Wikipedia:Reference desk/Archives/Computing/2008 May 17

= May 17 =

DHCP automatic allocation override?
I regularly connect to a small wireless network that (I believe) uses automatic IP allocation DHCP. I'd like to know if there's a way to sort of override the DHCP and get a specific IP address, instead of a randomly allocated one (of course only within the IP addresses available to the network). Thanks, --Bmk (talk) 02:02, 17 May 2008 (UTC)
 * Note - I am not the network administrator, so I'd like a way to do it from the connecting computer side (i.e. I can't change the DHCP setting or anything). Thanks  --Bmk (talk) 02:13, 17 May 2008 (UTC)


 * You can get your DHCP info, which will give you your gateway and nameservers. Then, hard-set your network info as you like.  As long as it doesn't conflict, most networks will allow it.  However, DHCP won't know you are using it and will likely give the address to someone else - causing conflict.  So, you need to ask yourself if it is worth that to have a specific IP address without simply asking the network admin for one.  Why do you have to secretly do it? --  k a i n a w &trade; 02:17, 17 May 2008 (UTC)
 * Cool - thanks! I'm not sure why I didn't think to just try that.   I would have thought that DHCP would be able to deal with the conflict problem - what are the consequences of IP address conflict?  And it's not that I'm trying to keep it secret; to be honest, I'd like to spoof GoogleBook's pageview restrictions, so I'd like a way to change IP addresses at will, and when I disconnect and reconnect I the network often allocates me the same IP address as before.  Thanks for your help --Bmk (talk) 02:57, 17 May 2008 (UTC)
 * And the network admin wouldn't mind giving me a specific IP, I just don't want to bother him about it (it's not a professional situation) --Bmk (talk) 02:58, 17 May 2008 (UTC)
 * It's very easy to set a static binding of an IP address to your MAC address on the DHCP server. It'd be more trouble for him/her to troubleshoot the problem when a conflict occurs. --antilivedT 04:20, 17 May 2008 (UTC)
 * Conflicts would normally be avoided by the DHCP server pinging an address before giving it out. --tcsetattr (talk / contribs) 04:34, 17 May 2008 (UTC)
 * Ok, thanks folks. --Bmk (talk) 04:55, 17 May 2008 (UTC)
 * Often DHCP will allocate numbers from a pool, and there will be a collection of numbers outside the pool for use by static allocations - such as routers. You may be able to use such a number, but it would be best to talk to the network administrator, they would not appreciate you just grabbing an address of your own use as it will make their work more difficult some time in the future when they have to solve the problem of the duplicate number, or an unexplained useage. Graeme Bartlett (talk) 09:39, 17 May 2008 (UTC)
 * Amazingly enough, I had a problem with someone's rogue DHCP just yesterday. :) It takes a while to troubleshoot with tech support, if they're not familiar with the problem already, and have it fresh in mind. Scaller (talk) 09:49, 17 May 2008 (UTC)

Speech synthesizer
Other than Microsoft Sam and Anna, is there any other free English speech synthesizer for Windows? -- Toytoy (talk) 03:52, 17 May 2008 (UTC)
 * Festival "will also compile on MS Windows platforms given a little work and patience" --h2g2bob (talk) 14:25, 17 May 2008 (UTC)

What is Prestoserve?
I know that it is a TURBOchannel card and that it has something to do with communications but what is it exactly? Rilak (talk) 07:47, 17 May 2008 (UTC)


 * After looking at a couple of manuals, it seems to be a disk write caching system from the early 1990's. The purpose was to speed up disk-write-heavy applications. The system was composed of an expansion card with some NVRAM on it, a driver to send write requests through the card, and a control utility to allow the system administrator to turn the caching on and off.
 * It must have become obsolete quite suddenly when hard drive manufacturers starting including cache memory directly in the drives. We have an article on that - disk buffer - but it doesn't have a history section to tell us when internal caches became common.
 * (Also, I don't think most modern hard drives use NVRAM for their internal write cache. Those pioneers who invented Prestoserve cared enough about data integrity to make it retain the data that was written just before a crash, and flush it to the disk on the next boot. How quaint!) --tcsetattr (talk / contribs) 09:54, 17 May 2008 (UTC)


 * If memory serves, the card used battery-backed-up CMOS RAM memory for its buffer.


 * Atlant (talk) 12:56, 19 May 2008 (UTC)


 * Thanks for the answer! Looks like my guess that it had something to do with communications was a bit off... :) Rilak (talk) 11:21, 17 May 2008 (UTC)


 * These days, if data integrity matters, you get a UPS for your system, or use a controller card with a battery-backed cache. Since modern hard drives are independent of the OS, if the computer crashes, they'll still flush any cached data to disk.  The only thing that can cause data loss from the cache is a power failure. --67.185.172.158 (talk) 19:29, 18 May 2008 (UTC)

SELECT syntax
This is making my self-taught head spin.. I have two tables: topics and subscriptions. The subscriptions contains the subscriber's name and the topic-id that they're subscribing to, indexed by subscription id. The topics table contains subject/body fields and the name of the topic-starter, indexed by topic id.

