Wikipedia:Reference desk/Archives/Computing/2013 April 18

= April 18 =

STEAM Game install problems
I just tried to install the game "Sniper: Ghost Warrior". I entered the 'key code' etc, was told it was installed (after what seemed like an unusually long wait), but my Steam account itself still says "NOT installed". Shut down PC, re-booted, & logged onto Steam again, but still "... not installed"!

2 days ago I 'installed' the game Homefront, and that also is not working. It appears to be stalled in the middle of an update. Nb. Steam defaults to automatically updating, so as soon as you load a game it starts making large downloads.

In addition I already had Metro 2033 installed, and after playing it since installing Homefront that has also changed to "not installed". It gave me message when starting the game about "needing to store Metro files in another format" or words to that effect, perhaps I clicked on the wrong button!

Is this a common problem with 'Steam'?

Any ideas on what to do? --220  of  Borg 03:38, 18 April 2013 (UTC)


 * What machine are you using? If it's a Windows PC my first move would be to try uninstalling those games via the Windows control panel, if you can.--Shantavira|feed me 07:10, 18 April 2013 (UTC)


 * Yes, Microsoft Windows 7 Home Premium (32 Bit) on a Toshiba laptop (Satellite L750 Model PSK2YA-05210), 4 Gb memory and about 150 Gb free HDD space. Uninstalling is certainly something to try, but then I will have to get on the Internet again to install, and I have not had an internet connection at home since 28 February when my ISP Unwired closed down.
 * (my attempts to get a 'Net connection via a 'Dodo' ISP USB mobile internet device is another long tale of woe in itself. The 'gizmo' works on every PC I have tried it on, except mine!)

I have used about 3 Gb (!) of my brothers Internet bandwidth to (so far) for zero result! My experience of installing games needing Steam activation is rapidly losing it's 'novelty'! I note that it seems some games will not even begin to install if you are not online and logged onto Steam. /whinge 220  of  Borg 11:01, 18 April 2013 (UTC)
 * /whinge


 * Update: Sniper: Ghost Warrior now says "ready to play!" . Fingers crossed! 220  of  Borg 11:03, 18 April 2013 (UTC)
 * And 'Sniper' seems to be working! But 'Homefront' needs another 5+ Gb and hours of download to work! 220  of  Borg 11:30, 18 April 2013 (UTC)
 * No such luck! After disconnecting from 'net, 'Sniper: Ghost Warrior' runs at about 1 frame per seecond (if that). Re-boots didn't help. Very puzzling  220  of  Borg 12:01, 24 April 2013 (UTC)

DOS operating system
I was browsing a local computer store, and was surprised to see that none of the laptops were sold with Windows as the default OS. A small number of laptops had Linux as the OS, but the majority of them were listed with DOS as the OS. As a layperson whose main memories of DOS include a b/w dialogue box that opened when wanting to play computer games in early editions of Windows, DOS to me would seem to be the equivalent of 'no OS'. What exactly would a DOS OS be? Would a person with no programming skills, like me, be able to use it, or would I need to instal a 'proper' OS? V85 (talk) 11:47, 18 April 2013 (UTC)


 * It's probably FreeDOS. They don't really anticipate that you'll actually use it, but rather that someone will install a capable modern OS. They're either doing this so they can advertise the machine at a lower price and then add on the cost of whatever Windows OS you want (as a Microsoft Small System Builder, they can probably put on a variety of OEM versions). It's also quite possible that they'd foresee the machines having Linux put on them, but they're not capable of supporting Linux (and don't want all the "this windows program doesn't work" calls it would bring them), so they sell the machine clean and say "caveat installer". -- Finlay McWalterჷTalk 11:57, 18 April 2013 (UTC)


 * “caveat installer” is great :) ¦ Reisio (talk) 15:23, 18 April 2013 (UTC)


 * Caveat onero ? Is that proper Latin ? StuRat (talk) 16:06, 18 April 2013 (UTC)


 * Disk Operating System was an OS; probably MS-DOS. By the time you're working with a DOS window you're now into Windows 3.1 (probably) territory, which is a different OS. Of course people still referred to the window as DOS, but it was a new OS emulating DOS (I'm sure someone could fault me for saying "emulating" here, but i'm speaking generally). Even today with Windows 7 you can pull up a nice black command window that looks an awful lot like DOS. But true DOS... I would be impressed to see someone do something interesting on a modern machine with it running an original version of DOS. Shadowjams (talk) 19:19, 18 April 2013 (UTC)


 * Thanks, this helps. (Particularly since it confirmed the point of view I already had. ;-) V85 (talk) 21:07, 19 April 2013 (UTC)


 * It's probably enough to verify that the PC works. You can test the keyboard, monitor, printer, hard drives, etc. (although I don't believe DOS used the mouse).  You can also check the sizes of the hard drives, etc.  StuRat (talk) 21:17, 19 April 2013 (UTC)


 * Assuming our article is correct, MS-DOS 4.x had mouse support.--Rockfang (talk) 15:11, 23 April 2013 (UTC)

address manipulation in assembly language
this is a simple instruction in assembly language.

