Wikipedia:Reference desk/Archives/Computing/2006 August 7

High-speed internet, DSL, and broadband
Could someone who is computer-savvy explain what the differences, if any, between the three terms are?-- The Count of Monte Cristo  Parley  03:37, 7 August 2006 (UTC)
 * High-speed internet - Broadband - xDSL --mboverload @ 03:43, 7 August 2006 (UTC)


 * High speed internet = Broadband. Both cable and DSL are "broadband" (high speed). DSL is a TYPE of broadband, much like cable. --Abnerian 04:30, 7 August 2006 (UTC)


 * "High speed internet" is just the informal term for broadband. Broadband generally refers to an always-on connection of 256Kbit/sec or greater. DSL and cable are two types of broadband, DSL being the most common. See broadband, ADSL.

Missing memory
Hello,

Recently, I've seen several computers with a certain amount of physical memory, yet, when the physical memory is examined in the operating system statistics, it shows up as slightly less.

The reported amount is retrieved through the "System Properties" Control Panel applet, the "DirectX Diagnostics Tool," and the Performance tab on "Windows Task Manager" (under the heading Physical Memory, Total).

Both machines examined were produced by HP/Compaq (after HP acquisition).

Now, I've heard lots of reports of the missing memory to be due to memory reserved by the graphics adapter. I must say, though, I find this theory highly unlikely in the case of the latter machine, as it has 256 MiB on the graphics adapter. (With the first machine, this theory makes sense, as it is 64 MiB on the graphics adapter.) It would be ridiculous to implement a fourth of the video memory in system memory, while leaving three-fourths as unshared video memory; it would be easier as all-or-nothing.

The second machine is new (just purchased), and has never been used; malicious third-party software is out of the question.

No, I'm not looking at "free memory," I'm looking at "Total Physical Memory."

Any thoughts?

Jdstroy 05:11, 7 August 2006 (UTC)

Is the graphics adapter integrated into the motherboard or a separate graphics card. If the latter, then that's out of the question. However if it's integrated then it explains the first case. I'm not sure about the 256 MiB being used as such. But it is important to clarify the above for your own sake. Harryboyles 07:11, 7 August 2006 (UTC)


 * Both are integrated. I'm most interested in the second case. Jdstroy 06:21, 11 August 2006 (UTC)


 * See direct memory access. Certain devices are granted, as the name implies, direct access to memory.  So, you can't use it as regular memory.  Other devices that commonly get DMA: parallel port, USB port, and high-speed drives. --Kainaw (talk) 14:09, 7 August 2006 (UTC)


 * That doesn't result in system memory being removed from the pool. It just reserves a section for direct access.  Most likely, it would show up as part of "(8)System". Jdstroy 06:21, 11 August 2006 (UTC)

Does the reported total physical memory amount include the space reserved for the operating system on Windows? On Linux it doesn't. It is also possible that the machine has two graphics adapters (one onboard and one on PCI/AGP), but the onboard one hasn't been properly disabled. --cesarb 15:04, 7 August 2006 (UTC)


 * Yes, the total reported memory does include the space reserved for Microsoft Windows. On my home computer, Windows reports 512 MiB, which is what I have installed.  There is only one onboard graphics adapter, currently. Jdstroy 06:21, 11 August 2006 (UTC)

I'd also like to note that something similar happens on another friend's Gateway laptop. 32 MB of system memory is missing, but the graphics adapter has 64 MB of video RAM.

Jdstroy 06:21, 11 August 2006 (UTC)


 * AGP aperture, perhaps? - mako 08:11, 14 August 2006 (UTC)


