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March 30

Core Duo processor

Some programs and operating systems say they will only work on a Intel Core 2 or newer. My laptop uses a Core Duo processor. Can it handle these programs? Is there a diagram of the full line of Intel processors? --T H F S W (T · C · E) 01:31, 30 March 2011 (UTC)[reply]

Despite similar names, a Core Duo is a much older and "weaker" type of CPU than a Core 2. It also lacks certain critical architecture features. If the software specification is correct, and does actually require the Core 2, then the Core Duo will not do the trick. Core 2 includes SSE4 and supports the x86_64 instruction set, and some software might require these features - in other words, will not run or will crash if you use a Core Duo. Other software may simply be suggesting the Core 2 for its higher performance; a Core Duo may under-perform and adversely affect your experience, but will still run the software. (We can't know which is the case without more specific details from you). We do have a comprehensive listing of all Intel microprocessors, and we have an entire list of lists of Intel topics and CPU types. Read the Intel Core 2 article; and don't let the confusing Intel brand-names get to you: Core Duo and Core 2 are not the same at all. Nimur (talk) 04:58, 30 March 2011 (UTC)[reply]

Computes reset during boot.

When I try to start my computer, the computer reset before it enters on windows, it happens on safe mode too. The computer reset and then start to boot again, just to boot again. Happens in the windows xp logo loading bar, before it and even if I choose safe mode. But it doenst happens while on boot setup (making the test right now, 5 minutes on boot setup without a reset).

What can be the problem? 201.78.136.48 (talk) 01:43, 30 March 2011 (UTC)[reply]

Sounds like it might be the operating system. If so, you need to find some way to boot from another device. Does it have dual-boot partitions ? If so, try the other one. If not, then you're down to booting from the CD/DVD drive, or USB pen drive (if boot from there is supported), or even a floppy disk. Of course, you will need a boot disk or pen drive to do this. Once you're able to get it to boot, then you'll have the opportunity to fix your original boot partition. Of course, all of this is quite complex, so a computer geek or repair shop might be in order. StuRat (talk) 05:15, 30 March 2011 (UTC)[reply]

Try using a Live CD. If that works, then you know it is not a hardware fault. I had a similar problem (using WinXP), except it would boot in safe mode, and I eventually found it was due to a defective driver. When the driver was deactivated, it booted up OK. 92.15.1.33 (talk) 15:48, 30 March 2011 (UTC)[reply]

Going on vacation, need gmail autonotification

Is there a setting where gmail will automatically tell people that e-mail me that I'll be on leave for 13 days?--Lenticel ^(talk) 06:25, 30 March 2011 (UTC)[reply]

"Settings" (top right next to your gmail address) then on the "General" tab you'll find the "Out of office autoreply" settings near the bottom of the page. Roger (talk) 07:12, 30 March 2011 (UTC)[reply]

Yup found it, thanks :) --Lenticel ^(talk) 07:15, 30 March 2011 (UTC)[reply]

Be a bit careful with these. They might be read as "I'll be away from my house for the next week or so, and so anyone wishing to break in can do so without my being there".--Phil Holmes (talk) 07:56, 30 March 2011 (UTC)[reply]

Well, only if you have local burglars listed among your contacts. But do remember to check the box that says "Only send a response to people in my Contacts" otherwise all the spam (and all the other out-of-office autoreplies) gets your message too.--Shantavira|^{feed me} 09:18, 30 March 2011 (UTC)[reply]

You also want to be careful if you have signed up for any email discussion lists. You can annoy a lot of people really quickly if every post to the list is followed by a "Sorry, I'm out of the office ..." response from you. (Probably the best way to handle that is to remove any mailing list posting addresses from Contacts and tick the setting Shantavira mentioned.) -- 140.142.20.229 (talk) 16:16, 30 March 2011 (UTC)[reply]

What if I send you a message, after you set autoreply, and set the autoreply myself? Will be messages be bouncing to and fro until we come back from vacation? 212.169.177.145 (talk) 19:15, 30 March 2011 (UTC)[reply]

I think auto replies only get sent once to each contact. I think there are other "processes" in place to prevent out of control nested looping situations like that. Vespine (talk) 00:52, 31 March 2011 (UTC)[reply]

The Vaction responder setting in Gmail says "If a contact sends you several messages, this automated reply will be sent at most once every 4 days." I assume other e-mail clients do something similar. --Bavi H (talk) 00:51, 31 March 2011 (UTC)[reply]

There exists an email header keyword, Auto-Submitted that indicates whether an email was automatically generated or not. Hopefully, vacation autoresponders will (a) set that header, and (b) not autorespond to something with that header set. Paul (Stansifer) 17:19, 31 March 2011 (UTC)[reply]

ms PICTURE IT

HELP!! I WILL BUY ANY PROGRAM THAT CAN OPEN/READ MY 50 CD'S OF PICTURES. THEY WERE MADE WITH MICROSOFT 'PICTURE IT, 1.0' FORMAT '.MIX'. Currently using win7. One idea, buy old computer with win95 and install PICTURE IT. Anything else? Thanks, Mike — Preceding unsigned comment added by DIVER0247 (talk • contribs) 17:32, 30 March 2011 (UTC)[reply]

Apparently Microsoft Word will read them (you should be able to drag a whole CD-worth from Windows Explorer and drop them on a fresh Word document) and you "save as webpage" to get it to emit them as JPGs. -- Finlay McWalter ☻ Talk 17:36, 30 March 2011 (UTC)[reply]

According to this, you can run Picture It on Windows 7 by settings Windows 98 compatibility mode in the file properties. They used Picture It 2001 (5.0), but it's worth a try with 1.0. You could also download a free PC emulator such as VirtualBox and run Windows 95 on that, instead of buying another machine. -- BenRG (talk) 17:54, 30 March 2011 (UTC)[reply]

And there's a lesson here: Don't put important things in a proprietary format or you can be held hostage by the owner of the format. StuRat (talk) 03:43, 1 April 2011 (UTC)[reply]

I know for sure that Picture It runs in XP without compatibility mode. If you really have to, you can dual-boot into XP or Win95 or even use a virtual to run Win95. No need, in this day and age, for another computer. Sandman30s (talk) 11:38, 1 April 2011 (UTC)[reply]

Microsoft Digital Image Starter Edition 2006, which is free from Microsoft, is supposedly able to open .mix files and convert them into JPEG or PDF files. You might need to run it in Windows XP Mode, though. 118.96.163.209 (talk) 15:23, 1 April 2011 (UTC)[reply]

Hi. Please avoid typing in ALL CAPS, as it is considered the online equivalent of shouting. Thank you. Rocketshiporion ♫ 03:11, 4 April 2011 (UTC)[reply]

Wireless Sky TV

Is it possible to have a second sky TV box in a second room with sky any room, but to connect the second box wirelessly and with the capacity to change channel separately from the original one.

If it is possible, what exactly would I need to buy.

Lucas 83 19:08, 30 March 2011 (UTC)

I don't think there is any way to decode satellite signals through a wireless connection. In theory it should be possible, but in practice all the equipment I've seen needs a co-axial cable to the decoder (box) then the decoded signal can be sent wirelessly to a TV. I would suggest that your best option would be a quad LNB (£10) at your satellite dish, and run a twin co-axial cable to a second SKY box which is then completely independent of the first box. Do you need the subscription channels in the other room(s)? Dbfirs 21:42, 30 March 2011 (UTC)[reply]

I would need the subscription channels and unfortunately I thought that what you said was true that a cable from dish to second box would have to be run through. It's possible, just requires lots of upheaval in the flat. Cheers anyway. Lucas 83 23:19, 30 March 2011 (UTC) — Preceding unsigned comment added by Lukerees83 (talk • contribs)

Sky's page on multiroom suggests they supply an additional Sky decoder box (and presumably a duplicate subscription card). If you were to combine that with Dbfirs' suggestion above - ie. fit a quad LNB on your dish and run another pair of coax cables from the quad LNB to the second box - you should then have the ability to watch (and record/pause) different things from that in the living room. Unfortunately, I don't know of a way to this wirelessly. The bigger problem though might be Sky's view on you changing your installation in this way (you are in effect creating two subscriptions for the price of one). Astronaut (talk) 06:01, 31 March 2011 (UTC)[reply]

Yes, safest to stay with Sky if you need their subscription channels. I think Sky regard the equipment as your property, but if you are relying on them for maintenance, then it is best not to make alterations. I've modified my own Sky installation, but only after I cancelled my contract with them. If you don't need more than two subscription channels at one time, then there are other options. You could purchase a wireless transmitter to relay a chosen channel from one room to another, and most such devices allow you to change channels from the other room. I've found these devices to be rather unreliable over time, but perhaps they have improved since I last used them. They can also interfere with wireless internet. Dbfirs 13:20, 31 March 2011 (UTC)[reply]

php

Resolved

I have the following php script which lists the files in a directory. How can I make it list in order of their modified date, newest first?

