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July 4

Memory not entirely recognized by laptop

I have an eMachines E627 laptop, and I have two 2GB memory cards installed (which, according to the technical specifications of the system, is the maximum amount of memory permissible for this model). However, it seems that only the memory installed in the inner slot gets recognized by the system, whereas the memory installed in the outer slot does not. I experimented with the system and determined that each individual memory card works fine when installed in the inner slot. Is this problem common? How can I get the system to recognize all 4GB of memory installed? 24.47.141.254 (talk) 02:43, 4 July 2013 (UTC)

What operating system are you using, and how are you determining that it can't see all the memory? RudolfRed (talk) 03:04, 4 July 2013 (UTC)

Also, have you checked if all 4GB is visible to the BIOS? WegianWarrior (talk) 03:49, 4 July 2013 (UTC)

I am using Windows 7. When I run setup at the beginning, BIOS shows 2048 MB of memory (instead of the expected 4096 MB), and the "System" function from my Control Panel shows 2.00 GB of memory (not 4.00 GB). During my experiments, I tried inserting one memory card into the outer slot and leaving the inner slot empty, and surely enough, the screen did not display anything when I powered up. 24.47.141.254 (talk) 05:08, 4 July 2013 (UTC)

If your BIOS does not recognize more than 2GB, there is no way the OS will be able to see it either. Not sure how to fix though, sorry. WegianWarrior (talk) 06:49, 4 July 2013 (UTC)

Try booting with RAM in the outer slot only. If it doesn't boot, the slot is probably broken. Also, try putting smaller modules in each slot or just the inner slot if you have any available. -- BenRG 23:31, 4 July 2013 (UTC)

I would go to www.crucial.com with that computer and have it scan your computer, and let it tell you how much RAM it sees and how much RAM it can take. I looked for your model there but I didn't find it. But I've found Crucial.com to be reliable about memory. Bubba73 ^{You talkin' to me?} 03:29, 5 July 2013 (UTC)

Or get a program like Speccy: http://www.piriform.com/speccy - it tells you that information. Bubba73 ^{You talkin' to me?} 03:32, 5 July 2013 (UTC)

Calculating Pearson correlation coefficient with Python

def pearson_correlation(a,b): # Python 3
    if len(a)!=len(b):
        raise ValueError('samples are of unequal size')
    mean_a=mean_b=0
    for i,j in zip(a,b):
        mean_a+=i
        mean_b+=j
    mean_a,mean_b=mean_a/len(a),mean_b/len(b)
    x=y=z=0
    for i,j in zip(a,b):
        x+=(i-mean_a)*(j-mean_b)
    for i in a:
        y+=(i-mean_a)**2
    for j in b:
        z+=(j-mean_b)**2
    return x/(y*z)**(1/2)

This function takes two samples as two lists and returns the Pearson correlation coefficient of them. Is there any thing wrong with it? Czech is Cyrillized (talk) 02:56, 4 July 2013 (UTC)

I see some possible problems:

1. The usual way to make multiple assignments on one line in Python is

mean_a, mean_b = 0,0

I think an expression like

mean_a = mean_b = 0

is assigning mean_a to the result of the expression "mean_b = 0" - although in this case that could be 0 anyway, so this might make no difference.

2. Be very careful with integer division in Python. One of the oddities of Python is that any arithmetic expression that includes only integers returns an integer value - so 1/2 will return 0, whereas 1./2 will return 0.5 because 1. is a float not an int. So your final line

return x/(y*z)**(1/2)

will always return 1 (I think) because the value of 1/2 is 0. You could try

return (float(x)/(y*z))**(0.5)

or you could use the sqrt function, but you have to import that from the math module. And if your lists a and b only contain integer values, there could be a similar integer division problem when you are calculating mean_a and mean_b. A good rule of thumb is that wherever you have a division expression that you expect to return a non-integer value, convert the numerator or denominator to a float to force the result to be a float.

3. Not a problem as such, but the loop where you sum the values in lists a and b is not necessary because Python has a built in sum function that returns the sum of values in a list.

Gandalf61 (talk) 11:40, 4 July 2013 (UTC)

If I understand your mean_a, mean_b calculations properly, and taking into account Gandalf61's wizardly advice about floats, the calculation of those two can be simplified to:

  mean_a = float(sum(a))/len(a)
  mean_b = float(sum(b))/len(b)

turning 5 lines into two (and to my mind being much clearer). edit yeah, I didn't read Gandalf's last point before posting.-- Finlay McWalterჷTalk 12:48, 4 July 2013 (UTC)

You can also change those calculations for x, y, z into sums on list comprehensions, like

x= sum([(i-mean_a)*(j-mean_b) for i,j in zip(a,b)])

- although that's not such an obviously clearer piece of code. -- Finlay McWalterჷTalk 13:01, 4 July 2013 (UTC)

• Assignment isn't an expression in Python; x = y = 0 works by special dispensation, not because of expression rules. So it's evidently an officially endorsed way of doing multiple assignment (and it's pretty common in Python code).
• There's a near universal convention of putting spaces after commas in Python code. You should follow it for readability's sake. It's also good practice to put spaces around infix operators.
• In Python 3.x, the / operator returns a floating-point result even if the arguments are integers, and // does integer division (as described in PEP 238). Since Python 2.2 (released in 2001), you can write from __future__ import division at the top and then just say sum(a) / len(a), etc. This is a good idea for forward compatibility reasons.
• Finlay McWalter's sum([...]) can be shortened to sum(...) as of Python 2.4 (released in 2004).

-- BenRG 23:27, 4 July 2013 (UTC)

Why cant Graphics processing units keep up with Central processing units?