 * Mako: No, I haven't thought of that... I shall see when I get access to those computers again. Jdstroy 21:47, 6 September 2006 (UTC)

more about my computer
hello I am the lady that asked the question about the "GIFS and JPGS" thank you all for your help.I have some more questions. When I look at info about my computer,it says I have an AMD ATHLON processor and 384mb of ram.Is this processor as good as a Pentium III ? Also on my hard drive my total space is 19.1gb. I have 13.7gb of free space I have tried and tried to get this one figured out in computer language but just CAN'T get it so let me ask this way.Put my GB in terms of DOLLARS. I started with $19.10.ok think of how much that is in PENNIES.When I install something how can I figure out how much space it will use? I know $1.00 would 100 pennies but are the kb or whatever, pennies, dollars or what? Am I totally confusing you guys ? I am set to start taking a computer course next week but people have tried to explain this giga byte thing to me before and like I said I just don't get it thanks so much signed totally comp.illiterate —The preceding unsigned comment was added by 4.244.177.22 (talk • contribs) 10:02, 7 August 2006 (UTC)


 * Do sign your posts, please. And if you get an account, even, you won't have to identify yourself via previous questions!  Anyway, there are many varieties and grades of Athlon processors; if your computer is less than about 5 years old, it's probably at least as good as at least some Pentium III  s.  As far as storage goes, all you need to know is that GB=1000MB; MB=1000kB; kB=1000B (bytes).  It ends up with "kilo"="thousand", "mega"="million", and "giga"="billion" (in the short scale); see SI prefix.  Except that sometimes some or all of the factors are 1024 instead of 1000 &mdash; different, but not too different.  So if you have 13.7GB, that's 13700MB, or 13700000kB, or 13700000000 bytes.  Hope that helps.  --Tardis 17:18, 7 August 2006 (UTC)


 * In the instructions of installing a program, it will have the requirements for your system. For example it will say you need Windows 98, Me, 2000, or XP or Mac OSX or later. It will also list how much free hard disk space you need, thus how much room it will take up. schyler 17:27, 7 August 2006 (UTC)


 * The processors from AMD, like the Athlon, are highly competitive with those from Intel. Consumers get the benefit, as each new effort from one company tries to best the other. Relax and enjoy.
 * Chances are you live in the United States if you are not familiar with the G and K prefixes, because they are standard fare for all kinds of units in most of the world, as part of the metric system. For example, a kilometer is one thousand meters, and a speed limit will usually be posted in those terms, as in 100 km/h (roughly 60 miles per hour). For now you can probably get by with learning three prefixes: "K", "M", and "G". Each is 1000 times more than the one before, except that in the computer world the factor may be 1024 (which is a power of 2 instead of a power of 10). So one byte is enough to store a single letter of the alphabet, one kilobyte will store 1000 bytes, one megabyte will store 1000 kilobytes, and one gigabyte will store 1000 megabytes. A similar logic applies to speeds. If the clock rate of your CPU is two hertz, you're using an abacus! A two kilohertz clock rate is from the early days of the electronic computer, two megahertz is from the dawn of the personal computer, and two gigahertz is respectable today. (Too bad the mileage of automobiles hasn't improved as much.) It might help to invent a silly mnemonic for yourself to jog your memory, like "Kiss More Geeks".
 * And do sign up for an account; it's easy, free, and anonymous (if you like). That way, when you sign your posts (per instructions at top of page), we'll see your user name, not your IP address. --KSmrqT 19:44, 7 August 2006 (UTC)

Question
Does anyone know of a way to turn off or erase that little box of recent searches? It's become really annoying in the past few days. It's the little pop-up box that appears whenever you type in the search, and it displays all your recent searches. Thanks.-Dark Kubrick 16:47, 7 August 2006 (UTC)


 * Are you talking about the Wikipedia site or Google, or some other site, or all sites? What browser, what operating system?  --LarryMac 16:52, 7 August 2006 (UTC)

It comes up on every site. I use Mozilla Firefox, but it's also on Internet Explorer. It appears in the search boxes of all sites.-Dark Kubrick 20:21, 7 August 2006 (UTC)


 * I use Firefox in Swedish so I'm not sure what the English names for everything is, but you can clear those from the config-window. Choose "Privacy", "Form data" and the "Clear form data"-button. I have no idea if that's what they're called (as I said, mine is in Swedish), but it's in the config dialog. You'll find it. Oskar 19:59, 7 August 2006 (UTC)

Thanks for the answer, but, uh, where the hell is the config-window?-Dark Kubrick 20:21, 7 August 2006 (UTC)


