Wikipedia:Reference desk/Archives/Computing/2010 June 1

= June 1 =

Computer graphics
What is flicker? How this can be reduced? —Preceding unsigned comment added by Ajit.abhishek (talk • contribs) 04:00, 1 June 2010 (UTC)
 * Computer monitors work by flickering. They flicker so fast that your brain doesn't notice so you see a solid image. It's also why you get tired after using a computer after a while. Why not read Flicker (screen) for more information. Chevy  monte  carlo  05:42, 1 June 2010 (UTC)
 * Well, I think so anyway :) Chevy  monte  carlo  16:29, 2 June 2010 (UTC)

Problems with Ubuntu Live CD
My Windows 7 desktop computer just crashed with no warning whatsoever, giving me a "disk boot failure - insert system disk and press enter" message. So, after several attempts of accessing my system drive with no success, I decided to try booting from a Ubuntu Live CD (v. 10.04 "Lucid Lynx", if that matters). I successfully burned the .iso to a disc and tested it under Parallels on my MacBook, but I can't boot into Linux with it on my desktop. It spends a long time telling me my SATA drive is misclassified, then it hangs for several minutes at a line that has syscall_call+0x7/0xb on it before going to a black screen, whereupon it is either hanging up completely or taking over 45 minutes to do whatever it is it's doing.

I've tried messing with the boot parameters according to this page, with the same result.

Here are my system specs:
 * Windows 7 Professional
 * Gigabyte GA-MA790GP-DS4H motherboard
 * AMD Athlon™ 64 X2 Dual-Core 6000+ 3.1GHz
 * Kingston ValueRam 2x2GB PC2-6400 DDR2 800MHz (5-5-5-15)
 * Sapphire Radeon™ HD 3650 725MHz, 512MB DDR2 1000MHz, PCIe x16, DVI /2
 * SEAGATE, 500GB Barracuda 7200.11, SATA 3 Gb/s, 7200 RPM, 32MB cache

Any help would be appreciated. 74.190.49.225 (talk) 05:50, 1 June 2010 (UTC)
 * Tried scanning your hard drive with Seatools? (Get the Dos version.) F (talk) 06:44, 1 June 2010 (UTC)
 * Or scan it with TestDisk (it might be able to recover your boot partition temporarily) but from what you've described it doesn't sound good; looks like a hard drive crash in which case you might need professional recovery services if you need any data back. Was the drive making funny clicking noises recently? Sandman30s (talk) 10:37, 1 June 2010 (UTC)
 * No, no funny clicking noises at all. It was working yesterday, then I turned off my computer and when I rebooted it, it gave me the disk boot failure message.
 * I scanned with Seatools and it couldn't even find the hard drive. I've swapped out cables and SATA slots on the motherboard, so I'm pretty sure that only leaves the drive. This thing is less than two years old. >:-( Am I wasting my time even trying to get into it via the Ubuntu Live CD? 74.190.49.225 (talk) 16:22, 1 June 2010 (UTC)
 * Try booting from the Linux CD after unplugging the probably broken hard drive - if it comes up without the syscall error you mentioned above, it is pretty likely that the hard disk is damaged beyond recognition. -- 109.193.27.65 (talk) 18:01, 1 June 2010 (UTC)
 * Yup, it booted successfully with the hard drive disconnected. Any suggestions for recovering the data from the drive (without spending lots of money on a data recovery service)? Thanks. 74.190.49.225 (talk) 19:44, 1 June 2010 (UTC)
 * All the cheap data recovery software I know requires the computer to at least recognize the disk. Try it in another computer? 203.167.190.79 (talk) 05:21, 2 June 2010 (UTC)
 * Afraid you're at the point where you have to consider expensive data recovery OR doing a lot of research to find software that can bypass the drive controller. You might be able to find something in one of the many boot cd's with software bundles that can read the drive at a lower level. I would also try, for example, attaching it to a USB external shell (or whatever it's called) and trying to mount it using LFS. I don't know, I've been here before and it gets really hairy. This is why the pros charge so much I guess, some claim to have tools to read the magnetism directly off the platters and raw data takes a long time to recognise and transform to usable data. It could be cheaper if you ask them to search for a specific type of file. G'luck! Sandman30s (talk) 06:35, 2 June 2010 (UTC)


