Wikipedia:Reference desk/Archives/Computing/2011 July 20

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July 20

Programming in MS Visual Basic

Can you do it without buying expensive tools? — Preceding unsigned comment added by 88.8.79.148 (talk) 00:56, 20 July 2011 (UTC)

Visual Studio Express is available at no cost. Products for all of the Microsoft development infrastructure are available at http://www.microsoft.com/express - including Visual Basic Express. All of the Microsoft Developer Network tutorials, API documentation, and information are available for no charge at http://technet.microsoft.com and at MSDN.microsoft.com. The official Microsoft Visual Basic Developer Center contains a lot of getting-started guides, tutorials, and technical notes. Nimur (talk) 02:49, 20 July 2011 (UTC)

If you want to try it on linux, you need something called Mono (software) for .NET Framework.[1] I kid you not. 99.2.148.119 (talk) 04:15, 20 July 2011 (UTC)

You'd be better off learning C or Perl and using a free text editor and compiler. ¦ Reisio (talk) 05:20, 20 July 2011 (UTC)

The OP specifically asked about programming in VB, so why should you assume he'd be "better off" doing something else? AndrewWTaylor (talk) 09:47, 20 July 2011 (UTC)

It's not an assumption. With C or Perl he can do more for less for longer and will be more employable. ¦ Reisio (talk) 21:18, 20 July 2011 (UTC)

Reisio, it's considered bad form to answer questions in this manner. It's not productive. If someone says, "what flavor of Windows should I get?," answering, "forget Windows, get Linux" is considered out of line for the Ref Desk. Your comment above is similar enough. If the OP asks, "what language should I learn?", feel free to offer suggestions, but if it's a question about VB, you should just let it slide. Anyway, you are making an assumption about what "better" means in the OP's context — assuming that doing "more for less" and being "more employable" (in some vague sense) is the "better" option. It might not be, though — the OP might be asking, for example, because the OP already has a job that requires learning VB, or because the code he or she wants to edit has already been written in VB, or whatever. That's what AndrewWTaylor is no doubt getting at. No language is objectively "better" than any other; it is always relative to the values one has in mind (some people want a language that sounds like an ape — in which case, Perl would be an awful substitute compared to Ook!). --Mr.98 (talk) 02:21, 21 July 2011 (UTC)

I concur. In addition the claim the OP will be more employable is unsupported by any ref. Do you know what the employment market for VB, C and Perl are in Spain? Nil Einne (talk) 08:58, 21 July 2011 (UTC)

I am not sure even in the US. My impression is that people developing in VB and other .NET products make up a huge percentage of the programming workforce even in the USA. I was surprised by this since one's experience amongst computer folk on the internet would lead one to think that they all write in Perl and use Linux, but I'm not sure that actually reflects the developer market. (And for the record, I loathe VB.NET, but what can you do.) --Mr.98 (talk) 14:51, 21 July 2011 (UTC)

Mr 98 has said much of what I was going to add. Other assumptions Reisio has made are (1) that the OP doesn't already know C and Perl; and (2) that he wants work as a software developer using VB: there are other possible reasons for the question. AndrewWTaylor (talk) 09:26, 21 July 2011 (UTC)

Thanks for the answers. No, I don't want C or Perl or whatever. I myself can program in Java, but I was not asking for me. I wanted to install a VB environment for someone at an entry programming level, in the same way people learned Basic as an entry level language (and then moved to another, more commercial language). 88.8.79.148 (talk) 19:43, 21 July 2011 (UTC)

I hope the original poster has found some of the above answers informative. Personally, I do not program at all in Basic, and rarely use any Microsoft tools these days; but I harbor no prejudice against them. I think Reisio might consider dropping some of his pre-conceived notions if he had actually ever used the Visual Basic Express development kit. I suppose "visiting the Microsoft website" and "downloading the tools at no cost" is too much effort; it is a lot easier to cling to ill-formed notions based on decades-old stereotypes. I notice that, despite vague claims about "better" tools for Perl or C, Reisio has not actually made any specific comment regarding the Microsoft Visual Basic language, nor its zero-cost toolkit and IDE. (I can name one serious issue that precludes me from using Microsoft Visual Studio in my hobby-projects, off the top of my head: the IDE is not open-source or freely licensed - but in perspective, how many Visual Basic editors intend to recompile and redistribute their IDE?) In any case, Reisio, if you intend to slander a tool, technology, or development style, at least make your claims specific and citable. Nimur (talk) 16:38, 23 July 2011 (UTC)

Is it possible to fool installer programs into thinking you have admin access?