Extended content

<?
$Directory = opendir(".");

while($entryName = readdir($Directory)) {
	$dirArray[] = $entryName;
}

closedir($Directory);

$indexCount	= count($dirArray);

sort($dirArray);

print("<TABLE border=1 cellpadding=5 cellspacing=0 class=whitelinks>\n");
for($index=0; $index < $indexCount; $index++) {
        if (substr("$dirArray[$index]", 0, 1) != "."){
		print("<TR><TD><a href=\"$dirArray[$index]\">$dirArray[$index]</a></td>");
		print("</TR>\n");
	}
}
print("</TABLE>\n");

?>

I made a few modifications. Commenting included. The trick is to make an array of the file modification dates, then sort those in a way that keeps the original index associations, which are identical to the directory array indices. Then instead for a for/next loop, you use a foreach loop to iterate over the file modification array in the order it has been sorted in, but use that index to call the directory array. Hope that makes sense!

Extended content

<?
$Directory = opendir(".");

while($entryName = readdir($Directory)) {
        $dirArray[] = $entryName;
	$dirFilemod[] = filemtime($entryName); //make array of file mod times
}

closedir($Directory);

$indexCount= count($dirArray);

arsort($dirFilemod); //sort the file mod times in reverse order (newest first), but maintain their original keys

print("<TABLE border=1 cellpadding=5 cellspacing=0 class=whitelinks>\n");

foreach($dirFilemod as $index=>$val) { //instead of using a for/next loop, use a foreach loop, running it over the file mod array in the sorted order
        if (substr("$dirArray[$index]", 0, 1) != "."){
                print("<TR><TD><a href=\"$dirArray[$index]\">$dirArray[$index]</a></td>"); 
                print("</TR>\n");
        }
}
print("</TABLE>\n");

?>

--Mr.98 (talk) 00:54, 31 March 2011 (UTC)[reply]

Thanks! 82.43.90.38 (talk) 11:56, 31 March 2011 (UTC)[reply]

Apple Keynote: "Reapply Master to Selection" if object has been deleted?

Hello,

I have another question on Keynote by Apple.

I know that I can make - for instances - Text Boxes in the Master Slide, and then choose Format->Define as Text Placeholder.

This way I automatically obtain a text box that I can move, change, resize, colour or even remove from one individual slide. I can also do "Reapply Master to Selection" if I want to go back to the default setting from the Master Slide.

But what I have simply removed that object? Is there any way I can "get it back"? Just copying it from another slide does not do the trick, it seems to lose any connection with the Text Box in the Master Slide.

Or am I missing something?

Many thanks, Evilbu (talk)

I don't think so. What I do in that situation is just copy the things I want, create a new slide, paste things back in. --Mr.98 (talk) 22:04, 30 March 2011 (UTC)[reply]

March 31

Weird Xcode Problem

I'm trying to build an application in Xcode, but every time I compile it, it gives me this error:

Error from Debugger: The program being debugged is not being run.

So, I navigate to it in the finder, and it has a little prohibitory sign. Double clicking it, it says that the application can't be opened because it is damaged or incomplete. However, I can get it to open by opening the executable in the Package Contents>MacOS folder. Could anyone explain what is going on? --Thekmc (Leave me a message) 00:28, 31 March 2011 (UTC)[reply]

Sounds like your info.plist file is missing or corrupt. --Carnildo (talk) 23:40, 31 March 2011 (UTC)[reply]

How would I fix that? --Thekmc (Leave me a message) 21:15, 1 April 2011 (UTC)[reply]

Microsoft Windows Server 2008 R2 Datacenter Edition - Temporary Licensing Non-Compliance

Hello RefDeskers!

If, on an eight-socket server with four installed processors running Microsoft Windows Server 2008 R2 Datacenter Edition, fifth and sixth processors were to be installed several days before two extra per-processor licenses are acquired and assigned, thereby causing license non-compliance, would the server continue to function normally or would the server stop functioning due to license non-compliance? I tried asking at Microsoft TechNet, but did not get an answer to the question, and was instead schooled on the importance of license compliance.

Thanks as always.

There is generally a grace period for license activation, usually 30 days. Server 2008 seems to have one for retail/oem versions ([1]). Our article on Client Access Licenses says that only two products currently use technical means to enforce licensing: SBS2008 and Terminal Services, but that is uncited. If you use volume licensing, the best thing to do might be to speak to your reseller or account manager, as they would be able to give you a definitive answer. --Kateshortforbob _talk 09:13, 31 March 2011 (UTC)[reply]

Upgrading to Firefox 4 from Firefox 3.6.16

Should I save any of my bookmarks, history etc before upgrading? Will the same add-ons be installed automatically? Thanks 92.29.119.112 (talk) 09:55, 31 March 2011 (UTC)[reply]

I had no issues with bookmarks and history, but you should definitely keep them backed up if they are important to you (not just when you upgrade). The add-ons should remain in place if they are compatible with Firefox 4; if not, they will be disabled until new versions are available. 130.88.134.221 (talk) 15:51, 31 March 2011 (UTC)[reply]

Firefox 4

Now that I've installed it, I have a few annoying minor problems. First, I keep having to log into Wikipedia each time. Second, where did the refresh, undo, redo, etc. go, and how can I get them back? Clarityfiend (talk) 18:04, 31 March 2011 (UTC)[reply]

Refresh is the little circle-arrow button at the right end of the URL bar. It changes to the stop (X) button when a page is loading. I don't know what you mean by undo/redo : if you mean the back/forward arrows, I still have them to the left of the url bar. -- Finlay McWalter ☻ Talk 18:09, 31 March 2011 (UTC)[reply]

All of that stuff is on the "navigation toolbar", which you may (now) have turned off. -- Finlay McWalter ☻ Talk 18:10, 31 March 2011 (UTC)[reply]

Undo/redo let you remove/restore your last edit or edits. They used to be on a menu, but the menus seem to have all gone the way of the dodo. Clarityfiend (talk) 19:07, 31 March 2011 (UTC)[reply]

Oh, I see what you mean. Those are still in the EDIT menu: you need to turn on the menubar to get it back. I'd have thought you should be able to get icons back for them from the customise option, but I can't immediately figure out how. -- Finlay McWalter ☻ Talk 19:34, 31 March 2011 (UTC)[reply]

Aha. I've got my menu bar back. Thanks. Clarityfiend (talk) 03:45, 1 April 2011 (UTC)[reply]

1) Make sure you're not in private browsing mode 2) ALT+v, Toolbars > Customize ¦ Reisio (talk) 00:20, 1 April 2011 (UTC)[reply]

Algorithm used in Mega Millions POS computers

I just saw a news story stating how the buyer of the ticket that recently won $319 million (before taxes) had someone cut in line and he opined that if this hadn't taken place, the other guy might have gotten the winning number. But that's assuming that the algorithm the machine uses is sequential in that the machine is seeded maybe upon startup and the time span between ticket purchases doesn't matter, i.e., the next number that comes out will be the same (even if nobody knows what it will be) whether you wait 25 ms or 3 hours. If upon each purchase the machine took a random seed like the time from the system clock, then not cutting in line almost certainly wouldn't have made the cutter get the winning number and also would have made the guy who did get the winning ticket get to the counter earlier than he did, almost certainly totally changing his numbers too. Is there any public specifications of those machines, or is that top secret information? Just curious. 76.27.175.80 (talk) 22:42, 31 March 2011 (UTC)[reply]

