail) instead of just being signed out? Difficultly north (talk) 10:28, 8 June 2012 (UTC)

How to clean a desktop computer monitor

What is the best thing to use to clean/wipe a desktop computer monitor? I mean, something liquid (to get out stains and smudges) – maybe along the lines of water or Windex? – as opposed to just an (ineffective) dry cloth or such. Thanks! Joseph A. Spadaro (talk) 18:56, 8 June 2012 (UTC)

Yes, Windex works great (that's an ammonia/water mix plus some alcohol and a few other ingredients). However, never use it with the last paper towel on the roll, as glue used to attach that to the cardboard core can be dissolved by the Windex and redeposit on the screen, making it look like somebody sneezed on it. StuRat (talk) 19:06, 8 June 2012 (UTC)

I wonder how you know that last bit... :) SemanticMantis (talk) 20:52, 8 June 2012 (UTC)

Windex is great for CRTs, and other glass surfaces. Many modern LCD screens do not have glass surfaces. Windex may indeed be fine on many of these, but e.g. Apple recommends using only pure water to clean the screens of its products. SemanticMantis (talk) 20:52, 8 June 2012 (UTC)

Just water should be enough for the vast majority of situations, anyways. ¦ Reisio (talk) 21:07, 8 June 2012 (UTC)

I don't think water is very effective on fingerprints. Plastics may be present, either on the screen or housing, but none of the ingredients in Windex is harmful to plastics. Acetone would be, as in nail polish remover, so keep that away, obviously. Some oils, like peppermint oil, might also dissolve plastics.

Also note that the ammonia in Windex is a lung irritant, so should only be used in a well ventilated area. I suggest leaving the room for an hour after you use the Windex. (Cleaning it before you go to bed is a good plan, unless the computer is in your bedroom.) StuRat (talk) 21:27, 8 June 2012 (UTC)

If by not very effective you mean the fingerprints might not magically disappear without some wiping, you may be right. ¦ Reisio (talk) 22:02, 8 June 2012 (UTC)

Since fingerprints contain oil, which does not dissolve in water, the best you are likely to do with water is smear them around a bit. I think there are some special surface treatments which hide fingerprints well, but, if you can see them to start with, you probably won't get rid of them with water alone. StuRat (talk) 22:04, 8 June 2012 (UTC)

Unless you're doing something other than spraying liquid onto your screen and just leaving it there hoping it will disappear on its own, like using a paper towel (or whatever super lint free matter you prefer). ¦ Reisio (talk) 22:10, 8 June 2012 (UTC)

TIP to remove oil spots including grease (eg from cooking etc) on sensitive optical components - lick it with your tongue - (try it and then ask a biologist for why it works) - then wipe with a damp (non-paper) cloth to remove the harmless saliva. Try not to drink cocoa immediately before doing this.Oranjblud (talk) 13:52, 9 June 2012 (UTC)

Keep in mind that some computer screens have various surface treatments like anti-glare coatings which may be removed by aggressive solvents. For example, a number of computer monitor manufacturers say (or at least used to say) that you shouldn't use alcohol or alcohol-based cleaners on their monitors, as prolonged use can remove the anti-glare coating. Depending on what the surface treatments are, they may or may not be stable to regular treatment with Windex or other cleaners. Check the manufacturer's recommendations to be sure. Generally, using plain water with a soft, lint-free cloth is best, if you can get away with it. For removing oils, etc. you might use a mild soap (like a neutral hand/dish soap), followed by a plain-water rinse. -- 140.142.20.101 (talk) 00:15, 9 June 2012 (UTC)

Whatever it is you decide to spray on your screen (and I agree that water is the obvious first choice - don't go to harder stuff unless you have to, right?), don't actually spray it on your screen. Apply the liquid to a cloth or paper towel first and then gently rub/scrub the screen with it. Most monitors are well enough made to keep out the spray, but if any liquid were to get inside the casing, the chances are much greater that it would do something unfortunate than it would do something good. Personally, I've had good luck with one of those looped microfiber cloths (used dry). YMMV, of course). Matt Deres (talk) 11:17, 9 June 2012 (UTC)

Don't use a paper towel . they can contain hard bits of wood matter which will scratch a screen (as any optician will tell you the same about plastic lenses/paper).

Use a damp (not wet) cloth (preferably lintless) - water works - it does remove fingerprints. those microfibre dish-cloths are particularly effective (don't use dry to avoid static)

Alternatively buy a box of screen wipes.

The manual will almost certainly tell you not to use detergents - the manual will almost certainly also tell you the above -either use a specific wipe, or a cloth.Oranjblud (talk) 13:49, 9 June 2012 (UTC)

I'd definitely agree if you have the option of something better than a paper towel, go for it, but an ordinary cheap soft paper towel has never done me wrong. ¦ Reisio (talk) 19:34, 9 June 2012 (UTC)

Thanks! Just so I am clear ... it's perfectly safe to apply water and/or Windex to a computer monitor? I had always thought that that was a no-no. And, hence, that was why I asked my original question. Thanks. Joseph A. Spadaro (talk) 16:55, 9 June 2012 (UTC)

A) If it's a glass CRT screen with no special coating, then either is fine (and fingerprints are highly visible on those). Paper towels are also fine on those, as glass is hard enough that it won't be scratched.