I know some installer programs call for admin access (and will shutdown without it) when their program has no need to be administrator. According to this video [2] by recompiling the installer code I can eliminate this requirement, but are there any other ways? 128.143.175.123 (talk) 04:26, 20 July 2011 (UTC)

This doesn't answer your question but is relevant to what you're trying to do; you could try using Universal Extractor to simply extract the program from the installer. This should work for programs that do not require registry changes and special drivers to be installed. AvrillirvA (talk) 10:47, 20 July 2011 (UTC)

how does a computer decide to allocate computations to a graphics card?

I've tried googling this (howstuffworks yay) -- but I am still rather confused. Does the main CPU simply say, "oh look here is some information that looks like vector information! I'm sending it over to the GPU?" If I make a graphically intense program, with my draw functions and so forth, I'm guessing I am using libraries that explicitly makes calls to a graphics card? I notice that say if a dedicated graphics card is absent, the CPU can do the task anyway. It's bad at it -- but it can still do it. elle _{vécut heureuse} ^{à jamais} (be free) 07:30, 20 July 2011 (UTC)

A programmer explicitly instructs the program that certain functions will execute on the graphics card. In the case of a modern GPGPU, using a programming environment like CUDA or OpenCL, here's the general process:

• A special set of instructions are written using a specialized programming language (CUDA or OpenCL)
• A special compiler is used to convert that into machine code for the GPU (not for the CPU)
• A specialized linker with knowledge of the graphics device driver is used to cross-link the GPU code with a standard (e.g., x86) program.

At the lowest level, the way this works is with memory mapped I/O. A programmer who has access to the spec-sheet for your CPU, your motherboard, and your graphics bus writes a special C program that gets compiled using a driver development kit (in other words, a compiler who produces privileged code that has unprotected access to machine IO and memory, in a way specific to your operating system). By writing values to certain memory locations, the graphics bus communicates the GPU program to the graphics memory and triggers a start-of-execution.

In the case of graphical (non-GPGPU) programming, all of the above is generally true; simply replace "CUDA" or "OpenCL" with "DirectX" or "OpenGL." As before, the programmer writes code in a slightly modified variant of the C language, then compiles it and links it against the device-driver and the host executable that runs on the CPU.

Today's technology is not able to automatically detect that certain code is vectorizable and "decide" to run it on the GPU automatically. However, at compile-time, certain compilers can auto-vectorize to take advantage of SSE, multiple cores, or other vector instructions if they are built onto your CPU. On many modern CPUs, that type of vectorization can even be determined at runtime, using advanced out of order execution and similar runtime code reorganizations/equivalent-code-substitution. Nimur (talk) 11:33, 20 July 2011 (UTC)

I guess I should have mentioned: if you use a graphics library function, or a GPGPU library function, then all of the above work was already done for you by another software programmer; but at some level, somebody had to write the code and the commands to explicitly invoke the GPU. For example, every time you write a "draw line" call, or a "rotate and scale texture and render it to screen" function, the library is delegating that to a pre-built graphics routine that manages memory transfer and GPU instructions.

The onus is on you, the user of a graphical drawing library, to learn whether the library uses the GPU, uses the CPU, or makes an intelligent decision at run-time to select hardware- or software-rendering. Such a detail should be clear from the library's documentation. Nimur (talk) 11:43, 20 July 2011 (UTC)

Thanks so much! Last question: say a dedicated graphics card is absent, and we have to use that awful onboard integrated video card. I know awful performance is a given, but what exactly happens in that scenario, as far as instruction passing goes? elle _{vécut heureuse} ^{à jamais} (be free) 19:58, 20 July 2011 (UTC)

There's a difference between "integrated GPU" and "no GPU." If your system has no GPU, a few things might happen, depending on exactly what code you executed.

