Wikipedia:Reference desk/Computing

Welcome to the computing section
of the Wikipedia reference desk.

skip to bottom

Select a section:

• Computing
• Entertainment
• Humanities
• Language
• Mathematics
• Science
• Miscellaneous
• Archives

Want a faster answer?

Main page: Help searching Wikipedia

   

How can I get my question answered?

• Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
• Post your question to only one section, providing a short header that gives the topic of your question.
• Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
• Don't post personal contact information – it will be removed. Any answers will be provided here.
• Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
• Note:
  • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
  • We don't answer requests for opinions, predictions or debate.
  • We don't do your homework for you, though we'll help you past the stuck point.
  • We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

• The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

See also:

• Teahouse
• Help desk
• Village pump
• Help manual

November 7

Youtube offline for smart mobile phones

Does anybody know how the 'Youtube offline' works on 'smart mobile phones'? Could someone show me how I could use the same method via PC? -- Space Ghost (talk) 03:39, 7 November 2015 (UTC)

Presumably it downloads videos and saves them for later viewing. youtube-dl is a popular program to do the same thing. There are others as well. --71.119.131.184 (talk) 06:11, 7 November 2015 (UTC)

You don't even need another program. KeepVid [1] and similar sites just use your browser. In the past, you generally needed to use a Java applet (so did effectively need an a program) but AFAIK this generally isn't needed for YouTube nowadays. Nil Einne (talk) 06:47, 7 November 2015 (UTC)

Don't want to download guys, I'm on 'pay bit as you go'. Check this out, this will give you an idea of what I'm searching for. I'm in need of this, very very important for my boring life. -- Space Ghost (talk) 21:23, 7 November 2015 (UTC)

Offline viewing works by downloading the videos in advance. If you can't afford to download the videos then you can't watch them offline. You also can't watch them online since that downloads them as you watch. -- BenRG (talk) 02:21, 8 November 2015 (UTC)

How do you think the video gets to your computer (cell phones are computers)? You're always downloading the video from YouTube's servers. This seems to be a common misconception some people have, that "streaming" is somehow completely different from "downloading". The only difference is that a "streaming" video player (like the one on YouTube pages) doesn't save the downloaded data to permanent storage. --71.119.131.184 (talk) 08:27, 8 November 2015 (UTC)

Yeah as BenRG and 71 say whether your streaming or retrieving for offline viewing, both will need to download the file and neither intrisicly save data. Offline viewing would actually often use more data because many people aren't going to watch everything they downloaded for offline viewing. And if you skip through the video to a certain point, it's possible your player won't have downloaded the previous portions if you're streaming (but you would have downloaded the whole thing for offline viewing). Plus a smart offline viewing application will probably choose a resolution close to your device resolution; which the online viewing/streaming also normally tries to do, but the streaming will often reduce quality if your device is having trouble handling it. On the flip side, caching tends to be limited so often if you watch the video again and sometimes even if you rewind a bit, you may end up needing to download from that point again when streaming. And if you're manually downloading, you can probably choose a lower resolution easily. (On the desktop, you can normally also easily choose resolution, but apps seem to be more reluctant to give that level of control.)

The cases when offline viewing may save costs (as opposed to data) would be if you download for offline viewing over wifi that you either don't pay for (i.e. free public wifi or similar) or you do pay for but at a lower rate (e.g. a fixed line connection); but when streaming you will need to use more expensive mobile data. Also if you use the same connection as for streaming (be it mobile data or wifi), but the costs depends on time of day (or whatever) and you download for offline viewing when it's cheapest but may not watch streaming content at the cheapest rates.

Technically it's possible whoever is providing the offline viewing app could work with the network provider (or are the network provider) to charge downloads for offline viewing at a lower rate (perhaps because the app is designed to be network load aware) but I don't think that's particularly likely. The primary reason for offline viewing in some developing countries is likely because the connection coverage there is more spotty, and also slower even when it exists so streaming is more problematic. (Things like Facebook Zero and Wikipedia Zero and similar initiatives exist, but these tend to be low bandwidth services and also aren't offline oriented. Some providers do offer unlimited Youtube, but this is usually at an additional cost and directed at streaming anyway.)

Nil Einne (talk) 17:56, 8 November 2015 (UTC)

Its the T.V. adverts, and someone showed me in their smart phone, telling me what I told you guys. I did not believe them at first, I was hopeful because the offline thing works where I'm currently based. That's why I was more exited...

Thank you all anyway, for teaching me a bit too guys. Regards. -- Space Ghost (talk) 18:36, 8 November 2015 (UTC)

IT Graduate Development Programme Job Questions

So, I applied for an "IT Graduate Development Programme" Job with Dell that was forwarded by my college and got this reply:

You will be contacted by a representative from our team for a 15 minute (maximum) phone screening conversation. This conversation will provide you with information about Dell. We will also have 7 general, very basic questions for you.

I would like to reiterate, this is not an interview. This is very much a screening process and a means for you to get some valuable information on Dell.

My question is, does anyone have any idea what types of questions I can expect? Are these likely to be technical or programming questions?