B) If it's does have a special coating, then the slight amount of alcohol in Windex could conceivably wear off that coating after many uses. So, try just water, instead, and use a cloth instead of paper towels, as those type of screens are far more fragile. StuRat (talk) 17:20, 9 June 2012 (UTC)

Yes - it's ok to use a damp towel/cloth (if it's dripping water then squeeze more water out of it). Many will advise against tap water - especially if you live in a hard water area due to limescale [1]. Commercial cleaners will are still 90% water plus some additives eg one example 96% water

Most important factor is not to press hard or at all on the screen - just wipe across with the wet thing - if the mark doesn't come off wipe again.

I assumed you are cleaning a LCD screen - if cleaning an old fashioned cathode ray type monitor the procedure is similar to cleaning a mirror.

There are plenty of sites that give instuctions on this-mostly the same - many suggest starting with a dry cloth - personally I recommend avoiding the dry cloth as modern fabrics (eg microfibre) can get a lot of static charge which gives a chance of static damage - wetting the cloth completely eradicates any static electricity risk. It also is needed if you are cleaning more than just dust.77.86.106.97 (talk) 18:14, 9 June 2012 (UTC)

My gut reaction is windex is too strong though diluted 1 to several parts it is probably a good choice.77.86.106.97 (talk) 18:17, 9 June 2012 (UTC)

June 9

Firefox's recent "File + New Tab" addition

In my last update of Firefox (13.0), they seem to be trying to copy Opera's selection screen (which I like) where you can select from 9 web sites. Unfortunately, it doesn't seem to work well at all:

1) There doesn't appear to be an option to manually change the selections, they just populate with random recently visited pages, including many different pages from the same site.

2) The is an X to remove unwanted selections, but they just repopulate the page when I next visit those sites.

3) There's also a push-pin which supposedly makes the selection a permanent addition to the screen, but doesn't seem to work. The next time I restart Firefox, I get a new random assortment of selections. And, sometimes when I use the push-pin, that selection deletes instead, as if I had hit the X.

4) Each selection has text only, no image, and the text is the title of that web page, with no option to change it.

So, is this new feature just "not ready for prime time", or is this really how they designed it to work ? StuRat (talk) 00:32, 9 June 2012 (UTC)

Wouldn't surprise me, even the extensions for Firefox for this aren't very good at it. about:config → browser.newtab.url ¦ Reisio (talk) 00:36, 9 June 2012 (UTC)

Kind of a nit-picky point but I think Safari was the first to come out with this feature. It's what I use on my Macs at home and it works perfectly, i.e. just how you seem to be expecting the FF version to work. So, if you want to use Safari, there it is. Dismas|^(talk) 17:44, 9 June 2012 (UTC)

Safari definitely gets this feature right, but has other problems. ¦ Reisio (talk) 19:32, 9 June 2012 (UTC)

Sounds like we need to create a Frankenbrowser, with this feature from Safari and the best features from the other browsers, too. StuRat (talk) 05:30, 11 June 2012 (UTC)

Microsoft Windows 7 - Microsoft Windows XP.

Hi there, Microsoft Windows 7 and Microsoft Windows XP. Consistently use Windows 7 to store photos and now find that like rabbits they keep on duplicating, this seems to be happening on the older XP also. Advised that if this continues it will eventually crash the computer! Have searched Microsoft for any downloads but find I am referred to another company which I suspect uses a Corporation in India, and my experience tells me to keep well away. Is there any free software that will fix this problem - or software at a one off cost - or any other solution? How binding is the agreement you agree to online to access the supposedly free download product? Clicked off and uninstalled product when the monthly cost came up. Eyesight does not allow me to scrutinize online contracts. Probably too old and old fashioned, but should not any company provide immediate free downloads to fix problems on their own product after you purchase it? Would it be a temporary solution to download all pictures on to a USB stick and then delete all pictures until problem is solved? Have all Microsoft latest updates automatically set to download, but apparently not one for this problem!!

Help!!!!

Hamish 84.Hamish84 (talk) 03:44, 9 June 2012 (UTC)

Are you using some type of photo management software ? If so, then, yes, by all means, uninstall it. Just put your photos in regular old computer folders. I agree that software support is pathetic. If you can't read items on the screen, make the text bigger (usually with CTRL +, and then make it smaller with CTRL -). StuRat (talk) 04:05, 9 June 2012 (UTC)

You greater problem may be what that company could be doing with the other data on both your computers. If you do remove your pics to a USB and delete the offending program then be sure to run a comprehensive security scan over both machines and your USB stick before you proceded any further. FYI, I use Google's Picasa3 for my photo management software. Its free an easy. Benyoch ^{...Don't panic! Don't panic!...} (talk) 04:24, 9 June 2012 (UTC)

I am not convinced there is a program deliberately duplicating your photos. It is quite possibly something in what you are doing when you access your photos which is responsible. How are your photos stored?

If you are storing them on your own PC, maybe using software that came with your camera, then different things can happen depending on exactly which method you choose to copy the photos to the PC; for example it is quite possible that when you connect your camera to the PC to copy any recently taken photos, all the photos in the camera are copied again to a new folder.

