Wikipedia:Reference desk/Archives/Computing/2010 June 3

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June 3

File Association

Resolved

I have a strange problem here one of my fellow while opening a song go for the Open with option and wrongly done some thing strange,now my every software i have installed including the firefox shortcut on desktop open in VLC Media Player.when i try to download a new program it also open in VLC Player.I know it is problem of file association but i am not able to recover it.please fix this for me that can install software with .exe format and all the shortcuts of installed software open in the dafault program. this can done with open with is well but this option is not available. thnx i am using windows 7. —Preceding unsigned comment added by 221.120.250.79 (talk) 11:44, 3 June 2010 (UTC)

I haven't tried this, but i have gotten some good advice on other issues here:

. [1]. ---— Gadget850 (Ed) ^talk 12:15, 3 June 2010 (UTC).

Thanks man the problem is solved.many many thnx

Do intel cores automatically have centrino inside?

hi.. how do i know if my intel processor has centrino in it (aside from obviously looking at the sticker on the laptop)? The sticker says "Intel Core 2 Duo inside." I read in wikipedia an article about centrino, in which it states something like it's part of the Intel Core 2 Duo under Sta Rosa and Napa Platforms---things I hardly understand. If you have any idea, please tell me. Thanks. —Preceding unsigned comment added by 112.202.194.203 (talk) 13:28, 3 June 2010 (UTC)

Centrino isn't so much a physical product, but rather a combination of specific motherboard chipsets, WiFi cards AND processors. I'd recommend reading the Centrino article for more information, but although your processor is likely "compatible" it depends what WiFi and motherboard chipset you have as to if it "qualifies" to have the Centrino branding (easiest way though is to literally look for a sticker as it's the sort of thing they want to show off it if has one). ZX81 ^talk 14:15, 3 June 2010 (UTC)

cryptography- software to analyse code?

How easy would it be to create:

• Something to run inputted text through every Caesar shift and select the most probable one based on recognised word patterns
• Something to do frequency analysis (just spit out the percentages of each letter)
• Something to detect patterns in transposition ciphers

and what would I use to do it? My teacher said you could just write a macro for Word, but I don't know how to do that either, so... {{Sonia|talk|simple}} 21:48, 3 June 2010 (UTC)

For any automatic decoder, you need to have a program that reads the decoded text and rates how much of it appears to be real words. That is the hard part. From a simplistic view, you can have a dictionary of 1,000 most common words and see how many of the characters in the decoded text match one of those words. To be more complicated, get the 10,000 most common pairs of words and look for word pairs instead of single words. If possible, check for real grammar and locate sentences, not just words. Once you have a program that can tell gibberish from real text, decoding and checking the outcome is trivial. You can write this in any programming language you like as every programming language that is common is easily capable of manipulating text. -- kainaw™ 21:52, 3 June 2010 (UTC)

Frequency analysis is fairly simple; it's just chugging through the ciphertext letter by letter and incrementing a counter every time a certain letter is found. I used Applescript because it's simple and the only one I know, but that only works on Macs. I'm sure an Excel macro would do the same job; I used Excel as an output anyway so I could get a bar chart of relative frequencies making it easier to spot frequent letters. The other tasks would be more fiddly. If you need to do some frequency analysis, there are a couple of free utilities online, like this one, which picks up small repeated strings for you as well. Brammers (talk/c) 22:40, 3 June 2010 (UTC)

As for doing a quick substitution cipher, this will shift everything by 13 (it shifts all 8bit ascii, so adjust if you don't want that)

cat File_of_text | perl -e 'undef $/;@i=split //,<>;foreach (@i) {if (ord() > 31 && ord()<127) {$_=chr(((ord() - 19) % 95) + 32)}}print @i'

If you want a different shift or to iterate through each version, then just add a modifying variable and put it through a loop ($i++; ... " - 19 + $i", etc.) Shadowjams (talk) 02:47, 4 June 2010 (UTC)

