Wikipedia:Reference desk/Archives/Computing/2008 July 26

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July 26

using a mobile Phone as a modem

Using Motorola Phone Tools in vmware Fusion, I managed to use a motorola 3G phone as a modem. As you might expect, it only works in Windows, not Mac OSX. I would have set it up System Prefs, but it asks for: telephone number, account name, password, APN and CID numbers. I don't have any of these things, and Motorola Phone Tools only needed to be paired with the phone. Is there any way you can learn from the setup in Phone Tools, and apply the same stuff to Mac OSX natively? I have tried myself, there is nothing technical on the surface of Phone Tools, and nor is there Motorola Phone Tools for Mac. It's Windows only. Are all of the above (account name, etc.) in fact relevant?78.148.164.133 (talk) 01:21, 26 July 2008 (UTC)

I'm in Scotland on the O2 network, and it's a Motorola v6 Maxx. Bluetooth Setup Assistant shows the model name as "Bitsurfer 56k."78.148.164.133 (talk) 02:00, 26 July 2008 (UTC)

I don't think you need Motorola software to do this. If you use Bluetooth, then there's no need for special drivers, and if your Mac shows the phone as a modem, then try creating a normal dialup connection (use *99# as a phone number). --grawity 14:12, 26 July 2008 (UTC)

Actually it works now. Thanks in part to you (for the phone number), the motorola stuff (which I ran in Windows, and borrowed some technical stuff from, when I looked further), more surfing, and trying it in USB before Bluetooth. (Trying in Bluetooth would be a bad idea, you don't know where your problems lie - with the modem connection, or with the bluetooth?) And then comes the letters from O2 telling me off. Do they even know that I have it connected to a laptop?89.240.129.112 (talk) 00:30, 27 July 2008 (UTC)

Quad-core question

Does Windows XP Home use multiple cores for its own purposes? Does Vista? It is rumored that it assigns separate tasks to separate cores when multitasking, but does it actually? Basically, my question is whether a quad-core CPU is good for anything but high-end games and CADs and the like. --Milkbreath (talk) 01:30, 26 July 2008 (UTC)

Any version of Windows that supports quad-core CPUs will schedule processes on all four cores. But it's uncommon for two processes to need the CPU at the same time on a typical single-user machine, and very uncommon for three or more, so most of the time you won't notice any benefit from this. -- BenRG (talk) 02:53, 26 July 2008 (UTC)

i got an hp quadcare (their multimedia baby) with vista and you can set up task manager to watch each core independently. i haven't thoroughly researched it, but just my curious watching shows it firing up two processors fairly frequently, but hardly ever more than that. this with no games and no multimedia either, so far, just pretty much dumb Internet Exploring and vista's internal housekeeping. Gzuckier (talk) 06:22, 27 July 2008 (UTC)

office productivity tool

íÉ≥ĵŲḶcan you pls.help me in my ass. about basic editing,how to use the keyboard & mouse,inserting & deleting text,overwriting 7 using the undo & redo command..thank you,,hoping for quick answers,. —Preceding unsigned comment added by 122.2.117.188 (talk) 02:40, 26 July 2008 (UTC)

........wut? --75.150.174.233 (talk) 04:31, 26 July 2008 (UTC)

I think I'll decline to "help you in your ass". However, I can help with basic editing. The following applies to most, but not all, Windows editors:

1) Use the arrow keys on the keyboard or use the mouse (and then left-click on it) to move to the area you want to edit.

2) To toggle between insert and replace/overstrike modes: Hit the Insert key (usually above the arrow keys on the keyboard).

3) To delete the character after the flashing text cursor: Hit the Delete key (usually above the arrow keys on the keyboard).

4) To delete the character before the flashing text cursor: Hit the Backspace key (usually above the Enter key on the keyboard).

5) To delete multiple words or lines: Highlight the text first by putting the mouse on one side of it, holding down the left mouse button, dragging the mouse to the other side, then releasing the mouse button. Once highlighted you can delete it all by hitting either the Delete or Backspace buttons.

6) To delete everything, hold down the Control key (the very leftmost, lower key on most keyboards), and hit A. This should select all. Then hit the delete or backspace button.

7) To undo an edit, hold down the Control key (the very leftmost, lower key on most keyboards), and hit Z.