Thanks, 2A02:8084:9360:3780:413C:2B61:770B:88F2 (talk) 16:10, 7 November 2015 (UTC)

These kind of things are usually a "pre-screen" - they're there to cut out people who an actual interviewer would know weren't going to be right for the job within the first minute of the interview. This kind of thing avoids them wasting their time (interviewing for a position takes a lot of people a bunch of time) and yours (you coming down there for an in-person interview, only to discover they're looking to fill an entirely different job than what you're looking for). Some typical reasons for these kind of misunderstanding and time-wasting scenarios, which the pre-screen is trying to avoid, are:

• they're actually looking for a senior person, and the bonehead recruiter has sent them a bunch of college graduate resumes.
• the recruiter (I don't mean to rag too much on technical recruiters, but I've seen some really useless ones) has simply keyword-searched the positions vs candidates - so you get someone who is a graduate in computer science (meaning software and maths) being matched for a job as a computer engineer (meaning designing computer hardware with logic elements or IC packages)
• some applicant is suffering from some major Dunning-Kruger, and is calling themselves a "C++ expert" because they finished the entry-level Udacity C++ course last week
• the applicant is obligated to apply for jobs (e.g. to continue to be eligible for government benefits) and is doing so wily-nilly; and the company is obligated to give everyone at least a rudimentary screen (again for some legal reason, like recent layoffs) and say why that specific person isn't suited. I once pre-screened people for a senior Java development position, and one guy had a degree in environmental science (and a bunch of related experience, I think to do with hydrology). Once it was clear that he wasn't experienced with Java, software development, or embedded systems, we had a nice chat about beavers.

So you can really only "fail" a pre-screen if somehow wires are crossed somewhere, and it's not a job you'd actually get (or want to get) in an actual interview. -- Finlay McWalterᚠTalk 16:39, 7 November 2015 (UTC)

For those unfamiliar with the term: Dunning–Kruger effect. I would also expand on Finlay's excellent answer a bit: this job might be something you're really not interested in, but thought you might be because companies are sometimes hamstrung by what HR/legal says they can put in the ad. This is a good time to ask one or two pointed questions about what the job really is about - that's what they mean by 'find out about Dell' - you're presumably already aware of the company :-) 99.235.223.170 (talk) 21:22, 7 November 2015 (UTC)

I had a cubicle between two phone-interviewers when I worked for a government contractor. Being government funded, they didn't want to hire Americans. They only wanted programmers from India and China. The interviewers asked them basic questions, such as "what is a pointer?" and "what is a buffer overflow?". They had enough of an idea of the answers to know if the applicant was saying something reasonable. It turned out that at least half of the PhD-level applicants failed the basic phone interview and never made it to the real interview to see how well they could program. I was lucky that I made it through the initial interview, a real interview, and then they flew me to San Diego for the final interview and I was hired. 209.149.114.132 (talk) 12:28, 9 November 2015 (UTC)

Are you saying that at least half of the Indian and Chinese PhD-level applicants who were interviewed over the phone don't know what a pointer or a buffer overflow is? JIP | Talk 09:58, 10 November 2015 (UTC)

Among other things. They are testing if you can read/write in English. Many cannot. I admit that I wasn't too great with English. I only took what you all call British English for two years in secondary school. But, I like the Beatles and I learned enough English to know all of their songs. You can imagine how hard it was for me to try and figure out what "I am the Walrus" means. After English, there is a problem with the validity of the degree. We joke that everyone in India has a PhD. Even those from India say that. It is because in India, and in China, you can get a PhD just by buying one. You don't learn anything. You just pay for it. So, you need to ask them questions to see if they went to school and got a real PhD or if they just bought one. It is happening in the United States now. There are many online universities that will give you a degree and you don't have to do any work. You just pay for the classes. They have a test for each class, but the answers are freely available online, so you easily pass all the tests without learning anything. Then, you get a degree. Soon, they will abandon all the middle work and let you just pay for the whole package and then give you the degree. So, it is still important to ask questions and see if they know the material. I think it is important to note that my experience is in computer science. So, when I state that half of the applicants either didn't know English or didn't know their degree, it is only in that field and only for those applying to work as a government contract programmer in the United States. I am not making the claim that half of the PhD holders in all of India don't have a real degree. I prefer the Chinese programmers, but I'm obviously biased. 209.149.114.132 (talk) 13:43, 10 November 2015 (UTC)

"Soon, they will abandon all the middle work and let you just pay for the whole package and then give you the degree." - sadly, this has already happened...and for at least the last 8 years. "Life experience degrees" require you to fill out a form describing your "life experience" and rate whether they think you have already demonstrated that you've qualified for their degree. Then you have a cat who earned a life-experience degree...which strongly suggests that this "rating" process is a rubber-stamp machine. Truly - when someone claims to have a degree - the only question is "Which college?" - and even then, you have to be VERY careful of cleverly chosen names for fake degree mills that are designed to fool you into thinking that they are a part of a 'real' collage. SteveBaker (talk) 19:25, 11 November 2015 (UTC)

It is very variable between companies - I've applied for jobs with six figure salaries and been asked "What is the biggest number you can store in a byte" and stupid stuff like that on the phone screen. On the other hand, I've also worked places where there is no script for the interviewer at all and you just chat about whatever (s)he fancies talking about. But as others have said - you shouldn't stress about it. If this is a job that you come within a million miles of getting, you won't fail the initial phone screen - it's there to get rid of people who have absolutely no clue and who should never have applied for the job in the first place. Subsquent interviews (which might also be on the phone or via Skype) will likely be the harder ones - expect at least one face-to-face interview after that. But the whole process is incredibly variable. My previous job needed one phone call and a 30 minute interview (at which they actually offered me the job, haggled over salaries and settled it all on a handshake) - but then my current job took five separate, hour long phone calls, then a gruelling 8 hour back-to-back set of 30 minute grillings by different team members...ending with a quiet stroll to the local Starbucks with my future boss...and then a nerve-wracking four week wait for an actual job offer! SteveBaker (talk) 22:01, 9 November 2015 (UTC)

November 8

Online maps for vertigo-safe roads ?