 * And then there's the old hard drive in the freezer trick. Of course I'd only try this if you're willing to risk further damage to the HDD before sending it off to a data recovery service. -Amordea (talk) 15:56, 5 June 2010 (UTC)

Enough power for USB 2?
My neice has a PC, a Dell Dimension desktop PC around 5 years old, with Windows XP SP3. After much hassle getting a stable connection to the internet using the wireless access point in a distant corner of the house, earlier this year I installed a Belkin N Wireless USB adapter which is connected to one of the USB ports on the PC, and now the connection is pretty reliable. Like many teenagers, she is heavily into social networking so has installed several messaging apps and Skype, and has recently got herself a webcam so she can hold video chats with her friends. Recently, there has been some problems when she connects a USB flash drive or a digital camera, the PC reports that the device has "malfunctioned". After a lengthy investigation last weekend, including a full reinstall of Windows, I have at least managed to find out something about the problem.

While the PC appears to have many USB controllers listed in the device manager, only one is a USB 2 controller. The wireless adapter is always connected to this controller. When the USB flash drive or a digital camera is connected to any physical USB port, it is also connected to this same USB 2 controller but draws 0 mA (the wireless adapter seems to draw all 500 mA available under USB 2). I strongly suspect the reason the PC reports the devices have "malfunctioned" is a lack of power, and this is reinforced because if I disconnect the wireless adapter, the other USB devices now magcally work again.

My investigation has led to a number of questions: Why does the PC allocate the other devices to the only USB 2 controller rather than one of the 3 unused USB 1 controllers? Is there a way I can reduce the power consumption of the wireless adapter? Would connecting an external, powered USB hub solve the power problems? Would buying a USB 2 PCI card, make additional USB 2 controllers available so that the PC can allocate the other devices there instead? Astronaut (talk) 13:20, 1 June 2010 (UTC)


 * I have had this as well, when I added too many USB devices that get their power from the port or used a long cable. The simplest fix is to use a USB hub with a power pack. The hub powers the devices, not the PC. ---— Gadget850 (Ed)  talk 13:37, 1 June 2010 (UTC)
 * Agree with the above. Just one additional note, AFAIK your PC doesn't allocate devices to a controller, i believe controllers are physically connected to USB ports. So the sockets you are plugging into are connected to the USB2 controller in your PC. If you have USB1 controllers in device manager or whatever, they might be connected to ports on the back of your PC or even possibly just headers on your motherboard which are not physically connected to any USB ports at all. Vespine (talk) 06:13, 3 June 2010 (UTC)

"In the news" archive
Is there an archive of the in the news section (right side of homepage)? I'd like to make a screen shot of a particular news event last week (maybe 2 weeks ago). Cheers! Aaadddaaammm (talk) 13:54, 1 June 2010 (UTC)
 * There is, of a sort: ITN_archives. But it appears to show, per month, all items listed in that month. (or perhaps added in the month). --Tagishsimon (talk) 14:07, 1 June 2010 (UTC)

Socially engineered malware
Hi, I'm trying to understand the term "socially engineered malware". I found this definition, but I still don't get it. What do the words "socially engineered" have to do with anything? Anyone any idea? —Preceding unsigned comment added by 86.185.76.171 (talk) 16:53, 1 June 2010 (UTC)


 * Your friend Joe's computer gets infected by malware, which then goes through his address book in his email client and sends a message to you, saying "Check out these pictures from my vacation!" You click on the attached picture file, because you trust Joe, and that file then infects your computer and starts the process over again. That's an example. "Socially engineered" relates to the way the malware is passed around. 74.190.49.225 (talk) 17:03, 1 June 2010 (UTC)