A 1,901 (2, 15)

1 = accumulator 901 = offset 2 = index register 15 = base register

the addresses contained in the three registers are added and the obtained address contains a value which is then added to the contents of register 1.

my question is: why do we have to go through the pain of adding three addresses to get the required address? why not use the required address directly?

P.S. i have just started studying System Programming from John J. Donovan... so, please go easy on the technical stuff. i'm not that tech-savvy. :P — Preceding unsigned comment added by 117.197.252.4 (talk) 14:29, 18 April 2013 (UTC)


 * It's generally very desirable for programs to be relocatable, in other words, written in a way that allows them to run correctly even if they are moved to a different place in the computer's memory space. That's what the mechanism you're showing achieves, if I understand it correctly. Looie496 (talk) 14:54, 18 April 2013 (UTC)


 * It looks like you're talking about an x86-like processor. The x86 family (at least in non-64-bit mode) has a segmented memory system. That is, by its intrinsic nature, memory addresses are made up of two words, frequently in two seperate registers, that are added together to get the absolute memory address. Note that for x86s, you can't just use any two registers. The segment address (base register) has to come from one of the segment registers (e.g. CS, DS, SS, ES), whereas the offset address can come from any of the general purpose registers. This allows for the relocatability as mentioned above, as all you have to do to move the program around is change the value in CS, DS, SS, ES, etc., as appropriate. - So why the offset? This makes working with aggregate data structures easier. You just have to load the pointer to the beginning of the data structure, and then you can quickly access data members with different offsets, rather than having an extra ADD/SUB instruction manipulating the address, and potentially leaving it in an unknown, varying state in loops and the like. It's extra conveniences like that which make x86s a CISC architechture, rather than a simpler, but more wordy, RISC. -- 71.35.127.8 (talk) 16:37, 18 April 2013 (UTC)
 * Allowing just a displacement and a register is done on some machines. This means more instructions are needed in many cases but the RISC argument was that the machine cycles could be shorter. It hasn't worked out that way the extra logic to deal with the possibility of two registers in forming an address sometimes has in general been found to be worth the bother. Plus the possibility of automatically scaling of the index register for the data size is often desirable as well. Dmcq (talk) 17:50, 18 April 2013 (UTC)
 * That instruction would also be valid on the IBM mainframes starting from the 360 range. The thing that RISC machines don't have is the direct add of whats loaded, they only have load or store instructions. The reason for this is that it takes time to loadf or store and one wants to schedule them separately from computations. A compiler will try and stick a few instructions between a load and the use of the loaded register, this makes it much easier to avoid just waiting around for something from store. Also encoding the computation operations would take more space in the instruction if it is already encoding an offset. Dmcq (talk) 11:09, 19 April 2013 (UTC)

Unix command to output specific text
This one should be pretty simple and I'm 90% sure I've seen it before, but it doesn't yield to searching easily. Suppose I want my bash to simply output "Hello." What should I type for this to occur? Presumably, I could also type command "Hello" > file (where command is the command I'm looking for) to create a file whose contents are "Hello". What's the command? ± Lenoxus (" *** ") 17:02, 18 April 2013 (UTC)
 * . There are various options and ways to quote, but that's the basics. --Stephan Schulz (talk) 17:04, 18 April 2013 (UTC)


 * Thanks! (Somewhere in my mind I thought it was "parrot" -- I should have just looked up "parrot" in a thesaurus!). The man pages should take me from here. ± Lenoxus (" *** ") 17:25, 18 April 2013 (UTC)


 * Not that it will matter much, but FYI  is frequently a shell builtin, so the technical authority would be  . ¦ Reisio (talk) 17:38, 18 April 2013 (UTC)

InterruptedException in java
Hi !

My doubt is on InterruptedException in java.

I am asking my doubt based on sleep method in java.

When we call interrupt  on a thread which is in sleep state then InterruptedException is thrown.

Below are my doubts:

1)Imagine that we have called  interrupt method on a  thread  named Thread1,which  has come out from a sleep.

Then will Thread1 throws InterruptedException?

2)Imagine that we have called interrupt method on a thread named Thread2,which will go to sleep.

That means now Thread2  is not in sleep state.

Then will Thread2 throws Interrupted exception? — Preceding unsigned comment added by Me shankara (talk • contribs) 17:53, 18 April 2013 (UTC)
 * The sleep stops as soon as the thread is interrupted. An InterruptedException will only be thrown by methods that are documented as able to throw that exception. Otherwise you need to check the interruption flag using isInterrupted. See and .  38.111.64.107 (talk) 18:47, 18 April 2013 (UTC)


 * If an interrupt arrives while a thread is not blocked or sleeping, the thread's interrupt status is set; attempting to block or sleep with that status set immediately (clears the status and) throws an InterruptedException. (The static method Thread.interrupted clears the status (and returns it), so it's possible to avoid the exception.)  --Tardis (talk) 02:08, 19 April 2013 (UTC)