I have vertigo and get dizzy when the landscape falls away from under me as I drive, which is dangerous. Is there an online resource that would show me which roads I can take that are vertigo-safe ? That is, they have a flat plain on both sides of the road ? (In general, going through mountains is a problem, but roads that go through tunnels are far better than those which hug the edge.) I suppose I could go over a contour elevation map superimposed on a road map and eventually figure it out, but I'd much rather have roads colored green, yellow or red to show degree of danger. StuRat (talk) 00:46, 8 November 2015 (UTC)

I should add that roads and bridges can be "vertigo-safe" if they have barriers on the sides that block the view of the depths below. On the other hand, expansion cracks in bridges that let you see the water below are bad for vertigo. StuRat (talk) 19:30, 8 November 2015 (UTC)

That seems like a tough thing to discover. Google maps does not include such thing, and I don't believe many people would have the same problem. Maybe you could avoid bridges all-together, or, let someone else drive, or, use the sun visor to block the view. --Denidi (talk) 00:12, 9 November 2015 (UTC)

The only one of those with any possibility is blocking the view, but the difficulty of blocking and unblocking the view quickly, while driving alone is quite a problem. Maybe some kind of blinders that could be flipped up and down on both sides of my sunglasses might work ? StuRat (talk) 05:22, 9 November 2015 (UTC)

How about trying to cure the vertigo? Ask your ENT specialist what he thinks of tissue salts if standard medicines like Stugeron don't work. Sandman1142 (talk) 09:36, 10 November 2015 (UTC)

Check the hatnote on vertigo; we're not supposed to be diagnosing people here but I suspect the term is being misused by all present. Wnt (talk) 12:32, 10 November 2015 (UTC)

Yes, I'm not looking for a diagnosis or treatment here. (If anyone is interested, I had a dual ear infection as a kid, and since then my inner ear balance system doesn't seem to work, making my brain rely exclusively on visual cues to balance.) StuRat (talk) 19:18, 10 November 2015 (UTC)

How do I type weird letters in Xubuntu Linux?

For example I want to type Fëanor with double dot on top of the e letter, or Andúril with the top accent u, and what is the correct term for that kind of weird character thingy? 139.193.247.7 (talk) 05:58, 8 November 2015 (UTC)

Take a look at this or this. In short, you configure one of the keys on your keyboard to be a Compose key, using the Keyboard Layout options under System Settings. You can then use that key in combination with others to generate many different accented and other special characters. For example, to generate a "ë", you could could type Compose+"+e. -- Tom N talk/contrib 06:37, 8 November 2015 (UTC)

Well it works, so now I don't need to copy paste words from google anymore

Resolved

139.193.247.7 (talk) 10:03, 8 November 2015 (UTC)

And to answer your question about what they're called... The first is an umlaut. Dismas|^(talk) 19:35, 8 November 2015 (UTC)

An umlaut (diacritic) rather than an umlaut (linguistics), to assist disambiguation. Tevildo (talk) 20:13, 8 November 2015 (UTC)

Some would prefer to call it diaeresis; Germany adopted it as an imperfect imitation of a mark already used to represent umlaut. —Tamfang (talk) 20:22, 8 November 2015 (UTC)

In general, marks that distinguish variants of a base letter are diacritics. —Tamfang (talk) 20:22, 8 November 2015 (UTC)

How can Skype run with Ubuntu on a windows computer?

I have 2 windows computers with Ubuntu which is anti-virus software and I need my brother to set up Skype because I talk to my friend a lot through Facebook and on the phone. She lives thousands of miles from me and when I use a computer I open several tabs and my brother set up my computers so I don't get virus. He says Skype can't run with Ubuntu. Please give some computer advice. 209.53.181.75 (talk) 22:44, 8 November 2015 (UTC)

Ubuntu isn't anti-virus software, it's a Linux distribution. It's not clear what operating system your computers are running—Windows or Ubuntu, or both? If you are running the Ubuntu operating system, Skype is available for Linux (and for Windows of course). --Canley (talk) 06:03, 9 November 2015 (UTC)

That site only gives a version suitable for Ubuntu 10.04, not the latest version. I've checked in the software centre, since installing Ubuntu on my Mac via Parallels, and it is not available. KägeTorä - (^影_虎) (もしもし！) 07:29, 9 November 2015 (UTC)

Actually, there's instructions for installing it on Ubuntu Palmtree5551 (talk) 17:12, 9 November 2015 (UTC)

November 9

http://adadvisor.net/adscores/g.js?sid=9276253823

I keep getting a script error saying that a script from http://adadvisor.net/adscores/g.js?sid=9276253823 is not working, would I like to keep running it or not. The problem is very recent compared to the age of my computer and the last reboot of my OS.

I run windows 7 on a Gateway NV78 laptop. The problem seems to be occurring whether I am using IE, Firefox, or Chrome, although I am not exactly sure if it corresponds to one of these browsers specifically.

I have run AVG, emptied all my caches and rebooted a few times. The problem continues. The best advice I can find via googe is to turn off my windows script error notifications, which sounds insanely unhelpful.

Can anyone suggest what's going on and how to fix it? Could it be a file on my desktop or some other problem? Who the hell is http://adadvisor.net/adscores/g.js?sid=9276253823? I am already insane, but this is slowly driving me into even deeper levels of Lovecraftian madness.

Thanks. μηδείς (talk) 03:42, 9 November 2015 (UTC)

Looks like code to control which ads you see. So, you surely don't need it. When exactly does it get called ? StuRat (talk) 05:17, 9 November 2015 (UTC)

To rephrase the above for understanding, is this just happening randomly, or only when you go to certain Web pages? Does it happen whenever a browser is open? General advice for getting help: remember, we can't see your screen. Screenshots are often helpful (just remember not to include any information you don't want public). --71.119.131.184 (talk) 08:52, 9 November 2015 (UTC)

Have you tried restoring your PC? Note: Don't if you are not good at handling PC; most of the time the restoring points are linked with other softwares. Also remember that restoring always creates problems starting from the first time you do it. Now:

1)Check your 'uninstaller program window' and check the 'restoring point window', see if you find this rubbish. If not uninstall the web browsers, but first 'right click' the browsers 'shortcut' icon, go to 'properties' and or open its file/folder location. Delete the files and folders of the browser(s) thereafter uninstall is complete. If wished: After you uninstall the browsers, ensure you delete its folders and sub-folders from 'AppData' Folder. Delete the browser's hierarchy available in the PC (recommended for professionals because some files are requisites). Use CCleaner (or something), reboot, reinstall the web browsers... If it doesn't work and you choose to use restoring point window, make sure you keep a Windows OS CD handy for the near future.

