Wikipedia:Reference desk/Archives/Computing/2008 April 3

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April 3

Memory addressing?

“ Assume one computer uses byte address. It uses 32 bits for its memory address, which means the maximum virtual memory space for this computer is 232 bytes. For its demand paging, this computer uses page size of 4 Kbytes and each page table entry takes 32 bits, i.e. 4 bytes. If the page table is held in memory, how much memory (in bytes) would it take? ”

I am not sure exactly what it's asking. But, by reading it, it would seem that 4 bytes or 232 bytes would be the answer, but that would seem too obvious? 143.43.8.32 (talk) 03:21, 3 April 2008 (UTC)

It's 2³² (which is 4,294,697,296), not 232. "4 Kbytes" probably means 4096 bytes. (It could also be 4000 bytes, depending on how "K" is to be interpreted) Thus, there are (4,294,697,296)/(4096) = 1048756 total page table entries. Since each entry requires 4 bytes, the total space required for the table is 4,194,304 bytes. - SigmaEpsilon → ΣΕ 03:37, 3 April 2008 (UTC)

This is computer memory we're talking about. In that context, the "K" suffix always means kilobytes of 1024 bytes -- not even marketing departments have dared to try to change it. --Carnildo (talk) 19:14, 3 April 2008 (UTC)

proxy

wat is a proxy website? and how can i get to one? —Preceding unsigned comment added by 76.14.124.175 (talk) 04:22, 3 April 2008 (UTC)

A proxy server is a server that makes requests on behalf of a user. Instead of the user connecting directly to a server, a proxy server will act as a 'middleman'. Check the wikilink for more in-depth detail. That's just a quick definition. And as for using one, just Google 'list of proxy servers' or something along the lines of that. crassic!^[talk] 04:34, 3 April 2008 (UTC)

Your internet service provider most likely has a proxy server. To use proxy server, you insert the proxy server addres in your web browsers settings. For example on IE7, select Tools → Internet options → Connections tab → LAN settings (assuming you are using broadband connection). Your service provider has given you the instrunctions. Some service providers always route everyting through proxy regardless of your browser settings. --PauliKL (talk) 23:19, 4 April 2008 (UTC)

TCS

wat is TCS??????? —Preceding unsigned comment added by 61.17.179.157 (talk) 05:00, 3 April 2008 (UTC)

Assuming this is unrelated to the proxy question, I've added a header for it. We have a list of possibilities right there: TCS. --tcsetattr (talk / contribs) 05:48, 3 April 2008 (UTC) (although my username starts with "tcs", it's not part of the answer. that's just a signature)

There's some interesting scope for misunderstanding here. I can picture a general saying "Send in the TCS (meaning troop carrier squadron), but by mistake the Toronto Choral Society are sent into the front lines. -- Q Chris (talk) 13:54, 3 April 2008 (UTC)

encode as base64 in html

Is it possible to store an mp3 file (or any file for that matter) inside the code of a HTML file as base64, and have it act like it were a real link to an mp3 file? Also, how can I store jpeg images in HTML files as base64? I have an encoder for base64. xxx User:Hyper Girl 12:27, 3 April 2008 (UTC)

This seems to be what you're after [1] [2] and [3] Think outside the box 12:56, 3 April 2008 (UTC)

Basically, data: URI scheme. --grawity ^{talk / PGP} 14:12, 3 April 2008 (UTC)

GMAIL in html

Is there any way to get gmail into html format? Is there a classic gmail option? --Gary123 (talk) 12:33, 3 April 2008 (UTC)

Gmail has a basic mode. You can force it into this mode at [4] or [5]. The latter is the HTTPS one which is more secure if a little slower. x42bn6 Talk Mess 13:31, 3 April 2008 (UTC)

Movie on iPod

First, I'll get the basic facts out of the way: I have a 8GB 3rd gen nano iPod, a Dell PC, and the latest version of iTunes with all the bells and whistles. (Last time I asked a question here I was told that telling you that sort of stuff was useful.) So here's my problem. I had a video in mpg format, because that's what plays on Windows Media Player, which I usually watch the video on. But I wanted to put it on my iPod, and it said it didn't recognize the format. Then I right clicked on the video icon and noticed a handy-dandy feature that says "convert for iPod." So I did, and then my iPod accepted it, but somewhere along the way, it lost all sound and I'm only getting the picture. I found nothing useful on Apple Support. Any ideas? Thank you! Cherry Red Toenails (talk) 12:38, 3 April 2008 (UTC)

Try using a 3rd party converter. I myself use Videora iPod Converter which is free and pretty simple to use.TheGreatZorko (talk) 14:13, 3 April 2008 (UTC)

Thank you so much! It worked perfectly!!! Cherry Red Toenails (talk) 17:38, 3 April 2008 (UTC)

Why laptops wide only?