I don't know specifically which vendor(s) supply the Mega Millions lottery equipment, but some lottery system vendors use the "Trusted Draw" system, which is made by Szrek2Systems. This white paper has some (scant) details. It seems they take a realtime clock (which I guess is in the crypto card in the lottery terminal), cons that with the user data (I guess the terminal ID and stuff like that) and take a Digital Signature of that. They don't say specifically which DS scheme they use, but they say the signatures have the "cryptographic strength of 1024 bit RSA digital signatures" (there are several RSA-based DS schemes, including RSASSA-PSS and RSASSA-PKCS1-v1_5). Assuming things are implemented properly, and the clock ticks quickly (which surely it will), and that the random number is generated when the "print ticket" button is pushed, then pushing the button even a fraction of a second sooner or later would result in entirely different numbers. This seems like a pragmatic scheme (it's tempting to say they should use an analog random-number generator, but that gives them problems with later auditing). The simple scheme you suggest (seed a PRNG and then just print off tickets deterministically) would be very vulnerable to all kinds of abuse. -- Finlay McWalter ☻ Talk 23:16, 31 March 2011 (UTC)[reply]

April 1

how to fix a flashlight

I unscrewed all of the components of my flashlight and put it back together and it does not work anymore. How do i fix it? —Preceding unsigned comment added by 74.96.187.202 (talk) 02:57, 1 April 2011 (UTC)[reply]

(Taps claw, gestures toward a desk with a question-mark statue on it) —Jeremy v^_^v ^{Components:V S M} 03:18, 1 April 2011 (UTC)[reply]

Repeat the process until it works. There must be a contact somewhere that's out of position. StuRat (talk) 03:38, 1 April 2011 (UTC)[reply]

... and clean all the contacts (possibly using the graphite from a "lead pencil") to improve conductivity. Dbfirs 08:18, 1 April 2011 (UTC)[reply]

Is the bulb still working? Are the batteries still good? Did an insulator fall between the contacts somewhere? Really, flashlights are pretty simple devices - there's not a lot that can go wrong. Astronaut (talk) 15:00, 1 April 2011 (UTC)[reply]

Offline world map software

Please, recommend me an offline, free, world map software. It doesn't have to be 3D. To be able to search for countries, geographical locations and cities would be important. Something like Amiglobe, but up-to-date would be perfect. —Preceding unsigned comment added by 109.74.50.52 (talk) 04:02, 1 April 2011 (UTC)[reply]

The first thing that pops into my head is [Google Earth]. General Rommel (talk) 07:27, 1 April 2011 (UTC)[reply]

Google Earth works offline? --Sean 18:01, 1 April 2011 (UTC)[reply]

There are Microsoft Encarta, Microsoft MapPoint, and Microsoft Streets & Trips from Microsoft, but they are not free. There is also The World Factbook Maps from the CIA, but it is not a computer software. 118.96.163.209 (talk) 08:25, 1 April 2011 (UTC)[reply]

I forgot to not that it is not offline. However, if you are looking up a small area or just a general area, first in settings set it to 2000mb disk cache, look where you want, wait till all info has been downloaded (bottom right there is a small circle) and close. Disconnect yourself and try and see if you can search for places. I don't think it will work though if you are looking for small things- a detailed map of the world is quite a large file. General Rommel (talk) 04:06, 3 April 2011 (UTC)[reply]

Youtube 1911 mode

I know it's a april fool's of some sort but could you point me towards any maps of the incident or otherwise general discussion involving it? —Preceding unsigned comment added by 207.196.181.93 (talk) 07:39, 1 April 2011 (UTC)[reply]

There's an article about it on Techcrunch here. --Kateshortforbob _talk 13:44, 1 April 2011 (UTC)[reply]

no-ip

how to configure no-ip server for my video survilience system..webcam monitor software.....its not also working for gmail...which other emil messenger should i use.. —Preceding unsigned comment added by 59.93.129.246 (talk) 10:32, 1 April 2011 (UTC)[reply]

Firefox 4 - do not like the large buttons on the 'Navigation Toolbar'

On what I think is called he "Navigation Toolbar" there are to the left of the address slot, the icons for various things. They are small icons within large buttons which take up a lot of room. Is there any way of changing them back to the way they looked in Firefox 3 please? Thanks 92.15.8.176 (talk) 13:32, 1 April 2011 (UTC)[reply]

Right-click on the toolbar -> customise -> use_small_icons -- Finlay McWalter ☻ Talk 13:39, 1 April 2011 (UTC)[reply]

Thanks. 92.15.8.176 (talk) 15:06, 1 April 2011 (UTC)[reply]

BIOS password reset

Is it true that it is now more difficult to impossible, as this article describes, to reset or disable a motherboard's BIOS password? I mean, no more "default password", "remove battery", "short battery", "change jumper", or "press button" method anymore? 118.96.163.209 (talk) 14:41, 1 April 2011 (UTC)[reply]

Funnily enough, that article doesn't actually mention the usual method: remove the small battery and let the BIOS forget its settings. Astronaut (talk) 14:54, 1 April 2011 (UTC)[reply]

The author did address such things in the comments section of the article. 118.96.163.209 (talk) 15:00, 1 April 2011 (UTC)[reply]

By the way, if I think about it, it is indeed very possible to create BIOS password system that is very difficult to crack, because BIOS is simple, thus easy to be made secure. Combine that with tamper resistant hardware techniques, and you get a system that is uncrackable by majority of people. 118.96.163.209 (talk) 15:00, 1 April 2011 (UTC)[reply]

Most evil things that you can do by tampering with the BIOS, you can also do by taking the hard drive out and putting it in another computer. Paul (Stansifer) 15:07, 1 April 2011 (UTC)[reply]

Thank you for your comments. I am merely asking whether it is difficult to reset or disable BIOS passwords in modern computers. I know that BIOS passwords are inadequate as a security measure. 118.96.163.209 (talk) 15:31, 1 April 2011 (UTC)[reply]

The BIOS password may be stored in the Trusted Platform Module instead of the battery RAM. Also, many modern hard drives have firmware password support. In that case moving the drive to another computer won't help. As far as I know, though, there are still many motherboards that store the password in battery RAM. -- BenRG (talk) 16:42, 1 April 2011 (UTC)[reply]

Drives may also use BitLocker or other encryption. There are even monitors with anti-theft technology— the driver has a password that matches one set in the monitor. ---— Gadget850 (Ed) ^talk 17:40, 1 April 2011 (UTC)[reply]

Thank you for all your answers. 118.96.155.154 (talk) 04:56, 7 April 2011 (UTC)[reply]

Creating .pdf files

What software is required to create .pdf files ? Jon Ascton (talk) 16:11, 1 April 2011 (UTC)[reply]

Adobe acrobat is one, the 'official' software, Word 2007 can save as PDF though it requires a free download to do so, unless Service Pack 2 is installed. See Office 2007#PDF. Also PDFCreator & Category:Free PDF software - 220.101 talk^\Contribs 16:41, 1 April 2011 (UTC)[reply]

Even better, List of PDF software. Buddy431 (talk) 17:09, 1 April 2011 (UTC)[reply]

Under Windows, you can install a printer driver called CutePDF Writer to allow any Windows program to "print" to a PDF file. Comet Tuttle (talk) 22:30, 1 April 2011 (UTC)[reply]

What you're looking for is PrimoPDF! Rocketshiporion ♫ 22:39, 1 April 2011 (UTC)[reply]

The best answer is pdfLaTeX, because that would get you using the best system for creating documents in the first place. --Trovatore (talk) 01:38, 3 April 2011 (UTC)[reply]

Legal status of the GUID Partition Table layout ..?