2) Just follow the advice on how to delete the code, if possible. I'm sure someone will assist you in a step by step manner. -- Space Ghost (talk) 10:31, 9 November 2015 (UTC)

Adadvisor.net is owned by TARGUS information corporation [2]. They are "... a leading, independent provider of real-time, on-demand information and analytics services including Caller ID..." [3]. Which makes it sound a lot like they are shadily trying to collect your browsing info without your express consent. I don't know what the problem is, but I'd generally advise the use of NoScript to keep malicious javascript from messing with your computer. That will solve this and many other issues, at the cost of having to whitelist pages that you trust. SemanticMantis (talk) 16:01, 9 November 2015 (UTC)

Oh, my. Now I really am paranoid. I have both a restore point, and backup install disks, so I am not totally clueless, and I did actually reboot this computer from the install disks a few months ago. I have never gone back to a restore point, though. My big question at this point is, is the script something that's now on my hard drive, so it doesn't matter what browser I am using? Or is it a browser related issue? I can basically avoid IE, firefox or chrome until I can fix the problem. If it's on my hard drive I will make fixing it a much higher priority. Thanks for all the help above so far! μηδείς (talk) 02:03, 10 November 2015 (UTC)

Your complain sounds like its on your hard drive. I'm not sure though, because this problem should be saved temporarily somewhere in the 'AppData' Folder or in the 'temp' folder (could be somewhere that I don't know, e.g., internet problem). Its up to you what you wish to do. Two options are provided. Option (1) Have you checked on the two enquoted points I stated? (2) Have you done what others stated? Option (1) is for the people who hate programming, also for those who only know reinstalling OS (uninstall the OS then install it again in a way that the computer feels new; no restoringrubbish...) if any virus or problem like yours occur, and so on. Try option (2) first which is much easier, quicker and without a problem. -- Space Ghost (talk) 05:45, 10 November 2015 (UTC)

I don't know, seems to me like the javascript code is hosted that URL, and something has gotten in to your browser(s) or possibly OS to make calls to that script. I would recommend uninstalling and reinstalling a browser and seeing if the problem still persists on that browser, and for more than one web page. If so, then it's not limited to the browser. Seriously though NoScript will save you a lot of hassle, and help make you aware of all the weird third party scripts that websites attempt to load. SemanticMantis (talk) 17:07, 10 November 2015 (UTC)

• Earlier today I tossed all my cookies and rebooted. The problem recurred, so when I got home at dinner time I did a system restore to five days ago before the problem started, and then checked my windows updates and saw that the last 16 had been aborted. So I reinstalled and rebooted and the problem has gone away with no loss of files. Thanks for the assistance above. I probably would just have followed the very stupid advice to disable the script error notification. This is the first time I have used a restore point rather than a reboot from back-up disks, and it went very well. Again, thanks to all. μηδείς (talk) 03:36, 11 November 2015 (UTC)

Its not stupid, its probably the easiest and probably could've been the less problematic way for you. The logical thing is to do is the scripting. The illogical/dumb way to do is what I said. But I guess, since you have the utilities, you are alright. Regards. -- Space Ghost (talk) 07:24, 11 November 2015 (UTC)

Resolved

"Virtual" email address?

For many years I've had a domain name which I'll call "xxx.net" for privacy reasons. I have a small website and email servers at xxx.net, and my primary personal email address is me(at)xxx.net. The website is no longer worth the recurring cost of the domain name and the hosting, so I'm considering dropping both, but I don't want to change my email address if that can be helped. Is there some way to pull this off? 68.97.47.26 (talk) 13:27, 9 November 2015 (UTC)

If you stop renewing the registration of the domain name, then anyone else can take it over and intercept your emails. Your registrant might allow email forwarding without hosting, or you can move the registration to a registrant that does allow this. You can then spoof the "from" field when you send emails from any other free email address. I don't think there's any way to achieve what you require at zero cost, but xxx.net can be registered at very low cost (.net isn't the cheapest of domains to register, but perhaps as low as $10 per year if you shop around). Dbfirs 13:47, 9 November 2015 (UTC)

Seconded. If you want to keep the email address, you'd at least have to keep the domain name. Most big domain name hosts (GoDaddy, etc.) offer some sort of email package directly through them, and I'm willing to bet you can mark it as forward-only for a very low price, if not for free. This would simply forward all email sent to that address to another email address of your choosing. As for the cost of the domain name itself, most are only like $15 per year. RegistryKey^(RegEdit) 13:53, 9 November 2015 (UTC)

The idea that the new domain owner might be helpful and forward your email is a definite long-shot. The (many) domain names I've owned for short-term reasons and left to expire have all been bought up by domain name squatters within weeks of me abandoning them. Those organizations presumably think that I forgot to renew - and then pester me to buy the domain back for some outrageous fee. Those are clearly not very nice people - so I'd be absolutely astounded if they'd be of any assistance to you whatever.

It's also possible that nobody will buy your domain name - and when it lapses, your email will simply stop working.

A third possibility is that somebody will buy the domain - but will not want to make it appear that you are an employee of XXX-corp by letting you continue to use joe@xxx.com because of the huge risk that you might say something inappropriate online and people would think that they had said it. So all in all, you don't have a snowball's chance in hell of getting someone to be that helpful to you - and certainly not without a prolonged break in service while they get their site set up and mail-servers running - during which you'd get no email.

