Wikipedia:Reference desk/Archives/Computing/2006 October 10

Humanities Science Mathematics Computing/IT Language Miscellaneous Archives

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iPod

Is the ipod nano aluminum 8 gig a 5th generation ipod or is that just the ipod video?

From the iPod article: "As of 2006, the lineup consists of the 5th generation iPod that plays videos; the smaller, second generation iPod nano; and the display-less iPod shuffle. These models were updated in 2006." It's also explained in the article for the iPod nano. Dismas|^(talk) 06:10, 10 October 2006 (UTC)

Dos Exec CMOS Password erase

I have already asked this question before,but what makes me ask again is that you said it was not possible to access bios through dos.BUT I HAVE AN EXEC which can do just that.SO I would really like to know how that works. Also we have bios update through dos, so is it possible to have a virus/rootkit implanted in the bios? if yes, how do we detect and remove it?

The bios isn't stored on CMOS memory. On most bioses (which are stored on flash chips- flash isn't cmos) it's possible to "flash" them, which means erase and rewrite them, to do updates. As for the virus thing, it's very possible but I've never heard of a virus that actually does it. IIRC there's acutually a BIOS feature on some BIOSes that validates bios flashes before allowing itself to be written to.

The BIOS interfaces with the data stored on the CMOS memory. The CMOS is powered by a small battery and keeps track of system time and settings used by the BIOS (like the boot password). You shouldn't try to interface with the CMOS on your own without the help of your BIOS (though technically you can by writing to index port 70h and listening on data port 71h) since it's so highly BIOS-specific. Whoever said it wasn't possible is just wrong --froth^{T C} 20:44, 10 October 2006 (UTC)

The CIH virus is an example of a virus that could corrupt the BIOS. Splintercellguy 03:12, 14 October 2006 (UTC)

Seeking Info about Building Controlling Computer

Here it goes, We are a group of students who are working on our Senior Project, we are assigned to construct a Instructor Computer that will control all the PCs connected to a network domain, this Instructor PC will have Administrative rights on all the other PCs, and will be able to access them and do the required system setup. We are configuring this Computer to serve the instructors for teaching purposes. So we are wondering if anyone could provide us with useful information or links, and some details of some existing systems which would help us in implementing our project. Thank you in advance.

operating systems

what are the functions of a ready queue?

I'm rather surprised that there is no article on ready queue. So, I won't tell you to read the article. A ready queue doesn't really have functions. It is a holding area for jobs that are allowed to process. Normally, a long-term scheduler puts jobs in the ready queue when they are allowed to run and removes them if they are to be suspended. The short-term scheduler picks jobs out of the ready queue to run. The order depends on the OS. Usually, OS-design classes spend a good 2 months on job scheduling. --Kainaw ^(talk) 14:45, 10 October 2006 (UTC)

It is briefly mentioned in the CS article on scheduling. Operating systems manage a number of resources, including CPU time. Different tasks competing for CPU time each have dependencies on other resources. For example, a task consuming large quantities of data will depend on the next chunk of data being read from a hard drive into main memory, and until that data is available there is no point in scheduling the task to run; it is not "ready". Another task may be performing a peer-to-peer file exchange, and have everything it needs to process the next packet of data; it is "ready". The scheduling code will keep a queue of the tasks that are able to step up and do something useful at the next available window of CPU time; this is a "ready queue". --KSmrq^T 23:14, 10 October 2006 (UTC)

operating

what are the solution requirements to critical sections?

why are these solutions to the critical sections needed?

what does flushd do on a UNIX system?

what is a two paged table and how does it compare itself to the simple page table array?

what is buffering in input/output systems?

why is this buffering required in the input/output systems?

list a case where buffering in input/output systems has an advantage & a disadvantage?

hio ni ufala

I suggest you check your textbook, and in any case do your own homework. — QuantumEleven 13:41, 10 October 2006 (UTC)

LZMA

How can we implement LZMA compression in c++/c#/j# applications I downloaded the LZMA SDK but i could not understand anything from the readme. Can You please explain --Utkarshkukreti 09:54, 10 October 2006 (UTC)

Free video editing software

Hi, I just need a free video editing program which is compatable with .MOV format. Any of you guys/girls know of one? I just wanna upload a video to YouTube, cheers!--Hamedog_Talk|^@ 14:38, 10 October 2006 (UTC)

.MOV is just a container, and I think VLC Media Player can output to MOV. For editing, there is a List of video editing software.--Frenchman113 on wheels! 00:11, 11 October 2006 (UTC)

You don't need .MOV format for Youtube. I'd recommend just using AVI--its an open standard and supported by all of the best video-editing programs. I use it for all my Youtube videos. For a codec, use Xvid or WMV9, but generally YouTube supports pretty much anything, though they will convert it to their own FLV format anyways once you upload it. — Dark Shikari ^talk/_contribs 13:33, 11 October 2006 (UTC)