"Top" GPUs like Tahiti XT in AMD "Radeon 7970" and "7990" series Videocards or as GPU from Nvidia (GK110) in "GeForce GTX 780" or "Titan" labled Videocards work on a frequencies of 900-1000 MHz. Same time "TOP" CPUs from Intel like "core i7 3770K" or "core i7 4770K" run at 3500 MHz and additionally are known to overclock to near 5000 MHz as are CPU from AMD like "AMD FX-4350" starting even from 4200 MHz. Same with "big professional" brands like SPARC T5 (3600 MHz). Why is it that customers willing to pay beyond $ 1000 for a Nvidia "Titan" Videocard only get a 900 MHz GPU and one buying a 3500-4500 MHz CPU like "core i7 4770K" only has to pay $ 300. Also why exactly are GPUs not also clock atleast near with maybe 3000 MHz? --Kharon (talk) 07:18, 4 July 2013 (UTC)

Roughly, because "clock speed" is a really bad measure of performance. See Megahertz myth. Graphics cards do different things per clock, and they can use massive parallelism. In fact, GPUs are much ahead of CPUs in pure processing power, and there is an increasing trend to tap into that performance for general purpose computing. See General-purpose computing on graphics processing units. The high end Radeon Sky 900 is rated at nearly 6 TeraFLOPS, while the best multi-core i7 CPUs are stuck more than an order of magnitude behind that. --Stephan Schulz (talk) 08:29, 4 July 2013 (UTC)

Nonetheless it's an interesting question why GPUs tend to be clocked slower than CPUs. (I don't know the answer.) -- BenRG 23:29, 4 July 2013 (UTC)

Because clock speed is not the limiting factor for most GPU workloads. Unlike a typical CPU workload, there is much lower temporal locality in a GPU's operations. The little temporal locality that does exist already gets exploited by using a specialized pipeline. So, with little data reuse, the data transfer rate dominates performance. A very small parallel work-load, say four 32-bit integers wide, requires 128 bits per transaction. A fully-utilized GPU will therefore input and output 128 bits per clock - or, at 1 GHz, will require 256 GBits/sec of available bus bandwidth. No system-bus in the world can sustain that data-rate, at least not in 2013. So, clocking the GPU faster means that the GPU is under-utilized, most of the time. This is unlike the CPU, where a small amount of data is reused over many computer instruction cycles, taking full advantage of the processor cache.

If you look at the structure of a modern GPGPU, you will see that the best effort solution to this problem is to allow the kernel programmer to manage the GPU cache memory in very customized way. When I worked on the Tesla S1070, there were some 16 kilobytes of what you might handwavingly call the L1 cache - and using the CUDA extension to the C programming language, the programmer allocated that memory to each processing kernel (i.e. to each processing unit). Even with this kind of fine-grained control, it was uncommon to get as high as, say, 16 instructions per word for a typical massive parallel calculation. Inevitably, the cache was never very useful, and memory transfer time from main GPU RAM and system RAM overwhelmingly dominated the total process execution time. My program, calculating the wave equation, would burst for a couple microseconds, cranking along at an instantaneous rate of a few gigaflops at a time... and then stall for hundreds of milliseconds waiting to copy the result back to system memory, and copy in new work. Getting "lots of flops" isn't too hard if you have a thousand cores running at a mere 1 GHz! One billion instructions require just one millisecond of work! And our 960-core S1070 is now four-year-old technology - today's GPUs have more cores! Keeping the GPU busy for more than one millisecond out of each second - now that is still a challenge!

In other words, even at a mere 1 GHz, the GPU is still too fast for the memory and system to keep up. Clocking it faster burns power and accomplishes no extra work - the GPU will simply be spending more time waiting in a pipeline bubble executing no-op instructions. You can read about even more recent GPGPU architecture details at Nvidia's website: http://nvidia.com/cuda . Nimur (talk) 01:54, 5 July 2013 (UTC)

Thank you Stephan Schulz and Nimur for your very informative answers. But i still dont get why they need 2000 "stream cores" running on 900 MHz instead of 500 cores running on 3600 MHz. That wouldnt demand faster memory controlers and cache on Die can run on 3.6 GHz in CPUs already. That would clearly make GPUs much cheaper. --Kharon (talk) 10:01, 6 July 2013 (UTC)

Not every modern GPU is a massively-parallel behemoth; some are smaller, cheaper, and perform differently - better on some benchmarks, worse on others. For example, Intel HD Graphics are smaller and cheaper than the flagship Nvidia GPUs, yet they perform well enough for many common applications. GPUs for mobile platforms are designed to handle typical mobile workloads, so they have fewer cores and emphasize energy efficiency. Or consider the Tegra 4, specifically on its capability to shuttle data between a GPU, a CPU, and an ISP; it intentionally blurs the boundary between CPU and GPU logic. So, there is a lot of variety in the available platforms; today's technology capability defines a price, power, performance design envelope; and market forces dictate that the products available to end-users cluster around the extreme edges of that design envelope. Nimur (talk) 21:38, 6 July 2013 (UTC)

How does solar model works

Do all scientists use computer simulations and solar models to calculate future for the sun or only certain groups of astrophysics does that. Because I have problem think concrete details that is why I thought [1] when scientist do solar model all the variables are well-written. I cannot tell when they guess on the variable they don't know. When astrophysics create solar model do they have to fill out the data entry they are require to fill out all the variables? How can they guess on certain variables if they have to fill in variables on the solar model? If they don't know they can just leave that entry blank. Do solar model require all variables to be fill out in order to run the simulation? Can these two documents I linked above have alot of errors, I can't tell because I am not a concrete thinker--69.233.254.115 (talk) 20:20, 4 July 2013 (UTC)

Both articles are not based on the very latest data; one is from 1993 and the other is from 1997. The intended audience is also very different: The first is published in ApJ, a very well respected scientific journal in which astrophysicists publish the results of their research, and uses language and assumes knowledge that other astrophysicists would be familiar with. The second has a more popularist style suitable for being presented in a lecture to university undergraduates and the wider public at an observatory.