• If the library is smart, it will check the system hardware before executing code. Essentially, think of it as an if-statement that gets executed: if (hardware present) { use_hardware() ; } else { run_a_different_function_on_cpu(); } - and hope that the different function on the CPU produces similar results, albeit slower.
• If the library is crummy, it just assumes hardware is present, writes commands to non-existent memory locations, and potentially crashes your computer. You might see a segfault, or a blue-screen-of-death, or something similar.

An integrated graphics card usually has fewer capabilities, and less RAM. The software may query those capabilities, and decide (again, with an if-statement) whether to even try to run certain code. For example, in a video game, the software may realize your GPU is "weak" and decide not to animate clouds in the background. For example:

if (gpu_ram > 10000) { render_clouds(); }

else { /* don't bother */ }

You can use your imagination for more specific/realistic cases. Some software may make more dynamic decisions, based on measured performance (i.e., how long did it take to run the last block of code? Consider,

if (execution_time > 30 ms) { skip_rendering_clouds(); }

Properly-designed drivers essentially consist of the above pseudo-code "if" statement for each possible hardware-accelerated function. So, when GPU-A supports several functions, and GPU-B does not, and Computer-C doesn't even have a GPU, all three can run the same program with the same driver, who will intelligently decide which parts of code need CPU emulation, and which code needs to be skipped/ignored. In this way, well-designed graphics systems made by competent software-engineers are termed "scalable." Nimur (talk) 21:50, 20 July 2011 (UTC)

As a last note - (sorry to drone on so much) - if you want more realistic scenarios than rendering clouds, consider reading:

• Comparison of Nvidia graphics processing units

Pay close attention to the OpenGL API version supported. Now, read about different revisions of the OpenGL API for specific features. Presto: you now have a series of real, actual capabilities to fill in for your driver's "if (Installed_GPU supports Feature_X) { run_API_function_X1(); }" pseudo-code. Similarly, investigate the various revision-levels for OpenCL, CUDA, and other GPU APIs; and the capabilities offered by other manufacturers' hardware versions. Sadly, the explanations become more obtuse; after you get past the simple scalers, rotaters, and shaders, further graphics-capabilities become a little bit more esoteric than "render clouds". If you're a GPU engineer, "Texture Crossbar Environment Mode" makes perfect sense - of COURSE you'd want one of those to perform routing between different pipe caches! Imagine the performance boost due to reduced bus occupancy in scenarios where a pipe will be re-rendering a texture that was already rendered by a previous pipe! But it's hard to explain such features without giving you a dissertation, and I've already rambled. Nimur (talk) 22:19, 20 July 2011 (UTC)

Missing burner registry entries

I believe after I installed Nero 6, my iTunes started complaining of missing registry entries for burning, and said I should reinstall. I held off on it because iTunes takes an eternity to install these days, but a week or two later when I did reinstall, it didn't help. No burner programs are working. Is there any advice from the help desk on how to fix this? Mxvxnyxvxn (talk) 13:06, 20 July 2011 (UTC)

It sounds a lot like a problem with the filters settings in the registry, take a look at the Microsoft article here for more information and the changes you need to make to the registry to fix it (Make sure you reboot after changing them). Hope this helps!  ZX81  ^talk 13:29, 20 July 2011 (UTC)

Tried it, it's still not working. Mxvxnyxvxn (talk) 13:45, 20 July 2011 (UTC)

"what was the last city you logged in from???"

