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July 24

Not sure if the piggybacking routers are helping matters?

Hoo boy. I just moved into a co-op, and I've been elected the IT guy and I've been learning everything I can to improve the house's internet speed. It hasn't been easy, and I'm basically going to walk you through what I've learned:

  • There are four routers in this house, we'll call them A, B, C and D. Every router has its own network with its own password.
  • I had purchased a set of four wifi boosters in an attempt to improve their speed. But I was getting very confused at the fact that the boosters were only successfully connecting to Router A. Every other router could not connect to its assigned booster, either wirelessly or with an Ethernet cable, making it impossible for me to boost their signal.
  • I just learned today that only Router A has actual service from our cable company provider (TWC). It's also the only router TWC provided. The other three routers were purchased separately by the house and (I can only assume) are piggybacking off of router A. We pay a single bill to TWC for all our internet.

My question: Should I leave those other routers in? Are they actually limiting traffic from router A and freeing up bandwidth or helping in any way, or are they only making the problem worse since router A is now having to handle multiple networks? I was planning to upgrade the routers, should I upgrade all of them? --Aabicus (talk) 01:32, 24 July 2015 (UTC)[reply]

I'm guessing router A couldn't handle all the traffic alone, so they adding more routers to "help". I suspect upgrading router A so it can handle all the traffic alone would have been the better option. My suggestion is to upgrade A to a level that can handle all the traffic alone, then test performance with the rest connected, then disconnected. StuRat (talk) 04:06, 24 July 2015 (UTC)[reply]
If it's a large house, that would explain their setup. Typically, large sites have to be served by multiple access points to provide adequate range.
Typically, you design large wireless networks with multiple access points (APs, or what you refer to as routers). For example, an 802.11g wireless network, under ideal conditions outside, has a range of 300 feet. Any obstructions (e.g., walls) will lower that range significantly. So, you first perform a site survey by measuring the strength of the signal at various distances from the access point. You can just use a laptop for the survey. Once the signal becomes too weak, you place another access point at that location. But you put the AP on a different channel. For example, 802.11g has three clean channels -- 1, 6, and 11. If the first AP was on channel 1, you place the next one on either channel 6 or 11. That way, they don't interfere with each other. So, my guess is that's what someone already did. They put four APs at your site because it's too big to be served by a single AP. They put each one on a different wireless "network" so it could have a different channel.
However, you don't have to create different networks to get a different channel. You can give them all the same name (i.e., SSID) but just change the channel. Keep the password the same for all the APs. That's how I would set it up.
Having said that, the channel numbers and ranges I gave above are only valid for 802.11g networks. Different 802.11 standards different ranges and channels, so I'd need to know the model number of the APs to give you more specific information. It'd also help to know the IP subnet you're using along with the wireless settings the APs are using (namely, the channel, 802.11 standard, and frequency band -- 2.4 or 5 GHz). Also, are all the APs on the same subnet? You can find this information by logging into the Web page for the AP. I'm also guessing the APs are connected to each other using Ethernet cables? Typically, the AP will have a single router port and multiple switch ports. They're usually colored differently. The router port is used to connect different subnets and the switch ports connect to the same subnet. Are they just cabled through the switch ports or the router ports? I would just connect them using the switch ports. Connect Router A to the cable modem using its router port but connect each AP to Router A using the switch ports. Then, make sure each AP is on the same subnet. Then, disable DHCP on all the APs except for one. Then, reboot every end-user device and AP at the site so they get new, consistent IPs. That will simplify things and make everything operate faster.—Best Dog Ever (talk) 09:20, 24 July 2015 (UTC)[reply]

Different colors in digital photo

If I remember rightly from last Saturday, both the nearer-to-camera tree and farther-from-camera group of trees (in the center, not the stuff farther away on the other side of the river) were the same color. Can we guess how they ended up in different colors in this image? For this photo, I used the 55-200 mm zoom lens for my Nikon D3200, zoomed in all the way, and it wasn't taken through a window or other medium. With other images on the same settings, e.g. File:Robert Buckles Barn from the road.jpg, it's not produced the same result, so I doubt that it's a systemic problem with the camera. Nyttend (talk) 04:14, 24 July 2015 (UTC)[reply]

I'm not sure that this is really a matter for the Reference Desk, but to my eye it just looks as if the air is a bit hazy. If you look at groups of trees at progressively larger distances from the camera, the farther they are the duller the colors are. --65.94.50.73 (talk) 04:31, 24 July 2015 (UTC)[reply]
Also bluer, due to Raleigh scattering. The camera has accurately recorded the difference in colour (I'm a Brit) that was actually there. However, when you were looking, your brain was automatically processing the "raw data" from your eyes to correspond better with your "mental model" of the world. It does this all the time in several differents ways, which is why, for example, you don't usually perceive the more distant of two similarly sized objects as "smaller", even though its image is smaller on your retina. Our article Visual perception hopefully gives some leads relating to this subject. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 13:22, 24 July 2015 (UTC)[reply]
Also, when you say the trees were the same color, did you go closer to them to determine this ? If so, the apparent colors of the trees would then be the same, without as much hazy air in between, as in the photo.
As for the Raleigh scattering, that is exemplified in the America the Beautiful line "For purple mountain majesties". (The mountains aren't really purple, but appear that way from enough of a distance.)
One way the camera actually could change the color of just certain trees is if the far trees were out of focus, and thus the leaf color was blended with the color of the background. However, it doesn't look to me like that happened here. StuRat (talk) 15:40, 24 July 2015 (UTC)[reply]
Couldn't go closer (thus the poorer-quality distant photo), because it's on the grounds of a power plant, and this is the closest the road goes to the site. I suppose the Rayleigh scattering is the right answer; it never occurred to me that the brain would "fix" it, but your statement makes complete sense. And of course the camera doesn't know to "fix" such a thing. Here I figured it was something with the digital camera; that's why the question came here, not WP:RDS. Thanks for the help! Nyttend (talk) 16:46, 24 July 2015 (UTC)[reply]
It's not impossible to fix this digitally. The camera would need to be able to determine depth at various points in the frame, measure the color change with depth, and then compensate for it. Of course, this wouldn't be perfect, as the absolute color might actually change for items farther away. Also, I think many people like the natural "purple mountains" effect. StuRat (talk) 16:59, 24 July 2015 (UTC)[reply]
I agree that this is most likely either Raleigh scattering or Mie scattering - primarily because you mention a the distance disparity between the two trees. But there are other ways this could theoretically come about. Suppose one tree had leaves that reflected only green light - and the other had some small amount of reflectivity in red light as well as in green. If you viewed the scene in white light - at midday, perhaps - the difference in color between the two trees might be too subtle to notice. But at dawn and at dusk, when the sunlight is very reddish/orange - the tree that reflects no red light would appear significantly darker than the one that reflects a tiny bit of red so that small difference in color would be greatly magnified. There are other possibilities too - the average orientation of the leaves to the direction of the sunlight might be different in one than in the other and that would produce dramatic differences depending on the angle of the sunlight when the photo was taken. If one tree had very shiney leaves and the other was relatively dull, then the difference might be hard to see on a cloudy day, but very evident when it's sunny. There are many possibilities. SteveBaker (talk) 03:01, 26 July 2015 (UTC)[reply]
Looking at the Y channel of the pic in the CMYK color space the foreground tree in question is very bright, nearly all the background black. Is that Raleigh scattering?—eric 04:08, 26 July 2015 (UTC)[reply]
More or less. The Rayleigh scattering (note spelling, everyone) makes distant objects bluer, and yellow is complementary to blue. I don't know much about CMYK, but when you're on the blue side of white, it will probably use little or no yellow ink (unless it's a very dark blue). -- BenRG (talk) 20:40, 26 July 2015 (UTC)[reply]
The camera is using color balance. During the night the visible spectrum is cut by the electric light. Light bulbs have missing blue light. Compact fluorescent lamps and other fluorescent lamps not not give enough red light. The digital camera does the color balance by gamma correction and looking up in the pictures histogram for the lightest dots (equals pixels). There are several parameters more used for good gamma correction. Some cameras allow to turn of the color balancing or saving raw images (uncompressed bitmaps from the sensor) to the flash memory. Gama correction is always a lost of quality. By amplifying the missing blue of lightbulb lighted pictures, the blue channel of the pictures becomes noisy. For that reason the camera takes multiple pictures to cover the sensors noise. This disallows to display fast moving objects clear and sharp when even focussed correctly. Settings decide between noise colors and sharp captured quick moving objects of the picture. A simple trick to help the color balance algorithm is to put a white paper or similar beside the objects an keep the paper in the view of the camera which is being cut out or removed by photo editing, later. --Hans Haase (有问题吗) 08:51, 27 July 2015 (UTC)[reply]
All very interesting, but how does it relate to the Q ? StuRat (talk) 20:00, 27 July 2015 (UTC)[reply]