On the other hand, if you are using an online service like Picassa or Flickr, whenever you access the photo galley, your internet browser will keep a copy in the cache. If you then search your computer for all images, you find multiple copies of your photos - one where you expect and others in folders you have never heard of.

Unfortunately, this is often something which is hard to analyse without actually seeing you use your computer. Maybe you have a friend or relative who is familiar with the workings of Windows and who could sit with you for a while to see how you access your photos. Astronaut (talk) 13:30, 9 June 2012 (UTC)

pdf slow - images

Hello. I've begun to notice that pdf's of scanned documents are unnaturally slow - for example http://archive.org/details/gentshistoryhul01ohlsgoog (or any other from this site, or a downloaded pdf from google books)

Using the download link page http://ia600404.us.archive.org/13/items/gentshistoryhul01ohlsgoog/ - comparing .djvu , .pdf , and the jp2.zip files after decompressing. (using adobe, caminova, and picassa ACDsee to view)

On my (admittedly slow XP 32bit) machine (using single page, non-scrolling view) it takes nearly a second (or a good fraction) of to get the next page displayed after pressing PgDn. On the .djvu or .jpg file it is nearly instantaneous. To add insult the .pdf file doesn't appear to contain any text data - so effectively it's just a slideshow. Task manager shows .pdf uses much more cpu - the situation is just the same with google chromes built in pdf viewer.. (it's clearly not hard-disk bandwidth as the jpg slideshow is far faster)

So - is there an simple explanation for this? - are there better pdf viewers?, why is pdf such a dog for images? Oranjblud (talk) 13:43, 9 June 2012 (UTC)

There may be an argument that PDFs necessarily encode images in a slow way (they are usually compressed page by page and there isn't any caching usually, to my knowledge), but it almost certainly depends mostly on the PDF viewer in question. Adobe Reader is notoriously bloatware; try Foxit Reader and see if it does better for you. There are a number of alternatives to Adobe in any case. --Mr.98 (talk) 14:28, 9 June 2012 (UTC)

If I look at the DjVu and the PDF on that archive.org page you linked (where the two are almost the same in size, so the images are surely the same resolution) with evince the pdf and djvu perform identically. There's nothing intrinsically poor about PDF, and while there are sometimes ones around that have been strangely constructed, or have over-detailed scans, this case isn't such an example. So the poorness you're experiencing can, I believe, be ascribed to the crummy Reader. There's no text in the PDF because none was put there by the scanning program. -- Finlay McWalterჷTalk 14:53, 9 June 2012 (UTC)

I will try those and see how they work. The aside I made about text was that there is not OCR text overlay in the pdf to slow things down - in fact - there is one in the djvu and it performs better.. As far as I know they images are the same as you guess - the JP2000 file contains the original scans I believe.Oranjblud (talk) 15:04, 9 June 2012 (UTC)

I see what you mean about the text. It may be, incidentally, that cominoa and ACDsee use Adobe's .dll to decode and render the PDF, which would explain why they work as badly as it. That Chrome does too is more surprising, as Chrome has its own decode and render (which, as far as I can tell, turns a PDF into the same datastructure as Chrome uses to represent the DOM of an html+css document). One thought - you may have some security software which is checking the PDF (as PDFs can contain embedded scripts, which may, at least in theory, have malicious use). So if the security software is reading the PDFs but not the DjVus, that would be an obvious slowdown (but I'd expect that on open, not on page-down). -- Finlay McWalterჷTalk 15:19, 9 June 2012 (UTC)

(I used ACDsee for the JP2000s, and Caminova for the .djvu this one - both peformed well on those file types - afaik they don't display pdfs)

I checked with evince and foxit - it's clear that both are quicker (or at least 'snappier') on smaller pdfs. evince appears (?) to do extra near page caching as well.

However - when moving to bigger documents eg http://archive.org/details/cu31924013922905 (1000pages 100M) - both are as bad as adobe, evince is worse (tens of seconds pause). Foxit appears similar. Both have second(s) of delay when jumping to a new page somewhere in the book. But, when I try the djvu version its performance is good (1 sec initial program startup, fraction of seconds to jump). This is pretty much what I'd expect - as the book is essentially a slideshow of images.

I looks like the issue is intrinsic to pdfs filetypes - I can't imagine what they've done to the implementation of images to make it so slow. Does anyone know why this would be , or maybe suggest another experiment.Oranjblud (talk) 15:58, 9 June 2012 (UTC)

(more) (It's not indexing or an antivirus-scan that is causing the slow down - checked) - I think the cause might be the image decompression algorthym - I get heavy (ie full) cpu when moving to a page. The cpu then continues at full for a good while after - I discovered that it was fine tuning the image (only noticeable if I jump to a page with 300% magnification) - I would assume that it has multi-detail level images and it progressivelt applies the higher details as they load - however - my suspicion is that it is it is post processing the image - ie applying sharpness and maybe contrast filters (this would explain the delay) - the ammount of CPU suggests that it is not just adding a final dither to the image - but that it peforming post processing everytime - does anyone known anything about pdfs doing this. (and maybe if true a way to stop this nonsense?) Oranjblud (talk) 16:36, 9 June 2012 (UTC)

I've noticed this also and wondered about it. For this particular book, on the laptop I happen to be using right now, I get around 1-2 pages per second viewing the PDF version with Foxit, Sumatra or Evince, 4-5 pages per second viewing the DjVu version with Evince, and about 6 pages per second with WinDjVu. (Note that this contradicts Finlay McWalter's experience with Evince). I've found that to be typical, at least for books from the Internet Archive.