 * And, of course, we have an article on social engineering in general. -- Coneslayer (talk) 17:16, 1 June 2010 (UTC)


 * Right. Social engineering means you are relying on human interactions, rather than technical hacks, to gain entry to a system. So if I call someone up at an office and say, "oh, yeah, this is Joe from level 6, I need the admin password, you know? Cause I'm locked out and that's really gonna make the boss mad!" and they believe me, that's "social engineering" in the context meant here (as compared with, say, using my computer to exploit a bug in their system software). So social engineered malware is malware that takes advantage of human factors—you fool the human into doing something they really shouldn't do, not because their computer is lacking in proper security or has bugs, but because they are humans and they are fallible. --Mr.98 (talk) 20:41, 1 June 2010 (UTC)


 * Indeed many of the many of the more successful malware include some social engineering aspects. E.g. I selected these   [     from some random person's list of malware which include social engineering aspects (and in fact I didn't even include a few that were distributed by P2P which also use social engineering). The first few perhaps being famous for it [[User:Nil Einne|Nil Einne]] (talk) 21:54, 1 June 2010 (UTC)


 * Just as an aside, the concept of 'social engineering' really refers to the idea of coercing people into doing things they should do rather than doing the somewhat dumb things they actually do do. technically speaking, parking tickets are a form of social engineering - you convince people to behave civilly with respect to parking by making them pay if they behave rudely.  in hacker terminology it has the same semi-sarcastic, semi-self-justificatory sense as when a grifter talks about 'educating' a mark; if the mark is smart they will learn not to do whatever stupid thing it was that allowed the grifter to rip them off, and ultimately the world will be filled with better, more street-wise people.  -- Ludwigs 2  06:21, 4 June 2010 (UTC)

rss
I need a program that can monitor rss feeds every few mins and alert me if any contents in the feed match a specific keyword. I'm currently experiment with Thunderbird which is working quite well for just viewing feeds, but I want it to be able to alert me for specific keywords. Anyone know how this can be done, or better programs that might do this? Thanks 82.44.55.254 (talk) 19:06, 1 June 2010 (UTC)


 * You can create a keyword filter at Yahoo! Pipes and pass the original RSS feed through that, and subscribe to the pipe output in Thunderbird. -- Coneslayer (talk) 19:27, 1 June 2010 (UTC)


 * If you happen to use a Mac, you can use Mail and its built-in rules. You can set these up so if a message contains a keyword then certain actions (playing an alert noise, changing the colour of the message in the inbox) are carried out. This can be extended further using Applescript. Brammers (talk/c) 22:15, 1 June 2010 (UTC)
 * That's exactly what I want, but I don't have a Mac :( Is there a Windows port or clone? 82.44.55.254 (talk) 22:35, 1 June 2010 (UTC)
 * I had a rummage round. Although I don't use Thunderbird myself, it seems that there is a rough equivalent to rules called filters. Here and here might be of use, although I don't know how broad the range of actions are. It might be worth dropping by the Thunderbird community forums via the official website and asking there. Hope you manage to find a workable solution, Brammers (talk/c) 11:07, 2 June 2010 (UTC)

Excel - Inserting a link, programatically
In excel you can insert a hyperlink into a cell, so that you have an visible anchor and a hyperlink value associated with the cell; and if you click on the anchor, you get taken to the hyperlinked site. So far so good. I have a spreadsheet, it has one column of hyperlinks. I want to extract the hyperlink value, amend it, and insert it as a hyperlink in cells in a second column.

If you want to extract the hyperlink value from acell, it seems you need a custom function such as or.

What counterpart function would I need in order to set a hyperlink value around anchors in my second column? thanks --Tagishsimon (talk) 22:32, 1 June 2010 (UTC)


 * Ah. =hyperlink(link,anchor). --Tagishsimon (talk) 23:38, 1 June 2010 (UTC)