Measuring computer literacy

Are there reliable statistics about computer literacy? For example, how many people can navigate the web, send and read emails, write a simple text with a word processor, make a table with a spreadsheet, install a program, configure a mouse, and so on? The corresponding article here in wk is kind of thin, btw. I'd like to find stats for Europe, US and Japan mainly. --YX-1000A (talk) 08:29, 24 July 2015 (UTC)[reply]

It is very difficult to tell if people can use what they have. It is easier to tell what they have and assume that if they are paying for something, they know how to use it. (As an analogy, I run reports on medications. I don't know what people take. I know what their insurance paid for and I know what the doctor prescribed. I assume that most people take some of what the insurance pays for and, if it is over-the-counter, they take some of what is prescribed. When working with millions of patients, I ignore the specifics about any one patient. Statistics over anecdotes.) Internet access is rather easy to track because someone has to pay for it. You can see U.S. statistics on Internet use here. UK internet statistics are here. I didn't find Japanese statistics, but I found Japanese websites that appear to be Internet statistics. If I could read Japanese, I could be certain. 209.149.113.45 (talk) 13:10, 24 July 2015 (UTC)[reply]
Schools and colleges might be a good way to check computer literacy for kids and young adults, as that is one factor on which they are likely to report these days. Employment agencies might be another source of info for adults. StuRat (talk) 17:01, 24 July 2015 (UTC)[reply]
Here is a "Survey of Literacy, Numeracy, and ICT Levels in England" (from 2011), published by the Department for Business Innovation and Skills (a ministry of the UK government). It's 425 pages, and computer literacy is only one of its topics, but there might be something useful in there. AndrewWTaylor (talk) 19:29, 24 July 2015 (UTC)[reply]

July 25

Group by

Hello guys! Have basically such problem with SQL. Will show my problem with an example. I have such table (of course, it is only a small part of it):

ll_from ll_lang ll_title
1 ab lorem
1 az ipsum
1 bf foo
2 bab some
2 baz random
2 bbf text
3 bab some
3 baz random
3 bbf text

So I group by them by ll_from column. I want to get those groups, which doesn't have value az in one of ll_lang columns, that is, I would need ll_lang<>"az", which of course doesn't work in where statement. For this example I would like to get such output: 

select ll_from, count(ll_lang)
from table
group by ll_from;
ll_from count(ll_lang)
2 3
3 3

Yes, it is for Wikipedia. In Wikipedia-related terms speaking, I want to get pages (ll_from), which aren't in some language Wikipedia (ll_lang), sorted by number of iw.

I don't know if this is a performant way of doing it but you could try it. Put this after the group by clause:
having ll_from not in (select distinct ll_from from foo where ll_lang = 'az');
91.155.193.199 (talk) 19:54, 25 July 2015 (UTC)[reply]
No, it wasn't working. But I was able to find a correct solution, had to use sub-select in where part :) So thanks fot the hint, @91.155.193.199: --Edgars2007 (talk/contribs) 13:46, 29 July 2015 (UTC)[reply]

Removing the default profile from Chrome

Hi, I updated to the latest version of Chrome yesterday, and would like to remove the default profile, you know the one where your username appears in the top right of the screen. Usually it can be hidden through navigating to chrome://flags/#enable-new-avatar-menu and selecting disabled. But this option no longer works. There is apparently another option to add --disable-new-avatar-menu after the chrome.exe part of the target attribute, but when I tried that just now it took absolutely no notice. I know this thing is billed as an easy way to switch between profiles, but as I'm the only person using my desktop it's completely unnecessary, so I'd rather reclaim the space for open windows. Can anyone help? Thanks in advance, This is Paul (talk) 13:15, 25 July 2015 (UTC)[reply]

ok, I'm now gonna answer my own question, since I just discovered why it wasn't working. It seems that the change only applies to a specific shortcut and not all of them. Having modified the shortcut on my desktop I then opened Chrome from the taskbar, but this shortcut was still unchanged. So I had to delete the one from the taskbar and then add the modified desktop shortcut to the taskbar. The start menu shortcut also needed to be changed separately. Anyway it all works fine now and that irritating profile has gone. Hope this helps anyone else who downloads the latest version of Chrome and doesn't want the new facility. Cheers, This is Paul (talk) 15:12, 25 July 2015 (UTC)[reply]

Crowdlogs

Last month I asked about crowd funding tracking sites, and User:X201 was kind enough to tell me about Crowdlogs, which tracks both KickStarter and Indiegogo, but they stopped working a few days ago, with "Something went wrong." appearing on their front page. Their twitter account doesn't have any recent news and their blog page just says "Error establishing a database connection". Does anyone here know if they are experiencing technical difficulties or if they are shutting down operations?

Kicktraq is still working (though it doesn't track Indiegogo) but Kickspy shut down at the end of March after receiving some heat from Kickstarter (though they say their decision to shut down was completely independent of Kickstarter's displeasure). Are there any Indiegogo tracking sites still in operation? -- ToE 20:34, 25 July 2015 (UTC)[reply]

There is an email address for Crowdlogs on their 'About' page - you might maybe want to ask. SteveBaker (talk) 11:55, 26 July 2015 (UTC)[reply]


July 26

How many levels of abstraction when running ?