Most of the pages of gentshistoryhul01ohlsgoog.pdf are compressed with JBIG2 (about which I know a bit) and DjVu uses a closely related format called JB2 (about which I know nothing). Unless there's something in JB2 that allows much faster decompression, which I doubt, it must come down to software quality. I guess somebody put a lot of effort into optimizing DjVuLibre's JB2 decompression, while nobody ever made a fast open-source JBIG2 implementation. -- BenRG (talk) 19:07, 9 June 2012 (UTC)

ok, thanks. It looks likely the decompression is to blame. At least I know it's not just me. Not much I can do about this in the short term, except use the djvu when available. On the other hand the idea of using OCR'd data for text image compression is an interesting one (although JBIG doesn't seem to explicitly try to do this - maybe mk.2 should..)

Seeing as the compression appears to be the problem I think I might try printing the pdf - using print to pdf software to get an uncompressed pdf - and see if that helps at all..Oranjblud (talk) 00:36, 10 June 2012 (UTC)

"Fused off" features in Intel chips

I have read that a lot of Intel's chips are the same with certain features "fused off". What does this mean and does this have anything to do with silicon fuses? Are there any Intel chips that cannot be "fused off" as in they are entirely static in their structure? --Melab±1 ☎ 15:36, 9 June 2012 (UTC)

Silicon economics are very complicated. Start by reading how VLSI fabrication works. Sometimes, it is cheaper (or just makes more sense) to release two "versions" of a hardware product that are in fact sharing a lot of features. They may be built on the same wafers; they may even be identical all the way to the end of the fab line. At some stage on the proverbial "assembly line," the chips may be binned; and certain manufacturing steps are applied to different end-products. Depending when this occurs on the assembly-line, those subsequent hardware changes may be irreversible. For example, if a different photomask step is applied to different chips that originated from the same wafer lots, the resulting chips can never be made "identical" again - short of melting the materials down and starting from scratch. On the other hand, if the products diverge fairly late - say, after the silicon fabrication is done, the manufacturer might use a one-time programmable memory (the device you are vaguely referring to as a "silicon fuse"). As always, depending on the exact nature of that memory, these changes can be "permanently" burned in, or they might be reversible using specialized equipment. (Old-fashioned UV-light erasable EPROMs come to mind).

Intel's manufacturing process and the details of its massive product-lineup are very complicated, so you'll have to ask a more specific question about a specific technology if you want a specific answer. For now, you can accept the very generic case: "some end-products might be built from identical precursors." It is even plausible that similar variants of Intel processors are effectively identical, aside from a few bits in an on-chip ROM. Despite prevalent rumors on the internet, this does not usually mean that you can build a "home upgrade" kit to "unfuse" a device, turning a low-cost Intel i3 into a high-cost Intel i7 by "unfusing/enabling" its "locked" features. Nimur (talk) 16:02, 9 June 2012 (UTC)

I use "silicon fuses" or "eFUSEs" in place of "one-time programmable memory" when the fuses in question are not arranged in large enough amounts to hold a single program and are instead used for configuration. I though that maybe the bridges between the cores some in Intel's processors were connected by fuses for pathways. To sell a less powerful chip for a certain range, Intel would then blow the bridge between the extra cores and the rest of the processor. That is what I hypothesized, anyway. --Melab±1 ☎ 19:20, 9 June 2012 (UTC)

execution of correlated subquery in oracle

Sir my doubt is about correlated subquery execution When it has more than one sub query. I know correlated subquery execution when it has one sub query.but if it has more than one sub query I am not able to understand. I have refferd so many books and web sites.but I could not find it. Finally I am asking you. for me you spend some time and give detailed answer Below there are two queries.i know execution of query1.but I do not know execution of query 2. I am asking my doubts by comparing with query1.you please read clear my doubt.do not think this big doubt.i am expressing my doubt clearly .so it became big doubt.

---

query 1: Select e.ename,e.city from emp1 e where exists(select f.ename from emp2 f where f.ename=’ajay’ and e.city=f.city));

---

Query2: Select e.ename from employee e where exists(select ‘x’ from emp_company c where e.ename=c.ename and exists(select ‘x’ from company m where c.cname =m.cname and m.city=’bombay’));--

---

Doubt1: In first step of execution of query1 ,employee table’s first row ename,city considered. Then what happens in first step of execution of query2.

---

Doubt2: In second step of execution of query1 ,the considered city from main query is compared with every row of emp2. What happens in second step of execution of query2.?

---

third step of execution of query1:

while comparing city from main query with every row of emp2,if any row satisfies condition that rows ename is added to a list. What happens in 3rd step of execution of query2.?

---

In 4th step of execution of query1 ,the formed list is returned. To main query. What happens in 4th step of execution of query2.?