My question is: What combination of SELECT statements would print out all of a certain subscriber's subscription IDs (I guess SELECT sid FROM subscriptions WHERE subscriber = 'whatever') along with each subscription's topic-id, along with each subscription's topic-id's subject (I guess SELECT subject FROM topics WHERE tid = 'whatever')? You see the problem.. the first 'whatever' is given easily, but the second 'whatever' depends on each row of the first SELECT's result. I could run a separate SELECT on each row but if a subscriber has 500 subscriptions then that's insane. Is there any way to combine these statements with funky SQL syntax? (I'm using mysql 5) .froth. (talk) 13:07, 17 May 2008 (UTC)


 * Is it not something along the lines of

SELECT subscriptions.sid, topics.tid, topics.subject FROM subscriptions, topics WHERE subscriptions.subscriber = 'whatever' AND subscriptions.tid = topics.tid
 * Rawling 4851 13:36, 17 May 2008 (UTC)
 * That works fantastically! That table.field syntax was exactly what I needed, thanks .froth. (talk) 15:13, 17 May 2008 (UTC)
 * You can even shorten it a bit using the AS command:

SELECT s.sid, t.tid, t.subject FROM subscriptions AS s, topics AS t WHERE s.subscriber = 'whatever' AND s.tid = t.tid
 * It's been a while since I did SQL - it's nice to know that it comes flooding back (with a bit of help from the specification!) Rawling 4851 15:21, 17 May 2008 (UTC)


 * It might be useful to note that that JOIN syntax (the comma between tables is an implicit INNER JOIN) assumes the `sid` column is present in both tables and that no other columns share a name. If either of those is not true you might need a USING clause (e.g. "FROM subscriptions INNER JOIN topics USING (sid)") or ON clause (e.g. "FROM subscriptions INNER JOIN topics ON subscriptions.id=topics.sid").  --Prestidigitator (talk) 18:16, 17 May 2008 (UTC)

Vista Headset
I have this USB headset with a microphone in it. I plug it into OS X and it sees it and lets me use the headphones and the microphone. In Vista it only let me use the headphone part and doesn't seem to notice the microphone. Not even my games notice the mic. How do i fix this. --Randoman412 (talk) 13:54, 17 May 2008 (UTC)
 * It may need a driver. Check the manufacturer's website for drivers or help.  --—  Gadget850 (Ed)  talk 14:15, 17 May 2008 (UTC)
 * Have you tried adjusting the properties in Volume Control? (Start -> Programs -> Accessories -> Entertainment -> Volume Control) Think outside the box 18:52, 18 May 2008 (UTC)

Recording phone calls
Is there any software that would allow me to record phone calls on my Mac please?--Artjo (talk) 14:26, 17 May 2008 (UTC)


 * Well, audio recording is easy (e.g. Audacity). The hardest part is porting the audio into the Mac. You can buy little microphones with suction cups at Radioshack that are supposed to be used for phones but they are unpowered, and the mic-in on Macs (at least iMacs and MacBooks) is unpowered as well, from what I can tell, so they don't work. I've actually had fairly good luck just holding the phone near the microphone on my MacBook—you can usually catch both sides of the conversation that way. But yeah. Anyway. The problem is getting the audio feed into the Mac; the software side of it is trivial. --98.217.8.46 (talk) 14:55, 17 May 2008 (UTC)


 * Is it possible to use a USB modem like the Apple modem and use software to call? It is, at least theoretically, possible. Should the OP look into that possibility? Kushal (talk) 19:41, 17 May 2008 (UTC)


 * It would be trivial to put the person on speaker-phone and use a standard mic. However, this hits on one of my suggestions for cell phones - recording.  While recording a phone call can be used for illegal activity, imagine the useful qualities of the feature.  For example: If someone is giving your their phone number, you don't have to write it down right away.  Just record it.  If you are being given directions somewhere, don't write them down.  Just record it.  If you think you are being called by a phone-scam person, don't try to remember everything said, just record it.  Why don't cell phones have this capability already? --  k a i n a w &trade; 03:25, 18 May 2008 (UTC)
 * Um, they do. At least, the last several Motorola flip-phones I had would record if I pressed the small button on the outside while a call was in progress. 81.187.153.189 (talk) 17:31, 18 May 2008 (UTC)
 * Actually, at least one Nokia phone on the AT&T network in the US does recording in compliance with the law. There is a small beep about every five seconds (which is shorter than the legally required 15 second limit). Kushal (talk) 22:45, 18 May 2008 (UTC)
 * Dunno about US law, but my phone a Panasonic VS2 similarly makes beeps when recording. It also tags the recorded files as protected so I can't download them... (This phone is completely internal memory, so it's difficult if possible to overide the protected files function although even with phones with removable memory, given the nature of SD I suspect it's still going to be rather problematic) Nil Einne (talk) 18:20, 19 May 2008 (UTC)