When I tried to log into Google's gmail, it asked me for either the answer to my security question, or WHAT THE LAST CITY WAS THAT I LOGGED IN FROM! Can anyone find any evidence of Google asking specifically the latter question, or was this a phishing (or man in the middle) attack, where it wasn't really Google? I've fallen for a fake paypal message in the past and had my account cleared. This time I just gave the "last city" answer, if it wasn't Google, I can't imagine how anyone could misuse that... Did I do wrong? Thanks... 14:11, 20 July 2011 (UTC) — Preceding unsigned comment added by 188.36.85.63 (talk)

Have you been logging into gmail from lots of different computers? I once tried to log into gmail from a library computer and it asked me for a mobile phone number to send a text message to "verify" my account. Since I don't have a mobile phone that was pretty much the end of that account and all the messages in it. My advice; don't trust google. Have a backup account, have accounts with other providers like yahoo and aol, and keep local copies of your important emails 82.43.90.27 (talk) 14:14, 20 July 2011 (UTC)

Yeah I know about "send to mobile", but my quesiton is about the cities - is there any evidence in any forum online that Google actually does that?? Or was it a phisher?? Yeah, I did log in from different cities in different countries, but in order for it to be real, it has to actually be something Google does - which would have evidence on the net or in forums! So, can anyone find anything like that? Does Google do this?--188.36.85.63 (talk) 14:45, 20 July 2011 (UTC)

I've had it before although it also gave the option to answer the secret question which I chose instead. The best way to avoid phising is to be careful what you visit as a smart phiser (most not bothering) will just replicate what the site actual does meaning knowing what the site actual does and does not do is often not very useful. In particular if you want to visit Google or Paypal or whatever, type in the address yourself and make sure you visit the secure (https) site and check the certificate when it's likely to be needed (although realisticly your browser should warn you). Doesn't trust other sites and particularly not links in email or IM to take you to Google or Paypal. Nil Einne (talk) 18:35, 20 July 2011 (UTC)

I should add I sometimes use Tor. IIRC I've never received the message before but received it a couple of days ago or so and received it again today suggesting it's a new thing, which may explain why there's not much discussion of it. I can't remember the first time but the one I just got says:

It looks like you’re signing in to your account from a new location. Just so we know this is you — and not someone trying to hijack your account — please complete this quick verification. Learn more about this additional security measure.

With the link to the page as shown so there is obviously a Google explanation and it is in fact linked from current verification request itself.

Nil Einne (talk) 07:45, 21 July 2011 (UTC)

I wonder what answer they expect: your actual last location (perhaps it was a village), the nearest town, the state capital, the location of your ISP's servers,your country, or maybe the place Google's rather faulty geolocation thought you were in? The company I used to work for in the UK, had all its internet traffic routed through the Brussels office and Google often presented the search page in French or Flemish. The IP addresses my ISP assigns, usually geolocate to the north of England despite me living in the south. How can the casual Google user possibly guess this correctly? Astronaut (talk) 14:58, 22 July 2011 (UTC)

Question about a certain kind of URL

Sometimes, I get URLs with very long strings of characters. For example, the CASSI result for Journal of Biological Chemistry is hosted at

• http://cassi.cas.org/publication.jsp?P=DXaT8ZV7yNcyz133K_ll3zLPXfcr-WXfc-eO0t37Of0yz133K_ll3zLPXfcr-WXf-9sRQmIIxJMyz133K_ll3zLPXfcr-WXfw9Ii__qPrXffzKcm8PwFCg

Now there's just no way this has been decided manually, so what exactly am I looking at here? How was it built? Is there a way to "decode" the url? Headbomb {talk / contribs / physics / books} 16:35, 20 July 2011 (UTC)

They just took whatever info you submitted and encoded it as a string. This is usually called serializing. You deserialize or unserialize to get the original information back. There are many methods for serializing, so it is rather difficult to know exactly what method was used. However, you can see that it contains some repetition that may expose the method. -- kainaw™ 16:58, 20 July 2011 (UTC)

To try to determine the type of encoding, I did some simple differential analysis. Comparing the results when one searches for 'aaa' vs 'aab' one sees the two strings are almost identical, except for 11 characters after "WXf". As this single bit change in the input changes all 11 output characters (an avalanche effect) it's likely that these 11 characters are a diffuse function of "aaa" etc. I don't know what this function will be, but it's likely something like an md5-hash, truncated, and encoded with something like radix64. -- Finlay McWalter ☻ Talk 17:30, 20 July 2011 (UTC)

