Wikipedia:Reference desk/Archives/Computing/2007 May 4

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Computing desk
< May 3 << Apr | May | Jun >> May 5 >
Welcome to the Wikipedia Computing Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.


May 4[edit]

Backing up my hard drive[edit]

I know the importance of backing up one's hard drive, but I find the process using Windows XP's file explorer to be tedious and buggy.

Does anyone know of a free program that makes it easy to choose what to back up, divide it into the proper number of CDs and burn the data? Thanks -- Mwalcoff 00:05, 4 May 2007 (UTC)

There's a big difference between backing up the disk and just backing up the data. The former copies everything (including the OS, applications, and lots of incidental and temporary junk) making a large archive that can restore your machine to its current state (but that's not so useful for just recovering the data on a new machine). The latter just copies the important data you want (mostly stuff you made yourself, and maybe email). The former process is called disk cloning, and that article links lots of software that can do it. Our backup software and list of backup software articles describe a variety of solutions for backup. -- Finlay McWalter | Talk 00:22, 4 May 2007 (UTC)
Thanks. I don't need to clone the disk -- just back up data files. Thanks for the link -- Cobian Backup looks like it might do the trick. -- Mwalcoff 01:06, 4 May 2007 (UTC)


A lot of external HD manufacturers include "1-button" file-backup software w/ their products (so you can just press the button on the hard disk whenever you want to do a backup). I don't use it personally, but I know my external HD has it. NByz 20:35, 7 May 2007 (UTC)

Excel[edit]

Hi - Is there any free source of learning MS excel in very simple manner ? I have tried number of books and online tutorials, but have been unable to explore the full potential of excel.

67.180.49.99 00:26, 4 May 2007 (UTC)

My sugestion is just jump in and start trying to do things. If you are doing something relevant to your life or job it is easier to learn something. For instance you could create a budget spreadsheet each row could be a seperate expense, and the columns could be category divisions (groceries, utilities, entertainment etc) that are summed up into a total column. When you have a specific problem you are trying to solve it is often very useful to do a google search. If you are trying to figure out how to use the SUM function you could search "excel sum". If you are interested in macro programming here are a couple of sites with some basic reference information to get you started. I found these site myself just through general problem solving, and have them bookmarked, because they have a good overview of common programming topics in excel. Excel Faq and Julian's macros -Czmtzc 12:30, 4 May 2007 (UTC)
Mr excel (http://www.mrexcel.com/board2/index.php) is a great site for finding out answers to wanting to achieve a specific thing. You have to sign-up (free) to post questions but the people there are friendly and often have very good responses to requests for help. ny156uk 16:16, 4 May 2007 (UTC)

Airport Express[edit]

I've been trying to figure out how to set up my Airport Express as a bridge but can only find mentions of using it as a wireless bridge and I want it to be both wireless and wired. There's an ethernet port on the side but I can't get it to handle a wired connection. Basically, I have an ancient laptop with Linux on it that I want to be able to use in my living room where the AE is. If I plug an ethernet cable into each, I can't get online. I've tried it with another laptop that is newer and has Windows XP on it and that doens't get online either but they do if I plug them direct into the router downstairs, i.e. not in the living room. So, I know it's not the computers. Any ideas? Dismas|(talk) 00:29, 4 May 2007 (UTC)

Adobe Premiere[edit]

How do you stretch the timeline out so that there's more than 40 seconds to work with? —The preceding unsigned comment was added by 71.82.135.128 (talk) 01:27, 4 May 2007 (UTC).

At the bottom of the timeline window there should be a drop down box that displays the current length of the timeline. Select the arrow next to it and choose the timeline length. This page has a good visual reference. —Mitaphane ?|! 03:26, 4 May 2007 (UTC)

Qos Mapping[edit]

Hello,

What is Qos mapping(in relation to WiFi networks) I saw a program that offered to do this, and was curious about what is was.