These are not the answers I am looking for. I will give you the situation. I want to put a video on youtube. My camera records in the .MOV format. As Windows Movie Maker doesn't accept the .MOV format, could someone please tell me of a free piece of software which I can use to edit these videos. Thanks alot, Hamish.--Hamedog_Talk|^@ 12:45, 13 October 2006 (UTC)

List of video editing software. We're all volunteers here, and yelling at us will not get you faster answers.--Frenchman113 on wheels! 19:53, 14 October 2006 (UTC)

I wasn't yelling at all, I was saying I these answers aren't what I was hoping for, maybe my question wasn't clear.--Hamedog_Talk|^@ 12:47, 15 October 2006 (UTC)

Say, your camera records in lossy video? WTF, if I were you, I'd just return it and demand a refund.--Frenchman113 on wheels! 21:47, 18 October 2006 (UTC)

Err, if it's just a normal P&S digital still camera, that doesn't really sound that odd. -- Consumed Crustacean (talk) 21:56, 18 October 2006 (UTC)

The list of video eiditng software might help. If none of those support .MOV, you jsut have to find a way to convert from MOV to something more editable, and then open that up. You can use VLC Media Player to do this, or through a million other methods, such as using RAD Tools. -- Consumed Crustacean (talk) 21:56, 18 October 2006 (UTC)

Internet information

The internet blows my mind and I wonder does anyone know where all the information on the internet is stored?

On thousands of servers around the world. See Web server for an explaination. -- Zanimum 16:08, 10 October 2006 (UTC)

Everywhere! You might want to look at the internet article, which explains a bit about how all the networks and servers interconnect to make up the whole thing. --LarryMac 16:08, 10 October 2006 (UTC)

Google Video charging

How does an independent video producer charge on Google Video? I can't seem to find a page on their official site, describing how-to. -- Zanimum 16:04, 10 October 2006 (UTC)

Checking out their upload page ([1]), it looks like the service is still in "beta"? They make reference to having to "verify" the video before selling. I imagine this is something they still need to work out for smaller independent producers. I would try finding an email to get further info, if you can't find the info on their site. —Mitaphane _talk 00:37, 11 October 2006 (UTC)

Resuming an SCP transfer?

I'm backing up a machine that's on the other side of the internet. I have ssh access to this machine, and I'm using scp to copy its contents. However, it has a lot to back up; about 34GB. I'm getting about 100k/s, so it'll be done in four or five days, it seems. However, if something goes wrong, I'll have to start at the beginning, as scp will merrily overwrite all its previous work. I don't have the option of mounting the remote drive; if I did, I'd just use cp -vru source dest to take advantage of previous copying done. Is there any possible way of causing scp to skip existing files? (Or better yet, skip existing files which are not older nor smaller than the remote file?) grendel|khan 17:08, 10 October 2006 (UTC)

Check out rsync, it can hash and cross check files for similarities before copying, so you can 'sync' one location to another without moving all new data. What kind of files are you backing up? It works really well for large groups of small files (like an entire server's filesystem), I imagine it may also work somewhat well for a large single archive file. --Jmeden2000 18:00, 10 October 2006 (UTC)

I also recommend rsync (it can easily run over ssh, making things easier). --cesarb 18:59, 10 October 2006 (UTC)

The situation is an entire FS, not just an archive file. (If it were one large file, I'd have just used sftp, which supports resuming.) I ended up using SSHFS, which has the added benefit of handling symlinks. (Using scp just started duplicating things, which led to serious issues when there was a symlink to ".".) I think rsync requires a copy of rsyncd running on the server, doesn't it? The server in question is an old SunOS 5.8 machine that I can't install anything new on, and all I have to work with is its copy of sshd. grendel|khan 19:36, 10 October 2006 (UTC)

Though the rsync binary must exist on both hosts, rsync does not require rsyncd to be running on the remote host. Using the syntax "rsync -a --rsh="ssh -l username" host:/path/to/dir/or/files /path/to/local/dest", rsync will happily use ssh as the communication medium with no additional software beyond the rsync binary on the remote system. --maplebed 03:50 22 Oct 2006 (UTC)

DVD to mpeg

I used a DVD recorder to transfer a home movie to a DVD. How would I go about taking the video and extracting it onto my computer as a MPEG file, to edit in Windows Movie Maker or iDVD on my mac? 38.139.33.66 17:23, 10 October 2006 (UTC)

Mencoder can do the job, but it's a command-line tool. There are Windows front-ends available, but I have no idea whether they're mature enough to be useful at this point. --Robert Merkel 08:01, 11 October 2006 (UTC)

Doom9 --Kjoonlee 23:14, 12 October 2006 (UTC)

help with internet

i use firefox as my main internet. but i am also signed up to a bt one that came with my bt broadband. whenever i open a webpage from something that isnt firefox, it opens up bt internet instead of firefox. how do i stop this happening? thanks --86.141.226.175 17:32, 10 October 2006 (UTC)

You're thinking of web browsers, not "internet". In any case, this should be easy to fix.

In Firefox (assuming you're using the latest version):

Click the Tools menu at the top, then Options.

Choose the General tab. Near the middle where it mentions Default browser, there is a Check Now button which you should click.