A hash function is a one-way function. That is useless for this purpose. This is a serialization function because it must be two-way. You go one way to turn the user input into a string of characters. You go the other way to turn those characters into the original data. -- kainaw™ 19:25, 20 July 2011 (UTC)

Hmm.... well alternatively, is there a way to somehow crack the CASSI search engine? I'm selecting "CODEN" and search for "JBCHA3" to get the above string. (The end goal is to have a template that links to the CODEN result from CASSI, based on the CODEN itself, similar to ISSN 0123-4567 generated from {{ISSN|0123-4567}}.) Headbomb {talk / contribs / physics / books} 17:22, 20 July 2011 (UTC)

User-friendly tools to change MAC addresses?

With the recent political prosecution of Aaron Swartz falling close on the heels of the prosecution of a number of luckless teenagers who Wi-Fied to the LOIC website and pressed the button for Anonymous, it sounds like the abuse of MAC addresses for Big Brother purposes has hit the big time. And some years ago I remember reading that IPv6 was going to make them public on every packet of data transmitted anywhere on the Internet! So it seems like the general public needs a lot better tools than the semi-literate instructions in "MAC spoofing" (note: I'm not discussing actual spoofing; merely reliable randomization to protect privacy). Has anyone developed user friendly tools, for example for the typical PC user to ensure that a fresh MAC address is automatically generated each time it is powered up? Wnt (talk) 19:01, 20 July 2011 (UTC)

What exactly do you want? On most POSIX computers that have an ifconfig utility mechanism, setting the hardware's reported MAC address is trivial: simply edit the network interface configuration file /etc/network/interfaces/ and add a line, hwaddress ether 01:02:03:04:05:06. To do so from a GUI application is trivial; I can write a Java application in about three or ten lines that will display a "GO" button and run a script to do so. But, this only works if your network interface supports software-specified MAC addresses.

On a Windows computer, there is already a graphical utility, called the Control Panel, that allows you to graphically edit your network interface MAC address. As before, this only works if your network interface supports software-specified MAC addresses. (Here are detailed instructions from Microsoft to configure your network adapter's settings).

I think you are pre-supposing that a GUI will make this technical-process easy for non-technical users. While it may turn the operation into a one-click "GO" button, it has not simplified the decision-making stages: the user must still know how, why, and when to alter their MAC address; and the user must also profess the level of competence to verify the change, and establish whether the change was sufficient to anonymize their network-transactions, without breaking it. It is these followup steps that require technical proficiency, not the simple act of resetting the MAC address.

As a last note, you can not change your MAC address "any time you feel like it" and expect zero network side-effects. If you control your own ethernet link, you may be able to get by without any noticeable problem, but you seem to be misunderstanding the purpose of a MAC Address. It is part of the routing stack; it merely resides below the IP layer. Changing the MAC address at random will cause difficulty in the assignment and persistence of a DHCP address, for example. If you are connected to a link with a high volume of systems, all who randomize their MAC addresses very often, you will quickly be unable to receive an IP address, and will be unable to connect.

All that was rather long. Let me summarize this in one line: randomizing your MAC does not guarantee anonymity, so providing a trivially-simple user-interface would only serve to mislead non-technical users about the complexity of computer-networking. Nimur (talk) 19:44, 20 July 2011 (UTC)

I went through Device Manager and I don't see any obvious six-byte numbers. There are a tremendous number of 'details' and a whole lot of numbers but not those that I can see. The article suggested it was necessary to do other things like edit the registry to change this, which strikes me as a less than desirable alternative.

