Wikipedia:Reference desk/Archives/Computing/2011 October 17

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October 17

PS Home vs XBox Live

I don't have an XBox, but I have a PS3. I have seen PS Home. I have been asked how similar that is to XBox Live. Does anyone here have experience with both? I need to explain what XBox Live is all about to another person who only knows PS Home. -- kainaw™ 00:53, 17 October 2011 (UTC)

Xbox Live is just the online service. You know how when you plug your PS3 in you can play online games, and buy downloadable games? That's what X-Box live gives you.

The X-box has 3d avatars, and if you're on Live then your friends can see yours, but they're not in a 3d environment. They're just standing there on the menu screen. (They can also be used in certain games, like Wii avatars.) They're essentially just portraits that animate a little.

XBox Live is not a 3d walking around virtual environment like PS Home.

Did that answer your question? APL (talk) 05:27, 17 October 2011 (UTC)

Oh, there is something called Avatar-Kinect, which I think is something like PS Home. To be honest, I haven't tried AvatarKinect yet. APL (talk) 05:30, 17 October 2011 (UTC)

APL is correct about all the above. Xbox Live comprises all the online services you can get with an Xbox. It is free if you want a "Silver" account, and it is US$60 per year for a "Gold" account. Unlike on the PlayStation Network, you have to pay (i.e. subscribe to a Gold account) to play multiplayer Internet games over Xbox Live. A gold account also gives you access to Netflix and Hulu Plus and other paid services. Xbox Live is also a "walled garden" with no direct access to the Web or other Internet services outside of Xbox Live; you can't look at Web pages on an Xbox, for example. Microsoft has decided upon the philosophy that the avatar environment of PlayStation Home is not what gamers want — they think gamers want to play games rather than walk around a mostly-empty avatar environment — so Xbox Live features include things like an "Xbox Live Party" where a group of friends can play a game together over the Internet then all switch to some other game as they chat over their headsets. Comet Tuttle (talk) 15:54, 17 October 2011 (UTC)

Thanks all. I will explain that Xbox Live is basically like Playstation Store. I noticed the comment about paying to use Netflix. On the Playstation, Netflix is free to use (assuming you've paid Netflix). Do you have to pay both Netflix and Microsoft to watch Netflix on the Xbox? I remember that Playstation users griped at Sony because Xbox had Netflix built in and Sony still required a stupid CD to run Netflix. I assumed, from those complaints, that running Netflix on Xbox was free. -- kainaw™ 16:09, 17 October 2011 (UTC)

Well, a Microsoft employee would have a heart attack upon hearing you describe Xbox Live as PlayStation Store. Xbox Live also includes any network communication with Microsoft or any other Xbox customer; all these network communications are encrypted (and not hacked yet, unlike PlayStation Network). On the Netflix question, you have to have an Xbox Live Gold account (US$60/year) and you also have to have a paid Netflix account. Probably you should scan the table that is at Xbox Live#Xbox Live features. Comet Tuttle (talk) 17:33, 17 October 2011 (UTC)

It would more accurate to describe xbox live as the equivalent of the PSN, but you know, not free--Jac16888 ^Talk 17:37, 17 October 2011 (UTC)

Thanks again. It doesn't matter now. She mainly wants to watch Netflix and doesn't want to spend $60/year extra to do so. So, she is trying to trade the new XBox for a PS3. -- kainaw™ 12:40, 18 October 2011 (UTC)

Mac keyboard problem

Recently, when I restarted my computer, I had to restart all of my applications (FireFox, iTunes, etc.) However, whenever I type the "F" key, it automatically opens up the "Documents" section of Finder. Can somebody please help me with my issue? It is much appreciated. -- Luke (Talk) 01:28, 17 October 2011 (UTC)

Are you hitting the F key while in Firefox, iTunes, etc? Or are you in the Finder at the time? Also, is there a command key that is stuck? Command-F is the find command for the OS. Dismas|^(talk) 02:00, 17 October 2011 (UTC)

I tried to press it while on all of my applications running in the background. At first I thought it was just FF. The weird part is that I can do the capital "F", just not lowercase "f". -- Luke (Talk) 02:08, 17 October 2011 (UTC)

Now is your excuse to give up on facebook. Astronaut (talk) 14:54, 17 October 2011 (UTC)

I got it. -- Luke (Talk) 23:59, 17 October 2011 (UTC)