8) To redo an undone edit, hold down the Control key (the very leftmost, lower key on most keyboards), and hit Y.

9) To move to the top of the page, hit the Home key (usually above the arrow keys on the keyboard).

10) To move to the bottom of the page, hit the End key (usually above the arrow keys on the keyboard). StuRat (talk) 05:05, 26 July 2008 (UTC)

We have an article on keyboard shortcut and a nice table of keyboard shortcuts for various operating systems. --—— Gadget850 (Ed) ^talk - 20:57, 26 July 2008 (UTC)

Seeking data compression code for short strings

I'm looking for a data compression library (callable from C or Python) suitable for compressing short English strings, i.e. the algorithm should be pre-initialized with the statistics of English (such as by loading in a big static text file at the beginning) so that it can compress a 30-100 byte input down to some small fraction of its original size (the decompressor would work by first loading the same static file). Using something like gzip or lzo the normal way doesn't give much compression for such small inputs, since they start with no statistical knowledge and have to build it up as they go. I guess I could hack up gzip or lzo in the obvious way but thought I'd ask here first if anyone knew of anything already available. Thanks. 207.241.238.217 (talk) 06:04, 26 July 2008 (UTC)

Why would you possibly want to compress strings of that size? If you lots of little strings you want to compress, you could string them together (pun not intended) and compress that using the standard methods. Otherwise, I can't imagine a situation in any modern computer - or even an embedded system - where it would be practical to compress strings of less than 100 bytes. Especially if you are using Python as your programming language... « Aaron Rotenberg « Talk « 07:07, 26 July 2008 (UTC)

Our algorithm on the LZW algorithm includes Python code. The article says it achieves compression ratios of around 50% on large blocks of text, but I doubt you will get anything close to this on 100 bytes of input. You could create a pre-built optimised coding for single letters and common bigrams in English text, but I think this will have to be a bespoke design - standard compression algorithms do not use built-in statistical assumptions, because they are deliberately not language specific (or even specific to ASCII text input). Gandalf61 (talk) 09:45, 26 July 2008 (UTC)

You could try Huffman coding with a pre-calculated and pre-shared tree. --antilived^{T | C | G} 09:51, 26 July 2008 (UTC)

Actually most compression algorithms can be tuned for English text pretty easily, since most of them (bzip2 is a notable exception) read the input from the beginning, spitting out compressed data and building a model as they go. If you feed them canned text followed by the string you want to compress, the output will start with the compressed canned text (always the same) followed by the compressed string of interest (which will benefit from the model built up at that point). Then you can strip off the invariant prefix. This is slow, of course, but it's just a proof of concept. zlib supports the same thing in a more direct way with the *flateSetDictionary functions. Coming up with optimal training data might be hard, but as a starting point you might make a histogram of words from your training set and let the dictionary be the most common ones separated by spaces. This is probably the easiest way to get decent compression, and it's future-proof since zlib is ubiquitous (as long as you don't forget the dictionary!). You could probably get better compression from something in the PAQ series, either training it as above or using one of the variants that ships with a dictionary, but PAQ is very slow (both compression and decompression) and uses a lot of RAM (on the order of a gigabyte). Huffman would also work well, but it would probably take more work than the zlib approach. -- BenRG (talk) 11:08, 26 July 2008 (UTC)

You could save yourself some work and just index all of the strings you intend to use in an array or hashtable. During transmission, you only need to send the index (presumably, if you know you will never need more than 256 possible text-strings, you can index them as a single byte; etc). This method trades storage space for compute time, but it is not a true general-purpose compression algorithm (it cannot compress a string you didn't index!). Nimur (talk) 15:19, 28 July 2008 (UTC)

Thanks all. BenRG's approach of using *flateSetDictionary is promising and I'll check into it but I'm concerned about the overhead of copying so many dictionaries around. To Aaron Rotenberg et al: the application requires storing 100's of millions of these short strings and they have to be randomly accessible (i.e. I have to be able to quickly lookup the 23,456,789th string), so concatenating them all together and compressing in one lump won't do it. It's ok if the compression stats aren't optimal--I expect doing something simple like the *flateSetDictionary calls will be plenty close enough (if they get 3x compression instead of 3.5x, it's fine). I expect any type of LZ coding to work much better than Huffman coding. I hadn't heard of PAQ and will read about it. Zlib is the most attractive since it is very standard. I just have to do some benchmarks on the *flateSetDictionary calls and see if they're fast enough. 207.241.238.217 (talk) 21:04, 28 July 2008 (UTC)

Relating to game development, what is a ‘.CCZ’ file?