Thanks, Nathanww 01:55, 4 May 2007 (UTC)

When talking about computer networking, "QoS" means quality of service. I think "QoS mapping" is just allocating your QoS budget (e.g., how much guaranteed bandwidth you get) optimally, but I dunno. See Differentiated services. --TotoBaggins 02:47, 4 May 2007 (UTC)

Hashcash and P=NP[edit]

The Clay Mathematics Institute article describes the P-versus-NP problem as to determine "whether there are any problems for which a computer can verify a given solution quickly, but cannot find the solution quickly." Isn't outgoing hashcash such a problem, in theory, or is the quoted description inaccurate or woefully incomplete? NeonMerlin 03:20, 4 May 2007 (UTC)

I'd never heard of hashcash before, but reading our article on it makes it clear that it is not. The P/NP/NP-complete complexity classes deal with what is called decision problems, yes or no answers to questions. An example is the travelling salesman problem: Can a travelling salesman visit every town in America and only use X amount of fuel? What the Clay-text is referring to is that if you are given the answer in advance (called a certificate), you can quickly check that it is the right one. For instance, the subset sum problem is this: "Given a set of numbers, does any subset of them sum to N?". If someone provides you with an answer (i.e. a subset that sums to N), you can quickly check it, you just sum the numbers and see if they do, in fact, sum to N. The point is, NP and NP-complete problems are really hard to solve, but if someone can find one algorithm to solve any of the NP-complete problems in a fast way, then every single NP problem (and there are thousands of them) would be solvable using a fast algorithm. If someone finds that algorithm, it would be the single greatest milestone in the history of computers since Alan Turing invented the Turing-machine. --Oskar 05:46, 4 May 2007 (UTC)
You know, when I look at it a second time, you might be correct after all. The decision problem "Find a string which has a SHA-1 hash starting with N zeroes" is exponentially difficult, O(2^n) which would put it, I think, in NP. It's almost certainly not an NP-c problem, but you are probably correct that that sort of problem is exactly what P vs. NP is talking about. My Bad :) --Oskar 05:56, 4 May 2007 (UTC)
The description of the problem is very poorly worded. I'll fix it up just now. Yes, hashcash is hard to compute, but quick to check; there are *many* such problems (public-key cryptography depends on one of them). The Millenium question is whether P = NP, which is to say, "does there being an quick way to check the answer imply that there's a quick way to compute it?". --TotoBaggins 17:46, 4 May 2007 (UTC)
The point of the wording used by Clay is that we don't know whether there are hard problems of the kind whose solution can be verified quickly (in polynomial time) --- this point has not been proven. Even without proof, it is widely believed that there are such problems, and much of cryptography, like hashcash, is based on this belief. But at the present stage of computer science and mathematics, the possibility cannot be ruled out that there is a fiendishly clever algorithm that would efficiently solve NP-hard problems. If there is such an algorithm, current hashcash schemes would turn out to be based on wishful thinking only. 84.239.133.38 19:33, 4 May 2007 (UTC)

Dial-up internet connection with wireless router[edit]

I have recently had a separate BT telephone landline installed for two 2 oversea students who reside in my house. The students both have wireless lap-top computers that they wish to use. I am the subscriber and responsible for the line at BT.

For the students to use their laptops do I merely have to buy a wireless router? Would there be a charge by BT for every time the students use their laptop and the internet?

Technologically underinformed Landlord

86.129.150.56 07:27, 4 May 2007 (UTC)

I've split your question into its own section — Matt Eason (Talk &#149; Contribs) 09:25, 4 May 2007 (UTC)
This would likely depend on the company's service plan, although if you're going to be using wireless internet, you really should have broadband. Wireless internet tends to be slower than a wired connection, and dial up is unbearably slow nowadays. You can probably get DSL for under 40$, which shouldn't be too much more than dialup. If you can't afford it, you could ask the students to chip in. Broadband internet, again you'll need to check your service plan on this, is usually "Always On", so you don't spend extra money just for them being connected like you do on some dial up, although you should see if the service plan has a Fair Access Policy, or FAP, and check it very carefully, to see if you'll be charged for downloading more than a certain amount of content (I've heard of some plans that penalize users for downloading more than 1GB in 4 hours, for reference, I've downloaded over 4 GB in one hour before, easily). But yes, for your basic wireless internet, you plug your landline/cable into a modem, the modem into a wireless router, and the router into any wired computers. Usually your ISP will help you with this. -- Phoeba WrightOBJECTION! 09:41, 4 May 2007 (UTC)
You'll need a computer to do this, wireless routers don't take what a standalone modem will give you. The computer will need an ethernet port. You will need to share the outgoing dialup connection with the Ethernet connection using NAT (in Windows, it's called "ICS", Internet Connection Sharing) with the Ethernet connection. Plug the router into the ethernet port and set up the router to use DHCP. This should be the basic setup you need. —The preceding unsigned comment was added by 149.135.28.77 (talk) 07:52, 5 May 2007 (UTC).
An alternate solution may be to forget the second line entirely, and encourage your tenants to go really wireless with a GPRS (as in mobile phone) modem. The modems aren't the cheapest devices ever, but depending on where the students are from, they may be able to take the devices home and use them there as well. If they already have mobiles (intercultural note: that's what they call cellphones in the land of BT) of their own, it may be worth checking them for Bluetooth. Many Bluetooth phones will allow thier data conections to be shared with a laptop, a practice refered to as 'tethering'. In the US I just recently bought a USB Bluetooth adapter for approximately $25. One warning though - not all mobile plans allow data usage, and some charge by the kb. --Ptelder 07:18, 7 May 2007 (UTC)