I understand that it's part of the routing, but my assumption (am I wrong?) is that if you change a MAC address, then connect the computer to a new Ethernet plug or Wi-Fi network it's never been on before, there will be no ill effects. What I'm not clear about is whether there are other numbers being released that compromise anonymity - but the goal of any user friendly app would not be to guarantee anonymity overall, but just to guarantee the MAC address was no longer a useful tool to any attacker. Wnt (talk) 20:14, 20 July 2011 (UTC)

If Windows' Device Manager for your network adapter does not show you a configuration for MAC address, it means that your device (hardware or driver) does not support software-configured MAC address. You can try to customize your network-driver or switch hardware. Nimur (talk) 21:26, 20 July 2011 (UTC)

Whether there's no ill effects will depend on what it's connected to. For example, if it's connected to a router which rejects any unknown MAC addresses then there will be ill effects. In the unlikely event you have a MAC collision there will obviously be ill effects. And of course even if there's no direct ill effects to your computer, don't be surprised if whoever own the device you are connecting to is not so happy with the negative effects you may cause by continually randomising your MAC address and chooses to ban you (or perhaps banning any MAC addresses they don't know or implenting other measures like a captive portal thereby making problems for others because of your selfishness and paranoia). BTW if you are concerned about your MAC address being exposed via IPv6 just enable privacy extensions or use an OS like Windows which has it enabled by default rather then fooling around with changing your MAC address for no reason. As Nimur has said this isn't going to mean your are anonmymous. Nil Einne (talk) 08:09, 21 July 2011 (UTC)

I would also note free online games have been using MAC addresses as one of the methods of blocking users for a very long time. And I'm quite sure so have any other competent network admin for tracking and blocked when it's available and needed. In other words, there's nothing new here except perhaps your knowledge of it.

And I think many people will call in to question whether an attempt to block someone from a network by the owners/administrators because said person's activity was unwanted by said owners/administrators (whether people agree with their view seems moot) is really 'big-brother abuse'. (Note that although the person involved was a fellow at the university involved, it sounds like their access did not come out of that as they used guest accounts to make tracking/blocking difficult.) Even more so when the person involved then goes as far as to secretly install hidden equipment, hiding their face when doing so. Even more so when the reason why they had to go to such lengths is not clear, since their intentions with what they were attempting to obtain are unspecified. And more importantly it doesn't appear as if any actual attempt was made to talk with the people involved, who presuming the intentions weren't to release copyrighted material may have then allowed rather then blocked access. So such ridicilous rigmarole wouldn't be needed to get around the attempts at blocking. This of course is largely distinct from whether or not that warranted prosecution. [3] [4]

Because of the high data charges in NZ I'm unlikely to be running any wifis which I allow public access any time soon. But if I did and despite being far from a libertarian or a strong believer in the sanctity of property rights, I would definitely do so with the proviso I'm entitled to block whoever I want, for whatever reason I want, and think other people who also choose to make a network available are entitled to do likewise. (And in fact I would be quite angry at those who treat someone else's public network as something they are allowed to do whatever they want with, including carrying out activity that is clearly unwanted. Because of the aforementioned reason that it's liable to lead to restrictions on those of us who respect the right of the people running the network to control what people may do with it, particularly when there is no commercial arragement between the network owners and the person using the network. )

Nil Einne (talk) 08:09, 21 July 2011 (UTC)

Perhaps I've been too general here.

• First off, you're telling me that Windows by default will not release MAC address information when connected by IPv6, period? This is good to hear; maybe a sourced statement about this in the right article would alleviate certain paranoia for many.
• Next comes Wi-Fi and MAC addresses. I'm not talking about random users on your company network - just people who drive up to a Wi-Fi hotspot, turn on the wireless network, think they're anonymous, but they're not.
• Then there are the free online games. Is the MAC tracking in that case occurring because the game software is running on the user's computer and prowls around for numbers to send (which is obviously hard to block)? Or are you saying that even over the Internet IPv4 there is some way the MAC address is being released (I hope not!) Wnt (talk) 14:53, 21 July 2011 (UTC)