3D glasses for Blu Ray
I am interested in getting the 3D versions of The Hobbit and The Life of Pi for my ASUS gaming computer. I have a 3D set and a 3D compatible player. How do I know what glasses to get, since I see hey sell green/magenta, red/cyan, and polarized? Thanks. μηδείς (talk) 19:20, 18 April 2013 (UTC)


 * Most 3DTVs use expensive active shutter style glasses, rather than the cheap polarized types used in cinemas, although there are exceptions. Anaglyph glasses (with different coloured lenses) are used for viewing 3D images on a standard 2D screen, and aren't what you're looking for here. To the best of my knowledge, most active shutter TVs use proprietry glasses, so you would need to buy glasses for the specific manufacturer's TV. What is the make and model of your set?  AJ Cham  19:37, 18 April 2013 (UTC)
 * It's whatever glasses your TV manufacture uses. I know that Samsung are active-shutter, and most LG are passive polarized. Do a web search for " 3D glasses" to get suitable manufacture's and third-party glasses. CS Miller (talk) 20:08, 18 April 2013 (UTC)
 * Thanks, I understand theresponses, but I have no idea how to determine what type of 3d I have. I have an ASUS computer with an NVIDIA Gforce GTX video card.  When I type in 3d on the start search box (I have windows 7) it offers me the option of activating 3d but says nothing about active or passive shutter.  What should I be looking for and where?  μηδείς (talk) 20:33, 18 April 2013 (UTC)
 * Nvidia 3D Vision 87.115.151.155 (talk) 20:35, 18 April 2013 (UTC)
 * Thanks. Now I have to decide if I want to spend $150 on the glasses just to see what the 3D looks like.  Wonder if Sim City comes in 3D. μηδείς (talk) 21:00, 18 April 2013 (UTC)
 * If you do get it, make sure you get the 2.0 model, and the full kit (the USB adapter and a pair of glasses); don't just get the glasses, as you need the USB adapter too (it tells the glasses when to change). Some online reviews give the system reasonably marks, but with a 120Hz (vertical refresh) monitor - your laptop probably has a lower vertical rate (the nvidia app you already have in the control panel will show you), which may be flickery when the glasses effectively half it. 87.115.151.155 (talk) 21:24, 18 April 2013 (UTC)
 * How exactly would I find out if I have a 60Hz or 120 Hz display? (I can do it on my Mac and have tried with the PC, but am having no luck.) And if I want three sets of glasses do I purchase two satnd-alone glasses and one with USB?  Thanks. μηδείς (talk) 22:11, 18 April 2013 (UTC)
 * If you didn't explicitly pay for a high frequency monitor, or a super-expensive gaming system, then you probably don't have one. In the windows control panel: "screen resolution", then "advanced settings", and the vertical frequency is shown in the "monitor" tab (maybe). [That's windows 7, I don't know about other versions exactly]. 87.115.151.155 (talk) 22:21, 18 April 2013 (UTC)
 * Thanks. It is 60 Hz.  Let me repeat my other question.  If I want three sets of glasses so I and two others can watch can I buy two stand alone pairs, or do I have to pay for the full set three times?  μηδείς (talk) 00:14, 19 April 2013 (UTC)
 * It appears from the product literature that you can use any number of the additional glasses (I see them for sale by themselves, without the USB dongle). But I stress that I've no personal experience of this system, and as someone with whom 3D systems don't agree, they all seem like dim flickery migraine-inducing gimmicks. TinyLittleRobot (talk) 07:38, 19 April 2013 (UTC)
 * The above postings by 87.115.151.155 were me - I finally remembered my password TinyLittleRobot (talk) 07:47, 19 April 2013 (UTC)

how elevators talk
I want to know how elevators talk this applies to the us — Preceding unsigned comment added by 75.15.67.222 (talk) 21:14, 18 April 2013 (UTC)


 * Elevator control systems usually use one or several programmable logic controllers. These talk together with one another using something like Industrial Ethernet (or one of the proprietary automation protocols listed in that article) or with a simpler system like LonWorks or Ez-LINK. 87.115.151.155 (talk) 21:36, 18 April 2013 (UTC)


 * On this topic, is anything known about the "intelligence" of elevators? Specifically in cases where a tall building has multiple elevators, how do they work most efficiently? Ryan Vesey 21:42, 18 April 2013 (UTC)


 * A lot of study has been put into this, particularly for very tall buildings. Elevator lists some of the modes. Elevator companies like to claim tha their controllers for skyscrapers use advanced scheduling algorithms that know the specifics of traffic in that building; some use (or say they do) neural networks or machine learning. As with many real-world scheduling and queueing problems, fairness and efficiency often have to be traded against each other. 87.115.151.155 (talk) 21:48, 18 April 2013 (UTC)


 * You might also be asking how elevators talk to people, say when they announce the floor. In this case, a full speech synthesis system isn't required, as it only needs a very small vocabulary.  So, the elevator design company can just hire someone with a pleasant voice to say all of the phrases the elevator can say, and record those digitally for later use ("Oh, that must be Otis !") . StuRat (talk) 02:36, 19 April 2013 (UTC)