---

In 5th step of execution of query1,if the returned list is not empty then exists evaluates to true.then emp1 table’s ename,city added out put. What happens in 5th step of execution of query2.?

---

In 6th step of execution of query1 emp1 ename,city are selected from second row of emp1 table. What happens in 6th step of execution of query2.?

---

Can You please explain execution of query2 as I explained query1?. — Preceding unsigned comment added by Phanihup (talk • contribs) 16:42, 9 June 2012 (UTC)

I am not familiar with the specific analysis technique you are using, but here is my attempt at describing the behavior of Query2.

1. Consider each record of the employee table.
2. For each such record, consider each record of the emp_company.
   1. If the ename's of the employee and emp_company tables match, continue, otherwise ignore this emp_company record.
   2. For each emp_company record with a matching emp_record table, consider each record of the company table.
      1. If the cname's of the company and emp_company match and the city is 'bombay' continue, otherwise ignore this compay record.
      2. Add 'x' to list-A. (Note, for an exists() test, it generally doesn't matter what value is actually selected.)
      3. Repeat for each additional company record.
   3. After all the company records are processed, examine list-A.
   4. If list-A is non-empty, continue, otherwise ignore this emp_company record.
   5. Add 'x' to list-B.
   6. Repeat for each additional emp_company record.
3. After all the emp-company records are processed, examine list=B.
4. If list-B is non-empty, continue, otherwise ignore this employee record.
5. Add the employee ename to the final results.
6. Repeat for each additional employee record.

Note that in the above procedure, the subqueries are processed repeatedly for each candidate record from the parent and list-A and list-B are reset each time. In reality, the query optimizer of the database engine will utilize various shortcuts to improve efficiency and may even rewrite the query to something much different that was provided. For example, once a match is found in an exists() condition, it is not necessary to search for additional matches, Also, the engine might make use of database indexes to locate matches without actually scanning the tables. It might reverse the execution logic - first finding companies located in Bombay, then finding related emp_company records (using an index), and then looking up the matching employee records. The point is, while the above step-by-step procedure describes how the query is written, it is highly unlikely that the database engine will use that same method to actually retrieve the results.

I hope this helps. -- Tom N (tcncv) talk/contrib 01:52, 10 June 2012 (UTC)

June 10

catalyst overdrive

in that section of the driver panel, it has these various icons on the top of it, there is this power one, with a chord plug pictured on it, wHAT DOES IT MEAN?? IT shows zero on mine, im just curious as to what its for — Preceding unsigned comment added by 77.35.15.169 (talk) 09:58, 10 June 2012 (UTC)

It appears to be a tool to boost performance of the GPU by overclocking it. 77.97.198.48 (talk) 11:46, 12 June 2012 (UTC)

mojibake in OOo text file

A friend sent me a file (a short list of books) that she made in OpenOffice (.odt). I opened it in LibreOffice and saved it as Text (.txt), then opened the textfile in vi. As I manipulate it (experimentally sorting by different words), junk keeps appearing at the beginning of one line, looking like this:



I delete the junk and sort again, and it reappears on another line. Any idea what's going on? —Tamfang (talk) 15:49, 10 June 2012 (UTC)

At some point, something is adding the UTF-8 byte order mark to indicate the text encoding is Unicode UTF-8. At a later point, something else is interpreting the text with encoding ISO/IEC 8859-1, causing the UTF-8 byte order mark to appear as . --Bavi H (talk) 16:09, 10 June 2012 (UTC)

June 11

Nokia N8 fails to connect to WiFi

My Nokia N8 now fails to connect to WiFi services. I get to a café, order a beer, ask for the café's password, enter it, the status goes 'connecting' and then 'known' but not 'connected'. If I enter a wrong password it doesn't say 'connecting'. If I enter a password that is too short, it tells me to enter a longer one. But it doesn't connect. I can't find any settings that would have caused this. What can be done? Hayttom (talk) 19:57, 11 June 2012 (UTC)

Hmm. I don't have an N8 to hand, but maybe there are some things you can try. Firstly, does this happen with other WiFi networks, or only in this particular cafe? It might be worth trying a different hotspot to see if it's an issue on their end. Also see what happens with unencrypted networks - i.e. the ones you can connect to without a password. I saw murmurings about the N8 being incompatible with various forms of WPA on some forums. If you can't connect to any network, it is more likely to be a problem with the phone. See here for some other people with similar issues. You may like to try a) doing a firmware upgrade (look in the manual for instructions) or b) a 'factory reset' (that is, resetting the phone back to its original state. Make sure to backup any important data, photos, contacts, and apps before trying either of these steps. - Cucumber Mike (talk) 21:55, 11 June 2012 (UTC)

{OP} It happens everywhere I've tried recently. I'll try in an unencrypted network when I find one. I'm 99% sure this is a new phenomenon - but I'd have to retrace my recent travels (now in Vilnius, previously Warsaw and Krakow) to check hotspots that worked before. I can't do a firmware upgrade until I can connect. I don't want to do a factory reset - yet.Hayttom (talk) 04:19, 12 June 2012 (UTC)