When I run a java program, how many levels of abstraction are there? Is it bytecode - JVM - OS - machine language - physical switch?--Bickeyboard (talk) 00:33, 26 July 2015 (UTC)[reply]

That's gonna be implementation-dependent - and very often, there is a micro-code layer below machine code and above the level of physical gates (which in turn are abstractions of transistors and such). But the OS (Operating system) isn't a layer anywhere here. In a sense, the OS is nothing more than a different program that happens to be running on the same computer. SteveBaker (talk) 02:41, 26 July 2015 (UTC)[reply]
I wouldn't say the OS isn't a layer anywhere here. AFAIK, Java doesn't usually take care of things like file system implementations and CPU scheduling on its own; that's what the OS should do! That said, it is possible to run a complete program without any operating system (which is quite often the case in embedded systems). --Link (t•c•m) 14:51, 26 July 2015 (UTC)[reply]
No, of course Java doesn't do things like file systems - but the OS is more like a library as far as Java code is concerned. It's not a level of abstraction between JVM and machine code...no way. If it were a level of abstraction, then you'd be able to point to a complete description of your algorithm described in terms of the operating system - and that sentence doesn't even mean anything! And even if it was - it would still be implementation-dependent - you can run Java code on computers that don't even have operating systems. Consider something like Haiku-vm for Arduino - there is no operating system - there is no JVM either. It converts Java source code into bytecode, then uses a small C program to interpret the bytecode. The bytecode is never converted into machine-code either. Without reference to a specific implementation, the question doesn't even mean anything. You could (in principle) write a program to run on a Babbage analytical engine that would interpret ASCII Java source code directly from punched cards. It would still be a Java program - but there would be no byte code, no JVM, no OS, no machine language, no electronics...just a bunch of gearwheels. Java doesn't care how it gets executed...so it's meaningless to make generalizations about how it runs. Now, if you said "How is such-and-such implementation of Java run under Windows 8?", then we could provide a more definite answer. SteveBaker (talk) 01:16, 27 July 2015 (UTC)[reply]
It looks to me like the questioner thinks that the OS operates like a JVM. The OS is often referred to as an abstraction layer because programmers usually program for the OS, not the hardware. However, the OS does not convert the running program into machine code. It is a program that is running at all times and provides a common way to talk to a variety of different hardware devices. It is troubling to get tied down to a specific answer with "operating systems" because there is no universal answer to "What is an operating system?" It is clear though that it is not a "virtual machine". 209.149.113.45 (talk) 13:41, 27 July 2015 (UTC)[reply]

What language uses if!, enter!, exit!?

What language uses if!, enter!, exit!?--Bickeyboard (talk) 00:35, 26 July 2015 (UTC)[reply]

I don't know of one. Where did you see them? The context must provide some clue. Scheme has a builtin named set! and a bunch of functions with exclaimed names, but not the three you listed. Vim (text editor) uses ! as a modifier for some commands, but not those. -- BenRG (talk) 21:23, 26 July 2015 (UTC)[reply]
I used a stage play markup language (Shakespeare?) long long ago that ran on Perl. The markup language had "enter" and "exit" as commands for a character to enter or exit the stage. Once a character was in use, the ! was a shortcut for that character. So, if I had "John: I'm saying some lines." followed by "Exit !", it would add "[Exit JOHN]" to the stage play. I do not remember any conditionals, such as "if" in the markup language. So... you are probably referring to the Ruby programming language. 209.149.113.45 (talk) 19:35, 28 July 2015 (UTC)[reply]

replace character vs add character

I don't know how I got into this (perhaps some accidental control key combination?) but suddenly when I type text in the middle of a line, instead of just adding the next character, NotePad++ replaces the character, So, instead of adding 'c' as the sixth character of 'charater' -> 'character' I get 'characer.' What can I do? --Halcatalyst (talk) 16:49, 26 July 2015 (UTC)[reply]

I don't know NotePad++ but I guess you pressed the Insert key or chose it elsewhere. Try to disable the unwanted feature by pressing the Insert key. PrimeHunter (talk) 17:23, 26 July 2015 (UTC)[reply]
It worked, thank you! --Halcatalyst (talk) 17:47, 26 July 2015 (UTC)[reply]

Unicode Alternatives to: \ / : * ? " < > | in Windows filenames?

Resolved

The following characters are not permitted in Windows7 filenames:
\ / : * ? " < > |
Q: What are the Unicode characters that will look the most like them on a web page (from any browser or operating system) without giving any protests or problems from Windows when I want to use them in filenames?
(The three most urgently needed are alternatives to: the colon :, the slash / and the question mark ?).
Do you have any suggestions?
--Seren-dipper (talk) 17:44, 26 July 2015 (UTC)[reply]

One standard method is to use the Halfwidth and fullwidth forms - FULL WIDTH COLON (U+FF1A, ：), FULL WIDTH SLASH (U+FF0F, ／), FULL WIDTH QUESTION MARK (U+FF1F, ？). See the table in the article for the other symbols. Tevildo (talk) 18:10, 26 July 2015 (UTC)[reply]
Try the Unicode Consortium's confusables utility for some options. For : you can often substitute a dash. -- BenRG (talk) 20:27, 26 July 2015 (UTC)[reply]

Perfect! Thank you both! ☺
--Seren-dipper (talk) 01:51, 27 July 2015 (UTC)[reply]

Presumably you're aware that people will hate you if you do stuff like that. They'll try to type the file names and it won't work. Looie496 (talk) 13:09, 27 July 2015 (UTC)[reply]

hard drive error

File:Screenshot of HD error.jpg
screenshot of the error screen

This morning Windows started giving me warnings about a hard drive error. I ran SeaTools on it, and it detected a problem. It said to run SeaTools for DOS. I did that but it said "No hard drive found"... "no controllers detected"... I ran Chkdsk /f but it didn't find any problems. Is there some other free or cheap way to test for HD errors and try to fix them? Bubba73 You talkin' to me? 23:06, 26 July 2015 (UTC)[reply]

I suspect your hard disk controller requires a driver that was not available from the DOS version of Seatools you have. If it needs to be said, the very next thing you do before you run any more tests or whatever is ensue if you have ANY data you want to keep on this disk that it's backed up. In my experience, regardless whether you find some software that claims to have repaired your problems, a hard disk that's had an issue is just a ticking time bomb. The cost of disks these days, just replace it ASAP. Vespine (talk) 23:11, 26 July 2015 (UTC)[reply]
Thanks - it is a secondary HD and I have current backups. Bubba73 You talkin' to me? 23:22, 26 July 2015 (UTC)[reply]
What warnings did you get from Windows, and what problem did SeaTools detect? The only problem I can think of that might be (temporarily) fixable is bad sectors. You can run chkdsk /r to scan the whole disk for bad sectors and mark them as bad so that the filesystem won't try to write to them later. If any of the sectors were in use, you'll probably lose that data. Chkdsk will allocate a new sector for that part of the file, but I don't know what it does about the unreadable data; it may replace it with zeros, which could contaminate your backup. Hard drives with bad sectors are likely to develop more of them, causing more data loss, so it would be better to replace the drive unless you really don't care about the files stored on it. -- BenRG (talk) 23:53, 26 July 2015 (UTC)[reply]
I don't remember the exact errors - something about sectors, I think. I think that replacing it now is probably the best idea. I went out to get a replacement, but the stores that have internal drives wer already closed. Bubba73 You talkin' to me? 01:24, 27 July 2015 (UTC)[reply]
Warning: Inadequate try to repair may cause preventable loss of data. Use an external disk and a Linux Live-CD to backup data. Use another computer to get the CD/DVD's ISO-image. Just boot from the CD, but do not install Linux on such machine. In case of hardware damage, CHKDSK might not be able to write essencial blocks due phyically damaged sectors. First, do not overheat the drive. Second, backup You data first an mention, the files might be damaged already. Do not overwrite or delete existing backups. By booting from an other device, a damage of the operating system is skipped when accessing Your files. When finisted the backup, figure out if the drive is damaged phyically or the filesystem only which can be repaired or renewed by killing all data on the drive. To try a second backup I heard form a software called Spinrite. I suggest not to a drive with physical damage again. Even on notebooks the drive can be removed quickly. Today drives are installed in a tray or drawer of the computer as far it can be called a computer. --Hans Haase (有问题吗) 08:23, 27 July 2015 (UTC)[reply]