 * I googled and found a good screenshot. It's here: . Tools->Options, then select the "Privacy" button, and in one of the tabs you should find a button that clears the form data for you. Oskar 21:00, 7 August 2006 (UTC)

Thank you very much. -Dark Kubrick 00:59, 8 August 2006 (UTC)

Hello, I have had same problem but solution did not working. Please help because box is say "how to masturbate" and "masturbation tips". I was not the one who is typing. Thank you. Mahir.

internet security
hi, am sourabh.i am facing some problems with internet. 1.i use 'firefox' web browser,my os is 'xp'.i have a file sharing 'limewire' .though my popup bloker is enable i am getting a lots of popup,ican't not prevent them.my antivirus shows no virus at all(antivir xp). 2.another problem i am facing is ---suddenly(repteadly in a certain duratiion) my current http// adress is changing automatically.my spyware preventing program also running successfuly.is my computer affected with virus/spyware/adware/trojan/ or others bugs? 3.i have two files in my hard drives which are 'can't delete files',how can i delete those files?names of the files r 'kybrdfg_8 (*)(*)(*)(*)......' plese solve my problems.......--203.145.188.130 19:49, 7 August 2006 (UTC)sourabh
 * Spellcheck should fix some of your problems. For the rest, reformat your hard drive and install Linux.--Frenchman113 on wheels! 20:10, 7 August 2006 (UTC)


 * Formatting and reloading are not always the most convenient solution, Frenchman113. To the poster: You'll want to use multiple malware progrms, for instance, run both Ad-aware and Spybot: Search and Destroy (and make sure they are fully up-to-date). If those fail, try the program called HijackThis and post the log file to an appropriate forum (not here, most likely) where someone may be able to find out exactly what the problem is. It may take a fair amount of work, depending on exactly how bad the infection is. digfarenough (talk) 22:03, 7 August 2006 (UTC)

Changing the windows desktop image
I want to make a small program that once every day changes the windows desktop to one of these bad boys, so my question is this: what do you do to change the desktop image from inside software? A registry change or what? Oskar 19:53, 7 August 2006 (UTC)


 * Right-click on the desktop. Select properties.  Change the image file. --Kainaw (talk) 20:15, 7 August 2006 (UTC)
 * I just realized you may be asking how to write a program to change the image... Two options: registry entry (as you guessed) or have a file called something like "MyImageFile.jpg" and change the contents of that file from your program. If the user selects that file as the background image, it will be different every time they reboot. --Kainaw (talk) 20:16, 7 August 2006 (UTC)


 * Thanks, a good tip, the second one. Oskar 20:18, 7 August 2006 (UTC)

Connections across the internet
Generally my question is about connecting two computers, both behind routers, together across the internet without using port forwarding.

I have managed to produce a program using Winsock in a client/server setup to create a connection across the internet with just the client behind a router.

I understand that some programs that require internet connections have a central server which accepts connections from several clients and links ones that wish to be linked, eliminating the problem of routers. How do these servers work and are there any resources you would suggest me looking at?

How does a peer to peer network get around the router problem if there is no central server?

I know a little about protocols so if it is relevant i may understand it.

NB This is my first wikipedia question so i apologise if i've missed things off.

--PeteL 20:08, 7 August 2006 (UTC)


 * The main issue you are dealing with is the ability of a computer to accept a connection. Almost all home computer network use involves requesting a connection, not accepting one.  A firewall/router blocks the computer's ability to accept a connection - so you have to explicitly forward or open a port for the computer to listen on.  Having a 3rd server avoids this.  The server accepts a connection from each home computer (they are requesting connections).  Then, the server forwards traffic back and forth between the home computers.  There is no magic trick to get around the firewall/router and force a computer to accept a connection.  The computer/router must be configured to accept a connection. --Kainaw (talk) 20:14, 7 August 2006 (UTC)