Why have all the bad ass PC manufacturers stopped producing normal non-wide screen laptops? I have searched websites and called customer cares of all PC companies and all of them say NO. Is it because Vista supports only wide screen? —Preceding unsigned comment added by 59.92.114.92 (talk) 13:33, 3 April 2008 (UTC)

It's because stupid people buy that crap. Vista, and everything, works fine with 4:3. Buy an external 16:9 monitor if you just have to have your movies. :D\=< (talk) 13:35, 3 April 2008 (UTC)

It is all about money. Consider a laptop with a 21" screen. If it is 16:9, the 21" screen will be 18.3"x10.3" for a total area of 188.5". If it is 4:3, the screen will be 16.8"x12.6" for a total area of 211.68". They charge more for the widescreen laptops while producing over 23 square inches less of LCDs for the screen. The people buying the laptops get the warm fuzzy "I got a widescreen" feeling and the manufacturers make more money. Everybody wins. -- kainaw™ 14:01, 3 April 2008 (UTC)

I don't see why you wouldn't want widescreen anyway. It allows you to view two pages of A4 side by side, allows for more peripheral vision in games, means less black space in movies. By the way most non widescreen monitors are 5:4 now, which is even less horizontal space. TheGreatZorko (talk) 14:12, 3 April 2008 (UTC)

Do games actually use the widescreen space to show you a range that you wouldn't have already been able to see? I just figured it would be stretched or something. Do the programs have to calculate your screen size and decide how much world to show you? — Sam 14:46, 3 April 2008 (UTC) —Preceding unsigned comment added by 63.138.152.238 (talk)

No, they do NOT. In the few games that went insane and decided to support widescreen resolutions, you have the same horizontal view angle and it just cuts off the top and bottom of your view. :D\=< (talk) 15:07, 3 April 2008 (UTC)

Incorrect. Froth(:D\=<) is being misleading again. Most modern games (not just the ones that 'went insane') support widescreen. Quick experimentation shows that they do it both ways. Portal, Halflife 2, and other Source games give you a wider horizontal field of view while keeping your vertical constant. (Exactly like Froth said they wouldn't do.) Screenshots here. Bioshock does it the other way. Bioshock appears to keep your horizontal field of view constant while adjusting your vertical field of view. (Like Froth said.) Screenshots here. This is not unique to games. Both techniques are used when releasing movies in different aspect ratios, although I'm not sure which is more common. APL (talk) 22:53, 3 April 2008 (UTC)

Well there are to things in this, first is that user must see different area depending on aspect ratio, but they shouldn't have unfair advantage because of this, that said, most FPS have more or less flat maps, so seeing more in top or botton isn't big advantage compared to seeing more in sides. Also if game is rendered in 1280 horizontal resolution for example is much easier to simply crop top and bottom, and also it's correct way to do this, because if they scale, then wide and non wide monitors with same dpi will have different picture sizes. —Preceding unsigned comment added by 195.238.64.156 (talk) 10:38, 5 April 2008 (UTC)

Besides, whoever said that having a narrower field of view with greater detail is bad? -- Meni Rosenfeld (talk) 23:15, 3 April 2008 (UTC)

Widescreen is where things are going. Don't resist.. in every case I know of, once a person has gotten used to it, they like it and wouldn't want to change back. Friday (talk) 14:47, 3 April 2008 (UTC)

Resistance is futile, you WILL be assimilated. StuRat (talk) 16:26, 3 April 2008 (UTC)

It really depends on usage. I prefer 3 4:3 monitors. However, I am a developer, so my usage is abnormal. For the average user, a widescreen is fine. -- kainaw™ 15:31, 3 April 2008 (UTC)