I've added a screenshot of the error. It still comes up periodically. I ran a check of the drive with HDTune Pro 5.6 overnight (it took a few hours) and it didn't find any problems. CHKDSK /F didn't find any problems. I'm running CHKDSK /R right now. It is out of warranty, but it is a 2TB internal so I can replace it for about $90, so that is what I plan to do. Bubba73 You talkin' to me? 16:10, 27 July 2015 (UTC)[reply]

Seconding Hans Haase's advice above. That error typically means the disk is indeed failing rather than needing defragmenting/repair. It may still last quite a while, but especially if it's your boot drive, you should back up your data now and replace it ASAP (as it sounds like you're doing). I had a drive (which I stored some programs on but didn't boot from) give me that error on startup for more than a year before finally dragging the whole system down to a slow crawl until I disconnected it. One of those things best dealt with sooner rather than later. — Rhododendrites talk \\ 17:01, 27 July 2015 (UTC)[reply]
Thanks. I bought a new drive to replace it; I'm waiting on an extra backup to finish. This is not my boot drive, but it is where I keep just about everything other than Windows and the installed programs.
I haven't been very fortunate with hard drives over the years - nothing near their claimed MTBF. I estimate that about 1 in 4 or 5 internal drives has failed during the live of the computer and 1 in 3 external drives. Bubba73 You talkin' to me? 18:25, 27 July 2015 (UTC)[reply]
PS - it is getting harder to get internal desktop hard drives in local stores. Bubba73 You talkin' to me? 00:28, 28 July 2015 (UTC)[reply]
Resolved

I got the new drive installed and it is being restored from a backup right now. Bubba73 You talkin' to me? 03:22, 28 July 2015 (UTC)[reply]

Good call.
Having been in charge of mainlining disk farms with thousands of disks in them, I have the following advice to maximize life:
  • Keep it cool. Heat kills hard drives. Extreme cold isn't quite as bad, but should be avoided.
  • Keep it away from vibration. Cooling fans are notorious for making the entire case vibrate.
  • Get a high quality power supply from a reputable manufacturer. Voltage spikes are bad for hard disks.
  • Powering down a hard drive one or two time a day is fine, and leaving it running 24/7 is fine, but avoid turning it off ten times a day.
  • Run the S.M.A.R.T. diagnostic utilities every 6-12 months. The CCleaner program is a good way to access S.M.A.R.T. from Windows.
--Guy Macon (talk) 05:57, 28 July 2015 (UTC)[reply]
Thank You all for reply. Defragging a damaged disk may cause valid data is moved from used sectors into damaged sectors. Is is causing further unnecessary loss of this data. Defragging moves blocks to get them lined up to have quick access by reducing the actuators cylinder change. Each cilinger change of the actuator is in milliseconds range. Never defrag an SSD. SSDs have loss of lifespan by writing. The each block has identical access time. --Hans Haase (有问题吗) 22:02, 28 July 2015 (UTC)[reply]

July 27

."Wikipedia" - the name

How did The Free Encyclopedia get its name "Wikipedia"? Does the beginning of the name "Wiki" come from Latin?

"Wiki" is the Hawaiian word for "Quick" - see History of wikis. AndyTheGrump (talk) 00:54, 27 July 2015 (UTC)[reply]
See also Wikipedia. Dismas|(talk) 01:15, 27 July 2015 (UTC)[reply]
...And History of Wikipedia while we're at it :) — Rhododendrites talk \\ 16:49, 27 July 2015 (UTC)[reply]

Decoding QRCodes the hard way.

I want to write my own QRCode recognizer from the ground up...I have lots of programming and graphics experience - so you don't need to use baby-talk - but I've not done much image recognition.

What are the basic steps in doing such a thing? Assume I have a 2D array of pixels from a camera at no particular angle to the QRcode as a starting point.

24.242.75.217 (talk) 01:26, 27 July 2015 (UTC)[reply]