 * Actually, it gets way more complicated than that. This method is sub-optimal, because you need to relay every packet through a third party. It would be much better to get a connection between the computers directly. And you can!
 * First off, you have to realise how NAT-routers work. Since they serve many different computers, it has to know what computer to send an incoming packet to. It does that using mappings. If you have open a port (ie used port forwarding), you have created such a mapping. Say you have mapped port X to computer Y, then any time a packet that has a destination port of X gets routed to Y. The smart thing with NAT-routers is that they not only have these static mappings but they can also create dynamic mappings on the fly. Say computer A wishes to surf to www.google.com. It has source port B. The router sees that the out-bound request has source port B and realises that any traffic that comes into the router with destination port B should go to computer A. Therefore, it creates a dynamic mapping between port B and computer A, and Googles return packets make it through.
 * Now, follow these steps to see how clever NAT-traversal works. Computer A is behind router RA. Computer B is behind router RB. Somewhere on the internet is M, a third-party server that serves as a mediator. A and B wants to talk to eachother.
 * A sends outbound packets to M. It specifies port PA as it's home port. RA makes a mapping between PA and A (so any incoming traffic on PA will be routed to A).
 * B sends outbound packets to M. It specifies port PB as it's home port. RB makes a mapping between PB and B (so any incoming traffic on PB will be routed to B).
 * M now has recieved traffic from both A and B, and it knows what ports they use. M realises that RA must have made a dynamic mapping between A and PA. It sends PA (A's port number) and the IP address of A (actually RA, but that's just semantics) to B, and it sends PB and B's IP address to A.
 * A and B now starts to send packets to eachother on the ports they got from M. If everything has worked, RA now has now mapped PA to A, and any packets that comes into that port should get through to A. Same for B. So now B is able to make a connection to A, and vice versa.
 * Volia! NAT traversed, without having to use up all the bandwidth of poor M!
 * Get it? I'm not the best at explaining, but this is basically how it works. You take advantage of a mapping that wasn't really intended for you, but that exists anyway.

Oskar 20:38, 7 August 2006 (UTC)


 * (edit conflict) Are you asking because you are a geek and are interested in how these things work? If so, check out this episode of Security Now. It's a podcast where many issues regarding computer security is discussed, among them (in this episode) NAT traversal. They explain how it works pretty well. If you just want to connect two computers to eachother, I suggest using Hamachi which will connect any number of computers in a VPN. It's dead-easy to use, it will traverse ANY router, and is completly secure (everything that gets transferred is seriously encrypted). It's also free, lightweight and among the coolest pieces of software ever invented.

Oskar 20:15, 7 August 2006 (UTC)

Thats just what i was after, great explanation! It's how i interpreted the page on file sharing, but when i tried searching for it, nothing conclusive came back so i assumed my interpretation was wrong.

I've got Hamachi and think its fantastic. I've not had any reason to come across VPN's before, the main reason i asked this question was to attempt to build a program that would allow me to build a file sharing program that i could distribute between friends but now i think Hamachi will do it perfectly. Although i'd still like to know how to do this just if they chose not to get it. I see it will be very useful for linking computers for online games.

How does my central server operate? I have some cheap web hosting at the moment but i doubt that will be enough? I expect there are many different ways of doing it, but does one way involve java applications?

--PeteL 22:04, 7 August 2006 (UTC)
 * If you wish to implement a NAT-traverser like I described, you are going to have to do alot of coding. It's also a relatively new technology, so I don't think there are any free code available. This type of program certainly be implemented in Java (they have a great network-library) if you'd wish to code it. Note though that you'd have to code the filesharing part of the program too (which is also alot of code) since this method will only give you an open channel which off the top of my head I can't imagine how you would be able to "give" to another program. However, it is possible, and if your webhost allows you to run a java server on it, you could put it there. You could also run the mediating server on your own computer (make sure to forward those ports! ;) if you have it on alot.
 * However, if you only wish to share files (or play games) with a couple of your friends, Hamachi is definitly the answer. Activate Windows Filesharing (you should probably have it in read-only, otherwise your friends can either delete your files or fill your hard-drive with crap ;) and log on to Hamachi, and you will be able to see your friends files and share your own (through the native Windows filesharing system, since it'll think you are on the same LAN as your friends). Another good tip: If you use iTunes, activate sharing of your music (and get your friends to do it too), and you will be able to play songs from your friends libraries in iTunes (see for details). Feel free to ask if you want any more info Oskar 22:48, 7 August 2006 (UTC)