My friend bought one of those wide-screen laptops and the video card doesn't even support any wide-screen resolutions. I set it to put black bars on the side and he is quite happy that his image isn't horribly stretched. This is a fairly new laptop, mind you. I know that my recent Thinkpad has a normal screen, so I'd look to Thinkpads if I wanted no widescreen. All widescreen does is make the whole thing larger and more power-hungry with no advantage at all. 206.252.74.48 (talk) 16:04, 3 April 2008 (UTC)

Personally, I don't mind widescreen TV's, but I prefer my computer monitors to be "fullscreen" or whatever it's called. I guess that's why I only have a 17" monitor (but my TV is 61"). Useight (talk) 16:15, 3 April 2008 (UTC)

I, myself, do graphic designing and page lay out work and have been somewhat unsatisfied with my new widescreen laptop. The extra width isn't worth the loss of extra height. There are many situations that I find I have too much width and not enough height. Acceptable (talk) 22:12, 3 April 2008 (UTC)

One Query here:- I mostly spend time in browsers like firefox because I use PC for net only. Even if I use widescreen, I can use some sidebars which take some space and make firefox window a 3:4 one. But even if I do that, I think my browser user agent will say my laptop is widescreen and all websites will send to my PC, pages designed for widescreen and it will be horrible horizontal scrolling which I should do. Is there any way where we can change useragent info or do some thing else so that all webpages viewed be displayed in 3:4 size after adjusting firefox window to 3:4 ? —Preceding unsigned comment added by 59.96.136.58 (talk) 06:48, 4 April 2008 (UTC)

Your user agent doesn't tell your screen resolution- you're fine. And good job not browsing the internet widescreen; I think it looks terrible and keep the viewing area of my browser strictly at 5:4. :D\=< (talk) 18:55, 4 April 2008 (UTC)

There are no web pages designed for widescreen. However, some poorly made web pages do read the screen resolution from browser and adjust the width of page to the width of screen. Which is wrong, of course.

Web browsing is one of the applications where wide screen display is no good. After all, most web pages are taller in vertical direction than horisontal direction. That is true with most text documents, too. Watching movies is about the only use where wide screen is usefull. For example photos usually are 3:4 or 4:5 shape. And many photos are taken in portrait mode so wide screen is much worse than normal screen. Unfortunately wide screen monitors have become common as desktop monitors, too. If I were to buy a monitor now, I would buy a 3:4 monitor with pivot function for viewing portrait photos. --PauliKL (talk) 23:48, 4 April 2008 (UTC)

Hopefully you mean a 4:3 monitor o_o :D\=< (talk) 01:43, 5 April 2008 (UTC)

If the monitor has pivot function, the screen can be turned 90 degrees, so you can use it in landskape mode (4:3) or portrait mode (3:4). --PauliKL (talk) 11:42, 5 April 2008 (UTC)

Wait, you're sugesting that a web site should stubornly keep it's layout fixed as though it were a piece of paper and not respond to the user resizing the browser window? Or are you saying that some websites adjust themselves to screen size regardless of whether the window is maximized or not? If the later, can you give an example? If the former, I'd just like to say that I think you're crazy. APL (talk) 16:02, 5 April 2008 (UTC)

I came across some Javascript a long time ago to let you redirect according to screen resolution. I only used it for serving wallpaper images, though :p Rawling4851 18:33, 5 April 2008 (UTC)

@APL, even a non-widescreen screen at 1280px is too wide to be reading text in really, websites should have a limit to how far they stretch the main text area horizontally. --Random832 (contribs) 14:40, 9 April 2008 (UTC)

Detecting peripherals?