As I found out at university, there is no one standard computer model of stellar evolution and each model is (or at least our model was) wildly sensitive to the input conditions. For most models some data is well known, some has pretty good estimates (within a small range of values), and other data can be widely different. However, most computer models will treat a blank value as zero, instead of "I don't know", unless it has specifically been written to account for this. While zero pressure in space isn't too bad an estimate, zero kelvin at the star's surface is a really bad estimate. Astronaut (talk) 18:29, 5 July 2013 (UTC)

Does how old the articles are really matters on how accurate the information will be? How will newer data make older data more accurate. How will people be able to study things more accurate just 16-20 years timeframe? Is it short time frame phases only 10-50 million years needs deeper studies. So some models can estimate well, and others can range widely. What happens if you write "I don't know" on input entries? in astronomical time scale 100 million years really is only a small fraction of timescale right.--69.233.254.115 (talk) 20:12, 5 July 2013 (UTC)

July 5

mouse malfunction?

A lot of times lately an a browser when I click to go back, it goes back two pages. I'm wondering if the mouse is sometimes sending two "clicks" instead of one. Is there a way to test the functions of a mouse? Bubba73 ^{You talkin' to me?} 14:50, 5 July 2013 (UTC)

Try a paint program; if it's somehow generating two clicks the paint program would show two blobs and not one. 87.112.233.132 (talk) 14:58, 5 July 2013 (UTC)

I don't have a paint program loaded, as far as I know. Bubba73 ^{You talkin' to me?} 15:12, 5 July 2013 (UTC)

try http://api.jquery.com/dblclick/ On the "demo", when you double click it changes color.190.60.93.218 (talk) 16:25, 5 July 2013 (UTC)

Or try a Google search: online mouse click counter. There are even games about how many times you can click. PrimeHunter (talk) 16:32, 5 July 2013 (UTC)

But that doesn't tells if he has clicked or doubleclicked, also on Windows at Control Panel>Mouse you can modify the time limit on where to send a doubleclick. 190.60.93.218 (talk) 16:41, 5 July 2013 (UTC)

OK, I tried that link above and sometimes it is doing a double click. Then I went to the control panel/mouse and set the double-click speed all the way "fast". I clicked slowly, and sometimes it took it as a double click, about one out of 5 to 15 times. So it must be either the mouse going bad (it is a good Logitec but several years old) or maybe some malicious software. Bubba73 ^{You talkin' to me?} 16:57, 5 July 2013 (UTC)

This seems to suggest it might be a messed up microswitch; though this appears to be a common problem amongst Logitec users. Try plugging it into a different PC and see if the problem persists. Though you may have to end up replacing it. --Yellow1996 (talk) 17:45, 5 July 2013 (UTC)

Resolved

I went ahead and bought a new mouse a short time ago, but I haven't started using it yet. Bubba73 ^{You talkin' to me?} 20:58, 5 July 2013 (UTC)

The new one is working fine, so that is what the problem was. Bubba73 ^{You talkin' to me?} 22:30, 5 July 2013 (UTC)

Can computers/programs/algorithms/functions explain or create other functions or algorithms?

Is it possible that computers can create or explain functions? Like a normal human (programmer) does it all the time, Humans can do many things like from writing, drawing (abstract), etc... How can a computer do it? 190.60.93.218 (talk) 16:19, 5 July 2013 (UTC)

Synthesizing a new algorithm is a common process. This is sometimes lumped under the blanket-term polymorphic code - program code that modifies itself. There are many approaches. Among the most common techniques are genetic algorithms that try tiny modifications to a known, working algorithm; and gradually, the program evolves into an entirely new algorithm. The hard problem is not creating new executable programs - even a simple pseudorandom number-generator can easily spit out a random series of instructions! The difficult challenge is determining whether the new algorithm has accomplished a useful task. That problem is related to the halting problem; and it is also related to the discipline of optimization and classification. Some-how, the master control program needs to determine whether a newly-created algorithm falls into the category of "working" or "not working," which is a stickier problem than it seems at first glance.

"Explaining" an algorithm - in a way that a human can easily understand - is a challenge of natural language processing and semantic processing. This is a very new field - it is on the edge of very new research problems - so there are not really any currently-available tools that work out-of-the-box. Nimur (talk) 16:50, 5 July 2013 (UTC)

Note that "explain functions" is what a large part of machine learning is concerned with, i.e. finding a model that reproduces a given samples as exactly as possible. See e.g. computational learning theory for the more theoretical part of this. --Stephan Schulz (talk) 18:45, 5 July 2013 (UTC)

There are many programs that are designed to generate code, usually at a low level. For instance, a program that generates code to have a nice procedure to insert a record in a database while taking care of many things that are very boring to a programmer, like checking if someone tries to hack the system. The programmer would know exactly what the generated code would look like, it just saves a lot of typing and tiny but hard to find errors. Much cooler is it when the programmer doesn't know how a particular problem is solved. A compiler might be smart enough to think "You wrote 'if a=0 then a=1', but that will never happen so I'll just ignore that you wrote that". A much better example where the computer outsmarts the programmer is when you ask a database "give me all people living in Colorado, ordered by telephone number, who are actors listed on IMDB". Most modern databases don't start by first looking for all people in Colorado, then order all of those by telephone number, then removing every person that is not listed on IMDB. They make a "plan" and would for instance decide that, since there are not that many actors on IMDB, they should sort the names in IMDB, look up those names in the phone book of Colorado (which is much faster than matching all people in Colorado one by one. Such a phone book is called an Index), and after that sort just a short list by telephone number. While many people have thought about the ways such a plan should be made, the actual plan is completely dependent on the availability of an index, the number of people on IMDB, etc. There are even functions in databases where you can ask "how did you get these results" and "what other indexes would you like next time". I think that's where you can say the algorithm was really invented by the program instead of a human. (I think indexes will not even be created by people in the future, and databases won't "start searching" but will be "pushing" new facts they think might be interesting instead of having to be asked, but I'll keep the dreaming of a perfect database to myself :)) I don't think a computer would come up with a new sorting algorithm like Quicksort very soon if ever. I do think that the wisdom that a neural network develops while learning from looking at millions of tax forms or flight data recorders will at some point be completely automatically distilled into much simpler algorithms that are right 99% of the time, which is quite similar to how humans develop simple algorithms. Joepnl (talk) 00:51, 6 July 2013 (UTC)

The purpose of Bitcoin mining?