{OP} I couldn't find the reason (and so will not mark this question 'resolved') and needed to get a solution fast so I reset my phone by dialling *#7780#. I will have to re-load data but at least I can immediately download new GPS maps, which was urgent. Thanks Cucumber Mike (talk) for your help! Hayttom (talk) 11:03, 13 June 2012 (UTC)

June 12

The 'Ç' character with Swiss French keyboard

On the Swiss keyboard, I have been having trouble figuring out how to write the capital 'ç'. I can do it on Linux by means of the CAPS LOCK, but it doesn't work that way on Windows. Does anybody know how it is supposed to be inserted (other than with the CAPS key?). Thanks, Falconus^{p t c} 13:59, 12 June 2012 (UTC)

If you can't find anything better, Ç#Input describes the keymap independent way of entering, as an alt code. -- Finlay McWalterჷTalk 14:06, 12 June 2012 (UTC)

Okay, thanks. Falconus^{p t c} 15:00, 12 June 2012 (UTC)

Wikipedia ipv6

Since Wikipedia now supports ipv6, I was wondering how does one access the site via ipv6? Is it the normal address, or a special one like ipv6.google.com? 92.233.64.26 (talk) 16:29, 12 June 2012 (UTC)

You might want to inquire at the talk page of WP:IPv6.

—Wavelength (talk) 17:03, 12 June 2012 (UTC)

Unless you're an internet engineer, you don't need to do anything. It's the responsibility of whoever operates your network - your commercial internet service provider, or your institution's system administrator - to eventually migrate your connection to IPv6. All Wikipedia has done is make it possible for IPv6 routes to resolve to its servers. If you aren't using one of these new routes, (because, like most of the planet) your route to Wikipedia still uses IPv4 then you need take no action. There's no benefit or difference, as a user, because the website appears and functions identically, whether you access it over IPv4, 6, or any esoteric network protocol that can sustain HTTP protocol. One day, your ISP may make an IPv6 address available to you, and you will be able to use it transparently. Nimur (talk) 04:06, 13 June 2012 (UTC)

That isn't entirely true. Although unlikely, it's possible your ISP is already providing an IPv6 address. However although high end routers have supported IPv6 for a long time, a lot of even very recent home routers and CPE (particularly ADSL modems) have not. (See e.g. these fairly recent [2] [3] discussions.) If your ISP is providing IPv6 but your equipment isn't capable of supporting it, then you do have to do something to make it work. (Of course if the equipment is still owned by the ISP, then it becomes their responsibility again but in many countries this is exceptionally rare.) Similarly while most recent OSes have a dualstack network and have IPv6 enabled by default, it's possible that you have it disabled for whatever reason. In such a case, again you have to do something. Whether you want to bother or just wait until eventual normal upgrades fix the issue is up to you and as I said it's very rare ISPs provide IPv6 anyway. Of course you can probably get IPv6 working even if your ISP doesn't provide native IPv6 by default. A small number of ISPs provide IPv6 for on request either natively or via some other method like PPtP. And of course there's other options like tunnel brokers if your ISP doesn't. There are plenty of guides out there even long before World IPv6 day. Again whether you want to bother is up to you. There are some potential benefits, e.g. free binary IPv6 news servers (I've used them and they aren't too bad), the possibility of getting around a NAT issues if your ISP is not able to provide a public IP to each of their users, providing a public IP to each computer if you have multiple ones, in some cases getting around throttling imposed by the ISP (I was able to do this somewhat in the past particularly since I was using a NZ tunnel broker however my ISP throttles a lot less now so it isn't so important, and before anyone complains my tunnel broker clearly said they welcome use provided it's non malicious). Note that in the specific case of wikipedia, I would disagree functionality is identical. For editors, there's always the risk of being blocked for something you didn't do because of a shared IP. Even if you create an account, occasionally hard blocks of IPs are placed meaning unless you ask for and are granted an Wikipedia:IP block exemption, you're still SOL. IPv6 is too new that we don't know exactly how things are going to work out, particularly for services like tunnel brokers. But either way, depending a lot on where you get your IPv6 address from and the nature of your IPv4 address, there is the possibility you're at less risk of being blocked for something you didn't do. (There is also the risk you're more likely to be blocked.) Nil Einne (talk) 07:37, 13 June 2012 (UTC)

Thanks for the interesting answers. According http://test-ipv6.com/ I have "6to4" access and I've been able to access every ipv6 site, so it would appear I do have an ipv6 address? But I don't seem to be able to make a choice about which method I use when visiting a site that supports both, it always just picks ipv4. Do I have to do something else to make it used ipv6? I know there is no real difference in end-user functionality between the two, I'm just curious and want to see it work. 92.233.64.26 (talk) 10:10, 13 June 2012 (UTC)