 * Thanks Kushal, that is exactly what I am looking for, but does anyone know of a suitable software programme that does it?--Artjo (talk) 05:59, 18 May 2008 (UTC)

Continuing on what other OPs said, please stay on the safe side by saying "I will be recording this call" or something like that. FaxTalk seemed to have this capability in Windows. I wish I could help, but my macbook does not have a modem. I could, and will, look up in Google for certain keywords. I would love it if the program was free of cost. Kushal (talk) 14:41, 18 May 2008 (UTC)

a small piezo transducer inside the phone /on the phone might work. You can terminate it to a mini jack and record via audacity. 81.157.97.154 (talk) 20:19, 18 May 2008 (UTC)


 * It is a great idea, 81.157.97.154. Do you think it might be possible to keep two separate tracks for the audio from the other side of the telephone line and the audio from our side of the telephone line? Kushal (talk) 22:42, 18 May 2008 (UTC)

Resizing my home-partition on Ubuntu
I'm running ubuntu hardy on my desktop, and I have my home-directory on a different partition. I want to use GParted for resizing that partition and creating new ones (I know you can do it from the command-line, but GParted is easy and looks friendly, and I don't want to do something as destructive as resizing my partitions from the command-line). Of course, you can't do that when it's mounted. So, I commented my "home"-line out of /etc/fstab, and rebooted. I tried logging into my box using "root" (which I had previously created a password for, using "sudo passwd", for just this purpose), but it wouldn't let me. It said that it doesn't allow root to log in from the graphical screen. Annoyed, I went to my trusted command-line (Ctrl-Alt-F1) and logged in as root, created a new user in the admin-groop (so I could sudo using it). I tried logging in using the graphical screen, but while it did accept my user and password, the screen was blank (all white) with only my mousepointer on it. Even more annoyed, I tried a few different things, including trying to copy over my home-folder of my regular username to the system-partition (leaving aside some of my bigger stuff, which wouldn't fit), but after ten minutes of fidgeting with permissions and file-ownership, I got back where I started with the white and blank screen with only the mouse on it.

Before you ask: I've lost my live-cd and I'm on an anemic internet-connection, so it would take the better part of seven hours to download again. Besides, I don't have any blank discs around. Can anyone help me out? --Oskar 17:22, 17 May 2008 (UTC)


 * You can allow root to graphically login (presumably by restoring your home partition and logging in graphically in the normal fashion): go to the System menu, then Administration, then Login Window (passworded, of course), then the Security tab, and look for "Allow local system administrator login". Your more recent release of Ubuntu (this was checked on Gutsy) might have the names subtly different, but the option should still be there.  (Unless you have a long-term need for this, remember to re-disable it later!)  --Tardis (talk) 18:59, 17 May 2008 (UTC)

Clicks made by computer
Whenever any computer is doing something that takes a decent amount of resources, it makes all those clicking noises and usually a light flashes on and off in synchrony with the clicks. What does each flash of that light mean? 69.23.140.171 (talk) 17:25, 17 May 2008 (UTC)


 * For the clicking, it's definitely the hard-drive, reading and writing. It's basically the only moving part in the whole desktop (aside from the fan and the optical drive, and they don't make those sounds), so he's the culprit. The flashing is the same, I think. (didn't someone else ask this recently)? --Oskar 17:32, 17 May 2008 (UTC)


 * The light is just an indicator that the hard drive is at work, yeah. That can be useful if you have a particularly quiet hard drive or sound-proofed computer, or if the computer is in an environment with a high level of background noise. It's a bit of a relic from the olden days, really; nowadays the information that the hard drive is doing something is rarely all that useful. In the days of yore, though, before multitasking was the norm, the only easy way to know whether your computer was just slowly making its way through a program or whether it had actually crashed was to know whether the hard drive was still ticking away, so the light helped there. Of course, these days we have better and more accurate ways of tracking whether processes are still active. -- Captain Disdain (talk) 22:49, 17 May 2008 (UTC)


 * There's also an adware/spyware program that makes the mouse click sound repeatedly. Does it sound like that ? StuRat (talk) 14:48, 18 May 2008 (UTC)

Vista/XP
How do you dual-boot Windows XP onto a Dell Computer with Vista pre-installed. I want to put XP on a different internal hard drive, yet still keep Vista. Thanks -Delluser3521 (talk) 19:30, 17 May 2008 (UTC)
 * You'll need a separate physical hard drive or drive partition. Then install XP on that. Then when you boot up, it should give you a choice between Vista and XP. Useight (talk) 00:24, 18 May 2008 (UTC)
 * No, it will give you a choice of XP or XP (if it doesn't hose everything), because XP will install its own bootloader which doesn't support Vista. You should be able to fix it by simply running the Vista disc and telling it to do a "Startup Repair" or something of that nature; that fixes boot loader issues. Though when I did it it didn't do anything, and I somehow ended up hosing the filesystem (a chkdsk fixed it without any data loss, luckily); running it a second time worked. It's way easier to install XP first, then Vista (if you have the Vista disc). 206.126.163.20 (talk) 23:40, 18 May 2008 (UTC)