Can someone explain to me the purpose of Bitcoin mining? It's my understanding it's just hashing busywork. Are the hashes that mining generates have any purpose? --Navstar (talk) 19:26, 5 July 2013 (UTC)

Are you asking why individual people use their computers to do mining, or why the bitcoin system involves a mining component? They are quite different questions. Looie496 (talk) 20:52, 5 July 2013 (UTC)

The hashing is just busywork. See Proof-of-work system. People mine bitcoin for the same reason people mine gold, hence the name "mining". (Gold does have some uses, unlike bitcoin, but mainly it's valued because of its scarcity.) -- BenRG 00:58, 6 July 2013 (UTC)

Until someone discovers how to generate tones (or arrays and arrays) of BitCoins with a couple of mouse-clicks and forget about scarcity. OsmanRF34 (talk) 10:47, 7 July 2013 (UTC)

Bitcoin seems to be well designed cryptographically, so that's about as unlikely as someone figuring out how to cheaply turn lead into gold. Cryptographic attacks would be just as devastating to conventional currencies, since banks rely on cryptography to ensure confidentiality and integrity of transactions. Also, the number of bitcoins is fixed at ~21,000,000, and about half of those have been found already. If someone found the other half tomorrow, it might cause a catastrophic loss of confidence but it wouldn't intrinsically destroy the value of the existing coins. -- BenRG 22:39, 7 July 2013 (UTC)

Actually there's a subtle difference between Osman's worry about creating tons of bitcoins and Ben's comment about cryptography. The creation aspect of bitcoin would require processing sha-256 sums much faster, or reversing them, both of which are relatively unrelated to breaking ECC public key signatures. The latter would allow one to spend other's coins. The former would allow for creating lots of new coins (which of course would be quickly tuned back by the protocol because it adjusts to the mining rate). Shadowjams (talk) 01:10, 9 July 2013 (UTC)

MMO game Creating

....I Want To create an MMo Game i need to know just a few things....

1)Do i Need to be A perfect programmer to do this. or I simply can use many programs to make a Massive Game at last.

2)if i will use many different programs to create the game and then integrate/combine the results together. Example :

• using a program to create a map.
• using another program to design characters.

Then integrate the results to get eventually a Good Game. That will work or there is nothing like that at all???

3) If that works it will be able to be added to the other programs to make it MMO.

thanks Note:what i'am talking about may make no sense at all and that maybe because i don't see the whole thing clear so if that true....perhaps...you can give me some more explanation that will be really appreciated. thanks again

A MMORPG is a giant undertaking, and it's usually the work of dozens of people. 3D models for things like buildings and characters are often done in programs like Autodesk Maya, but mostly everything else has to be created by the development team. Maps are usually in a format that's peculiar to that game, so the team ends up developing its own map and scenario editing software. Sometimes you might use an off-the-shelf engine (from Unreal to Unity) or develop your own (a professional 3d engine is literally years of work). There's lots of work for programmers to do (network, game, graphics, tools, etc.), and not much of this can be bought off the shelf. MMORPGs are probably the biggest undertakings in game development, one that gets studios with lots of money and talented people into terrible trouble. I'd advise anyone starting out in game development to begin with small projects like flash games or iOS/Android game apps - even doing a decent job on a single player Android puzzle platform could take a talented person a year of work. -- Finlay McWalterჷTalk 23:15, 5 July 2013 (UTC)

What offers a gentle introduction to the programming side is an LPMud. Being text-based, it does not need all the artwork and deep multimedia frameworks. Also, it's more fun ;-). --Stephan Schulz (talk) 23:43, 5 July 2013 (UTC)

Yeah, you wouldn't have to be an expert programmer per se (you could just be the director of the project) and in that case you would need to hire some people who are. Either way you'll need a big team in order to create an MMO, so I third Finlay's suggestion that you start out small and work your way up. As a side-note, another good 3d model program I've worked with is 3ds Max, though I would reccomend Maya if you're starting out because (IMO) it is a little easier to get into. There are great tutorials available online for these sorts of tools. Good luck! --Yellow1996 (talk) 01:13, 6 July 2013 (UTC)

July 6

Separate clients for singleplayer and multiplayer

I've noticed that several games have done this practice, most especially first-person shooters. They would market the title as a single game, but it has separate executables for the SP and MP portions of it, while others, such as Max Payne 3, would just incorporate both in a single .exe, or just separate portions of it in two dynamic-link library files. Are there any real benefits to this, besides development, as separate teams could just do both portions at the same time?