How does an operating system detect peripheral devices on x86 computer? It might be my limited English but I haven't found anything with Google. --212.149.216.233 (talk) 14:54, 3 April 2008 (UTC)

It really depends on what type of device and interface your are talking about. There is some information in ISA Plug and Play and links to many other specific technologies from there. --LarryMac | Talk 15:15, 3 April 2008 (UTC)

For the most part, the OS just checks all the connections. For example, is there something on the fourth USB connector? The OS checks to see if anything responds on that connector. If so, something is there. If not, nothing is there. Much of it is handled by polling devices to see if there is a change. This is not limited to peripherals. Removable disks are often polled as well. -- kainaw™ 15:30, 3 April 2008 (UTC)

Modern peripherals all have some sort of "Configuration space" that describes, in pretty plain terms, what the peripheral is. The exact protocol varies but, for example, on the PCIbus, there's a specific set of device registers that every valid PCIbus device has to have, and these registers tell you things such as the manufacturer of the device and the specific device type. So using those registers, the CPU can identify all the different devices attached to its PCIbus. Then, one of those PCIbus devices may include (say) an ATA bus disk adapter. So the software reaches out through the PCIbus to the ATA bus and asks around of all the disk-like devices connected to the ATA Bus. Same thing for the various USB and FireWire/IEEE 1394 busses. Eventually, after it has "walked the tree" of all of the possible busses and bus adapters and peripheral devices, the software is able to "size" your entire hardware configuration. And announce that you need to download some more drivers ;-).

Atlant (talk) 16:30, 3 April 2008 (UTC)

Compare digital converter boxes with analog pass-through

My goal is to get a chart that lists all the attributes of those digital-to-analog TV converter boxes which support analog pass-through (hopefully with customer reviews of those of the 7 which are in stores now) for comparison, but I've had no luck. The seven which support analog pass-through and are FCC-coupon-eligible are:

Echostar TR-40 (not yet available)
Philco TB100HH9
Philco TB150HH9
RCA DTA800B1
Digital Stream DSP7700T
Digital Stream DX8700
Magnavox TB-100MG9

Any help would be much appreciated. StuRat (talk) 16:09, 3 April 2008 (UTC)

Wikipedia's own Comparison of CECB units has some information. (CECB stands for coupon-eligible converter box.) --Bavi H (talk) 00:24, 4 April 2008 (UTC)

Thanks, that list looks quite useful. StuRat (talk) 03:16, 4 April 2008 (UTC)

Widget/Application for a (intel powered) Macbook that will 'monitor' bandwidth usage

Hi,

I have 'mobile broadband' which I buy pay-as-you-go bandwidth for (1gb, 3gb or 5). I've tried to find a program/widget that will monitor my usage so that I can see how much i've downloaded/upload (or combined) so I can track how much my 'sessions' are taking up of my voucher. Does anybody know where I could find a bandwidth monitor program (for free of course!!) that will do what I describe. Basically i don't really know how much 'browsing' a 1gb limit will give me. For reference I don't download anything (save for maybe 5 tracks a month off of iTunes) but I do do a lot of browsing of sites like Flickr and Digg - which often links to little web-videos/flash-intensive sites. Any help greatly appreciated. ny156uk (talk) 17:13, 3 April 2008 (UTC)

Well, you can track per-session usage with Activity Monitor pretty easily (under the "Network" tab), but I assume you want something that will work even after you've rebooted (e.g. remembers your bandwidth). (Actually, I'm not 100% sure that Activity Monitor resets when you reboot, but it must reset at some point.) --Captain Ref Desk (talk) 17:52, 3 April 2008 (UTC)

Cheers, unfortunately whilst that does a reasonable job i'm really hoping to find something I can 'reset' the counter on at will and then watch as my usage is tracked up. I have 1gb 'credit' at the minute and 30 days before it expires - I'm going to just use the internet in my 'normal' capacity and see how long that lasts - I may have to start buying the 3gb credit if I run out too quickly, but hopefully I won't!! Thanks for the input ny156uk (talk) 19:22, 3 April 2008 (UTC)

You can use NetMeter, it is a software used for seeing how much data used daily, monthly etc. website: readerror.gmxhome.de/

Moving pages

In HTML/PHP/HTTP, is there a way to move a page so that:

• Googlebots (and other crawlers) know where it has moved (Location: /newpage)
• User gets a "Page moved" notice AND is redirected automatically
• The target URL is without /newpage?moved and such.

--grawity ^{talk / PGP} 17:42, 3 April 2008 (UTC)

If I use a GET parameter (if (isset($_GET['moved'])) displayNotice();) and do a 301 Moved Permanently redirect with Location: /newpage?moved, user can see a notice, but Googlebots get the incorrect new location (/newpage?moved instead of /newpage), which is also saved to bookmarks => user gets notice everytime. If I only do a redirect, user doesn't notice the redirect and a different URL, and doesn't update his bookmarks (the only way to come to the old page), it will once result in a dead link when I remove the redirect (old page). If I don't redirect, and put the notice to the old page, Googlebots won't know it has moved.