1) GIYF, 2) Wifi "drifters" are anonymous to the extent that their computer doesnt give them away (such as tossing out easily identified cookies or logging into facebook) and that they aren't literally observed by someone looking around the area, and 3) Online gaming systems use the Mac address as a semi-indelible serial number by looking at the local network connection, where it is trivial to identify. IPv4 doesn't embed the MAC data anywhere. And for what it's worth, I agree with those that think "how do i change my mac address to become anonymous?" is begging the question; your mac address is semi-indelible but also essentially local and untraceable to the extent that if you don't willfully identify it (by connecting to a network with it and proceeding to do something that can be traced back to you anyway) you can't be tracked by using it. The Swartz incident was obviously not made any better/worse for anyone by the ability of the perpetrator to change his/her mac address. If you want to be anonymous online, don't go breaking into monitored areas to do things that generate a lot of visibility! --144.191.148.3 (talk) 20:00, 21 July 2011 (UTC)

1. The host part of the IPV6 address can be automatically filled using the machine's MAC address. That in no means that it must be filled with the machine's MAC address. It doesn't even mean that it is common to do so (or that anyone at all is doing it). There is a huge difference between what can happen and what is happening.
2. You are not anonymous when using the Internet - especially if you use anything that is popular. There is far too much money in tracking users to allow people to be anonymous. Just look at the AOL search dump fiasco and you can see how easy it is to identify people by usage instead of things like MAC addresses and IP addresses.
3. It is possible to use MAC address as an identifier. It is more common to let people identify themselves through Facebook or Google+. They sign into the service and then they are tracked on nearly every page they visit. No MAC address or IP address is needed - just the fact that they logged into some social tracking service. -- kainaw™ 20:11, 21 July 2011 (UTC)

Windows thinks my hardware has changed, but it has not.

I have WinXP sp3. I do not have Windows Update running automatically, but go to its website from time to time. The last time I did that, yesterday, it downloaded quite a lot, about eight or nine updates. I also installed two or three programs since then. I used the Windows Clean Up option, and it compressed about twenty times as much material as it usually does. When I went to a computer forum (not sure if I did this before or after the Clean Up), I had difficulty closing the Firefox page and a lot seemed to be being downloaded, so I right-clicked on the "two computers" icon on the bottom right of the screen and chose disable. The icon disapeared.

I restarted my computer to restore this icon, but I got something coming up saying that a lot of hardware on my computer had changed and I needed to re-activate Windows. But no hardware has changed, apart from my changing a DVD drive around a year ago. I restarted my computer, same thing. I used a System Restore point from two days ago, same problem.

Windows says I've got THREE days to re-activate my computer - not the THIRTY days I've seen mentioned on the internet for this problem. I went to Windows Update again to see if this was a known problem. Something about "Windows genuine advantage" came up and I ran it - I remember running it long ago without any problem. It told me to buy Windows 7, which I don't want. It would not let me check for any updates.

I have an old 2nd hand computer. It does not have any disks. I have found the MS sticker on it with a OEM product code on it. It has been working happily without these problems for one or two years. I recall I did the verification for "Windows Genuine Advantage" succesfully in the past.

What has gone wrong? What can I do to fix this? I'd rather get WinXP running again rather than having a sudden forced switch to Ubuntu. 92.24.187.93 (talk) 19:23, 20 July 2011 (UTC)

Sorry that'll this sound a bit obvious, but have you just tried reactivating it? (you didn't actually say). The same thing that's telling you to reactivate will also give you instructions on how to do this. The easiest way to do this is just to let it do it automatically via the Internet, but there's an phone option as well. However, you said about you found the sticker with the OEM code on it, so is it not stuck to the computer? OEM licence codes SHOULD be stuck to the computer as they aren't transferrable to another machine so I have to ask was it originally from another computer? (or just simply that the original person who built and initially installed the computer neglected to stick it to the machine?).  ZX81  ^talk 20:09, 20 July 2011 (UTC)

The sticker was stuck to the machine, I did not notice it at first as my scanner was on top of it. I'm puzzled why it says I only have three days to activate, not the thirty days that seems to be standard. I'm wondering if some malware is the cause of this. 92.23.36.253 (talk) 20:17, 20 July 2011 (UTC)