What is the copyright and patent status of the "GUID Partition Table" (GPT) ..? The EFI extension which includes GPT is proprietary, but that doesn't implicitly make GPT proprietary. The Intel GPT white paper doesn't tell anything in regards to the legal status. Electron9 (talk) 22:12, 1 April 2011 (UTC)[reply]

I'm pretty sure this is exactly the kind of question we consider "legal advice," so we aren't really able to answer it definitively on this reference desk. Patents, trademarks, and copyrights exist pertaining to both GPT and UEFI. It is difficult to determine whether any of those particular intellectual property protections affect your needs and use-cases - exactly the reason you would need to consult with a technically savvy intellectual property attorney.

In the meantime, you can read the FAQs at UEFI: among other relevant information, the specification is made available without charge. "The Promoters of UEFI have agreed that any IP needed to implement the specification will be made available on reasonable and non-discriminatory terms..." and "Q: Can anyone build their own Unified EFI implementations? A: Yes..." But as you have already noticed, the extended specification for GPT may have further qualifications. Nimur (talk) 22:31, 1 April 2011 (UTC)[reply]

For possible open source developers it would be beneficial to know if the GPT specification is copyright/patent encumbered.Electron9 (talk) 00:30, 2 April 2011 (UTC)[reply]

Rackmount SSI MEB Chassis Manufacturers

Good day, fellow RefDeskers!

Does any manufacturer currently make SSI MEB compatible rackmount chassises? I've looked all the major brands I'm aware of (Antec, Chieftec, Intel, InWin, Supermicro, Trenton & Tyan), and none of them seem to have any MEB-compatible chassis. Specifically, I'm looking for a 2U or 3U chassis which will fit this Tyan motherboard.

Thanks as always. Rocketshiporion ♫ 22:46, 1 April 2011 (UTC)[reply]

Looks like you'll have to go with a tower form-factor. You can put rackmount rails on a tower, if vertical space isn't an issue. See this Dell rail-conversion kit, for example. Nimur (talk) 22:55, 1 April 2011 (UTC)[reply]

Even for the tower form-factor, which manufacturer has MEB-compatible chassises? Rocketshiporion ♫ 23:14, 1 April 2011 (UTC)[reply]

Usually you'd buy the barebones from the board maker. Click the barebones link on that page, they have a 4U unit. From your user page I get the impression you want to solve numerical PDE's with that thing? I think the trendy approach is with GPGPU's. 75.57.242.120 (talk) 08:23, 3 April 2011 (UTC)[reply]

April 2

Reading/copying Unix floppy on Windows XP system

One of the managers here at work thought I might be able to help them out with an issue they're having. I'm trying to help but am a bit out of my depth. And it's Friday night, so any real help won't be in until Monday morning.

I have a 3.5" floppy that is used on tools running some form of Unix. They want several more copies of this disk made. All I have available to me is Windows XP, a USB floppy drive, the original disk (they have more, they only gave me one), and a blank disk.

When I put the source disk into the drive and try to open it on my laptop, I get a warning saying that the disk is not formatted and I'm asked if I want to format it. Any ideas? Thanks, Dismas|^(talk) 00:33, 2 April 2011 (UTC)[reply]

Probably ext3 format or ext4. There are some Windows drivers for ext3, but I don't know if they support format and copy.[2] I used to use CopyQM Plus to copy non-Windows floppies and to create image files back in the day (they were system disks for a Kentek printer that booted from a hard drive).[3] ---— Gadget850 (Ed) ^talk 01:18, 2 April 2011 (UTC)[reply]

If you simply wanted to copy the disk without actually reading its contents, you can use any "floppy image" programs, like RawWrite or WinImage, to copy the disk. 118.96.157.155 (talk) 02:08, 2 April 2011 (UTC)[reply]

No, I don't actually need to read the contents. I just need to make copies.

What I got from fs-driver.org didn't allow me to read the disk
CopyQM won't work as it's not made to work on anything later than Win98
RawWrite doesn't work because I don't have a disk image on the disk. It still fails telling me that the disk isn't formatted.
I suspect the results for WinImage will be the same as RawWrite.

Anyone else? Dismas|^(talk) 02:22, 2 April 2011 (UTC)[reply]

Really? Did you image ("read") the disk first before writing it in RawWrite? Also, even if Windows keeps saying that the disk is "not formatted", if you copied the disk using RawWrite, it is still copied no matter what. Copying a disk has nothing to do with Windows saying the disk "formatted" or "not formatted". 118.96.157.155 (talk) 02:29, 2 April 2011 (UTC)[reply]

Really. I opened the program, clicked on the "Read" tab, and it's asking me for a disk image file. If I go looking for one on the disk, the program tells me that the disk is not formatted and asks if I want to format the disk. Dismas|^(talk) 02:32, 2 April 2011 (UTC)[reply]

Don't do it. Instead save the image on your hard disk with the "Read" tab, then write the saved image to a blank disk with the "Write" tab. To use CD burning analogy, the "Read" tab is used to "rip" the disk to a disk image, and the "Write" tab is used to "burn" the image to a disk. 118.96.157.155 (talk) 02:37, 2 April 2011 (UTC)[reply]

I didn't. What I'm trying to get across is that there is no image. There is nothing, according to Windows or RawWrite, on the disk. There's nothing there to rip as far as the program is concerned. Dismas|^(talk) 02:39, 2 April 2011 (UTC)[reply]

There is indeed no image in the disk. You need to create the image first from the disk, then write the created image to a new, blank disk. 118.96.157.155 (talk) 02:41, 2 April 2011 (UTC)[reply]

When the "Save As" dialog comes up, you should choose a place to save the (newly created) image on your hard disk. The floppy drive is selected from a different drop-down box in the main application window. -- BenRG (talk) 03:04, 2 April 2011 (UTC)[reply]

(indentation reset) Here's a walkthrough:

Insert the source disk into drive A:.
Launch RawWrite, then do the following:
1. select A: in the Floppy drive list box,
2. select the Read tab,
3. enter C:\asdfghjk.img (or any non-existing file on your hard drive) in the Image file text box,
4. press the Read button, then
5. follow further instructions onscreen.
Eject the source disk from drive A:, then insert a blank disk into drive A:.
In the RawWrite again, do the following:
1. select A: in the Floppy drive list box.
2. select the Write tab,
3. enter C:\asdfghjk.img (the file name you enter above) in the Image file text box,
4. enter 1 in the Number of copies text box,
5. press the Write button, then
6. follow further instructions onscreen.

Good luck. 118.96.157.155 (talk) 03:07, 2 April 2011 (UTC)[reply]

Well, I no longer have the disk. It had to be returned. And I don't see how "Read" means "Create an image file". Doesn't seem very intuitive to me at all. Dismas|^(talk) 06:25, 2 April 2011 (UTC)[reply]

I am sorry you couldn't copy the disk on time. Next time someone is asking me how to copy floppy disks, I probably should tell them to run the DISKCOPY A: A: command instead. It is simpler and more intuitive (yet far less powerful) than RawWrite or WinImage. Oh well. 118.96.154.96 (talk) 08:34, 3 April 2011 (UTC)[reply]

I wonder if you are able to download and burn a (small) linux live CD. Boot your PC from the CD and use linux to copy your floppy. Don't have a CD?... maybe some virtual machine software will work directly with the live CD's .ISO file and let you start linux without needing a CD. Astronaut (talk) 07:24, 2 April 2011 (UTC)[reply]

Microsoft Comfort Mouse 4500 in Ubuntu

Hi everyone, I recently bought a new Microsoft keyboard and mouse. The keyboard works perfectly except for a few of the random Messenger/Documents/Zoom buttons which I don't care about, but the mouse is driving me crazy - the scroll wheel seems to act as a Page Down/Page Up button! Scrolling down by one click is the same as using the page down button, and scrolling up acts like Page Up. I'm using Ubuntu 10.10 and I thank you in advance for your help :)