Having multiple teams wouldn't be a good reason to have multiple executables, as both modes share so much code. And even single player modes are often built in a client-server way; single player has a local server where the game logic, physics, AI, etc. work (this division is evident in games like Quake and Half Life 2, where messages about, and variables to configure, the server are evident throughout the single player console). Not having the game/server logic in the multi-player binary makes for a smaller binary, but a modern OS demand-pages binaries anyway, so really that shouldn't be an issue. Perhaps single player Max Payne /isn't/ coded with a clear client-server divide, meaning the multiplayer version would either have lots of "if multiplayer foo else bar" checks or compile those out (which would mean a distinct binary); I don't know why they'd do things that way (the local server for single player seems like a simple, clever architecture to me) but maybe they do. Or it may all be an artefact of whatever anti-cheating technology they're using (PunkBuster or whatever), as such things check in the client binary for illicit patches (Blizzard's Warden does that kind of thing), and giving it the smallest simplest binary to check, with simply no exploitable game logic present at all, might make that a more tractable process. -- Finlay McWalterჷTalk 11:25, 6 July 2013 (UTC)

Permission to open Outlook file.

My computer recently broke so I bought a new one and downloaded the latest version of Outlook on it, and successfully added all my email accounts. So far so good.

But I have a copy of the .pst file from my old computer and for obvious reasons I want to be able to view it. But when I attempt to open it, it says "File access is denied. You do not have the permission required to open the file..." etc.

So can anyone tell me:

1. WTF? Who should need permission to access a file on their own computer?
2. More importantly, how to work around this?

Best, AndyJones (talk) 13:16, 6 July 2013 (UTC)

You may need to "take ownership" of the file in question. Instructions: XP, Win7. -- Finlay McWalterჷTalk 13:20, 6 July 2013 (UTC)

Excellent, that worked. Many thanks for your help. AndyJones (talk) 16:53, 6 July 2013 (UTC)

Wikipedia Dumps to import them to SQL

Dear Sir/ Madam

From website http://en.wikipedia.org/wiki/Wikipedia:Database_download, I have downloaded dumps from http://dumps.wikimedia.org/. How do I import these huge files to My SQL table format. I tried whats written in the website but it didn't work out.

Is there any easier and alternate solution. Its very urgent as I need to mine some data from the huge files for my journal paper.

Waiting for your reply.

Regards

Most of the dumps are XML, not MySQL-dump format, and need to be imported by a functional MediaWiki install, not MySQL's own tools. The process is described here -- Finlay McWalterჷTalk 20:05, 6 July 2013 (UTC)

USB 2 card (int. hub), power output

Useless w/o follow up. Board seems to be pro's for pro's only in my personal experience

If I replace a 2 slot USB 2 module with a 4 slot USB 2, do I get at least the same power on each slot like I had on my old card or will it be divided, like initial power divided by four? Was it divided by two with the 2 slot card? It actually comes down to the basic question on how much power I can get from a USB slot so I don't have to use something like a powered external USB multiple port devise? Think simple and you'll understand my question as I might not used the proper technical terms ;) Thanks in advance for any help, TMCk (talk) 23:55, 6 July 2013 (UTC) I assume you mean you're replacing a PCI usb card with a bigger one. Looking at Universal Serial Bus#Power, a USB2 device can draw 500mA from 5V, which is 2.5W. If we look at Conventional PCI, we see that a PCI card can pull 25W off the backplane. Obviously some of that is used to run the card itself (the UHCI/EHCI), but its unlikely that it's remotely close to using all of that 25W (only graphics adapters use serious amounts of power). So (as best as I can say without reading the datasheet for your proposed PCI adapter) it should have plenty of power to run all its ports (indeed, it would be defective if it had more ports than it could supply max power to). 87.112.233.132 (talk) 00:32, 7 July 2013 (UTC) Thanks for your input. My old USB (PCI) card is about 10 years old (yes, 10 years) and working fine but the other day I connected my GPS for power only and although it worked, my system told me there is not enough power to run the devise. Maybe it meant the devise + other devises connected to it, like an ext. hard drive on one slot and an ext. USB hub (with external power unplugged) with a printer connected. The latter is where I connected my GPS. I would love to install the 4 slot internal (PCI?) USB hub, run the (new) external drive + an older one and a printer one 3 of them while having 1 slot left for other temporary devises. Maybe I should mention that I have a couple of USB 1 slots in use on my PC too. Don't know if they could cut down the amps available at other hubs but if so, I can retire those. Can they [cut down the amps available]? What solutions are there for my system and which one would most likely work the best? And of course, which one would work with what I have? Any idea or do I need to post more information? Please stay on it, thanks, TMCk (talk) 01:58, 7 July 2013 (UTC) Also, I have no datasheet for my new 4 slot USB(PCI) card as it came "plain". All I can say is that is has 4 slots externally and one internally. If there is some info printed on the circuit board that might be of help please let me know and I'll provide anything printed on it.TMCk (talk) 02:10, 7 July 2013 (UTC) Add on: And if I need more power, do I have another option besides an external hub? And if not, is there something I should look out for when buying a new ext. hub? The one I have is not recognized by my system unless I unplug the power cord while starting up my system or coming out of hibernation.TMCk (talk) 00:06, 7 July 2013 (UTC)

July 7

Purpose of transformer component in USB charger/adapter

I have this USB charger/adapter. To use it, you connect either the wall or car transformer to the desired output plug through an extendable cable. The wall transformer's output is given as "5V(DC symbol)400mA±5%", and the car transformer's output is "DC 5V±5% max: 500mA". My question is about the cable, which itself is attached to a small transformer. It's labelled "input: DC5.0V 500mA, output: DC5.5V 350mA MAX". What is the purpose this transformer? --118.174.206.134 (talk) 05:17, 7 July 2013 (UTC)

I guess some devices need a 5.5V input, for example some Panasonic phones take 5.5V. So you need a small transformer to step up from the 5V from USB to the 5.5.--Salix (talk): 16:16, 7 July 2013 (UTC)

Dhaka Lahan, East Champaran, Biahr

Dhaka Lahan is small and peaceful village of Dhaka constituency. It is situated one km west from Gandhi Chowk Dhaka,There are Two wards in this village ward no 19 and 20,the total Population of this village is around 4600 of civilian,if voter concerns in ward no 20 is 1334 and ward no 19 is 900 by 2013.