Animated gifs[edit]

How does one go about making an animated gif file like the ones shown here? I assume it's a matter of getting a number of sequential still images and stitching them together somehow, but if someone can tell me the basics I'd be very grateful. Many thanks. Oh, and just out of curiosity - why are these small animated files always gifs? Is there any such thing as an animated jpg? --Richardrj talk email 07:41, 4 May 2007 (UTC)

Yes, you take a series of images and put them together in a program such as ImageReady or GIF Construction Set. I'd imagine there are also freeware alternatives available. The last paragraph of the 'Alternatives' section of the GIF article gives some alternatives to GIF for web animation. As far as I'm aware there's no such thing as an animated JPEG. — Matt Eason (Talk &#149; Contribs) 09:21, 4 May 2007 (UTC)
As always GIMP is one of the free alternatives. Make each image a layer and select "save as animation" when you save your GIF. --Kainaw (talk) 13:12, 4 May 2007 (UTC)
There is such a thing as a motion JPEG, but it's not very common. Eventually, PNG's derivatives will support animation; it can be used to make more "natural-looking" pictures than GIF, although it's not as good (in terms of compression, particularly) as JPG for such things as photographs. --Tardis 16:01, 4 May 2007 (UTC)

Lenovo Laptop[edit]

How do you switch the bluetooth on on a ThinkPad R60? Zain Ebrahim 13:05, 4 May 2007 (UTC)

Fn+F5 [1], assuming your laptop has bluetooth in the first place. You need the system software thingie. -- Consumed Crustacean (talk) 22:23, 4 May 2007 (UTC)

Google Web Accelerator & Wikipedia[edit]

Wikipedia does not allow edits when using Google Web Accelerator. Is this because the IP address changes (or does it, even?). Incidentally, I've stopped using it, as, even though my internet searches, etc., get faster, it slows my computer down considerably, defeating the whole purpose of the thing. Scouse Mouse - 日英翻訳 13:17, 4 May 2007 (UTC)

It's a vandalism prevention thing apparently. There's a page on it at WP:GWA. — Matt Eason (Talk &#149; Contribs) 14:15, 4 May 2007 (UTC)

Credit card data - where does it go?[edit]

Im about to buy a product off steam, but im paranoid about giving out my credit card information over the internet to an American company, i trust valve but im so far away if anything went wrong theres nothing i could do, but anyway my main question is how does it all work?, i mean, what happens with your credit card number? Does valve read it and take money out of it, but wouldn't that mean they charge you whenever they want even if your not buying anything, i know it probably doesnt work like that but im a student and cant afford to be getting hit by fraud like bills for $3000 or something.... thanks. —The preceding unsigned comment was added by Bwa32123 (talkcontribs) 13:55, 4 May 2007 (UTC).

The general process is described in credit card, although the emphasis there is on person-to-person transactions.
To charge your account without authorization is fraud in most places. Were you in the United States (which you've noted you aren't), the Fair Credit Billing Act would allow you to dispute unauthorized credit card charges. Since you aren't, you government may or may not give you some consumer protections. You should check your credit card agreement to see what rights you have against unauthorized transactions, if any.
There is a risk, as always, of credit card fraud, especially of unscrupulous companies misusing your credit card number. You have to decide whether or not the company is trustworthy enough to risk giving your credit card number to. If you are concerned, you should monitor your monthly billing statement (you should anyway!) for any kinds of unauthorized transactions. –Pakman044 14:48, 4 May 2007 (UTC)
I would note that steam (content delivery) are a large respected online company and that it would be extremely unlikely that they (as a firm) would take money other than when you bought a product/subscribed to a service. Sending information over the internet does have a risk of fraud (internet fraud) but so does non-internet transacations for all types of credit card fraud. I have purchased products on steam from the UK and had no problems at all. ny156uk 16:13, 4 May 2007 (UTC)
The problem you note about an unscrupulous company reusing your information for a later purchase is a real one. Here's a story about giving credit cards a built-in one-time password to fix that issue. --TotoBaggins 18:22, 4 May 2007 (UTC)
You never know what establishment will have a computer security data breach so perhaps you should use one credit card for higher risk e-commerce and another to use where you have high confidence in the retailer due diligence. User:AlMac|(talk) 22:06, 6 May 2007 (UTC)