110.175.208.144 (talk) 06:13, 2 April 2011 (UTC)[reply]

A mouse will typically come with a driver CD which allows you to customize this type of behavior. Is the problem that this driver lacks Linux support (or specifically Ubuntu) ? (It wouldn't surprise me if MS does everything possible to sabotage Linux users.) StuRat (talk) 16:40, 2 April 2011 (UTC)[reply]

Duplicate file detection

Is there an easy way to detect and perhaps remove duplicate files from a directory? The files could be anything: documents, text, images, music, etc, but there could be hundreds of files to process. Any duplicates would have some things in common, but other things could be different: filenames, dates, other meta data. I thought about writing a program to do this, something using MD5 and moving duplicates to a different directory, but maybe there's already such a program available (preferably for free). Astronaut (talk) 10:01, 2 April 2011 (UTC)[reply]

There are lots, I like this one 82.43.90.38 (talk) 10:26, 2 April 2011 (UTC)[reply]

See fdupes. ¦ Reisio (talk) 20:40, 2 April 2011 (UTC)[reply]

I like Duplicate Cleaner http://www.digitalvolcano.co.uk/content/duplicate-cleaner , and Visipics for finding similar images http://www.visipics.info/index.php?title=Main_Page . Both freeware. Edit: I used the 1.6 version of Duplicate Cleaner. I havn't tried the latest version yet, which seems somewhat different. 92.15.2.39 (talk) 16:31, 3 April 2011 (UTC)[reply]

Similar file detection

Following on from my question immediately above, is there a program that can identify similar image files (again, preferably for free)? By similar, I mean perhaps an image has been converted to a different file format (eg. .jpeg -> .png), or has been resized, or has broadly the same colour palette (I'm thinking something along the lines of the colour selection in Google's image search). Astronaut (talk) 10:01, 2 April 2011 (UTC)[reply]

This program can 82.43.90.38 (talk) 11:30, 2 April 2011 (UTC)[reply]

Content-based image retrieval ¦ Reisio (talk) 20:41, 2 April 2011 (UTC)[reply]

Visipics, as mentioned above. Something similar that would be very useful would be a program that sorts similar images into the same sub-directories. 92.15.2.39 (talk) 16:33, 3 April 2011 (UTC)[reply]

Laptop

Which brand is most reliable among laptops. Is it OK to buy one without an OS ? Will it be as easy to install Windows (XP or Vista) as on a conventional desktop ? Is the laptops BIOS any different from desktops ? Jon Ascton (talk) 17:57, 2 April 2011 (UTC)[reply]

Of the major brands, I doubt there is much difference in quality. I have an 11 year old Dell that a relative still uses; I've most experience with Acers, and they've proven to be very reliable. But others will doubtless have good experiences with other brands, and maybe bad experiences with these. You'll find it very difficult to find a laptop without an OS; these days most have Windows 7 Home Premium or Home Basic - netbooks might still have XP. The BIOS is much the same as for a desktop and a laptop. In general installing XP on a laptop is straightforward, but you will increasingly run into problems where there is no XP driver available for some of the laptop's hardware. Laptop manufacturers figure they're shipping the machine with Windows 7, so they need only code a driver for Windows 7. -- Finlay McWalter ☻ Talk 18:20, 2 April 2011 (UTC)[reply]

http://tuxmobil.org/laptop_oem.html ¦ Reisio (talk) 23:34, 2 April 2011 (UTC)[reply]

Note that you'll probably wind up paying more for Windows this way. Microsoft sells OEMs Windows for an undisclosed but probably large markdown over buying it off-the-shelf. It makes sense to buy OS-less computers to install Linux on them, but not Windows. (Sadly, it often makes sense to buy a Windows computer, even if you're going to install Linux on them, because there aren't many options when purchasing OS-less or Linux laptops.) Paul (Stansifer) 08:10, 3 April 2011 (UTC)[reply]

One caution: It may be impossible to fully test a laptop without an O/S. So, if you do purchase one this way, make sure you install an O/S and fully test it out, well before the warranty expires. StuRat (talk) 23:25, 3 April 2011 (UTC)[reply]

RAR for mac

Anyone have a recommendation for a good free application for unpacking RAR files using a Mac?--141.155.147.132 (talk) 21:03, 2 April 2011 (UTC)[reply]

There's a command line version of WinRAR available here and a mac version of 7zip available here. I've never used a mac so I don't know how good they work 82.43.90.38 (talk) 21:40, 2 April 2011 (UTC)[reply]

StuffIt Expander (link) can extract .rar files. 118.96.156.239 (talk) 01:36, 3 April 2011 (UTC)[reply]

Thank you both for the effort. However, let me repeat my question with a bit of emphasis: "Anyone have a recommendation for a good free application for unpacking RAR files using a Mac?" I downloaded the first, installed it, then, when I tried to use it, I learned you must register for it to work, which requires getting a serial number, which in turn requires payment. Stuffit is "free" alright, you just have to "successfully sign up with or purchase from any one of our affiliate partners during the TrialPay checkout".--141.155.147.132 (talk) 04:10, 3 April 2011 (UTC)[reply]

Okay, I have downloaded this, blindly, though at least it's through a site that appears to be reliable.--141.155.147.132 (talk) 04:21, 3 April 2011 (UTC)[reply]

Oops. Sorry. I gave you the "wrong link" (StuffIt Expander is indeed free). Here is the corrected link, but I guess it's too late now. 118.96.154.96 (talk) 08:16, 3 April 2011 (UTC)[reply]

P.S. If you are still interested in StuffIt Expander and want to download it, ignore all the "Buy", "Special Offer", and "TrialPay" links, and all the banner ads on the page. As I say, StuffIt Expander is indeed free. 118.96.154.96 (talk) 08:43, 3 April 2011 (UTC)[reply]

April 3

SeaMicro SM1000-64 System

Hello RefDeskers!

The SeaMicro SM10000-64 Server is stated to comprise 256 dual-core processors, with 4 processors on each of 64 Compute Cards. Does this mean that the SM10000-64 is a single enormous 256-processor server, or is it a cluster of 64 quad-socket servers?

Thanks as always. Rocketshiporion ♫ 03:03, 3 April 2011 (UTC)[reply]

Cluster of 64 4-socket servers, and the cpu's are not very powerful. It's for cloud hosting, not a supercomputer. 75.57.242.120 (talk) 08:27, 3 April 2011 (UTC)[reply]

If I am not mistaken, the SM10000 is a cluster of 256 servers and associated infrastructure in custom packaging. A SeaMicro white paper (SeaMicro Technology Overview) seems to agree. It describes each server as a credit card-sized board that is installed in groups of four into a motherboard. It then describes each credit card-sized board as a node. I doubt the Atom processor which the SM10000 uses has support for inter-socket multiprocessing since it is a low-end processor. Rilak (talk) 08:56, 3 April 2011 (UTC)[reply]

Awww... No supercomputing on the SM1000-64. Darn! And I thought I'd found a supremely-powerful supercomputing platform. Rocketshiporion ♫ 05:15, 4 April 2011 (UTC)[reply]

W3C standards as a source for browsers, or vice-versa?

I've heard it claimed that new feature additions to the W3C standards for HTML, XHTML, CSS, DOM and JavaScript are usually made to comply with, or arbitrate a compromise between, what the major browsers are already doing, and that it is the browser developers that invent new functionality. Is that right? I thought it was more common for features to be first codified in W3C working drafts and then implemented in browsers. Neon Merlin 03:22, 3 April 2011 (UTC)[reply]

I don't know much about the W3C specifically, but industry standards bodies are normally made up of representatives from organizations interested in implementing the standards, and implementations are written in parallel with the standards themselves, so that neither one comes first. It's also common for standards to simply document existing practice and introduce nothing new. An ivory-tower "standard" developed without the input of likely implementers would probably just be ignored. -- BenRG (talk) 22:15, 3 April 2011 (UTC)[reply]

All the principal browser vendors are part of the W3C. ¦ Reisio (talk) 01:11, 4 April 2011 (UTC)[reply]

Yes, but in the olden days they all gladly innovated independently, giving us things like the infamous <blink>blink tag</blink>. Much of the internet has been developed by "rough consensus and working code", and this carried over into browser land. Nowadays, however, the W3C spec is, more-or-less, leading implementations. --Stephan Schulz (talk) 02:17, 4 April 2011 (UTC)[reply]

DVD world "Zones" - How to increase the allotment?