Deleting corrupt wiki page

I want a second opinion on this: would deleting and undeleting fix database corruption affecting a Mediawiki page? I'm referring to Confusion Gate on the La-Mulana Wiki, where the latest page is inaccessible and doesn't permit regular users to touch it. Prior versions of the page still work. What's the worst that could happen? --Sigma 7 (talk) 02:19, 17 October 2011 (UTC)

I blame it on MediaWiki 1.12.0. →Στc. 03:07, 17 October 2011 (UTC)

VPN troubleshooting

I recently set up a new box to be used as a file server, its running a windows 7 professional x64 and I set up a VPN as per http://www.pcworld.com/article/210562/how_to_set_up_vpn_in_windows_7.html these instructions, the client connects fine (I can tell because I see the connection appear in the Network connections window on the VPN host computer, yet the client computer can't see any shared folders or the host device when I go to map a network drive, and also can't ping the host device even though its clearly connected to it. Any help in this regard would be greatly appreciated, i've spent a few hours troubleshooting now. — Preceding unsigned comment added by 131.172.81.234 (talk) 05:04, 17 October 2011 (UTC)

Have you changed the windows firewall to allow ping and drive sharing? Have you shared a drive or folder so that it can be accessed from a remote box? Graeme Bartlett (talk) 01:48, 18 October 2011 (UTC)

Have you enabled the File Sharing options in Control Panel -> Network and Internet -> Network and Sharing Center -> Advanced sharing settings ? Nanonic (talk) 06:37, 18 October 2011 (UTC)

how do i set cookie exception in firefox

for locally hosted files? tried localhost, file, 127.0.0.1, c, all do not work. all punctuation is truncated. — Preceding unsigned comment added by 203.116.187.1 (talk) 07:39, 17 October 2011 (UTC)

In Firefox 6 and newer, there is a utility called about:permissions. Simply type that into the location bar to start the Firefox Permissions Manager utility. Read here: "How do I manage website permissions?" This interface lets you simply set up your cookie preferences for localhost, 127.0.0.1, or any other address you are using to access your locally-hosted server. Nimur (talk) 17:28, 17 October 2011 (UTC)

best data card (price+speed)

i want to buy a datacard for my laptop but unable to decide which one to go for whether for aitel,aircel,tatadocomo or somethng else,,please help me — Preceding unsigned comment added by 42.107.101.233 (talk) 08:05, 17 October 2011 (UTC)

It depends on where in the world you are, how much you want to spend, and what you define as "best". Astronaut (talk) 14:52, 17 October 2011 (UTC)

Unix time

I've been reading the Year 2038 problem article and I don't get it. It says that after 2038 unix time won't work because it's too big. But it's a number, and numbers are infinite aren't they?

It isn't really a number, it's a representation of a number stored in a computer. Usually computers reserve a definite number of bits to represent a number, and when the number is too great to fit in the number of bits that have been reserved, the program gives erroneous results. It's really no different from US gasoline pumps in the 1970s, where there were only three digits to represent the price of gas, in cents and tenths of cents. When the price exceeded $1, the pumps had to be replaced. Jc3s5h (talk) 14:41, 17 October 2011 (UTC)

It's the same thing as the Year 2000 problem, but applied to a different number and domain. Imagine I wrote a program that stored all years in a two digit format — 45 for 1945, 60 for 1960, and so on. When I go over 99, I'm back at 00, and lack the capability for 2000. "No big deal," you say, "just make sure the number goes to 100 and then work backwards." Yes, no doubt, but that requires re-writing the software. The Year 2038 problem is the same way: it is totally and completely fixable, but it will require re-writing a ton of code to make it backwards and forwards compatible, and replacing that code in every system that runs it will be non-trivial. It's not that Unix is incapable of understanding dates beyond that point — it's just that the specific way it stores dates runs into problems after that point, and just jumping in and saying "make the number bigger!" will actually break a lot of older programs. --Mr.98 (talk) 17:11, 17 October 2011 (UTC)

To further explain why it breaks old programs, here is a rather simplified example. You have a program. It stores your birth month followed by your birth year. It has 2 digits for each value. So, in memory (or in a file or in a database) it may have 0385 to indicate a birth date of March 1985. You decide to "fix" the 2-year problem by allowing for three digits in the year. But, you don't go back and fix every single program. So, your program here gets a month of March (03) and a year of 100 (for the year 2000). It stores the 03. Then, it stores 100. The result is 0100, which indicates a birth date of January 1900. If it stored the year first and then the month, it would end up with 0300, which is March 1900. You need to go into the program and, anywhere it stores year, expand the storage to 3 digits. That is a lot of work in a lot of programs. As for the Unix time issue, it is a matter if increasing storage space also, be it in memory or on a disk or in a database, etc... -- kainaw™ 17:19, 17 October 2011 (UTC)