Erm? Do you want someone to write you a tutorial? Have you read QR? There are more than a few resources online for similar projects. Vespine (talk) 01:32, 27 July 2015 (UTC)[reply]
Hmmm - I doubt either of those things will be of much use to our OP. QR Code doesn't say how it's decoded, and the Swift-reader description you linked can be summarized as "Call the QR-code reading library". Our OP said "from the ground up". I can't find a 'ground up' explanation.
I believe you start off using some kind of edge-recognition approach to recognize the three corner boxes (to be honest, I'm a little vague on that part!) - and once you know those positions, you can generate a matrix that you can use to transform the image of the QR code into a simple, axially aligned 2D square...and from that point on, it's just a matter of reading and thresholding the pixels in the areas where you expect the data dots to lie. There is an error-correcting code (Reed–Solomon error correction) that is applied to extract the actual data.
First you need to detect that there is a QR code. To do that you need to search for the FIPs (the three "finder pattern" squares). This paper talks about using Haar-like features; this discussion talks about using contour detection and analysis, which is a kind of feature extraction. Both of those examples use OpenCV to do the lower level stuff, but you can always choose to do that yourself. The ISO QR spec gives a rather simpler scanline-ratio based algorithm, but I don't know how robust that will be for real-world photos of QR codes. Once you've figured out the locations of the three corner FIPs, you need to transform the image so that it's square (because a real picture of a QR code will likely have some perspective distortion and some rotation) - that's discussed in the second link I give above. At some point (I guess now) you'll need to downscale so one black/white box becomes one pixel, and convert to a 1-bit image (a clever system will presumably use contrast for that, to accomodate images which have a shade gradient over them; a simple decoder might just choose to use a threshhold (based on the range of tones within the inter-FIP area)). From there, you can use the decode algorithm detailed in the ISO specification - this page links to that. If you want to read someone else's code that already solves the problem, you could try Zbar's, although I had a brief look at their QR code and it's rather tulgey. -- Finlay McWalterᚠTalk 11:18, 27 July 2015 (UTC)[reply]
The algorithms to locate barcodes can be explained rather easily. Locating a linear one, like an EIN or UPC, is nearly identical to locating a QR.
  1. Pick an angle from 0 to 180 degrees (this can be random, it can step through the angles, whatever...)
  2. Begin at a location on the left or top of the image and follow the angle across the image (the starting point can be random or step through every point...)
  3. If the pixel is blackish, record a 1.
  4. If the pixel is whitish, record a 0. (Some algorithms preprocess the image to get a point halfway between the darkest and lightest pixel to be the border between black and white)
  5. Scan the image for the sequence that indicates the beginning/end of the code, such as 1n0n1n1n0n1n where n is a quantity. You would match 101101 or 110011110011 or 111000111111000111 or 111100001111111100001111. Some algorithms allow for variance. So, this would match even though there is a missing 0: 11110000111111110001111.
  6. If you didn't find TWO beginning/end sequences (most barcodes require a special code at the beginning and end, so they come in pairs), go to the first step and start over.
  7. For QR codes, you now have a beginning/end box and the angle of the line between them. Scan at a 90 degree angle off both boxes to find the elusive third box. If you don't find it, go back to the first step.
Once you have the beginning and end of the barcode, scanning the lines or squares between them is a completely different process. This is just for locating the barcode. There are many algorithms that do this. The big trick is finding the "fastest" and "most reliable" method of locating the beginning/end codes. 209.149.113.45 (talk) 13:24, 27 July 2015 (UTC)[reply]
That sounds OK for 1D barcodes - but for 2D QRCodes, picked up via a camera - not so much. What you suggest presumes that the plane of the camera sensor is more or less parallel to the plane of the QR code so that a right angle in the QR code is a right angle in the photograph. If it's not then the lines between the top-left corner box and the top-right and bottom-left boxes aren't at right angles and the sizes of the blocks in the code will vary from one place in the image to another due to perspective and such. Also, the pattern of 110011110011 (or whatever) shows up in places other than the corner box. The QR code for my website (http://RenaissanceMiniatures.com) has that pattern showing up in several places - close to the bottom-left corner of the QR code for example).
A good algorithm should also verify that the detection of the three corner boxes is correct by looking for the smaller 4th box that's inset a few blocks in from the bottom-right corner of the code.
SteveBaker (talk) 19:22, 27 July 2015 (UTC)[reply]
Often an approximation of a Hough transform is used to estimate how the rotation of a photo of a 2D barcode. Then image rectification attempts to remove most of that rotation. Sometimes perspective control is used to remove most of the perspective projection distortion.
Alternately, I hear that some people use something like a generalized Hough transform#Circle detection process to detect the precise position of the 3 big fiducials (and sometimes the smaller fiducials), then use linear interpolation/extrapolation from those positions to find the approximate size and position of each "module".
Some of these steps are exactly the same for almost every 2D barcode.
"How to put your logo in a QR code" has a few details.
You might be interested in seeing how other people decode QR codes. There are several open-source barcode scanners available, including:
  • ZXing ("zebra crossing")
  • QrCode.Net [1]
  • Open Source QR Code Library [2]
  • ZBar bar code reader [3] (Thank you, Finlay McWalter)
(My understanding is that Wikibooks: Android/PhoneGap#Barcodes uses ZXing).
Is there a better place to describe and discuss techniques for decoding 2D barcodes "from the ground up", and ideas for designing entirely new 2D barcodes that are even easier to decode? (My understanding is that Wikibooks is more accepting of such "how-to" information than Wikipedia WP:NOTHOWTO).
--DavidCary (talk) 01:33, 29 July 2015 (UTC)[reply]

Movie file

Hello, I recently collected a movie of two copies, one of which is 1.56GB and the other 4.00GB.

  1. Which one of this should I keep in my ‘treasure box’?; both copies look alike without any defects/pixel issues…
  2. What software decreases the GB?
  3. What do I lose, together with the ‘kb/Mb/Gb’/What's the difference between the two files I possess; rather than the 'GB'?

Space Ghost (talk) 18:41, 27 July 2015 (UTC)[reply]

@Russell.mo: What format are the two files? What information do you have about them? Are these DVD rips? Captured streaming video?
The relevant articles are video file format, Comparison of video container formats (these two articles are actually a little redundant, it appears), and video coding format.
Basically a movie is a bunch of video data (for which there are multiple formats) and audio data (for which there are multiple formats) wrapped one of many "containers". The size of the original audio and video data, the kind of compression, and the level of compression are what lead to varying file sizes. Practically speaking, if they look exactly alike [and sound exactly alike] what kind of rationale would there be to keep the bigger one? — Rhododendrites talk \\ 19:02, 27 July 2015 (UTC)[reply]
It might be that the larger one has a higher resolution, but this difference isn't visible at the resolution he is using. The place I find the resolution is most obvious is in the credits, particularly the tiny tiny ones at the end, like these: [4]. StuRat (talk) 19:17, 27 July 2015 (UTC)[reply]
@StuRat: Where is the resolution in that image? Are you talking about the kind of film/camera/aspect ratio the film was shot in? It's indeed true that the resolution of the bigger file may be higher than in the smaller one and the difference is small enough that OP would need a bigger display to really notice. I suppose it's possible that the credits vary based on medium such that the DVD, BluRay, streaming, etc. versions all have their own figures, but that wouldn't be the same as what resolution the video file is, because not only can you reduce the resolution to reduce the size, but you can also artificially increase the resolution (no real gain, but it would certainly take up much more space). The resolution of the file should be visible in the properties of the file as visible through any playback application. — Rhododendrites talk \\ 20:38, 27 July 2015 (UTC)[reply]
You may have misunderstood me. I don't mean that they list the resolution there, I mean that you can get an idea of the resolution by viewing tiny credits. If they are blurry, it's low res. The image I linked to is only 640×360, and, as you can see, it's rather blurry. A 1920×1080 image would look crystal clear, but of course, only if you displayed it at full resolution, and it had never been downconverted then upconverted back to full HD, had a lossy compression applied, etc. So, when I get a copy of a movie, I go right to the credits to see if it's a good version or if it's crap. (If it's total crap, I may try to find a better copy or just not bother watching it.)
And yes, I have noticed that newer 1920×1080 movies have started using even smaller credits, just when I finally was able to read them all. It's a conspiracy I tell you ! StuRat (talk) 20:46, 27 July 2015 (UTC)[reply]
Ah. Yes. I did misunderstand. I see now that you're suggesting a practical test for comparing image resolution (focusing on a detail with high contrast). Makes sense. — Rhododendrites talk \\ 22:00, 27 July 2015 (UTC)[reply]
That's right. Just looking at what it claims is the resolution won't tell you if it's been downconverted then back up, or had a lossy compression applied, but this test will. StuRat (talk) 22:30, 27 July 2015 (UTC)[reply]
Rhododendrites, StuRat: '.avi' is on 1.56GB and '.mp4' is on 4GB. I heard and checked on the internet something similar to what both of you said, a long time ago, can't recall now, that either the picture/sound (or both) is affected. Based on your experience, up to what 'Kb/Mb/GB' would you guys suggest, in order to retain a movie? The bigger the better of course, but...? -- Space Ghost (talk) 22:55, 27 July 2015 (UTC)[reply]
In my experience it's a completely personal preference. Sometimes I don't mind retaining even a 800MB file of a movie, but sometimes i want to retain the 4GB or larger version. Is the movie very "visual"? Does it rely on special effects and amazing cinematography? (Big file). Or is it a indy drama filmed on a low budget? (small file). Would I watch it with friends if I'm having a movie night? or am I likely to watch it on the train on my ipad? (Small file). And, certainly not the least consideration: how much disk space do you have left? ;) but if you watch both and you literally can't tell the difference, just keep the small file. Vespine (talk) 23:10, 27 July 2015 (UTC)[reply]
Points you stated, noted, thank you.
1TB (931GB) RHDD, 560GB available. I have many useful softwares, good games and movies, and at least 10GB of adult videos (you’ll never get tired of it). I’m planning to make it a ‘treasure’ box (RHDD) for my upcoming future. -- Space Ghost (talk) 19:02, 28 July 2015 (UTC)[reply]
On the large end are VOB files, which is what commercial non-BluRay DVDs use. I find they take about 8 GB for a 2 hour movie. Did you do my suggested test and look at the smallest credits ? That will allow you to compare the visual quality. StuRat (talk) 00:08, 28 July 2015 (UTC)[reply]
Yes I have, thereafter messaging you guys yesterday, a slight blurriness seen that can be tolerated I guess, as I would not have known/noticed it if you didn’t point it out…thanks. -- Space Ghost (talk) 19:02, 28 July 2015 (UTC)[reply]