If you want to keep your email address - then you very definitely need to keep ownership of the domain name...which, as others have pointed out...ought to be very cheap if all you need is email and a one-line HTML file saying that your site is no longer available.

SteveBaker (talk) 21:41, 9 November 2015 (UTC)

Got it; drop the hosting, keep the domain, add forward-only, changing registrars if necessary. The only piece I was missing was the possibility of forward-only support. Thanks all. 68.97.47.26 (talk) 07:18, 10 November 2015 (UTC)

Crypto-currency Mining

How profitable can crypto-currency mining of currencies like Bitcoin, Litecoin, Dogecoin, Peercoin, etc be if I can source all the electricity I need for free?--Lukepeters36 (talk) 19:04, 9 November 2015 (UTC)

Even with free power, you'd still likely need to invest in dedicated mining hardware, like FPGAs and ASICs, if you actually wanted to turn a profit. And those aren't cheap. 67.133.155.66 (talk) 19:33, 9 November 2015 (UTC)

Is this primal-general-simplistic axis accurate?

I'm just starting to learn some JS programming. I never did porgramming before and never studied even half a course in computer science. Trying to arrange my humble knowledge into a frame, I created for my self a primal, general, and simplistic axis that describes the main stages from the electricity in the Hardware, to the JS on the screen. Please tell me if I am wrong anywhere, in the most simple words you can:

Program.

^

One or more programming language(s). Usually high, in this level.

^

--- optional ---

Server database (Server DB).

^

Server-proxy (If there is one!).

^

Server.

---

^

OS shell 1 (CLI) || OS shell 2 == GUI.

^

Operating system [OS] (and it's DB's, like registry).

^

One or more programming language(s). Usually low, in this level, and surly in the levels under it.

^

One of the assembly languages.

^

Assembler.

^

Machine code (MC). Usually binary.

^

Electrical processes in the chemical hardware, bootstrapped and maintained by the nature of the hardware by a given electrical current.

Thanks, Ben-Yeudith (talk) 21:43, 9 November 2015 (UTC)

Unfortunately, we don't appear to have an introductory-level article on this topic. Operating system#Components and Kernel (operating system) aren't quite as impenetrable as most of our Computer science articles. Tevildo (talk) 22:06, 9 November 2015 (UTC)

Maybe include interpreters or compilers as well, below the high-level language item I guess. --Canley (talk) 06:18, 10 November 2015 (UTC)

Can you please (in great plea) detail a bit more; I know what they are doing (interpret row after row, or compiling all to a single end product) but I would like to know why you suggest to put them there, Thanks Ben-Yeudith (talk) 09:28, 10 November 2015 (UTC)

user:Canley? And user:Tevildo can you guys please elaborate more? It's very important for me to have these data. Ben-Yeudith (talk) 21:17, 10 November 2015 (UTC)

Well, I may have misunderstood your axis diagram, but basically a "program" in a high-level programming language without something converting it to machine code/binary and executing/running it is just text. I suggested it sits below the high-level language item because interpreting or compiling program code is dependent on the lower factors of the system such as the OS and the microarchitecture. --Canley (talk) 22:43, 10 November 2015 (UTC)

[ec] I'll see what I can do.

Let's start with the client machine. This has its own hardware, including the CPU, memory, and disk drive. When it boots up, the OS kernel is loaded from the disk drive into memory. This knows how to talk to the specific pieces of hardware in the machine, and is unique to it. On top of this runs the OS itself. This is common to millions of similar machines, and provides an API to allow developers to write applications for that OS (without having to know the details of each individual machine it might be running on). Part of the OS will be the TCP/IP stack, and one of the applications running on it will be the web browser.

Now, the server machine. This has its own hardware, OS kernel, and OS, on top of which runs the server application itself (Apache, or something similar). On the server is stored the web page which contains the JavaScript. The server application knows how to send this web page to the client machine.

When the user wants to visit the webpage, they use the web browser on the client machine. This sends a request via the TCP/IP stack, the modem, and the internet, to the server. The server then sends the web page, containing the JavaScript, to the client.

The web browser on the client sees that the web page contains JavaScript. It sends this to its local JavaScript interpreter. This calls the various API functions in the client machine's OS to display the application to the user and interact with them. It may also talk to the server (via the TCP/IP stack) to request information from the server database. Tevildo (talk) 23:00, 10 November 2015 (UTC)

If you're learning JavaScript, I don't think these are the sort of concepts you need to concentrate on. You should think about JS in terms of something like: a web browser and web pages it displays are sets of objects (see Document Object Model); each object has its own properties, events and methods; a script is a series of instructions, what JavaScript does is interpret these instructions to access and manipulate those attributes of certain objects. --Canley (talk) 00:31, 12 November 2015 (UTC)

I do learn Javascript and do concentrate on these concepts: Properties (Generally, holds values), Methods (Generally, Get's a value), Object (A part of the DOM), etc; I just want to have this axis before I continue to greater stages and because of more reasons I have to know it. BTW, I've sent you an email. Ben-Yeudith (talk) 03:10, 12 November 2015 (UTC)

November 10

Which was the first video recording format?

Could anyone tell which was the first video recording format?--Joseph 08:42, 10 November 2015 (UTC)

The very first was the BBC's VERA system (1952) using steel tape, but that wasn't particularly successful. The earliest usable commercial format was Ampex 2" Quadruplex (1956). The first domestic video recorder was the Sony CV-2000 (1965). Tevildo (talk) 09:13, 10 November 2015 (UTC)

And the earliest digital video format was CCIR 601 (1982). Tevildo (talk) 09:21, 10 November 2015 (UTC)

Thanks a lot.--Joseph 12:17, 10 November 2015 (UTC)

 Done

Are there different type of film magazines?