Internet Explorer 7[edit]

Here's the problem: the "File Download" window. I accidently unchecked the "Always ask before opening this type of file" option in that window and now i now have to view Word documents directly from IE (which on my monitor resolution show most of the words one on top of the other), rather than downloading them.

So anyway, how do I get IE to prompt me to open Word documents again?

And where on earth is that option? It doesn't really do anything besides annoying me, but I've realised I could have had a serious problem if I had unchecked the "Always ask before opening this type of file" for .exe files. —The preceding unsigned comment was added by 82.36.162.32 (talk) 18:35, 4 May 2007 (UTC).

A quick browse of IE preferences and help doesn't reveal the answer, but according to the help entry on 'downloading files' (in IE 6, I assume this has stayed), there is no such option for .exes: IE always asks. 131.111.8.104 22:06, 4 May 2007 (UTC)
Not sure about this either, but surely you can right-click on the given hyperlink and say "Save As...". One place you can check (but I don't think will help) is if you click Tools -> Manage Add-Ons -> Enable or Disable Add-ons. When that loads, you could look at the various add-ons you have and maybe disable on for Microsoft Word if you see one - but doing it on my computer doesn't show any such addon. Other than that I'm sorry I don't know. Rfwoolf 14:06, 5 May 2007 (UTC)
Open My Computer. From the Tools menu, select Folder Options. Click on the File Types tab. Select the file type you're interested in from the list and click Advanced. Check the box for Confirm open after download. Bavi H 06:09, 6 May 2007 (UTC)

How can I retrieve data from my old hard drive?[edit]

My computer bit the dust recently, and I have no desire to repair it (I was planning to buy a new one in June anyway). However, I had a lot of stuff on the hard drive that wasn't backed up, and I'd like to retrieve it somehow. As far as I know, the hard drive itself isn't damaged. Is there anyway I can get the data off it somehow? Any help would be highly appreciated. GhostPirate 19:42, 4 May 2007 (UTC)

You'd just plug it into the new computer, or into a friend's computer (and copy the important stuff onto DVDs or whatever there). Or, if the dust-biting was due to its Windows install just going wonky then you can boot the machine from CD into something like Knoppix and burn/copy the data directly. -- Finlay McWalter | Talk 19:44, 4 May 2007 (UTC)
So I can just put it in a different computer? I wondered about that. Now to convince someone to let me crack open their computer and preform a "brain transplant"...GhostPirate 19:49, 4 May 2007 (UTC)
Yep. Assuming it's an IDE disk you may have to flip a jumper on its rear to 'slave' (from 'master' or 'single'), and you might have to temporarily evict an existing IDE device (like a DVD drive) if there aren't enough free connections. Another alternative is to buy a cheap USB-IDE disk enclosure. You put your old IDE disk in that and it becomes an exernal USB disk for any computer you plug it into (and this way you don't need to perform surgery on someone else's machine). -- Finlay McWalter | Talk 19:59, 4 May 2007 (UTC)
It doesn't have to be a whole "transplant". Instead of thinking of it as taking out one brain and replacing it with another, think of it as taking out one brain and then making it a slave to someone else's brain. Or something like that. In any case, you can hook up multiple hard drives to a computer at the same time, as long as you specify one to be "in charge" (the master), and then you can copy files off of the other one (the slave) with impunity. It's pretty easy and the worst that generally can happen is if you don't have the jumpers set right it won't start up until you change them. In fact, when you get your new computer you can hook up your old hard drive in it as well as the new one and just use both of them, if you wanted to. --24.147.86.187 21:45, 4 May 2007 (UTC)
See this article for more information. -- Finlay McWalter | Talk 22:27, 4 May 2007 (UTC)