I restarted my computer and chose the "reactivate" option, or whatever its called. After a long pause and getting past the page where MS asks if it can send me lots of spam, it simply said my computer had been reactivated. It did not ask for the product code or anything. What was the point of that, Mr. Gates? Two hours of worrying that my computer was about to become unusable just so that you can try to get me to sign up to spam? That experience was an excellent advert for Linux. 92.23.36.253 (talk) 20:39, 20 July 2011 (UTC)

The Windows Genuine Advantage update probably forced a reactivation to make sure the software was legitimate (it likely found something that flagged up an alert, but wasn't sure and hence forced re-activation so the Microsoft server would confirm yes/no). That's basically the whole purpose of the WGA updates, to check/attempt to stop piracy of the operating system. It doesn't need your product code because it's already in the registry, it's only stuck to the PC for your purposes incase you need to reinstall it or there's a query. Also, it won't reactivate automatically because people complain about it sending information across the Internet without checking, hence it stopped to confirm with you. Hope this helps to explain what probably happened and glad to hear it's working again now!  ZX81  ^talk 20:51, 20 July 2011 (UTC)

Linux here I come. 92.23.36.253 (talk) 21:09, 20 July 2011 (UTC)

Wiping clean an iPhone

Resolved

My wife has just sold her old iPhone but she wants to wipe clean its memory before handing it over. Any thoughts on how to do that? AndyJones (talk) 19:28, 20 July 2011 (UTC)

Here is detailed information from the official Apple help site: iOS: Understanding 'Erase All Content and Settings' . You can also take the device to an Apple retail store for assistance. If you don't currently have the device in your possession, but you set up the Find My iPhone application, you can also cleanly wipe the entire device using Find My iPhone's remote-wipe tool. Nimur (talk) 19:37, 20 July 2011 (UTC)

Hello, you can try this: On your iPhone, go to "Settings", then go to "General", and there should be an option that says "Erase All Contents and Settings". You can try looking here or go to Apple's Support Page for more information on wiping your iPhone before re-selling it. -- Luke ^Talk 19:39, 20 July 2011 (UTC)

Great advice, thank you! AndyJones (talk) 19:57, 20 July 2011 (UTC)

iPad app, for only one system

Could a museum develop a very bare bones iPad app for its display, and have it on the tablet for the public to access, without being connected to the internet, without offering it in the app marketplace, without joining the Apple iPhone Developer Program... basically it would be there and there only. Is this possible? -- Zanimum (talk) 20:48, 20 July 2011 (UTC)

With a wireless routing system you could offer a local web app. ¦ Reisio (talk) 21:22, 20 July 2011 (UTC)

Really? That's great! -- Zanimum (talk) 15:50, 21 July 2011 (UTC)

If it's for a public-facing kiosk use, you probably want to disable the general iPad user-interface (both from a security and a ease-of-use-and-support perspective) - that's true either if your interface is an app or, as Reisio suggests, a web-app. Some Google searching suggests this and this; I've no personal experience of either; the latter one also offers some other museum-kiosk type features that you might want. The advantage of a well-written web-app is that it should work much the same on an iPad, an Android tablet, or on a regular Windows, Mac, or Linux PC. -- Finlay McWalter ☻ Talk 16:16, 21 July 2011 (UTC)

If you really needed it to be an app then you can join Apple's Developer Enterprise Program, which allows you to load apps yourself (without using the app store) - but it costs $300/yr. If you're talking about delivering content to only one, or a handful, of iPads then this isn't a very cost-effective way of doing things. -- Finlay McWalter ☻ Talk 16:36, 21 July 2011 (UTC)

For this sort of situation, a tablet based on the Android (Operating System) might work out better than an iPad. It's easy and free to install an app on an android tablet without going through the google marketplace. (For kiosk use I'd be sure to get a tablet with a iPad-like capacitive touch-screen, and not the cheaper resistive touch-screens.) APL (talk) 06:24, 24 July 2011 (UTC)