Which are the different types of film magazines..?--Joseph 12:42, 10 November 2015 (UTC)

Do you mean publications about films, or types of camera magazine? --Canley (talk) 13:25, 10 November 2015 (UTC)

Talking on general. I think that will include too.--Joseph 10:25, 11 November 2015 (UTC)

Slow connection in china

My access to wikipedia in Shanghai is incredibly slow. Assuming I manage to connect at all, the loading time of pages is nearly 5 minutes. Generally I can only access wikipedia with a VPN, which is inconvenient. This situation has only been occurring about a week or so. Does anybody know what might be causing this, and what I can do to resolve the issue? — Preceding unsigned comment added by 45.56.158.91 (talk) 13:20, 10 November 2015 (UTC)

The Great Firewall entirely blocks the Standard Chinese language Wikipedia and I think the Cantonese one too. It selectively blocks pages on the English language wikipedia (such as the Tiananmen Papers article). Further, because Wikimedia hosts all the encyclopedias on the same IP addresses (well, that's how it appears in the European cluster, I'm not sure that the Asian cluster is configured the same way) they can't do selective blocking based on IP address alone - they have to be parsing the URLs too - which is a much more resource-intensive task. If you're seeing slowdowns specific to Wikipedia, but not other international sites, it may be that the Great Firewall's filtering resources are in high demand. -- Finlay McWalterᚠTalk 13:42, 10 November 2015 (UTC)

If you use https, it will be even slower. The Great Firewall has to decrypt everything and then encrypt it again. 209.149.114.132 (talk) 14:09, 10 November 2015 (UTC)

Programs closing all over the place...

I was messing around in Control Panel on my Windows 10 PC the other day, and just for a laugh I attached a silly sound effect to the "Close program" event in the Sounds menu. Not surprisingly, the sound was played when I exited programs in the normal way, as I expected. However I found that it was also triggered at all sorts of random times – frequently, but with no pattern – when I wasn't actively using anything. I presume there are background tasks opening and closing all the time, but staring at Task Manager for a few minutes didn't reveal anything obvious. Any thoughts? – I'm just intrigued, rather than concerned! Cheers, Hassocks5489 (Floreat Hova!) 13:28, 10 November 2015 (UTC)

I would guess that services may be starting & stopping within various instances of svchost.exe, and they're firing the "Close Program" event for the OS while the host process continues on. I would also guess that other programs may occasionally do the same/similar things. FrameDrag (talk) 20:32, 10 November 2015 (UTC)

That would make sense. Interestingly when I looked at the svchost.exe article, it says it was introduced with Windows 2000 – and when I used to have a Windows 95 PC which had sounds attached to close program events, the behaviour I described above didn't happen, so that would suggest it is to do with svchost.exe. Cheers, Hassocks5489 (Floreat Hova!) 09:02, 11 November 2015 (UTC)

Windows 386-enhanced/95/98/ME was a completely different operating system from Windows NT/2000/XP/Vista/7/8/10. Consumer-oriented versions of Windows switched lineages between ME and XP. If the app-close-sound behavior changed then, it could be for any number of reasons because most of the code was rewritten. I doubt it's related to svchost.exe, which was just a performance optimization; the NT lineage always had services and the 95 lineage never had them. I doubt it's related to services at all, because they run in a separate user account that's supposed to be isolated from the GUI. My first guess would be third-party software of some sort. In this person's case it was BOINC. -- BenRG (talk) 18:41, 11 November 2015 (UTC)

Found this that might shed light on what exactly is making sounds, if you're still curious. I know I'm curious now... FrameDrag (talk) 21:48, 11 November 2015 (UTC)

Black hacking, Scammers etc., etc.

Good afternoon all. I am in my late 60's, a Briton in Britain, fairly IT Literate (as a regular user) and becoming increasingly terrified about logging into any of my very many internet accounts, whether Banks, Building Societies, Pension Providers, Amazon, Pay-Pal, Health Service providers, Store Accounts, Credit Card providers et al. I even play the National Lottry online. I buy plane and train and holiday bookings online. And I am very aware that I am not in the minority. Heck, even by posting this help for advice I will probably have made myself an attractive potential target for some unsavoury criminal. But unless I want to cancel all my online accounts and instead revert to carrying cash and keeping my nest-egg at home (under the mattress?????), how can I keep my identity and property safe. I never share my passwords, I change them frequently, and I never use the same password across my accounts. But is that enough? I have a regularly updated virus scanner and I double - lock my doors at night. Any advice would be most welcome. Thanks in anticipation. 92.236.124.188 (talk) 16:18, 10 November 2015 (UTC)

First fact: Nothing is secure. To make your computer secure, you must completely destroy it. Dropping it into an active volcano might do the trick. As long as there is any hint that it was once a computer, it is not secure. Second fact: There is no such thing as privacy. Everything about you is known by someone (many someones). The concept of privacy is a state of mind. Do you feel private? Feeling private does not mean you are private. So, what to do? You can make yourself less of a target by never using anything that has electricity running through it. Move to a cabin in the woods. Survive off of berries and squirrels. A more common solution is to make yourself a harder target. You are doing that. Don't sign up for every online service you see. When you do sign up, use a hard-to-crack and unique password. What many people do not do is delete the account when you don't need it anymore. I actually use a password so long that I could never ever remember it. Then, if I use the service again, I do the whole "I forgot my password" thing. For services I do use, I use strong passwords and change them every 6 months. Finally, expect to be hacked. Expect someone will steal your credit cards. Expect someone will steal your identity. What will you do once that happens? Have a plan in place. I talked to my bank and I know exactly what to do if my bank card is used by someone else. I talked to the Social Security administration and I have already gone through the paperwork required to claim someone stole my identity, just to see it work (they ended up showing that someone DID once use my SSN for a temp job in another state). So, you are doing better than most people. Most people freely share all their personal information and use passwords like "password" for every service. They use 1111 as their bank PIN. By simply being harder to hack than them, you are protecting yourself. 209.149.114.132 (talk) 17:15, 10 November 2015 (UTC)