I believe it depends both on the browser and potentially the OS. I believe most new browsers and OSes prefer IPv6 where it's available but I could be mistaken and I'm not sure if this applies to 6to4. It may also depend on other factors as concern over buggy set-ups (where the OS and browser think IPv6 is working so try to use it but it's not) was one of the reason many sites chose not to turn on IPv6 until the recent world IPv6 day (the decision was made partially based on the results of the previous world IPv6 test day). See e.g. [4] [5] [6]. Note that if you're using 6to4 you're unlikely to have any specific advantages when it comes to accessing wikimedia sites unless perhaps you're a network admin and want to track abuse which from the discussion is not the case. Nil Einne (talk) 07:43, 14 June 2012 (UTC)

dim screen

Is this section just for computing or also for computers? How much relative energy efficiency can I get from dimming my laptop computer's screen? (I only hope for general answers but my laptop is a Sony Vaio VPC-YB3V1E - which I just read has a "A high resolution screen and fantastic keyboard, but performance and battery life are underwhelming") Hayttom (talk) 18:33, 12 June 2012 (UTC)

This is the right desk. You probably don't mean efficiency, as that may even go down with a dimmer screen, meaning less light is produced per energy used. What you care about, I suspect, is total battery time at the dim vs. bright settings. Giving it a test yourself, at each setting, is the best way to get an answer. StuRat (talk) 19:22, 12 June 2012 (UTC)

1) You're right, I meant total battery time. 2) If I manage to do the tests I'll post the results. (I suppose I'll have to monitor closely to see when the computer shuts itself down, and using the computer would skew the results.)Hayttom (talk) 03:48, 13 June 2012 (UTC)

Excellent, I look forward to your results. BTW, the figure the seller gives for how long the battery lasts is probably on the dimmest setting with the computer doing nothing, using a brand new battery. So, it's virtually impossible to get that much life out of it in the real world. StuRat (talk) 21:39, 13 June 2012 (UTC)

June 13

Help me my laptop DVD drive is damaged!!!

It was when I inserted a DVD into my laptop's drive, then suddenly the DVD drive icon dissapears. I cannot open the drive; restarting did not help. Why? 117.5.2.187 (talk) 11:42, 13 June 2012 (UTC)

Is your DVD drive one that can be slid completely out of the computer? Maybe when closing the drive you managed to bump something just right to slide the whole drive out a little bit, disconnecting it. If it is a removable drive, try removing it then pushing it back into place. 209.131.76.183 (talk) 13:01, 13 June 2012 (UTC)

Thanks. Seems like my drive work again automatically. 117.5.9.218 (talk) 13:08, 13 June 2012 (UTC)

OK, I will mark this Q resolved. StuRat (talk) 21:35, 13 June 2012 (UTC)

Which version of Ubuntu is Wikimedia using for their servers?

Which version of Ubuntu is Wikimedia using? 117.5.9.218 (talk) 13:17, 13 June 2012 (UTC)

Does this help? Thincat (talk) 14:28, 13 June 2012 (UTC)

Security check website

What is the recommended way of checking the security of a (my own) website (php,mysql)? I found some tools, but don't know how recommended or useful they are: skipfish, nikto, wapiti, spikeproxy, ratproxy, prewikka, paros. The website should be checked on a test server, pre-use. The tool should run on linux. bamse (talk) 17:54, 13 June 2012 (UTC)

Wiki having trouble after migration

We run a community wiki, and recently had to switch providers. Our main sysop C&P'ed the entire wiki to the new server, but since then we've run into a number of problems. Notably, images are not displaying correctly, and tables aren't working, either.

If you know what's wrong and can recommend solutions, that would be awesome. If not, I'd be happy to know where I can go for help, or what I can read that will help me to understand the problem myself (right now we really don't know why things aren't working; they worked fine before migrating to the new server).

Here's an example of a problematic page: http://wiktenauer.com/wiki/Andr%C3%A9_des_Bordes

Problems:

1. The thumbnail at the top isn't displaying (even though the raw image is located in the correct place).
2. The wikitable at the bottom isn't rendering properly; it should be a collapsible table, not a standard table.
3. The infobox at the top should be self-contained and allow text to wrap around it. It's not doing that.

I've tried searching for solutions extensively, but I've been unable to figure out what the problem is. The Jade Knight (talk) 18:17, 13 June 2012 (UTC)

If you look at http://wiktenauer.com/wiki/Special:Version, it shows the version of the MediaWiki software that your server is running, and the extensions that are added to it. Most likely you are running different versions of things on the new system than on the old one. Without knowing more about the old system it is hard to be more specific. One thing I notice is that your version of MediaWiki is 1.15.3, which was released back in 2010. Looie496 (talk) 18:39, 13 June 2012 (UTC)

Looie, that is incorrect. Run some maintenance scripts like update.php. Find them at mediawikiwiki:Manual:Maintenance_scripts. --J (t) 00:31, 14 June 2012 (UTC)

Two or more people call the same cell phone number at the exact time

(I wasn't sure if this question should go in this section or the "Miscellaneous" section, but I had to pick one of them).

I have two questions regarding this.

My first question (which is, yes, very theoretical, but still technically possible): What would happen if two or more people called the same cell phone number at the exact time (and I mean exact; and, for that matter---just thought of this as I've been typing---, what would happen if two or more people pressed the "Edit" button on the same Wikipedia article at the exact time, as well?)?

Going along with this, lets say (using cell phones as opposed to home phones) "James" calls "Kyle." Kyle isn't able to get to his phone. While James hears ringing and Kyle's phone is ringing, "Bruce" calls Kyle; what would happen---to both Kyle's phone (in one respect, I mean what would happen if you pressed the "talk" button, since two people are calling at once) and James's and Bruce's phone calls (would they continue ringing for them)?