This is the computing reference desk - do you need help finding information related to a computer topic? If you need help editing Wikipedia, start with WP:HELP or Wikipedia:Tutorial/Editing. You might also consider asking for help at the talk pages of Bihar constituencies, or East Champaran district. Nimur (talk) 08:09, 7 July 2013 (UTC)

iPhone needs Apple car charger?

OK, I have a generic car cigarette lighter to USB adapter I got probably out of the bin next to the cashier at Walgreen Drugs (i.e., it's really generic), which works on my old LG dumbphone and on my new Samsung smartphone, but won't work when my friend's iPhone 5 is plugged in to it; it's not the iPhone cable, since that works with the wall charger. Is there some handshake official Apple car chargers need to do to the cable? The phone doesn't come up with one of those "not the right cable" messages like my old Motorola used to do (even when the cable worked), it just doesn't acknowledge the existence of the car power supply in any way. Gzuckier (talk) 07:13, 7 July 2013 (UTC)

iPhones do recognise (some?) Apple chargers, and charge faster though them. But I've also charged them with generic USB chargers, and regularly charge mine via a computer USB port. In my experience, car USB chargers often supply marginal or below spec voltage (and current), so not all devices accept them. --Stephan Schulz (talk) 08:16, 7 July 2013 (UTC)

Remote administration: different OSs

Can you remote administer a group of users using different OSs (Windowses, Linuxes and Macs) from just one computer (running whatever is more convenient, but preferably Linux)? Or is it only possible when the OSs match (Windows - Windows, and so on)? OsmanRF34 (talk) 10:39, 7 July 2013 (UTC)

Remote administration might be of help. It sounds like it would be a hassle, but I would say it is possible. 64.201.173.145 (talk) 18:22, 7 July 2013 (UTC)

No, it's not. Maybe with a virtual-machine running the other OSs, but then you'll have to buy a license for them, I suppose. I was just wondering if there is a kind of universal interface for that (this is a vague hope). OsmanRF34 (talk) 20:36, 7 July 2013 (UTC)

RDP is available for MAC but not properly supported. You can get remote control software, and X-windows or SSH with command line may be available for the three main platforms. For user management I don't know if active directory can be integrated with any of the other OSs. Graeme Bartlett (talk) 21:18, 7 July 2013 (UTC)

What are you trying to accomplish with this "remote administration"? You have a few different ways of going about all this, depending on your needs. If you just need to perform some tasks on remote computers and feel comfortable with the CLI, SSH is very good for this and works regardless of the OS. If you need a GUI or are trying to show a remote user how to do something on their workstation, VNC will accomplish this and is also multiplatform. In either case, if you are not on the same network as the remote machine, you will need to forward some ports on the remote router's firewall (edit - on second thought do not forward ports for VNC to the internet, it would be a gaping security hazard) or create a VPN tunnel.

Please give us more detailed information about what you are specifically trying to accomplish so we can better help you. -Amordea (talk) 21:47, 7 July 2013 (UTC)

It's for a small company, sometimes it's about admin tasks like configuring your wireless connection to a new printer, how to configure the email client, or how to solve some problems in MS-Excel. The Mac inclusion is not very important. A perfect solution would be were a less utterly lost guy, preferentially using Linux, solve those problems. OsmanRF34 (talk) 22:09, 8 July 2013 (UTC)

AC transofrmer markings

greetings everyone

When an AC transformer says on its label that its secondary winding is as follows 0.....15 white white i.e. two wires of white coloring are designated as ground (0) and 15volts. but because it is ac I take it doesn't really matter which of these wires is exactly at one point in time is 0v or 15v.. so can I connect them to my pcb where it says 0 volts and 15 volts terminals interchangeably ? right? THAnks!!

Warning: I'm no electrician, so someone please correct me if I'm wrong!! But, I don't see why not. --Yellow1996 (talk) 17:53, 7 July 2013 (UTC)

I think you are correct for this, the polarity does no matter if neither side is earthed. For higher voltages, you should check the isolation, as the windings should be well insulted from the mains winding, and preferably near the neutral end. Graeme Bartlett (talk) 10:53, 8 July 2013 (UTC)

Broadband Reports - user names & PW hacked

I tried to log into my account at Broadband Reports but it wouldn't take my user name and password. I told it to email me the way to reset the password, but the email address it had on file for me is nothing like my email address. Broadband Reports talks about user names and PWs being hacked in 2011. I may be a victim of that. I used that password only on that site. So someone can log in and see my broadband test results - big deal - is there any other way that could hurt me? Bubba73 ^{You talkin' to me?} 23:26, 7 July 2013 (UTC)

The biggest concern when your account on a doesn't-matter-anyway site being hacked is if you used the same password on other sites. It's only pragmatic for a black hat, having obtained the password for Bubba73@broadbandreports.com to try to use it on Bubba73@gmail.com, Bubba73@yahoo.com. And maybe one of those is the registered password recovery address for DNS hosting, banking, etc. - something you've forgotten even exists. -- Finlay McWalterჷTalk 23:40, 7 July 2013 (UTC)

I checked and I didn't use that password anywhere else. Could they link my name to my URL or something? Bubba73 ^{You talkin' to me?} 23:48, 7 July 2013 (UTC)

If you are positive you never used that password anywhere else, then you have nothing to worry about; other than the creation of a new account if you wish to continue using that site. --Yellow1996 (talk) 01:12, 8 July 2013 (UTC)

Yes, I have a long list of the usernames and passwords I use, and I searched it. I have created a new user account there. Bubba73 ^{You talkin' to me?} 02:31, 8 July 2013 (UTC)

I trust that your "long list" is securely password protected. Dbfirs 16:04, 8 July 2013 (UTC)