Thanks for your contribution. It would be more helpful if you could provide references, as otherwise this is just WP:OR that you're asking us to trust on faith. SemanticMantis (talk) 17:17, 10 November 2015 (UTC)

Looks like you're using most of the best practices for internet security. Posting here won't make you any more of a target for anything. Most "hacks" and identity thefts work via botnets, i.e. they aren't after you, they're just trawling to see what comes up (things like port scanning). You will likely not be a specific target of attack unless you are a celebrity or very very rich, e.g. your threat model is probably not one of personal attack, though you may well be caught up in something like the Target security breach, but that affected people who used cards at brick-and-mortar stores too.

See also browser security. You might like the podcast Security Now, which discusses some of these issues. You don't mention what browser you're using, and advice will vary, but I like using NoScript with Firefox to help minimize my security risks while browsing. Also many people recommend setting the browser to use https by default, and possibly using the add-on HTTPS_Everywhere. SemanticMantis (talk) 17:17, 10 November 2015 (UTC)

Thanks folks. It seems that no longer can "forewarned is fore-armed" be relied upon. I was once travelling South from Scotland into Northern England when Pan Am 103 was exploded out of the sky killing 270 innocent folks (259 in the plane and 11 on the ground- -I think). And so it goes on. It missed us by a matter of minutes. You just don't know anymore. What a sad race of creatures we have become. But thanks again.Tenosynovitis (talk) 17:39, 10 November 2015 (UTC)

What's the longest a process has been waiting on a mainframe?

Obviously on an old OS that allows processes to get preempted indefinitely. 20.137.7.64 (talk) 17:22, 10 November 2015 (UTC)

I think you're going to discover that this is not a well-defined question: for example, are you including software that intentionally runs on a schedule? Surely, somewhere somebody has a software system that schedules work for many years in the future. Will you consider that to be "the same" process, if it has ever been virtualized and migrated to new hardware? Are you only counting work that has actually persisted on a single incarnation of a single piece of computer hardware? Is it "the same" process, in the technical sense, if the computer's system software has assigned the same work-load to a new process?

We can try to upper-bound this problem by seeking out the system with the largest uptime; but as you dive deep into the gory details of historical computers and installed infrastructure with complicate schemes for redundancy, you may even discover that "uptime" is not as well-defined as you think it is.

Nimur (talk) 17:43, 10 November 2015 (UTC)

The longest a process has been waiting on a mainframe would be Ada Lovelace's program to calculate Bernoulli numbers on the Analytical Engine. Program written in 1843, still waiting on the Analytical Engine being built. They built a Difference Engine in the 1990s, so all hope is not lost. Some would say that the program at [ https://www.fourmilab.ch/babbage/contents.html ] meets the criteria. See [ https://www.fourmilab.ch/babbage/authentic.html ].

(Note clever use of the fact that "waiting on a mainframe" can be read two ways...) --Guy Macon (talk) 18:20, 10 November 2015 (UTC)

I once optimized a mainframe program that was originally a batch job, since it took so long to complete. I got the time down to where it was fast enough to process interactively. When I showed it to a user, he wrote down the starting time, grabbed his coffee cup, stood up to go, then was shocked to see the results immediately pop up. But then his shock turned to disappointment, as he realized he'd have no more "bonus coffee breaks" in his day. StuRat (talk) 19:28, 10 November 2015 (UTC)

I found the story I was thinking of in my copy of Operating System Concepts, Sixth Edition, by Silberschatz, Galvin, and Gagne, page 162, though it starts with "Rumor has it..." Rumor has it that, when they shut down the IBM 7094 at MIT in 1973, they found a low-priority process that had been submitted in 1967 and had not yet been run. 20.137.7.64 (talk) 19:56, 10 November 2015 (UTC)

I don't think I believe it...http://www.cs.tau.ac.il/~nachumd/horror.html (item number 85) relates the story in the exact words you quoted - but let's look at the whole thing: "In a heavily loaded computer system, a steady stream of high-priority processes can prevent a low-priority process from ever getting resources. Generally, one of two things will happen. Either the process will eventually be run (at 2 A.M. Sunday, when the system is finally lightly loaded), or the computer system will eventually crash and lose all unfinished low-priority processes.... Rumor has it that, when they shut down the IBM 7094 at MIT in 1973, they found a low-priority process that had been submitted in 1967 and had not yet been run. From Silbershatz and Galvin, pp. 142-143."...so "either the process will eventually be run...or the computer system will eventually crash and lose all unfinished low priority processes". So for this to be true, we're expected to believe that the computer never once crashed from 1967 until 1973. That would be fairly remarkable - but not impossible. Now, let's look at this: http://www.multicians.org/thvv/7094.html - another remeniscience of that same machine. It recalls that the computer was used for Multics operating system development - and had switched OS's several times over the years. There is NO WAY for an old task to survive an OS switch. The story simply isn't credible. SteveBaker (talk) 23:19, 10 November 2015 (UTC)

Not necessarily. Multics had dynamic reconfiguration, and you could do things like adding and removing CPUs, memory, and I/O controllers while the system was running. Not the last CPU or last bit of memory, of course. That would require magic. Only if you upgraded the hardcore supervisor did you have to kill all processes and restart the OS, but big chunks of Multics could be replaced with newer versions by leaving old modules on disk when installing new versions. New processes would use the new modules, while processes that had already linked to the old versions would continue to use those.