Any help on this would be great. Thanks!

P.S.: Sorry for asking three questions in one section, but I hope you see how they are all very related. — Preceding unsigned comment added by 108.85.4.130 (talk) 19:25, 13 June 2012 (UTC)

The resolution of simultaneous access to a shared physical medium is called collision management and is well-studied in network engineering. The exact details of how the "machine" would resolve the collision (that is, how two phone-calls trying to reach the same end-point) would depend on specifics (which type of telephone network). For a very thorough overview of one type of resolution protocol, you can see how a packet switched network like ethernet works: Carrier sense multiple access with collision detection. The standard procedure is first to detect that multiple clients are trying to use the network; and then to resolve that simultaneous access by either sharing the medium, or denying access to one client. Many telephone networks use ethernet and IP at the long-haul layers, so this is actually a very probable resolution in practice.

Your follow-on questions are essentially answered in the same way; and ultimately depend on specific details of the software and hardware in use. Nimur (talk) 19:46, 13 June 2012 (UTC)

The "Kyle" question is most easily answered: a call made to a number that is already ringing (or is the source of a call that is ringing) is redirected immediately to voicemail (as if the target phone were turned off). For a (single-line) land line target, a busy signal is produced, even if it has call waiting. (A corollary is that calling your own number produces a busy because your phone is already dialing out and cannot ring.) The other points are ultimately decided by arbiter circuits at some junction or another. --Tardis (talk) 04:53, 14 June 2012 (UTC)

June 14

Global and local variables in JavaScript

Is an if block considered a function for the purposes of determining whether a variable declared with the var keyword is global or local? — Preceding unsigned comment added by 203.116.187.1 (talk) 01:59, 14 June 2012 (UTC)

While not an authoritative reference, this site indicates that the answer is no. -- Tom N (tcncv) talk/contrib 03:26, 14 June 2012 (UTC)

Are there time machines?

No. :-) StuRat (talk) 02:34, 14 June 2012 (UTC)

Are technological devices intended to travel into the past (time machines) available now? 117.5.13.52 (talk) 02:35, 14 June 2012 (UTC)

What's your hurry? --Trovatore (talk) 02:55, 14 June 2012 (UTC)

How long will a modern computer take to break an Enigma cipher?

--113.105.70.226 (talk) 03:54, 14 June 2012 (UTC)

That depends on what you mean by "break." Do you intend to provide a program to perform the decryption, and measure how long it takes to try "all possible inputs"? Nimur (talk) 04:13, 14 June 2012 (UTC)

Let's say we have the settings of the scramblers and some ciphertext already and what we need to do is to determine the Key setting.--211.162.75.201 (talk) 08:14, 14 June 2012 (UTC)

This page suggests that a mostly brute-force search of the entire key-space for a 4-rotor enigma would take 4 days CPU time on 2006 hardware. In practice, guessing a crib would enormously reduce the search space. This 2005 paper by Geoff Sullivan and Frode Weierud seems to be frequently cited. Gandalf61 (talk) 09:09, 14 June 2012 (UTC)

If you have the programming skills and tools you can try it yourself. There are plenty Enigma simulators available online that you can use to generate an encrypted source text. Roger (talk) 09:31, 14 June 2012 (UTC)

There's a difference between "how long would it take to break" and "how long would it take to guarantee a break". While it's tiny, there's a chance that your first random guess would be correct and thus you'd break it immediately. Nyttend (talk) 11:06, 14 June 2012 (UTC)

Playing .swf file in Powerpoint (.pptx)

I've inserted a .swf file into a .pptx presentation after going to much trouble. But now, everytime I play the slideshow, the video keeps getting stuck. If it plays properly once, it gets stuck on all the subsequent trials, because the "Play" parameter in teh .swf file's properties keeps getting reset to false. Is there any way I can fix this? Thanks 204.4.182.16 (talk) 05:36, 14 June 2012 (UTC)

Video to GIF in Ubuntu 11.10

Can anyone suggest me any software which can covert video to gif? Ubuntu software centre software will be better! Please add a tb in my talk page if possible! --Tito Dutta ✉ 08:30, 14 June 2012 (UTC)

IPv1, IPv2, IPv3, IPv5

IPv1, IPv2, and IPv3 redirect to Internet Protocol, while IPv5 redirects to Internet Stream Protocol. Why is v5 different from the rest — was it simply an editorial decision, or is the protocol substantially different? And if the latter, in what ways? I notice the edit summary here, but the article text says nothing of that, unless I'm overlooking something. Nyttend (talk) 11:13, 14 June 2012 (UTC)

I suspect it's because IP protocoll number 5 is Internet Stream Protocol. See List of IP protocol numbers. But, with the exception that IPv4 has number 4, I don't think protocol number is the same as protocol version. Taemyr (talk) 11:47, 14 June 2012 (UTC)

I might be wrong. According to Internet Protocol IPv5 is Internet Stream Protocol, so the difference between IPv5 and IPv1-3 is that we have a seperate article for the former. Taemyr (talk) 11:49, 14 June 2012 (UTC)