A dialog box should pop up asking if you want to make Firefox the default browser; click Yes.

If you're not using the latest version, go here and download it. The instructions I just gave will vary slightly for older versions. You should keep up to date anyways for security purposes. -- Consumed Crustacean (talk) 18:08, 10 October 2006 (UTC)

Thanks--86.141.226.175 18:39, 10 October 2006 (UTC)

Exception handling in MATLAB

I'm solving a big problem that involves solving a boundary value problem for millions of different boundary conditions. For some of those conditions, the Jacobian of the system becomes singular, and my program (which uses bvp4c inside a loop) stops immediately. I want it to skip that iteration, and continue with other boundary conditions. Unfortunately, there's no way I know to check beforehand if the Jacobian will be singular. Is there any exception handling in Matlab at all? deeptrivia (talk) 19:07, 10 October 2006 (UTC)

Oh, so Matlab does have try and catch. I've been reference-desk-happy lately. deeptrivia (talk) 21:08, 10 October 2006 (UTC)

Cheapskate question about internet cable

Oh knowledgeable and wise IT Wikipedians, I seem to have damaged my 50 ft internet cable's plug head enough that it now needs replacing (bendy bit snapped off and a couple of the little coloured wires are cut). Is it possible for a store to just repair this by fixing in a new plug head, or do I have to go buy a new one? Thaaaanks. Bwithh 20:26, 10 October 2006 (UTC)

Assuming you can find a place with the appropriate connector (I'm assuming it's an RJ-45)and a crimping tool, it should be simple enough. Not sure what kind of shop you'd need to find though. If you lived nearby, I'd be happy to help, so keep that in mind for the next time ;-) --LarryMac 20:32, 10 October 2006 (UTC)

It sounds like you are referring to a Cat 5 cable. They are not expensive. I would suggest buying a new one. You can replace the ends, but you will need to buy a Cat 5 cable crimper and a new end (you'll have to buy a pack - they don't come one-per-package). All in all, you'll end up paying more than just buying a cable. --Kainaw ^(talk) 20:33, 10 October 2006 (UTC)

Thanks very much guys! I'm not sure if its a Cat 5 or a RJ-45 (have to go home and check)... the wikipedia pictures look very alike to me. I'll bring it to the store tomorrow and see if they want to throw me out... Bwithh 20:44, 10 October 2006 (UTC)

Sorry to be confusing. Cat 5 is the cable. RJ-45 is the connector on the end. A network cable consisting of Cat 5 cable and two RJ-45 connectors goes by both names and many others, such as "patch cable", "ethernet cable", "that blue cable with the fat phone plug on the end"... --Kainaw ^(talk) 20:52, 10 October 2006 (UTC)

If you can make friends with someone who does network cabling, they can replace an end in less than a minute with a part cost of almost nothing. However, if you do it yourself you will need to buy or borrow a tool, and exercise some care in stripping the ends and in wire order. [2] A basic replacement cable can be found for less than the cost of the tool. A few cautions are in order: Longer cables sometimes wind their way through awkward places, so extracting or running the cable can be the biggest part of the job. The older Cat 5 cable has been superseded by Cat 5e (with Cat 6 also available, though probably not worth worrying about here); be sure to get Cat 5e. Cables differ in construction details and quality, including solid or stranded, and booted or unbooted ends; the longer the cable the more it matters. In some circumstances building codes (or common sense) may dictate the use of more expensive plenum cables, to guard against the rapid spread of a fire. Color doesn't matter unless a facility is wired according to a consistent convention; but do label the ends so there is no later confusion about what connects where. --KSmrq^T 00:08, 11 October 2006 (UTC)

Rays and lines in MS Word

Does anybody know of some sort of downloadable add-on for MS Word that would allow me to put a single or double headed arrow above two letters to indicate the notation for a ray or a line? User101010 22:03, 10 October 2006 (UTC)

Have you checked the MS website? They have piles of stuff there. Anchoress 22:15, 10 October 2006 (UTC)

Sorry... I should have mentioned the fact that I checked there. I found one thing on MS that looked close but it was for Mac.User101010 00:59, 11 October 2006 (UTC)

I answered this question at WP:RD/MA. --jh51681 00:47, 12 October 2006 (UTC)

Hans Reiser

Hans Reiser, leader of the ReiserFS project, has been arrested today on the suspicion of murdering his wife. It's likely this article will get a lot of traffic once Digg, Slashdot, etc pick up on the story. Does anyone (attendees at OS conferences etc.) have a photo of him - Google images finds a few, but none look very like the one on his website. Also a few people should add the article to their watching lists, I think. Thanks. Viva Tibbles

Nice catch but this should probably go on WP:HD --froth^{T C} 22:10, 10 October 2006 (UTC)

Debian and MSN

Say I'm using Debian, and I want to chat with my friends on MSN. I also want my microphone and webcam to be working. How do I do this? --HappyCamper 22:21, 10 October 2006 (UTC)

Use amsn. Microphone, webcam, everything. --froth^{T C} 22:27, 10 October 2006 (UTC)