This is mentioned in [ http://queue.acm.org/detail.cfm?id=1640399 ]:

"The real continuous approach comes from Multics, the machine that was never supposed to shut down and that used controlled, transparent change. The developers understood that the only constant is change and that migration for hardware, software, and function during system operation is necessary. Therefore, the ability to change was designed in from the very beginning."

Another common use of this method was running production and development as subsystems on the same machine. You could (usually, unless you needed to upgrade the hardcore supervisor) intall and test several new versions on development without disturbing the production side. And now we have gone full circle: you can do the same with virtualization on a modern PC.

On the other hand, if you look at [ http://www.multicians.org/mult-sched.html ] it is hard to see how a process could be starved forever. I also find it hard to believe that anyone would tolerate an overloaded Multics system for long. So I think it's possible but I don't buy it actually being true.--Guy Macon (talk) 10:31, 11 November 2015 (UTC)

It's inconceivable that over years of operating-system development, they never crashed the machine or were forced to reboot it. I might buy that an uber-reliable machine with a reconfigurable operating system might continue to run that long - but not if people were using it to develop the OS and had to test buggy kernel modules. Clearly this statement is meant as a kind of joke - based on the supposed reliability of OS and hardware and on the fact that the machine was so often heavily loaded...but it's certainly not plausible for a machine that was used to develop the very OS it was running. SteveBaker (talk) 19:12, 11 November 2015 (UTC)

As far as I can tell, MIT's IBM 7094 ran only CTSS. It was used to develop Multics, not run it. The "process" in question might have been a job of some sort that survived reboots. Still, the rumor is most likely a joke.

Regardless, the idea of processes that can survive OS upgrades is perfectly reasonable, even if it's not supported by any widely used OS today. It's a type of process migration. -- BenRG (talk) 22:09, 11 November 2015 (UTC)

The authors definitely infused humor into the book at points. From section 1.4, Operating System Structure, speaking of multiprogramming, "As long as at least one job needs to execute, the CPU is never idle. This idea is common in other life situations. A lawyer does not work or only one client at a time, for example. While one case is waiting to go to trial or have papers typed, the lawyer can work on another case. If he has enough clients, the lawyer will never be idle for lack of work. (Idle lawyers tend to become politicians, so there is a certain social value in keeping lawyers busy.)" 75.75.42.89 (talk) 03:23, 12 November 2015 (UTC)

SQL parametrisation question

It turns out that I have to maintain yet another project at work. The project in question is a tool that can make SQL queries to different kinds of databases, such as Oracle, MySQL and Microsoft SQL. There already seems to be an abstraction of all these in C#, so all I have to do is to find out the specific database type and construct a database connection based on it, and then I can access all of them through a unified interface as I please. But how do I do parametrised queries? The ways to mark the parameters in the queries can differ. For example, Oracle seems to use the colon (":") to mark a parameter, but the other databases might not necessarily do. Is there some unified way which would work for all of these, or will I have to resort to a hack to find the parameter character in the query and change it depending on the database? JIP | Talk 20:16, 10 November 2015 (UTC)

Does the tool have you make a selection as to which kind of database you intend to query? FrameDrag (talk) 13:23, 11 November 2015 (UTC)

Yes, it's set in a configuration file. JIP | Talk 16:49, 11 November 2015 (UTC)

In that case, I think the best course would be to use some other delimiting character and then, depending on that config option, convert it to the proper delimiter. There's not really a "unified" way to do it since they're all oh-so-slightly different dialects. You can make it appear unified, but behind-the-scenes the logic has to be there to interpret your unified notation to Oracle/MySQL/SQL Server.

The other option is to assume that the user knows the parameter delimiting character, but that presumes certain things about the knowledge level of the user, and depends on whether or not you're willing/able to reveal which type of database they're connected to. Though, with this option, you don't have to add a large amount of conversion logic. FrameDrag (talk) 19:57, 11 November 2015 (UTC)

I like the first option better, as it makes transition to a new database system far easier. StuRat (talk) 20:59, 11 November 2015 (UTC)

Detail(s) Handling software sought

Is there software available like MoneyManagerEX that can be synchronised with PC to phone and from phone to PC, for ‘Customer/Client/Company details’ handlings? An open source software is sought. -- Space Ghost (talk) 20:25, 10 November 2015 (UTC)

November 11

Digital camera focus length

Not sure if this goes here, or Science, or Miscellaneous. Please move this section if you think it goes somewhere else.

Consider File:Clelland House at maximum zoom.jpg, File:Trinity Memorial ME site, Clarksburg.jpg, File:Court east of Columbia, West Union.jpg, and File:The Stone House historical marker.jpg, all of which I took a few days ago with my Nikon D3200 camera on "Auto" mode, except with manual flash suppression. "Maximum zoom" used the zoom lens, and the others used the normal lens. You can see the lens focus length in the metadata sections of these images. Now the question: since the zoom is adjusted by physically rotating part of the lens (I don't just hit the "zoom in/out" button like on the previous camera), how does the camera know the focal length? Is it because I'm using the auto focus, rather than focusing it manually? I'm nowhere close to being an expert; I don't really understand most of the terminology. Nyttend (talk) 03:01, 11 November 2015 (UTC)

I don't think it's related to the auto focus. I think the lens would just have a sensor inside it which knows the position of the zoom ring and communicate the focal length to the camera. Vespine (talk) 03:19, 11 November 2015 (UTC)

Yes, there is a lot of processing capability in modern lenses, and a lot of data can pass back and forth through the 10 pins you'll see on the lens and the mounting ring. There is a little bit of information in Nikon F-mount, but I haven't struck on the magic Google string to find more details. --LarryMac | Talk 16:13, 11 November 2015 (UTC)

November 12