I thought mathematics could be used to estimate, for example if 1.50GB (.avi) file producing credible quality resolution and sound - comparing with the 4GB (.mp4) - then will at least (or less than) 1GB movie file do the trick, for treasuring purpose? Or does it also depend on the 'file extension'? If so, what 'file extension' is the best? -- Space Ghost (talk) 19:02, 28 July 2015 (UTC)[reply]

Well, it's all going to depend on the time, resolution, color depth, frames per second, etc., and some types of video (like traditional animation with large areas of constant color) will compress far better than others (like a dark scene with live action). And then there's personal preference for how much quality you are willing to trade off for how much space savings. Somebody might be able to answer on which formats (file extensions) are better, although again with lots of caveats. For your particular case, since you said the visual quality is acceptable on the smaller file, I'd use that one. StuRat (talk) 19:08, 28 July 2015 (UTC)[reply]

Migrating Fedora Linux to a new hard drive

My 2 TB hard drive for Fedora 20 Linux is almost filling up. I think it won't even last until Christmas. I can buy a new 4 TB hard drive, which should last for several years, but how do I transfer my system to it? I know I can just plug both hard drives in at the same time and use cp to copy my entire /home directory partition and the entire partition where I keep my photographs in (which takes up the vast bulk of the drive). But what about the /boot and / partitions? Can I just use cp to copy them across as well and have a bootable system?

I'm also planning to finally upgrade to Fedora 22 Linux in the process. But a fresh install of Fedora 22 Linux would mean I would lose all my installed programs, only keeping my personal data and my photographs. Is there a way to copy them across or do I have to reinstall them all over again? JIP | Talk 20:59, 27 July 2015 (UTC)[reply]

Copy the old disk to the new (boot sectors, partition tables, etc.) wholesale from the old disk to the new with dd (Unix). Then use GNU Parted to resize the partitions on the new disk to fill the disk up. I don't know anything about upgrading Fedora. 84.51.142.140 (talk) 21:18, 27 July 2015 (UTC)[reply]
With Fedora, you should be using lvm virtual file system. You can put in the new drive and expand your virtual partition to contain the new drive. See the many lvm expand tutorials for how to's.
Though brief, I agree with this. If you have the ability to add the new drive along with the old drive, use LVM. Fedora's Anaconda uses LVM by default (even if you only have 1 drive). So, you should have an LVM drive that you are using - which is a virtual drive that encompasses your current drive. Now, add the new drive. Now, hopefully, you installed system-config-lvm. Run that. It is a nice and easy GUI. You will see the second drive listed as unused. Select it and add it to your LVM. Now, you will see both drives as a single 6TB drive and you won't have to copy/move any files. 209.149.113.45 (talk) 13:47, 28 July 2015 (UTC)[reply]
That would be a good idea, but my current computer is actually my company's property, and it only has two drive bays, both filled up. One has my Fedora 20 Linux system and the other has a Windows 8 system I'm not allowed to wipe clean in order to install Linux there, it must remain intact. However, I haven't actually used the Windows 8 system in over a year. I might be able to simply remove it and keep it in a safe place, and then put the new 4 TB Linux drive in its place. If my company ever wants the computer back, I can simply swap the drives again, putting the Windows 8 system back in place. Then I have to buy a new computer with more drive bays. JIP | Talk 17:06, 28 July 2015 (UTC)[reply]
I would ask if you could just drop the Windows. The immediate answer is always "No", but sometimes you get a delayed, "Well, if you never use it and never update it and it is just sitting there wasting space, go ahead and remove it." I've been lucky. I haven't had to use Windows since 1994. 209.149.113.45 (talk) 18:36, 28 July 2015 (UTC)[reply]
The thing is, everything about this computer except the Linux drive and the Linux on it is actually my company's property, not mine. It's technically just on loan. The company has a finite amount of Windows licences and likes to hold on for them, and as well as that, the Windows drive has my company's own proprietary code on it. So wiping the Windows drive is not an option. Temporarily removing it is. And anyway, I've never used LVM like that before. My current Linux drive has separate partitions for /boot, /, /home and /storage. The last one is by far the largest and has all my photographs on it. It would be that partition I want to expand, keeping the others intact. Is that possible? And how does LVM across several physical drives even work? If the drives ever separate, will each have its own share of files or are the files themselves somehow spread? How is it determined which drive gets which files? JIP | Talk 18:45, 28 July 2015 (UTC)[reply]
I have never converted a hard partition into an LVM partition because, since about F16, LVM was default. I'm not certain that it is possible. But, as for working across multiple disks, that is exactly what LVM is used for. Instead of having multiple mount points, you have one root. Internally, it manages the disks (kind of like a RAID with no striping or mirroring). Once you have LVM running, you can add disks, remove disks, resize the volume, etc... I've also used it to get around problems. For example, I had a JBOD with 12T of data on a very old Gateway machine (yes - that old). The server would corrupt the disks all the time because, as I discovered, the SCSI driver never expected more than 4T of space to work with. So, I split the JBOD into 4 3T logical drives (staying well below 4T) and then used LVM to make it all one volume. I've also done what you are trying to do. I added a disk to an LVM, which was rather quick. Then, I told the LVM that I didn't want to use an older disk. It took a while to get everything off the old disk. Then, when it was done, I popped out the old disk and I was done. 209.149.113.45 (talk) 19:17, 28 July 2015 (UTC)[reply]
Well, if LVM was default since about F16 and I have F20, it might be that I'm already using it. I'll have to check. But I still need an answer to my question about the files. Does each physical drive get its own share of the files, or is the data spread out at a lower level? And how is it decided which drive gets which data? I need to know this so I know what to do when I have to update the drives again. And I think that to preserve the integrity of the files, it's a good idea to copy them all to a new drive every couple of years instead of keeping them on the same drive for decades. After all, every physical medium is prone to fault, and physical faults in the drive's disks themselves will corrupt the files. JIP | Talk 19:54, 28 July 2015 (UTC)[reply]
I just found out that F20 dropped system-config-lvm. So, there's no GUI for LVM. Why? They switched from LVM to LVM2 and the old tool wasn't apparently designed to handle LVM2. So, you are apparently stuck using command-line tools. They aren't actually complicated, just not as easy as the GUI. For example, sudo lvdisplay will quickly tell you if you are using LVM by displaying all logical volumes in use. 209.149.113.45 (talk) 13:50, 29 July 2015 (UTC)[reply]