No, it is not password protected. It is a file on my computer with a non-obvious name. Bubba73 ^{You talkin' to me?} 16:42, 8 July 2013 (UTC)

You would be much better off using a password storage program like KeePass. Have it generate cryptographically hard passwords per account, and you only remember the one password which gets you into everything, but which never goes over the wire. -- Finlay McWalterჷTalk 18:22, 8 July 2013 (UTC)

Yes, I would. I started this list long ago, probably over 15 years ago. That was the way back then. Bubba73 ^{You talkin' to me?} 19:07, 8 July 2013 (UTC)

Is there anything built into Windows 8 or Firefox or an add-on to Firefox that does what KeyPass does? Bubba73 ^{You talkin' to me?} 22:51, 8 July 2013 (UTC)

LastPass Password Manager. --Yellow1996 (talk) 00:58, 9 July 2013 (UTC)

Resolved

July 8

Installing Apache Tomcat for Eclipse on a Mac

Hi. I am currently trying to install Tomcat on my Mac using these instructions [2] but have quite quickly hit a stumbling block and need help. When executing the first line of step three, the shell returns to me the error message

The BASEDIR environment variable is not defined

This environment variable is needed to run this program

Then, when trying to execute the second line of step three, I see the output given on the webpage but also

Using CLASSPATH: /Users/Conor/apache-tomcat-6.0.37-src/bin/bootstrap.jar

touch: /Users/Conor/apache-tomcat-6.0.37-src/logs/catalina.out: No such file or directory

/Users/Conor/apache-tomcat-6.0.37-src/bin/catalina.sh: line 373: /Users/Conor/apache-tomcat-6.0.37-src/logs/catalina.out: No such file or directory

What do I need to do to make this work? I take it it's just a case of setting BASEDIR to the appropriate value (though I don't know what that value is) and creating the file catalina.out (thought I don't know where or what information it should contain by default). Thanks. meromorphic [talk to me] 11:47, 8 July 2013 (UTC)

This seems to be a fairly common problem for example see [3]. You might be able to just set use export BASEDIR=/Users/Conor/apache-tomcat-6.0.37-src. --Salix (talk): 12:24, 8 July 2013 (UTC)

why is memory so expensive in phones?

Why does Apple charge you $100 extra dollars if you want 32 gigs of space instead of 16 and $200 more if you want 64 gigs. What is so expensive about putting extra memory inside the phone?--Jerk of Thrones (talk) 17:46, 8 July 2013 (UTC)

Price discrimination Hcobb (talk) 17:51, 8 July 2013 (UTC)

I don't think that's shockingly expensive. I typed "price 32g dram" into Google and it seems to cost more than $200 at current rates, whereas "price 32g ssd" came up with things in the neighborhood of $100, but looked too big to stick in a phone. Are you maybe comparing against HDDs? That's not the right thing to compare; you can't really put an HDD in a phone. --Trovatore (talk) 17:57, 8 July 2013 (UTC)

The string to search for is "32gb sd". Which is well under $30 these days, if only Apple allowed SD cards to plug in... Hcobb (talk) 18:30, 8 July 2013 (UTC)

SD cards are slow. I don't know whether that's an issue for the phone in question or not. --Trovatore (talk) 18:38, 8 July 2013 (UTC)

Our OP asks why memory is expensive. The expensive part is making the whole thing work.

Nobody stops you from building a silicon fab in your back yard, designing your own digital logic to implement nonvolatile memory; worrying about all the troubles of electronic design automation and design for manufacturability; supplying high-quality silicon wafers that are not full of defects; acquiring the necessary photolithography machinery; spinning the photoresist, etching the wafers, dicing the wafers, packaging the wafers, gluing them to the phone in a way that does not break, snap, crack, or otherwise fail in any condition; making sure that the electronic connectivity is all working correctly...

...and of course, market pressure dictates that you must do all these things at a cost lower than anyone else who could supply an equivalent product.

But, despite much very uninformed propaganda designed with very nice bold-face fonts angrily declaring that this stuff ought to be easy for some reason, almost nobody wants to expend this sort of effort. Instead, most consumers willingly pay someone else to do it, and because there is a healthy market demand, the final retail supplier can charge $100, more or less, for 32 GB of memory. Nimur (talk) 19:06, 8 July 2013 (UTC)

Actually I expect a good class 10 microSD card is faster than the flash memory in the iPhone or at least the same (let alone a UHS class I) and you can buy one for under US$30 retail. To be fair, some of these probably have rather poor small file performance which you likely don't want in a phone, but not all and I think that's usually more related to the controller than the flash chip. Remember SD and to a lesser extent microSD (but the standards are basically the same) are used in devices far more demanding of speed, like some cameras and video cameras, than the iPhone or any phone.

In any case it's a moot point, SSDs cost under $1 per GB retail in the most bang per buck capacities which I think is currently around the 250GB mark. (A 32 GB SSD will probably cost more for various reasons in retail channels including the fact it's too small to be considered useful for anything but a cache drive but you should be able to buy one for under US$50. There may be reasons to pay slightly more depending on what you want from your drive but if you're paying $100 in the US for such a drive, I strongly expect you're paying way too much.) These are definitely faster than the flash memory in the iPhone (and while the sizes I'm referring to are obviously bigger and may use more chips and may use SLC rather than MLC, they also have more capacity, the size is as much about form factors and the faster speeds expected as anything).

I don't get why you are comparing the price of DRAM when the OP was clearly referring to flash memory in the question even if the title was unclear. The iPhone 5 only has 1GB of RAM whichever model you buy. And while there is surely some correlation between the prices of flash memory and DRAM since they're both part of related industries with similar manufacturers, the DRAM industry seems a bit insane with frequent lows due to gluts followed by manufacturers all cutting production to increase prices. I actually expect there's more correlation between HDD prices and flash memory since they still compete to some extent in the SSD market. It's a moot point though since HDDs are still far cheaper per GB while flash has cheaper per GB for a while now according to our SSD article it was in 2004 so it's little use taking in to account either.