The good news is that fixing the Year 2038 problem is relatively simple. Simply storing time as a 64-bit value instead of a 32-bit value should suffice, and even C's primitive type system will help programmers do this correctly. It requires changing existing code, but at least the changes are minor. Paul (Stansifer) 19:53, 17 October 2011 (UTC)

That fixes the programs, but what about stored values. If you try to pull a 64-bit number out of data where it was initially stored as 32-bits, you'll get unexpected values (unless you are very lucky and the 32 preceding bits all happen to be zeros). -- kainaw™ 19:58, 17 October 2011 (UTC)

Many values are stored in text, in which case there's no length limit. If they're stored in a database, the database software knows how to handle these issues. If it's stored in (ick) a custom binary format with fixed-widths, the storage format will have to be changed, but that's going to go along with the change to the program itself, which is probably poorly-enough-written that it's already done far more damage than any date troubles will cause. Paul (Stansifer) 21:30, 17 October 2011 (UTC)

With some exceptions, Unix, unlike the mainframe world, has a strong tradition of plain text storage formats, so I expect the Y2038 problem will be much less of a big deal than Y2K. --Sean 14:37, 18 October 2011 (UTC)

database

I want to download a url page every hour and store it. I was advised by a friend to use a database. How?

I'm not sure you need to use a database. What do you want to do with the stored pages? You may just be able to save them in a folder. Hard Boiled Eggs [talk] 14:46, 17 October 2011 (UTC)

The advantage of a database is that it lets you organize the information with a bit more granularity and subtlety than a directory full of what will over the course of a few weeks become hundreds of static files. The disadvantage is that you've got to know how to set up and use a database, and that might be more trouble than whatever this task requires, if you don't already know how to do it. In the end I would suggest setting up some sort of system (e.g. with cron) that downloads all of the pages as text files and gives them useful names (e.g. a timestamp). Later if you want to upgrade and import all of those into a database, it will not be very hard by comparison. --Mr.98 (talk) 15:46, 17 October 2011 (UTC)

If you're use MacOS or something else Unixy, just open a terminal window and type this:

 while true; do
   name=$(date +%F-%T.html)
   wget --output-document $name
   sleep 1h
 done

--Sean 14:41, 18 October 2011 (UTC)

How To Calculate Total Computing speed of a computer

Hi,

I know to calculate multicore processor speed but nowadays computer boards are coming up with many cards with built in processor like for 3D and other thing so it increases the spreed so how come one can calculate that. Is there any particular formulae for that.

I will appreciate if you can help me on this.

Thanks & Regards K.S.Sailesh — Preceding unsigned comment added by 117.204.116.227 (talk) 17:31, 17 October 2011 (UTC)

In short, there is no easy formula. You must define the compute-task, and specify a large number of parameters, before you can correctly calculate the execution-time for any particular program on a modern computer.

You need at least a rudimentary understanding of computer architecture if you want to quantitatively analyze the computational speed of hardware. As computer architectures become more complicated, it has become more difficult to tell you one number that accurately portrays the computer's "speed."

I highly recommend the textbook, Computer Architecture: A Quantitative Approach, by John L. Hennessy, who made a very successful professional and academic career out of explaining just how fast a computer can compute.

You might also start by reading instructions per second and instructions per cycle. Read about pipelined calculation. Read about memory hierarchy, Non-Uniform Memory Access. Read about computational scheduling; particularly, throughput as opposed to latency. Learn about modern hardware implementations that make use of asynchronous digital computers, and frequency scaling. Understand microarchitecture, and understand that software and hardware abstraction exist at many levels of the compute platform. Also read Amdahl's law.