Can anyone help me with this question please? All I know from a forum is that its a smaller version of a .cc file and I dont know what a .cc file is either. Thanks. 88.106.59.56 (talk) 13:47, 26 July 2008 (UTC)

I guess .ccz means it's a .cc compressed with gzip (.tar.gz -> .tgz and .svg.gz -> .svgz). FILExt lists many uses for .cc, and this says it's often used for C++ source code, but gzipping it would be a little unusual... --grawity 14:08, 26 July 2008 (UTC)

Of course, file name extensions are usually more of an "optional" convention; it's quite possible that this file is something else that has been intentionally obfuscated to slow down reverse-engineering efforts. A file's name and its contents are not necessarily meaningfully related. Nimur (talk) 15:14, 28 July 2008 (UTC)

Relating to game development, what is a ‘.CCZ’ file?

Answer:

When using Sony´s CD/DVD Generator, *.CCZ is the file format for creating a Master Disc or Master Copy.

safety of phone line wiring

Hi, I've been having problems with my phone line, so I tried to fix it by tampering with the phone jack, then I rang Telstra (the phone company in Australia) and asked them whether this was in fact safe. They told me no, the lines were classified as dangerous. This struck me as strange, because I always thought phone lines were so low voltage there was nothing to fear. Can anyone tell me what the voltage/ current are in Australia, and how dangerous it is playing around with the lines? Could you get a shock from them? thanks in advance, 203.221.127.38 (talk) 17:25, 26 July 2008 (UTC)

See Tip and ring. —Ilmari Karonen (talk) 20:34, 26 July 2008 (UTC)

regular phoneline voltage is around 40? 50? which is pretty safe under normal working conditions, but if your skin is wet or if you jab the wires into yourself to reach the nice saline interior, can deliver a decent current, which in the right place or to the right person can have unfortunate cardiac effects. the ring votage is like 100 which will give you quite a buzz, and likewise for the danger. but i find that most people, including myself, don't disconnect it before working on it. if i had a pacemaker or some such, i probably would. Gzuckier (talk) 06:19, 27 July 2008 (UTC)

Thanks for your help folks, 202.89.166.179 (talk) 16:04, 31 July 2008 (UTC)

Virus Issue

I have Windows XP and what I've heard from my university's IT people is a really good school-distributed version of McAfee antivirus. But lately it's been doing something weird. Every time I try to explore my C drive (which is my laptop's only local disk) I get a popup "VirusScan Alert!" from my antivirus program telling me that in the temp folder in local settings (C:\Documents and Settings\(my name)\Local Settings\Temp) it has detected a Trojan ("dtkcsly.dll") and deleted it. After I get this message, I have no trouble exploring the C drive, with the notable exception that Local Settings appears to no longer exist (and it isn't just hidden; I made made sure that hidden folders were visible.) To see what was up, I did start, run, and entered the address (or whatever you call it, I forget the name) of the problem folder that seemed to no longer exist: C:\Documents and Settings\(my name)\Local Settings\Temp. Run opened it up. No problem. I didn't even get one of those virus alert messages. And an in-folder search of all files didn't turn up the dtkcsly.dll file I was warned about. The other thing is, if I get McAfee to do an on-demand full-computer virus scan, it doesn't report anything. Only when I open C. And every time I open C. With the exact same problem. (And every time, it says that the file has been deleted, giving the time of deletion as that instant.) I'm confused. Any idea what the problem could be? The solution? Thanks a lot for any help. 41.249.20.34 (talk) 17:37, 26 July 2008 (UTC)

Hmm., obviously a serious problem. But don't worry friend, just uninstall the antivirus software and install it again. If this does not solve the problem, then proceed as follows:- 1.From the control Panel, open User Accounts. 2.With the guest account turned off, create a new administrator account. 3.Switch to the new account and after transferring your personal settings and documents, delete your previous account. 4.Install the software again.I think it will obviously work properly. Thank you for asking questions. Best Wishes.117.201.96.242 (talk) 20:16, 26 July 2008 (UTC)

You could have a bad install of McAfee, but it is not necessary to create a new user to install it properly. Just uninstall McAfee and install it again.