On my Dell Inspiron 1720, I have only about 4 more times to change the zone/regions. I plan to be some type of a jetsetter in the coming years, so it would be essential to keep changing DVD regions. What can I do to increase the allotment of region changes? Or how can I make it a universal-region DVD? --70.179.169.115 (talk) 04:12, 3 April 2011 (UTC)[reply]

Unfortunately, there is no 'legal' way of altering the number of times you can change the region code. If you want to try, please by all means try it yourself- I think under the no legal advice section is that we cannot tell people how to circumvent these security measures. General Rommel (talk) 10:48, 3 April 2011 (UTC)[reply]

General Rommel - perhaps you can quote the law or statute that you have in mind here - any jurisdiction will do. I find it difficult to believe that it is illegal to alter these settings on hardware that you own, with properly licensed software, and for a legitmiate reason e.g. you are frequently moving to different countries. It may be technically difficult, it may void certain warranties, it may not even be a sensible solution to the original problem, but how exactly is it illegal ? Gandalf61 (talk) 12:33, 3 April 2011 (UTC)[reply]

I agree with the sentiment, but see Modchip#Legality. To not buy multiple copies of a DVD is a circumvention of copy protection, and so is preparing to not buy them. 81.131.41.83 (talk) 13:33, 3 April 2011 (UTC)[reply]

I was not expressing a sentiment - I was asking General Rommel for a source for their assertions. Modchip#Legality says "The nonuniform interpretation of applicable law by the courts and constant profound changes and amendments to copyright law do not allow for a definitive statement on the legality of modchips", so it sits on the fence. Our article on DVD region code lists several ways of bypassing region codes through software or firmware; none of these methods are stated to be illegal. Indeed, the article says that the legal staus of region codes and mechanisms that enforce them is unclear in several jurisdictions, and in New Zealand, for example, they have no legal protectionat all. Gandalf61 (talk) 14:46, 3 April 2011 (UTC)[reply]

(EC) I don't know if 'not buying' is really the issue. I do agree there's a fair chance it may fall foul of the Digital Millennium Copyright Act restrictions on circumvent copy protection measures (although for other reasons it may depend on the reason you need to use a different region see [4] for example). As with many areas of copyright law in the US, I don't think this has been tested but see [5] and also consider the fact the US Copyright office has refused to grant an exemption for removing regional restrictions [6]. [7] (consider why the EFF felt it necessary to ask in the first place) and [8] (the US Copyright offices view appears to be that the current limited number of changes is fine). This is even more likely to be a problem if you use something~~, like VLC,~~ which uses DeCSS to get around the restrictions, see DVD-Video#Content Scramble System as there is case law ~~strongly~~ suggesting it is not allowed (unless exempted) AFAIK (looking a bit more I think it's only distributed which is accepting as not allowed, possessing has not been tested and a is common I suspect it never will [9]). However as our article DVD region code notes, the legality of DVD regions themselves is questionable in some countries like Australia and possibility NZ. The OP however appears to come from the US at the current time. P.S. I seem to remember discussing this before so there may be more sources in the archives. Nil Einne (talk) 15:06, 3 April 2011 (UTC)[reply]

From VLC media player: VLC is one of the free software and open source DVD players that ignores DVD region coding on RPC-1 firmware drives, making it a region-free player. However, it does not do the same on RPC-2 firmware drives. - might be worth a try. -- 78.43.60.13 (talk) 11:40, 3 April 2011 (UTC)[reply]

All drives manufactured since 2000 are RPC-2 drives. But I think that VLC also bypasses region coding on RPC-2 drives (i.e., the article is wrong). There certainly are players that do. Also, the various DVD ripping programs work on modern drives. There are custom patched firmwares for some drives that disable the region lockout. There are also some software products (none of them free, as far as I know) that transparently remove the protection for all applications. The most straightforward solution is probably ripping to the hard drive and playing from there. As mentioned above, the legal situation is unclear. -- BenRG (talk) 01:44, 4 April 2011 (UTC)[reply]

I should have said that that was purely first reaction statement. But I believe it's just not gright to.. But if you do want, I can say that usually using a cheap $20 DVD player from an Asian electronic store will usually do the trick. General Rommel (talk) 13:04, 4 April 2011 (UTC)[reply]

One thing to note, and at the risk of stating the obvious, your PC's DVD drive doesn't know which country you are in. If your existing Region 1 disks play now, they will still play if you visit Europe, Asia, etc. You only need to change the drive's region if you want to play DVDs from other regions or you buy new DVDs locally. For the latter, it might be better to buy a local drive as Gen Rommel suggests, especially if you can get one that is already multi-region capable. Astronaut (talk) 13:35, 4 April 2011 (UTC)[reply]

DOS in laptops

Some models of laptops are coming with what they advertise as "Free DOS". What exactly is this ? DOS, as I remember, was an operating systems that is now history, it was used when there was no GUI and commands had to be written as text, what is meaning of using DOS in today's computers ? Jon Ascton (talk) 14:14, 3 April 2011 (UTC)[reply]

FreeDOS. -- Finlay McWalter ☻ Talk 14:16, 3 April 2011 (UTC)[reply]

I've seen a fair few laptops like that in Malaysia. I'm not surprised if the situation is similar in India. AFAIK it's far less common in NZ and I would guess other places like the US, UK etc. FreeDOS is basically selling the laptop without an OS (by actually including an OS they can show something when they turn it on and I guess they can claim they aren't encouraging copyright violations because they did include an OS it's not their fault if the customer doesn't like it). I doubt many people use the FreeDOS for long if at all because there's not that much you can do with it. They could use Linux, FreeBSD or something else but that creates additional support issues. The reason for selling without OS is I'm pretty sure to reduce cost (or at least create the illusion of reduced cost, as our article notes they aren't always cheaper), with the assumption the customer is going to install their own own OS perhaps one of the aforementioned options but far more likely some copyright violation version of Windows (probably Windows 7 Ultimate or perhaps Windows XP Pro) or occasionally Mac OS X and hence the reason this is common in places like Malaysia and India. Notably while they could probably add a cheap version of Windows 7 for not that much more they may figure many are just going to change it to Ultimate anyway. I've also seen this tends to be with the cheaper models. Of course not everyone will do this, some may get the shop to install a legitimate version of Windows for them. (In other words, even if the customer is going to pay for the OS, you again create the illusion of lower cost by excluding the OS cost from the upfront cost.) I don't know whether the cost will be the same since Windows OEM licensing confuses me but labour time wise it's probably insignificant compared to many developed countries where it would likely add a fair amount to the cost. Nil Einne (talk) 14:37, 3 April 2011 (UTC)[reply]

Nil Einne is spot on. A laptop is sold with freeDOS so that the seller doesn't need to buy a copy of Windows to put on it. Most people won't use the FreeDOS: they'll quickly upgrade, typically to something else free (pirated Windows, or some sort of Linux). If you do plan on installing Windows legitimately, it's almost certainly cheaper to buy a laptop with it installed (if you can), as Microsoft gives discounts on their OEM licenses over retail licenses. See this helpful guide. Buddy431 (talk) 16:04, 3 April 2011 (UTC)[reply]

Won't totally removing this DOS from laptop's harddisk will present any problems ?