Administrating
Hi! What was the name of that web page, that allowed you to experience how it is like to be an Administrator?--Captain ginyu 22:33, 7 August 2006 (UTC)
 * Admin of what? Wikipedia? --Yanwen 01:32, 8 August 2006 (UTC)
 * It allowed you to experience web page administrating, like having the different user interface, I don't think it was any page specific.--Captain ginyu 07:31, 8 August 2006 (UTC)
 * There are hundreds of content management systems. You may not realize the impossibleness of your question. --mboverload @  10:02, 8 August 2006 (UTC)
 * No, no, you didn't understand my question. You go to that page, and, should I say, play the role of Administrator, that is set so you could experience the Administrator user interface and similar things. It is not like a real page, where you have to become an administrator after you prove yourself etc., that page is just set for your fun, so anyone can see how it is to be an Administrator. Get it now?--Captain ginyu 14:41, 8 August 2006 (UTC)
 * Again, there are countless web page administration tools. cPanel, DirectAdmin, Plesk, Cube Panel, etc.  See more at Control panel (Web hosting).  The point being that no single page can simulate web administration, because there are many tools available.  --LarryMac 15:01, 8 August 2006 (UTC)
 * so what? There are generic similarities between all those tools.
 * I wonder if you are talkng about Content Management Systems demonstrations. Those allow you to use the CMS with admin permissions. Try a Google search for CMS demo. Phelan 07:56, 12 August 2006 (UTC)


 * I think you mean a WP Administrator? Like a SIM Admin Sandbox or something? Don't think they have that here. Maybe if you're good friends with an admin you could sign in as them for a few minutes to look around. Oops, probably shouldn't suggest that, kind of like saying 'BOMB' on an airplane, lol. I shouldn't tell people to shove beans up their noses. I'll shut up and go to bed now.--Anchoress 17:05, 9 August 2006 (UTC)

Linux CD tray not opening or shutting
I have a dual boot machine with a CD burner in it. In Windows, it works fine. Press the button and it opens/shuts as expected. In Linux, it will not respond to either opening or shutting. It doesn't matter if the CD is mounted or not. Sometimes, for no apparent reason, it opens halfway and then gets stuck in a cycle of opening and closing. Pressing the eject button causes the light to blink a few times, but nothing else happens. Right now, I have to eject by sticking a paperclip in the manual eject hole. I have to put a CD in by forcing the tray shut. I can't find a google search string that turns up reasonable results. Anyone have any hints? --Kainaw (talk) 23:00, 7 August 2006 (UTC)


 * You seem to already know that some versions of UNIX require you to unmount the CD, using root account permissions, before you can eject the disk. So, if that isn't the problem, I suspect the CD driver in Linux isn't the correct one for the CD drive.  Try removing the old driver and installing a new one (download it, if possible).  StuRat 22:50, 8 August 2006 (UTC)


 * He's probably using the kernel IDE/USB/SCSI(/IDE-SCSI) CD-ROM driver. (Assuming IDE-SCSI isn't dead yet.) --Kjoonlee 09:14, 9 August 2006 (UTC)


 * Have you tried "eject /dev/cdrom" or "eject -t /dev/cdrom" to eject/close the tray? --Kjoonlee 09:14, 9 August 2006 (UTC)


 * Thanks. I ran "eject -v /dev/cdrom" and it said /dev/cdrom wasn't mounted - even though I was playing music from it.  Then, I ran "eject -v /dev/hdd" and it killed the music and ejected.  So, I think the problem has something to do with the system using /dev/hdd and the OS using /dev/cdrom. --Kainaw (talk) 12:58, 9 August 2006 (UTC)
 * You don't need to mount a CD-ROM drive to play audio CDs. What does "ls -al /dev/cdrom" tell you? You might want to run "ln -sf /dev/hdd /dev/cdrom" if it points to the wrong device. --Kjoonlee 00:18, 10 August 2006 (UTC)
 * If it's a CD burner, it's possible that the symlink is  instead of  . --cesarb 20:50, 10 August 2006 (UTC)