Friends, has anybody seen the 2D (cartoon) version of 'Transformers'? I'm planning to download the complete version (full/all the episodes or seasons) using 'YTD' (Youtube Downloader), would anyone kindly guide me to the link(s) please? I'm also willing to change the 'downloader' if required...whatever you guys recommend... -- Space Ghost (talk) 23:08, 27 July 2015 (UTC)[reply]

Just a note that doing so is likely illegal wherever you may live. There's a 15 disc version available for purchase. Dismas|(talk) 13:19, 28 July 2015 (UTC)[reply]
Yeah, I forgot. Sorry.
I'd be grateful if you could let me know the title of the 15 disc version one... If can, does it have everything? All the seasons, episodes, and so on? -- Space Ghost (talk) 18:18, 28 July 2015 (UTC)[reply]
Which series of Transformers are we talking about? If it's the original 1980s one I'd also be interested in purchasing this 15 disc version. JIP | Talk 19:14, 28 July 2015 (UTC)[reply]
The 15-disc version is, to my knowledge, the original series (80's). To be certain, this is the series with Peter Cullen as Optimus Prime. See it here. 209.149.113.45 (talk) 19:24, 28 July 2015 (UTC)[reply]
That's exactly what I was wanting. And the price seems affordable as well. But will the DVDs play here in Finland? After all, the entertainment industry seems to be doing its utmost to set up limits on how people can use the content they bought fully legally and paid good money for. JIP | Talk 19:46, 28 July 2015 (UTC)[reply]
Only if you have a DVD player that will play Region 1 DVDs. Here is a link to the Transformers: The Complete Original Series in Region 2. CambridgeBayWeather, Uqaqtuq (talk), Sunasuttuq 00:54, 29 July 2015 (UTC)[reply]

July 28

Simulating scanner distortion

I'm looking for an online service that can simulate the characteristic distortion that a scanner makes. Basically I have a JPEG image of a document, and I want a JPEG image of how said document would look if it were printed out, and then scanned. Currently I'm printing them out and then scanning them, which is A. a waste of time, and B. a waste of trees. Please help me save some trees. Thanks. My other car is a cadr (talk) 13:52, 28 July 2015 (UTC)[reply]

What type of "distortion" do you mean ? If it's just a loss of resolution, that's simple enough. Or maybe it goes from a full color image to black and white ? That's easy too. If you could include before and after pics, that would help. StuRat (talk) 14:42, 28 July 2015 (UTC)[reply]
You've never seen a scanned document before? Here's a random example I got off the net[5]. Notice how there are random specks of dust here and there and that the edge of the document contrasts with the white scanner bed. The resolution doesn't need to be changed, and it can stay a colored image. My other car is a cadr (talk) 15:02, 28 July 2015 (UTC)[reply]
OK, so you are talking about a raw scanned image, not cropped to the document and not cleaned up to remove specks. No OCR either. StuRat (talk) 15:11, 28 July 2015 (UTC)[reply]
I have seen thousands of scanned images. Sometimes there are specks. Sometimes there aren't. Sometimes the text looks great. Sometimes it gets some aliasing. Sometimes there are lines cutting horizontally or vertically across the document. Sometimes it is tilted. Sometimes you can see text from the other side of the sheet. Sometimes the scans are in color. Sometimes they are grayscale. Sometimes they are strictly black and white. Sometimes they get darker. Sometimes they get lighter. That is just a few things that COULD happen - and you didn't explain a single one in your question. So, why do you think it is acceptable to ask a belligerent question like "You've never seen a scanned document before?" Try putting some effort into asking a well-formed question. 209.149.113.45 (talk) 15:15, 28 July 2015 (UTC)[reply]
Thanks, but I didn't see it as belligerent, they just didn't know that scanning causes a wide variety of "distortions" (defects). StuRat (talk) 16:45, 28 July 2015 (UTC)[reply]
For the speck/dust look, try something like this [6]. That might be good for single-page bed scanners, but it won't help with the shearing you get when a document feeder changes speed a little bit, nor things like the crease on the inside of book's spine. See also similar questions and decent answers here [7]. Here's even a way to do it in LaTeX: [8]. The Gimp has a photocopy-effect tool [9], and it looks like ImageMagick does as well [10]. SemanticMantis (talk) 15:22, 28 July 2015 (UTC)[reply]
Thank you so much! That ImageMagick command does the trick perfectly! My other car is a cadr (talk) 16:52, 28 July 2015 (UTC)[reply]
I liked the one suggestion of rotating it 1-2 degrees (in addition to speckle, downrez, etc). I thought that was a nice touch that really helps sell it :) Also funny that several of the other threads' OPs seemed to have the same motivation as you... SemanticMantis (talk) 18:28, 28 July 2015 (UTC)[reply]
BTW, I am curious, why do you want to make images look bad ? StuRat (talk) 16:47, 28 July 2015 (UTC)[reply]
Soulless bureaucratic machine expects each document to be printed out, stamped, scanned, and then shredded. Your tax dollars at work, people.My other car is a cadr (talk) 16:52, 28 July 2015 (UTC)[reply]
Resolved
So, you are basically cheating the government by pretending that you print, stamp, and scan the digital documents, right? However, how will you explain that there won't be any shredded paper left over? --Yppieyei (talk) 22:01, 28 July 2015 (UTC)[reply]
(This is off topic - OP asks questions, we give references if we choose. If you want to question the morality of the scenario, keep in mind you know very little about it. Also I'm reminded of a quote from MLK "One has not only a legal but a moral responsibility to obey just laws. Conversely, one has a moral responsibility to disobey unjust laws." [11] SemanticMantis (talk) 13:18, 29 July 2015 (UTC)[reply]

July 29

Extracting tagged text

What algorithm can I use to, for example, extract "abc" from "xxx<abc>yyy" if I give it "<" and "> as delimiters (or another, extracting mediawiki style templates)? What is the most efficient way to do this? 24.255.17.182 (talk) 01:33, 29 July 2015 (UTC)[reply]

The usual way of completing this sort of task is to use a Regular expression.--Phil Holmes (talk) 07:04, 29 July 2015 (UTC)[reply]
Right, that's sed, available by default on Unix (including OS X), and Linux systems, Windows users commonly access it via cygwin. Some text editors also have built-in regular expression support. SemanticMantis (talk) 13:12, 29 July 2015 (UTC)[reply]
The "algorithm" is very simple. Given a value START as the start character and END as the end character, then a STRING as the string of text:
  1. Make an empty string DEST.
  2. Set a flag TAG to false (or zero).
  3. Set a pointer to the first position of STRING.
  4. Set CHR to be the character in STRING at the pointer.
  5. If TAG is true:
    1. If CHR equals END, set TAG to false
  6. Otherwise (else):
    1. If CHR equals START, set TAG to true
    2. Otherwise (else), append CHR to the end of DEST
  7. If the pointer is not at the end of STRING, increment the pointer to the next character in STRING and go to 4.
  8. DEST contains all chracters in STRING, omitting everything found from START to END.
This algorithm does not handle escape characters. It is not better than a regex as it is the algorithm used by regex. 209.149.113.45 (talk) 13:36, 29 July 2015 (UTC)[reply]

Release data of Raspberry Pi 2 Windows 10 ARM port?