Nil Einne (talk) 21:56, 8 July 2013 (UTC)

Trovatore, comparing DRAM to flash memory is a giant red herring distraction from the original question. You must know that comparison is shockingly misleading. As for the reason, it's simple price discrimination. If there was a product out there identical in every way to the current iphone, but one charged $30 and one charged $100 more for the extra storage, it's obvious. But there's not an identical one, so Apple maintains pricing power. Shadowjams (talk) 01:06, 9 July 2013 (UTC)

Well, whatever — I don't have a smartphone, never liked the idea much (I like large, convenient user interfaces for computing, and small, easily pocketable telephones), so I didn't know what sort of memory was being discussed. I'm not particularly a fan of Apple, their closed ecosystem and non-DYI-friendly attitude being prime reasons; I just didn't think this particular comparison was especially outrageous. --Trovatore (talk) 02:48, 9 July 2013 (UTC)

Whatever whatever. You don't need to be an apple fanboy to recognize that volatile memory is quite different from flash memory. Either you are much more ignorant than I expected given your history here, or you're being misleading in your comparison. Your concerns about Apple's closed infrastructure are quite valid, but I'm not sure why that requires the responses you've given here. Shadowjams (talk) 05:26, 9 July 2013 (UTC)

You're not making any sense, SJ. My response on the memory was if anything pro-Apple, in spite of my predilections; I was saying I didn't see their behavior as particularly out of line, at least this one time.

Of course I know volatile memory is different from flash memory, but I didn't know which kind the OP was comparing -- my bad, I suppose I could have figured it out if I'd wanted to go to the trouble. What I don't understand is why this upsets you so much. --Trovatore (talk) 07:56, 9 July 2013 (UTC)

Desktop remains black except task bar and mouse pointer

Hello there. Yesterday evening, I suddenly encountered this irritating problem. I don't know what exactly caused this problem. When I start my desktop (Windows 7, 64 bit), it appears completely black except the task bar which contains only start menu icon. Other icons in task bar don't show up at all. I can move my mouse pointer anywhere, but when I move mouse pointer on task bar it shows that it is processing something (I mean a "O" circling). I tried bringing task manager by pressing ctrl+alt+del, but even it did not show up at all. All I have to do is, reboot the system and run it either "Safe mode" or "Safe mode with networking". I can't run any software or applications that requires high graphic intensity (I am not talking about video game). Even I can't run office 2010, let alone video and audio. I checked the hardware but all seems working fine. My specs are:

• Core 2 Quade 9400
• Nvidia Geforce 9800 GT
• Ram 4 GB
• Motherboard Gigabyte UD3L
• Thermaltake power supply (750 watt)

What's the problem? What am I missing here? I shall be grateful if anyone help me out on this regard. Thanks in advance.--180.234.228.132 (talk) 19:38, 8 July 2013 (UTC)

Sure sounds like malware to me. If you have an antivirus program I would suggest you run a scan with it; and if not, then you should definitely get one (popular free ones include AVG, Avast!, and Ad Aware.) The malicious program is probably blocking task manager from appearing so you can't terminate it's processes. --Yellow1996 (talk) 00:52, 9 July 2013 (UTC)

Another possibility is that it's some piece of software which loads at boot time, and is caught in an infinite loop. Did you add any software or do any downloads/upgrades recently ? If so, you might want to disable those apps. StuRat (talk) 06:27, 9 July 2013 (UTC)

I have the same or similar occasionally happening with windows 7.x and Safari. The only solution has been close and reopen, sometimes after reboot too--but I cannot say reboot's necessary. μηδείς (talk) 06:30, 9 July 2013 (UTC)

Android Tablet Help

I have a Samsung Galaxy Tab 2 7.0, and I have the option of making a folder on one of the screens. This would be handy, but I can't seem to find out how to put anything in it. I have 6 files, downloaded from email I sent to a client, and would like those files sitting in the folder I made. However, when I go to the 'Download' folder, the only options I have are to either share by various means or to delete them. Is there any way I can get them into this folder? I really would like to have them there. KägeTorä - (影虎) (TALK) 21:41, 8 July 2013 (UTC)

Some intense Googling and I turned up this page (among many others); and it looks as though folders are only meant for app shortcuts, not your own files... --Yellow1996 (talk) 01:07, 9 July 2013 (UTC)

For some reason I have never been able to fathom Google doesn't consider working with files and folders in this way a core feature of android, so the only way to do this is using a third party app such as ES file explorer (this is just the one I use, there are many file managers available for android). This has the ability to add shortcutsto the android home screens by long pressing on the file/folder and selecting "more" then "add to desktop". Equisetum (talk | contributions) 14:33, 9 July 2013 (UTC)

July 9

66 years old and going soft in the head - I should have asked my 13 years old Grandson.

I recently signed a 3 year contract with T-Mobile/EE for an Android Smartphone (Samsung S3 Galaxy). It's brilliant - no complaints. I then went and bought for cash, an Apple iPad4. And now all the new info is coming home to roost and I have discovered that my 2 new toys are incompatible when it comes to putting all my PC Music in the iCloud because they operate on different platforms, plus I can't swap Bluetooth stuff without a cable instead of back to back. I don't want to let go of either piece of kit for at least a couple of years if at all possible, but don't want to wake up at 70 years of age and find once again I am an even older dinosaur than presently. Any advice will be gratefully received. Thanks in anticipation.80.6.13.178 (talk) 14:57, 9 July 2013 (UTC)

Is there a question in there? 64.201.173.145 (talk) 15:53, 9 July 2013 (UTC)