Of course it is perfectly possible that the customer already has a license for a version of Windows they are comfortable with, and has no interest in an upgrade. 84.239.160.59 (talk) 17:03, 3 April 2011 (UTC)[reply]

Removing DOS shouldn't be a problem: when you install your new operating system, you'll reformat the disk, essentially erasing what was on it before. And you are correct, if a person has a valid license from an old computer, or a license that's good for multiple computers (I think Microsoft's retail licenses are typically good for up to three computers at once), they could install that. Note, however, that most licenses for OSs that come with the software are only valid for the machine they came with (so called OEM licenses). It is not legal (or at least against Microsoft's terms of use, legality depends on jurisdiction, how good your lawyer is, etc.) to install one of these on a new machine that it did not come with. Technically, you may be able to do it anyway, depending on the reactivation process, and how well you can lie to Microsoft if you have to reactivate by phone. Buddy431 (talk) 19:23, 3 April 2011 (UTC)[reply]

Home Wi-fi networking question

I have several devices in a part of the house where there's no wired Ethernet port. I have a Wi-fi AP in the house but the devices in question don't have built-in Wi-fi support. What would be the best or simplest way to connect these devices to the (W)LAN in the house?

I've seen "Wi-fi extender" products with Ethernet ports, which seem to be a possible solution. Are wireless routers these days also usable as Wi-fi extenders? (I'm asking because, given the choice, I'd rather get a device usable in several ways than a special-purpose one.)

I remember seeing mods for converting a wireless router into the kind of Wi-fi extender I just described, but that was from quite a few years ago. If it's no longer necessary to do any mods, using a device unmodified is preferred.

--108.36.90.190 (talk) 16:57, 3 April 2011 (UTC)[reply]

If you say that the devices are incapable of WIFi or Ethernet, or any other wireless way of communication, well that would mak it very tricky.... General Rommel (talk) 01:45, 4 April 2011 (UTC)[reply]

I believe the OP was saying it's the part of the house rather than the device that lacks ethernet. --Sean 16:32, 4 April 2011 (UTC)[reply]

Limits of lossless data compression

How close is something like 7-Zip to the theorectical limit for lossless data compression? I recall reading something about this in the past - why cannot the best possible algorithmn for lossless compression be deduced? Thanks 92.15.2.39 (talk) 17:10, 3 April 2011 (UTC)[reply]

How do you define 'best' ? Fastest, highest compression? Specific to which domain of files to be compressed? All algorithms make trade-offs to better suit the type of file they intend to compress, there cannot be a 'best' algorithm for 'all' possible files. But the theoretical limit for an algorithm suited to one specific file, might be 1 bit. Unilynx (talk) 21:26, 3 April 2011 (UTC)[reply]

Why not 0 bits ? That could be used to mean that the file is in some default state, hopefully the most common state for that type of file. StuRat (talk) 23:17, 3 April 2011 (UTC)[reply]

A large file of apparently random bits might be a bunch of zeros encrypted by some algorithm with some key. In that case the entire file can be compressed down to almost nothing if you can find the key, but is probably incompressible if you can't. This shows that optimal compression is at least as hard as breaking current encryption algorithms. Compression is also related to science, because the shortest representation of data is more or less the same as the simplest theory describing the data in the sense of Occam's razor. So optimal compression is as hard as doing science. It's related to artificial intelligence too, for similar reasons.

The only estimate of an optimum compression ratio that comes to mind is Shannon's 1951 paper Prediction and entropy of printed English, where he used the prediction ability of human subjects to estimate an entropy of about 1 bit per letter for written English (about 8:1 compression of ASCII text, in modern terms). The modern state of the art is around 8:1 for 1,000,000,000 bytes of an XML dump of Wikipedia, but this is not directly comparable since it includes a lot of metadata (and punctuation, which I believe Shannon didn't consider). 7-Zip didn't do very well on this test, with a total size about 40% higher than the state of the art (using PPMd). -- BenRG (talk) 02:15, 4 April 2011 (UTC)[reply]

I thought it had been mathematically proved that the theorectical limit for (dictionary-less, lossless) compression was a lot lower than achieved by current algorithms? 92.29.115.116 (talk) 10:31, 4 April 2011 (UTC)[reply]

If you look at the average over all possible files, the limit of compression is 1 (as in "no compression"), as can be seen easily by a counting argument (to uniquely identify an n-bit file, you need n bits). If you look at a finite subset, then Shannon indeed describes that limit. English text has a lot less entropy than random noise, and most program texts have less, again. In principle, encrypted files should have about the same entropy as their un-encrypted counterparts. However, they are mapped into the space of all texts in a way that makes them very hard to differentiate, and hence in practice they compress badly. --Stephan Schulz (talk) 11:51, 4 April 2011 (UTC)[reply]

random numbers and the system clock

Why don't computer random number generators just use the last few digits of the system clock, ie. measuring fractions of a second? I know they use the clock, but only as a seed. Why would the last few digits of something measuring fractions of a second not be random enough? Is it because a computer program runs so quickly, and with such regularity, that there would be inevitable patterns in the stream of numbers thus produced? Thanks, It's been emotional (talk) 17:14, 3 April 2011 (UTC)[reply]

You pretty much have it. If the program asks for random numbers quickly enough (that is, faster than the counter wraps around), they aren't going to look random at all - they'll be in increasing order. Secondly, under similar loads, computers tend to run at about the same speed, so that any two invocations of the call to get random numbers will be at about the same difference in time so the two numbers will have a non-random difference between them (this applies even if the counter wraps around several times) - this is a killer if you have a loop to get multiple random numbers, say to shuffle a deck of cards or simulate a population. In either case you would need to pass the resultant value through a function which would "deorder" the values, and amplify the small variations between close numbers: this is effectively what pseudorandom number generators do. They also have the benefit of being repeatable; that is, with the same seed, you will always get the same string of "random" numbers - handy for debugging. -- 174.21.244.142 (talk) 17:37, 3 April 2011 (UTC)[reply]

Additionally, from a practical perspective, getting the current time from the system clock will require a system call, which is a comparatively expensive operation. Grabbing the time once, and then using a quick pseudorandom number generator thereafter, means the program has to make only one syscall; grabbing the time whenever a random number is needed will be a lot slower. —Bkell (talk) 17:49, 3 April 2011 (UTC)[reply]

On x86 processors the Time Stamp Counter can be read without a system call, probably a lot more quickly than the execution time of a decent PRNG. But, as already mentioned, it's not random enough. -- BenRG (talk) 01:26, 4 April 2011 (UTC)[reply]

Sound Card and Microphone Questions

Ok I have two questions. Firstly how do I check my sound card on Windows Vista. I have read that looking under the "Sound Video and audio device", section of the device manager or that running "Dxdiag" and checking the sound tab, should have my sound card listed however the only thing listed in the device manager is"high definition audio device", while the sound tab of dxdiag says "Digital output device (SPDIF) high definition) both of which seems more like a description of a sound card, then a sound card itself.

My second question is how do I get my speakers to output what I say into my microphone directly on Windows Vista. I have read that right-clicking the volume control, in the bottom right of my screen, clicking on playback devices. Then right-clicking on speakers and selecting levels should let me uncheck a box to unmute my microphone, but the only thing there is a section called "speaker/headphones" which isn't muted. So could anyone help me with these problems. 86.162.151.128 (talk) 17:32, 3 April 2011 (UTC)[reply]

For what it's worth, on the Vista system I am currently sitting at, the relevant entry in Device Manager is "Sound, video and game controllers", and the two items are "ATI Function Driver for High Definition Audio" with a part number, and "IDT High Definition Audio CODEC". These are indeed just driver files. The dxdiag tool has three relevant tabs, "Sound 1", "Sound 2", and "Sound 3", for the three hardware audio outputs on this machine. Comet Tuttle (talk) 18:39, 3 April 2011 (UTC)[reply]

RAID 1 and Subversion questions

Hi,

I am new to setting up RAID systems. I'm currently setting up a Subversion server using Windows XP, having used this guide to getting Windows XP to format two drives (not including the Windows drive) as a single software RAID 1 volume. No errors have been reported.