Hello everyone. Does anyone know when the free ARM port of Windows 10 for the Raspberry Pi 2 will be released? I would imagine it wpuld have been released when Windows 10 it self was released right? Thanks for your help in advance. —SGA314 I am not available on weekends (talk) 14:33, 29 July 2015 (UTC)[reply]

Information about this Microsoft port is available through their developer program: Windows for IoT, as announced in Windows 10 Coming to Raspberry Pi 2, a February 2015 blog update. Here are instructions: Setting up Raspberry Pi. Here are downloadable files. If you aren't already in the developer program, consider joining; they'll give you first-hand news and information long before it hits a wider audience. Nimur (talk) 14:45, 29 July 2015 (UTC)[reply]
Ok cool. so it has released already. Here is question 2. I have only 1 32gb sd card. So how would I setup the pi to dual boot off the sd card? For instance, on a pc you can set it up to boot into Linux or Windows on the same hard drive. How would I do this with Raspbian and Windows 10 n the Pi's sd card? —SGA314 I am not available on weekends (talk) 15:57, 29 July 2015 (UTC)[reply]

Glympse or alternative

Background: I will be an adjunct at another university this fall. It is a little over 1 hour's drive away. I will be giving myself 1.5 hours to drive there, but in that long of a trip, there is a high possibility of traffic issues. The class period is 1.5 hours. I don't want the students to walk out after 10 minutes if I am just 5 minutes away. But, how do I let them know if I am close or still very far away? Question: Is there an application that will share my location for a certain period of time with anyone and everyone in the world? I don't want to deal with having students sign up for a service and then become "friends" in the service and then install apps on their phones and then lose their passwords and have to reset them every class... I want to turn on an application on my phone and then anyone who knows something, such as my user ID, can see where I am until I turn the application off. I looked into the following:

  • Google Maps: I don't see how to share a "here I am" pin automatically.
  • Life360: I can only share with my "family" or "circle". So, everyone has to have an account and install Life360 to see me.
  • Glympse: This looks promising, but they have almost no documentation on their website. There is a video, but I don't watch videos. I am not illiterate and I don't have time to waste when I could quickly scan text (if there was text) ... trying to avoid a rant about the general shift of the Internet to publishing all information in videos instead of text.

So, any suggestions? On my end, I have a lot of resources. I own multiple web servers. I have an Android phone with GPS and I doubled the battery (screw the warranty). I have handheld GPS device that has WiFi. I can write my own Android app, but I would like to avoid doing so if someone else already wrote something that does this. 209.149.113.45 (talk) 15:13, 29 July 2015 (UTC)[reply]

For a decidedly "old school" approach, you might consider walkie-talkies. Although they claim ranges up to 30 miles, the longest you are likely to get is about 2 miles: [12]. Still, if you are pulling into the parking lot 5 minutes after the class starts, you should be able to use the walkie-talkie to tell everyone you are almost there. The advantage: You wouldn't have to rely on anyone checking anything, just leave the other unit plugged into it's charger and turned on in the classroom, and it will speak when you speak on your unit, without anyone having to answer it or check anything. If theft is a concern, I suppose you could lock it up in such a way that it can still be heard (in a metal cage ?).
I also agree that video sucks for giving info. When somebody asks or "answers" a Q here with a 2 hour video and no time index, I rarely bother to watch it. StuRat (talk) 17:08, 29 July 2015 (UTC) [reply]
I don't own the classroom. So, I would be dependent on one student to always be in the class with the other handset. Optimally, I would like to find something that I can embed in a web page. I own my web servers and I can ask that the first student in the class direct the overhead projector to my website, which would then have a map showing where I am - along with notes that I can update every day, indicating what they can do while I'm stuck in traffic. 209.149.113.45 (talk) 17:14, 29 July 2015 (UTC)[reply]

Networking switch query

I have 2 computers connected to powerline ethernet adapters, and a 3rd connecting to my router. This can be a little slow sometimes (at least for game streaming and stuff). To speed things up would I be able to connect the 2 PCs via a switch, and then route that switch to the router via a powerline adapter? If I send traffic from 1 PC to another does the traffic have to go all the way to my router then back (presumably what is happening now), or will it go via the switch, which should be much much faster, as both PCs have Gigabit ethernet? 81.138.15.171 (talk) 15:42, 29 July 2015 (UTC)[reply]

What I would first do is get a crossover cable (very cheap) and plug both computers into one another. You will need to hard-set the IP of each one to something like 192.168.0.1 and 192.168.0.2. Then, you will have the absolute maximum speed of data transfer between the two computers. If there is lag, it isn't the network. Next, if you think you can make your network better, a hub will do. Two computers on a switch is a bit of a waste - especially when you are combining both signals into one upstream. 209.149.113.45 (talk) 16:07, 29 July 2015 (UTC)[reply]

How to do a dual boot of Windows 8 and 10: no USB drive or DVD?

I have already created the hard-drive partition.

Currently running Windows 8.1, with a 1 TB laptop. —24.228.117.156 (talk) 16:30, 29 July 2015 (UTC)[reply]

There's not a single USB port on there? What input options are there? Ian.thomson (talk) 16:41, 29 July 2015 (UTC)[reply]
Considering that upgrading from Windows 8.1 to Windows 10 is done through windows update, using a USB drive or a DVD is most likely not necessary. —SGA314 I am not available on weekends (talk) 17:05, 29 July 2015 (UTC)[reply]
First you must create a botable image f the partition that contains Windows 8.1. Next, you must 'extract' that image onto the other partition. you will need a special program to do this. do a Google search for something like 'hard drive image creator' or 'bootable hard disk image creator.' when you find the right program, use it to create an image of your partition that contains 8.1. This file should be roughly the same size as the size of the windows 8.1 partition. You should store this file on a SEPARATE hard drive or if you have enough space, on the 8.1 partition. This will allow you to extract the image onto the other partition. It would be helpful if you gave the amount of space taken up on the 8.1 partition as well as the size of both partitions. —SGA314 I am not available on weekends (talk) 17:02, 29 July 2015 (UTC)[reply]
This is actually the exact same thing I am going to d as well except that i will use a separate hard drive instead of dual booting. —SGA314 I am not available on weekends (talk) 17:07, 29 July 2015 (UTC)[reply]
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