This does all versions:

undef $/;@i=split //,<>;($lr, $hr)=(32, 126);while($i < ($hr-$lr)){my @loop=@i;foreach (@loop){if (ord() > $lr - 1 && ord() < $hr - 1){$_=chr(((ord()-$lr+$i)%($hr - $lr)) + $lr);}}$i++;print @loop}

To adjust the ascii range it deals with, change the $lr and $hr values (ascii 8, the printable characters start at 32 and end at 126, so if you just want letters, change it to 65 and 122. Shadowjams (talk) 03:16, 4 June 2010 (UTC)

Okay, thanks all.... but how? @Shadowjams: thanks for the message on talk page, but (me being tech-illiterate) I don't know what I'm supposed to do with it. Put it into command prompt? save it as a .exe and run it? Make a macro (which I still don't know how to do)? {{Sonia|talk|simple}} 12:52, 4 June 2010 (UTC)

The first one is a command-line command that executes a Perl program (everything between the single quotes is the program). The second one is a different version of the Perl program. In any event, you'd need to have Perl installed, which isn't the case by default on Windows systems, but isn't too hard, I think. I don't think that the Microsoft Word macro language is all that expressive, so writing a macro for this would probably be a pain. Paul (Stansifer) 14:20, 4 June 2010 (UTC)

Lian Li power supply not turning on

I have a Lian Li case with the included power supply. I know it has some sort of fancy power failure detection thing in it. What that means - if you get sudden power failure, the computer cannot be turned on by pressing the power button. After a week or so, it will begin working normally, but I cannot figure out how to convince the computer that it is OK to turn on sooner. Anyone here have experience with these stupid things and knows how to turn one on after a power failure? -- kainaw™ 21:56, 3 June 2010 (UTC)

Solved: Remove and reinsert the CPU. A bit of a pain, but it gets the dumb thing to turn back on today instead of a week from now. -- kainaw™ 01:09, 4 June 2010 (UTC)

You probably don't want to experiment now, but I'd imagine that holding down the power button for 5 seconds might have persuaded it; that seems to be a common signal to intransigent PSU microcontrollers that you really really do want to turn on or off. -- Finlay McWalter • Talk 10:01, 4 June 2010 (UTC)

Tried that first. Even tried smacking it around a bit. Tried leaving it unplugged. Removed/replaced the CMOS battery. Nothing worked until I removed/replaced the CPU. -- kainaw™ 14:40, 4 June 2010 (UTC)

I've seen that effect with one of my older mainboards and the power supply I got with it. It was an ATX power supply, but still had a physical on/off switch on the A/C side as well, not sure if that matters. What seemed to help was to remove power by setting the switch to "OFF" (maybe pulling the power cord would have worked, too), *then* holding down the power button for 5 seconds or so (there was an LED on the mainboard that would still glow even when the power cord was removed - it would start flashing and becoming fainter and fainter when you pressed the power button long enough). After that, it would either power on by itself after power was restored, or after a long (~5 s) push on the power button.

My guess is that something's fsck'ed up regarding the ATX/ACPI stuff so the mainboard forgets to supply power to the button that would trigger a full power-on (or maybe it doesn't know how to interpret the button's signal when it's in that confused state), or something like that. I retired that machine recently without tracing it down (might be the PSU, might be the mainboard), so I'm sorry I can't tell you what the exact problem is, only how to work around it for a while.

I retired the machine because it started to have other issues, like occasionally forgetting the existence of one of its two RAID disks, which is totally not fun, especially when it would lock up during resync, then the next time it boots up, it comes up with only one disk again - this time the one that was in the middle of the resyncing process.

So keep an eye on that box, now that you got it back to work, who knows what other surprises it might have in stock for you.

You could also check your BIOS settings for an option to "resume last state" or "always power on" after power loss, that might help you around your problem, though in my case, it didn't change a thing. -- 109.193.27.65 (talk) 20:47, 7 June 2010 (UTC)