Question 1: I now want to perform the practical test of disconnecting each of the drives in turn to see whether the other drive has in fact got all the data expected, but I realize that as soon as I boot up the system with one drive disconnected, something is going to get written to the active drive, so the two drives won't be mirrored anymore. How do other people perform practical tests of a RAID 1 volume's mirroring?

Question 2: When one of the two drives in the RAID 1 volume fails, and I install a replacement, what tool is used under Windows XP to mirror the good drive to the replacement drive?

Question 3: A Subversion question. All workstations will be running Windows. Is it stupid for me to set this server up as a Windows XP machine rather than an Ubuntu machine? I have the vague notion that the most recent Ubuntu may have better tools available for administration of the server; but I find it a little appealing to run a Windows server to service Windows clients — we've run into one problem in the past with a GNU/Linux Subversion server, when my users were renaming the case of files, and the Linux server allowed both the files "hello.c" and "hElLo.c" to exist in the same directory, which caused problems with all the Windows clients. In a vague way, I have the notion that a Windows server might prevent other, similar problems.

Thanks! Comet Tuttle (talk) 18:34, 3 April 2011 (UTC)[reply]

A tablet computer question

Dear Wikipedians:

With tablet computers replacing netbooks as the latest "fad" in computing, I myself am thinking of getting a tablet. I will probably not get an iPad, for reasons that will become obvious after I have outlined my questions below. But I do have the following questions before I make my tablet computer purchase decision.

I remember that for my recent desktop PC, I went to my local computer store and bought all the parts, like motherboard, CPU, memory chip, a new SATA 250 GB hard drive, and then assembled them at home. Since the hard drive is new, there is obviously nothing on it. So I had to partition, format and then install my favorite operating systems. Now the PC works like a charm.

Now I am wondering, for tablet computers, do I have the option of going out there and grab different parts and assemble my own tablet? Barring that, is there a tablet computer that comes as a "clean slate" and allow me to install whatever operating systems I want on it, including options for multi-booting, just like what I do with my desktop PC? Barring that, if I get a tablet, say, with Windows 7 preinstalled, can I wipe it out and then setup a Windows XP/Linux dual boot system, just like what I do with my laptop computer? And by "tablet" I don't mean the clunky early tablet computers with the pivotable screen like the Lenovo Thinkpad X, but rather the "cool" one-piece tablet like iPad's form factor.

Now to push the envelope a bit, for smartphones, do I have the option of going out there and grab different parts and assemble my own smartphone? Barring that, is there a smartphone that comes as a "clean slate" and allows me to install whatever operating systems I want on it, including options for multi-booting, just like what I do with my desktop PC? Barring that, if I get a smartphone, say, with Android preinstalled, can I wipe it out and then setup a Windows XP/Linux dual boot system, just like what I do with my laptop computer?

And if the answers to my above questions are "no"s in their most restrictive sense (i.e. the only option I have is to put up with whatever crap the OEM throws at me). Then my question is: What is the reason for this erosion of my digital freedom, where I am able to do anything I like with my desktop PC, yet can do nothing with my tablet/smartphone? And should I be worried about this trend of OEMs gradually taking stronger controls of us consumers, and telling us what we can or cannot do with the gadgets that we bought with our own money? Am I witnessing the beginning of the end of our liberal, western democratic states?

Thanks,

L33th4x0r (talk) 23:15, 3 April 2011 (UTC)[reply]

Increasingly, many tablets and smartphones are designed so that it is difficult to access the actual layer (like behind the nice interface of a phone) and do things like delete folders. As well as that, Hardware for such things nowadays tend to be customized by the manufacturer. And as for the customization of tablets and phones, it will become increasingly difficult because of the fact that these devices are ever so becoming smaller, which means that it will become very hard to DIY. You could try building your own tablet, but you will probrably end up with a large sized one instead. General Rommel (talk) 01:42, 4 April 2011 (UTC)[reply]

I'd hardly call the trivially larger form of the Lenovo Thinkpad X tablet clunky, particularly when comparing it to something so much less versatile, less powerful, & incredibly less extensible such as either model iPad. You're not going to find a time where a Thinkpad X won't fit and an iPad will, it just isn't going to happen. ¦ Reisio (talk) 02:08, 4 April 2011 (UTC)[reply]

At the moment tablets are closer to an Embedded system then a fully functional "computer". That might change in the future, but at the moment you probably find that most of what you are "hoping" for is not possible on tablets or smart phones. There might be some hackers who get a different OS running on a tablet or a phone, but no doubt it will take a LOT of hacking and will also probably offer only limited functionality compared to the device it was designed to run on. Might be worth to note that the same thing could have been said of most laptops ten years ago, now it's not uncommon for people to dual boot macbooks and the like, it's possible when tablets become more common and ubiquitous they might become also more interoperable. Vespine (talk) 02:17, 4 April 2011 (UTC)[reply]

April 4

PAM

can u explain me in detail the pulse width modulation using frequency division multiplexing? — Preceding unsigned comment added by Saiffuddin (talk • contribs) 02:24, 4 April 2011 (UTC)[reply]

Have you read our article Pulse-width modulation? Comet Tuttle (talk) 03:09, 4 April 2011 (UTC)[reply]

jdbc insert query problem

I am using JDBC with oracle data base, All the table are well formed normalization . After INSERT THE TABLE I NEER TO GET THE INSERTED PRIMARY KEY VALUE

PLEASE HELP ME

tHANKS IN ADVANCE

—Preceding unsigned comment added by 192.8.211.14 (talk) 08:05, 4 April 2011 (UTC)[reply]

You had to create a sequence before you created the table to get auto-numbering, which I assume is what you are doing or you would know the primary key. Oracle doesn't have a "this was the number" column like most other databases. You have to fetch it beforehand. The sequence will have a field "nextval" that contains the value that will be used next in autonumbering. There is a problem. What if you fetch the next val. Then, I fetch the next val. Then, you insert. Then I insert. We both think we are using the same primary key. Another solution is to set up a trigger that saves the primary key and the username of the person performing the query to a separate table whenever an insert is performed. That is useful as long as you don't repeat the same issue above with two people (or two programs) using the same username. Yet another method is to do an insert and then fetch using all the info you just inserted sorting from most recently changed to most distant and grab the first row returned. Then, you get the ID off that. Finally, there is another rather foolproof way. Set up a server-side script that hands out unique IDs. You select an ID from it and it is guaranteed to be unique and not handed out before. Then, use that when you do your insert. You will know that you are always using a unique ID and you will know what the ID is. -- kainaw ™ 12:41, 4 April 2011 (UTC)[reply]

What about sequence.currval? 98.103.60.35 (talk) 16:50, 4 April 2011 (UTC)[reply]

Thunderbird and Archiving

Would anybody happen to know if Thunderbird archives mail, say, when it gets to a certain full level (rather like the message history of WLM)? I have Thunderbird as my default mail client, with four email accounts running on it - three of which are Gmail and one from my ISP. One of my Gmail accounts (the one I have used longest) now has no mail in the inbox prior to 29th March 2011. I know this 'lost mail' can still be accessed by going to the 'Google Mail' folder (which has all the mail in, whether sent, received, or flagged as spam), and I can also access it just by logging in from the browser, so it's not a problem. I am just wondering where all my mail 'disappeared' to. Would it have been archived for some reason? If so, where to? I'm using Thunderbird 3.1.9, if that's any help. TIA! --KägeTorä - (影虎) (TALK) 12:39, 4 April 2011 (UTC)[reply]

Searching Twitter feeds

I'm having a little difficulty searching on Twitter. I'd like to find all mentions of the terms "atemporal" and "atemporality" from the feed GreatDismal, but the search query https://search.twitter.com/search?q=atemporality+from:GreatDismal yields no results despite references existing. The feed is not marked private. Is the query malformed? Takk, Skomorokh 15:35, 4 April 2011 (UTC)[reply]

Not all tweets are indexed. Nanonic (talk) 15:50, 4 April 2011 (UTC)[reply]

Ah, that explains it, thanks. Any feasible workarounds? Skomorokh 16:03, 4 April 2011 (UTC)[reply]