However, a quick google for "dtkcsly.dll" suggests it really is malware. When I have a virus/malware detected by McAfee, then it mysteriously returns and then I can't find it using Explorer, I start to suspect I have a rootkit which is hiding a lot more than that one file. Astronaut (talk) 09:21, 27 July 2008 (UTC)

Thanks, both of you. But what's your suggestion, then, Astronaut? Just reinstall? Or can I try to delete it manually? Or...? Thanks, 41.249.10.71 (talk) 18:09, 28 July 2008 (UTC) So I've got some additional weirdnesses for those of you interested in helping me to contemplate. a) I just downloaded some free fancy schmanzy rootkit finding program called Gmer. And searched. And nothing was found. b) while nothing has been found or deleted since I last posted, for some reason, when I open C, the popup no longer appears. c) it would appear that the Local Settings folder is indeed hidden, as I got to it through Run again, and the folder details on the left say it's hidden, and also as every time I go into the Documents and Settings\(my name) folder options to select "Show hidden files and folders," and then press "apply", nothing changes, and when I go back into the folder options, "Do not show hidden files and folders" is selected again. And at no point in between is the Local Settings folder visible. So I'm confused. Is there some rootkit/virus there that nothing can find that keeps instantaneously changing the folder options to keep local settings hidden? (And why?) And what's to stop me from just deleting the entire contents of the Temp folder. Is there anything really useful in there? It's taking up 1.3+ gigs of my hard drive and seems to be harboring something nasty. Thanks again, 41.249.72.25 (talk) 00:04, 29 July 2008 (UTC)

Owner of ImageShack image

I noticed that many pictures posted on various forums are hosted by imageshack. Often, the poster is not the person who owns the imageshack account for the image. So, when I see an image I like and I want to see more of those images, is it possible to somehow backtrack through imageshack to find the owner? The urls are similar to img49.exs.cx/img48/18203/some_image.jpg. I can tell that the "img49" is random. The "18203" is not shared by a single user. I find multiple, very different, images under the image directories. The image name tends to appear to be the name the user uploaded. None of that appears to be related to the actual user's account. -- kainaw™ 18:53, 26 July 2008 (UTC)

Membership is optional on imageshack. You can upload images without having to create an account. So the only ways to track users are cookies and IP, but they can be deleted or changed respectively. I believe imageshack does not create anything you can call a 'user album' for the unregistered users. -Abhishek (talk) 13:54, 27 July 2008 (UTC)

Java

How can I insert a previously compiled Java program into any electronic device such as DVD Player?117.201.96.242 (talk) 20:08, 26 July 2008 (UTC)

Uh, I don't think you can. I mean, you could certainly put the program on a DVD, but the DVD player doesn't know how to execute it. -- Captain Disdain (talk) 21:26, 26 July 2008 (UTC)

Blueray players can run Java, and so can many Digital TVs. If there is such a thing as device-independent deployment, it might be associated with the Globally Executable MHP effort. This discussion however indicates that installing Java software on home electronics may be too much to ask for, and the only option may be to embed the software on discs or TV broadcasts. 84.239.160.166 (talk) 18:33, 27 July 2008 (UTC)

Are you getting at the cross platform nature of Java? You can read about it in the Java (software platform) article. But a simple version of the "how?" is: your "previously compiled Java program" was compiled to be run by a Java Virtual Machine (which is itself a program) and not by any particular electronic device. This means that so as long as your electronic device has a JVM then it can run the Java program. And JVMs have been written for all sorts of things - nearly all major computer architectures and operating systems and stuff like mobile phones too. Note, if it's not clear from the above, that a JVM is written in some language or other but then compiled into device-specific code.

If you knew all this already and you're asking exactly how then I should think it depends on the device and is a right pain for an end user to figure out or do (since you wouldn't want people to be able to break their mobiles / DVD players / toasters easily or by accident - rather you'd want software installed in a factory and a backdoor available for updates). --78.86.164.115 (talk) 22:56, 26 July 2008 (UTC)