Ideas? --grawity ^{talk / PGP} 17:48, 3 April 2008 (UTC)

What if you used the PHP to check the UserAgent, give it a Location: header if it is not a browser, and serve up a META REFRESH if it is a browser? There'd be a few obscure browsers and bots that would slip through the cracks but I don't think they'd amount to much. In any case, using the UserAgent might be a decent way to distinguish between what you serve to bots and to humans, even though it is not infallible. --Captain Ref Desk (talk) 17:48, 3 April 2008 (UTC)

What is the problem? The normal way to move a page is as follows:

1. Store the pages at the new location.
2. Remove the pages from old location and replace them with a short page that contains text such as "Page has moved, please update your link/bookmark" and a link to the new page. Do not use any redirect.

A user who uses old bookmark sees this message, cliks on the link and then stores the new location as bookmark. Bot will automatically follow the link and index the new pages.

--PauliKL (talk) 11:58, 5 April 2008 (UTC)

scandisk/defragment problem

I'm running Windows Me. Firstly, my computer is working OK, though it's a bit old, I want to make sure it's healthy so it doesn't die on me.

Now, Disk Defragmenter (Windows) won't work because it says the hard disk is damaged. It says to use scandisk to fix the error.

Scandisk won't work, it gets to two blips or so and then starts again, and gets stuck in an infinite loop in which it tries and tries but gets not very far at all. It does this in full and lite versions of scandisk. It does this even if I deliberately don't switch it off properly so it goes to scandisk at startup.

Firstly, should I be particularly worried about my disk being damaged?

Secondly, given options:

• Can I start it in safe mode, and run scandisk? it doesn't want to go into safe mode, but I can try again.
• Can I boot it into DOS and run scandisk? (remind me how I do this, I have to make a 3 1/2" floppy, right?)
• Can I run something else instead of scandisk? —Preceding unsigned comment added by I am not a dog (talk • contribs) 20:04, 3 April 2008 (UTC)

Yes, you should be worried. It seems that the disk is indeed damaged; if you value your data (and time) at all, you should immediately back the data up by whatever means you can. Damaged hard disks tend to go downhill fast, and you may not have many reboots left in it before it goes altogether and your data is lost. If you're just keeping this old machine around for sentimental/museum type purposes, you might (after the backup) reformat the disk and reinstall ME. -- Finlay McWalter | Talk 20:11, 3 April 2008 (UTC)

I get something similar in Windows 98. The "damage" never seems to be anything much, and it keeps restarting because it says "Disk contents have changed". If you watch it like a hawk, you might see that message flash at the bottom of the screen briefly when it restarts. DSL seems to be the culprit in my case. It periodically changes the hard drive contents, even when not actively in use, because it's "always on" (it's selling point). Apparently it feels the need to log that it did a handshake to the server or some such nonsense, which stops the defrag or scandisk cold. I could pull the DSL cable out, but have opted to stop the defrags instead, since I have plenty of open disk space, and defrags really are only needed when disk space is low. StuRat (talk) 20:54, 3 April 2008 (UTC)

I read IANAD's case correctly, the scandisk hangs even in the boottime scandisk run - in this case only scandisk is running (the internet stuff and various 3rd party progs haven't started yet). That "disk contents have changed" thing really can't happen in then, and so a failure (or hang) is indicative of significant problems. -- Finlay McWalter | Talk 21:01, 3 April 2008 (UTC)

Yeah, it's not got Internet access (I'm using a different machine to speak to you), so it's not that. There is a really old virus scanner running in the background. I wanted to defrag because I'm running out of space, and also am thinking of installing Linux on it as well as Windoze. I'll make sure I copy all my important files over to somewhere, then have a think about it. Possibly buy a new hard drive anyway, but reinstalling windows could be interesting (though I might not bother and just use Linux, if I can get my head round that). —Preceding unsigned comment added by I am not a dog (talk • contribs) 21:14, 3 April 2008 (UTC)