As I said, there is not a simple formula to account for modern hardware: there's a very complicated formula (and it varies for every combination of hardware and software). It's based, at its core, on the relation between a computational task, defined as an algorithm, and its mapping onto a particular instruction set architecture; and finally, the implementation of the ISA in hardware, which defines the wall clock time execution speed. Nimur (talk) 19:08, 17 October 2011 (UTC)

Windows now displays a simple numeric score, as of Windows Vista and Windows 7, called the Windows Experience Index, with the intent of having software publishers (especially video games) specify that you need a "4.1" or higher score in the "Gaming graphics" measurement, instead of having to talk about the graphics card's fill rate, polys per frame, texels per frame, GPU clock speed, GPU memory, and all that stuff that regular consumers will never understand. Comet Tuttle (talk) 22:52, 17 October 2011 (UTC)

As far as I'm aware, video games publishers are ignoring this 'feature' of Windows, on the basis that it is actually of little use when determining whether software will run on particular hardware. AndyTheGrump (talk) 00:15, 18 October 2011 (UTC)

The problem is that you can no longer ask "how fast is this computer", but "how fast is this computer at a specified task". Graphic cards (GPUs) in particular will give you large speed-ups for some applications but will be next to useless for others. Same is true (if to a lesser degree) for multicores. The way out is to define a benchmark program (i.e. something that simulates a typical application that you want to use the computer for) and simply time with a stopwatch how fast that will run.

In the world of supercomputers (i.e. the list at www.top500.org) the benchmark used is LINPACK (pure number crunching, which is typical for the use of these machines, but would not be typical for a gaming computer). Indeed top500 lists for every machine its theoretical peak (i.e. just adding up the speed of all computing cores regardless) and the LINPACK speed.

Of course even a benchmark only gives an indication of what is achievable with a well written program. If your given program is lousily written, having all that extra cores and GPUs may make no difference whatsoever. 109.148.237.59 (talk) 23:36, 17 October 2011 (UTC)

Firefox zoom

I hit the wrong keys (command-shift-something, or command-option-something, or ...) and Firefox's content pane expanded to fill my whole screen. Since I didn't know what I'd done, I couldn't reverse it except by quitting Firefox.

Anyone know what the keystroke was? I might someday have a reason to do it intentionally, and I can't find anything like it in the menus. —Tamfang (talk) 17:38, 17 October 2011 (UTC)

That would be the "fullscreen" option in the View menu, usually accessed with F11. If it happens again, you can move the mouse up to the top of the screen and a menu will pop up -- or you can just hit F11. Looie496 (talk) 18:02, 17 October 2011 (UTC)

Thanks but F11 in MacOS does something else entirely, and my hand wasn't anywhere near F11 when it happened.

... Now I see it in the View menu: command-shift-F. Funny that I couldn't find it before. —Tamfang (talk) 21:53, 17 October 2011 (UTC)

Any way of formatting SDHC card to work in SD card reader?

Bought an SDHC card by mistake and fell foul of SDHC#SD_and_SDHC_compatibility_issues. Any way to format the card so that the equipment I need to use it in will recognise it as an old-style SD card? I'm not fussed if I lose some capacity. Or is there some sort of adapter I can buy? It's either that, or put it up on eBay and take a loss on it (can't take it back to the shop as I've unsealed the packet). Thanks. --Kurt Shaped Box (talk) 20:53, 17 October 2011 (UTC)

Sorry, but no. You can't change the card back to SD format, you'd need to change the reader to one that supports SDHC. If you just to connect it to your computer then you can just buy a cheap USB SDHC card reader, but I'm guessing you probably want to put the card into a camera or something else so this won't really help you :(  ZX81  ^talk 21:20, 17 October 2011 (UTC)

CD player, actually. I can read the thing in my computer just fine. Nothing exists that plugs into an SD card slot that you can then plug the SDHC card into? --Kurt Shaped Box (talk) 21:23, 17 October 2011 (UTC)

I've personally never seen such a thing, but I'm sure someone else will point out if one does exist. You could try creating repartitioning the card so that it's a single 2GB FAT16 partition (and lose everything else), but I doubt that it'll work (and that assumes your CD player can support up to 2GB).  ZX81  ^talk 21:30, 17 October 2011 (UTC)

Are there any Facebook App games that teach us Hindi and how to use the stock market?

Since Hindi and the stock market would apply to what I hope to master in real life, I wonder if there's a language game and one that I can learn how to use a stock market from. If they engage me for hours, then they'll also help me learn in better ways than I've found thus far.

A search for them on there didn't pull up any promising results last time. Maybe I didn't use the right set of keywords? --70.179.174.63 (talk) 21:28, 17 October 2011 (UTC)

This is a Web game minus the Facebook friends, but HSX is a stock-market-like game where people buy and sell shares of movies that have not come out yet. You can go long or short, place market orders and limit orders, and there are call and put options. Comet Tuttle (talk) 22:55, 17 October 2011 (UTC)