There could be any number of things happening that cause scan disk to think the disc contents have changed and start all over. I've had that problem before with a drive C. Take that drive out. Put it in a second computer as drive D and scan disk and defrag it on that PC. I cannot think of a time that has not worked. But, it does mean finding a second PC and knowing how to put a second drive in a PC. It's very easy, but I could see how it would be a little scarry if you've never done it before. If you have a second PC and need to know how to make a primary drive a secondary drive on another PC, let us know.--Wonderley (talk) 21:31, 3 April 2008 (UTC)

I'd be OK with taking it apart (done that before). I also have a spare machine (this one) which ought to have a slot (though my Dad might grumble). Is there anything else I have to do other than plug it in? —Preceding unsigned comment added by I am not a dog (talk • contribs) 21:47, 3 April 2008 (UTC)

If the computer has a recent BIOS, then just plugging in the hard disk correctly should do the job. On an older machine, you may need to hit Escape or Del or some other key as it boots to get to a setup screen, and use the setup screen to tell it that it has a new hard drive. rspeer / ɹəədsɹ 22:19, 3 April 2008 (UTC)

Yes you can put the faulty disk in another computer, but if they are on the same cable you might have to change the jumper settings on the back of both disk drive units. When you take the machines apart, take a look at the back of the disks and you will see a collection of 6 or 8 pins with a small jumper plug joining two of the pins. Somewhere on the drive casing, there should be a diagram of these pins, or maybe next to the pins there is some small text in the plastic. The faulty drive should be identified as "slave" (sometimes "SL") and the main drive as "master" (sometimes "MA"). This is done by moving the jumper to the approprite pair of pins.

It's all fresh in my mind, because only yesterday I canibalised my two old WinMe machines (one with a faulty drive) to make one good one dual-booting WinMe and Linux.

Small world eh? Astronaut (talk) 23:00, 3 April 2008 (UTC)

---

Astronaut is correct. CS - Cable select is also an option on the jumpers. If you look at the ribbon cable you will see a notch in it that cuts into one of the wires. That is how the drive can also tell which one it is. However, selecting the master (AKA Primary) and slave (AKA secondary with jumpers) is the one way you can be assured it's set up right. But, if the PC you are using now is currently set to CS, you'll have to change it's jumpers too.

Don't be worried. It's not that big of a deal. The safeest way to do this is:

- IMPORTANT! Every time you start to touch the PC, touch the metal chassis of the PC first so that you do not have static electricity burn something up.
- Power off your PC. Get the make and model numbers off of the drive itself. Look at the jumpers and see if it make sense. Make a note of how it is now and what cable it is plugged into. The ribbon cable for the drive has two jacks for drives.
- With it all together, look online for documentation on your drive and print it out. That's not necessary in but it might make you and your dad feel better.
- OK, power off again and with just your good drive C have the jumpers set to Master (primary) and power up. Your PC should work just like it was. That should make you feel better.
- Now power off and add the second drive (the one you want to fix) with the jumpers set to Slave as a slave (secondary) drive. Tada, Power on, and it's drive D.
-If at any point something doesn't work, power off and go back to the previous step. If you do something like have a secondary drive set as a primary drive, or have both drives as primary, it's no big deal. The worst that happens is that the PC does not boot up. Put it back like it was and it's back working.
- Static electricity is only way I can think that you might damage something.
- This may work out well for you. Knowing how to do this can help with outher prolems and hard drive upgrades. I move drives around all the time. PCs for some reason tend to come set up as cable select. I set the jumpers myself. I have had brand name drives not work right when set to cable select.
Hope it helps--Wonderley (talk) 10:52, 4 April 2008 (UTC).

---

Wikipedia's CSS

Anyone know precisely how to duplicate Wikipedia's font and font size on my own website? The .css files are insanely complex.... Evercat (talk) 23:18, 3 April 2008 (UTC)

Wikipedia simply uses sans-serif, which defaults to whatever your browser is defined to use (usually 12pt Arial, I think). It doesn't define a specific font. x42bn6 Talk Mess 05:40, 4 April 2008 (UTC)

If you get Firebug, you can inspect any element on the page's CSS settings, both explicit and inherited. It's awesome. --Sean 12:43, 4 April 2008 (UTC)