Wikipedia:Reference desk/Archives/Computing/2012 July 7

= July 7 =

RTL and LTR marks
Is there any term that embraces both right-to-left marks and left-to-right marks? "Digital directional marks"? Someone proposed a merger some time back, but because they're quite equal in nature, it would seem much better to merge them both under a neutral title instead of having one title redirect to the other. Nyttend (talk) 05:17, 7 July 2012 (UTC)
 * No. It seems to me that Unicode has no official term for both. - Presidentman talk · contribs Random Picture of the Day (Talkback) 17:52, 7 July 2012 (UTC)

PDAs
Is there any company that still manufactures PDAs? All the ones I find online are either used models being resold or legacy items from companies that no longer make them. 173.2.164.121 (talk) 05:39, 7 July 2012 (UTC)
 * It would depend what you mean by Personal digital assistant. As our article mentions, smartphones have by and large replaced PDA for most people. If you actually want to buy one as opposed to just wanting to know, it may help if you specify what you want in a PDA or why specifically you don't want a smartphone. There are plenty of low to mid ranges smartphones (generally Android) which would make an okay PDA and are the sort of price you'd expect to pay. If you don't want access to a mobile network, the extra chipset may add cost and a small amount of weight/space but I think the market is just too small, so few bother to make a wifi-only phone-sized slate. I've never heard of any Android wifi only devices that small (they may exist, never looked that hard), that's only really common with larger tablet size devices (generally 7" of larger). With Android devices at least, you should be able to use them without a SIM card and reduce exposure of phone calling and other apps so they don't generally get in the way if you don't want to use such functionality. There is of course the iPod touch even if it isn't marketed as a PDA about the only one I'm aware of in that form factor. I guess one of the biggest issues is that most devices with big screens have power hardware to match which doesn't matter so much if you don't intend to use demanding apps but means high cost. If you want a stylus, the Galaxy Note is one of the few capactive touch smart phones or tablets to come with one but isn't exactly cheap. You can of course use specialised styluses with most capactive touch phones but you'd need someway to attach it and the device may not necessarily be well designed to use it. There are a few devices including Android ones with physical keyboards although I'm pretty sure they're all with the phone portion. Nil Einne (talk) 06:09, 7 July 2012 (UTC)
 * Edit: See there's also the Samsung Galaxy Player. Nil Einne (talk) 06:11, 7 July 2012 (UTC)
 * It is not for myself I am seeking a PDA, it's for a friend. He just needs a device that is akin to a PDA, where he mainly uses it as an electronic daily planner. He emphatically does not want a smartphone, for reasons like this. I'm aware that there aren't many options outside of smartphones and tablets, but I'm truly lost as to what to do. And can I convince him to change his mind about his preferences? Nope. 173.2.164.121 (talk) 07:50, 7 July 2012 (UTC)
 * Does that mean your friend wants a PDA without any sort of network access? As it's illogical to think there's any difference between a wifi enabled PDA and a wifi enabled phone sized media device (or whatever they call them) like a Samsung Galaxy Player or a iPod just because of the name or OS. Of course if you disable all networks in a phone (or whatever) there's little chance anyone could track you but I guess that's not going to convince your friend. Nil Einne (talk) 10:55, 7 July 2012 (UTC)

Hotmail/Live
I have been locked out of my hotmail and MSN because apparently there was some suspicious activity, which I take to mean my account had been hijacked and was sending out spam. Now, in order to get back in, I have to get a confirmation number sent to an email address which I have recently deleted. As you will understand, I will not get this confirmation number. Is there any other way to get back in? Gmail will send the confirmation number to your phone, if necessary, but Microsoft..... KägeTorä - (影虎) (TALK) 08:30, 7 July 2012 (UTC)
 * Is there a way to get the deleted email account back? That may be the simplest.--Canoe1967 (talk) 16:49, 7 July 2012 (UTC)
 * You can send confirmation to your phone from Hotmail also. - Presidentman talk · contribs Random Picture of the Day (Talkback) 17:52, 7 July 2012 (UTC)

how multiplication works in c
hi! If we want to perform addition of ,+75 and -50 the following procedure implemented in c language. +75 = 01001011 -50 =11001110(in two’s complement form).addition will b e like below.

+75 = 01001011 -50 = 11001110 --- 1 00011001 ->+25(last bit dropped) ---

Now I want to perform multiplication of -2,-1. how it is performed on bits of -2,-1. What procedure is followed in clanguage? Can you explain detailedly? — Preceding unsigned comment added by Phanihup (talk • contribs) 17:11, 7 July 2012 (UTC)


 * You may be looking for our article on binary multipliers. However, you should not assume that the when you compile and run your C language program, the machine will use the bit representations you are assuming in your worked example.
 * The C language does not specify the representation of its numeric types. To be totally correct, the C language defines several basic data types: int, short, long.  The qualifier "unsigned" can be applied to any char or integer type, and requires that arithmetic be treated as modulo (2n) for a type of n bits.  On most modern compilers, it is safe to assume that the "int" type is represented in the "best" format for the machine, but that is a detail of the C compiler, not the C language.  Along the same lines, the actual mechanism that a machine uses to convert the C expression "(-1) * (-2)" into a sequence of machine instructions not specified by the C language: all that is required is that the value of the expression evaluates correctly.
 * The actual circuit used will vary from CPU to CPU. Because integer multiplication is such a primitive and common operation, most modern CPUs have many many different multiplier hardware units, each used for various purposes; so the same C statement "(-1) * (-2)" may compile to a different machine-representation and sequence of operations, depending on context.
 * As a simple example, pointer arithmetic for an array dereference often involves adding a base and an offset (index * sizeof(data_type)). This operation occurs very frequently will commonly be allocated a dedicated multiplier in hardware.  As before, the C programming language does not specify how the machine implements such arithmetic.  Nimur (talk) 17:44, 7 July 2012 (UTC)


 * If you want to multiply two fixed-width two's-complement numbers by hand, you can do it as though they were unsigned, as long as you truncate the result to the same length:

1111  (-1)    x 1110   (-2) 11110   111100   1111000   ---  11010010  xxxx0010   (+2)


 * But as Nimur said this has nothing to do with C. The C standard just says that the result is the mathematical product of the inputs if that fits in an integer of the appropriate size, and undefined otherwise. It's unsafe to rely on any particular overflow behavior even if you know you're running on a two's-complement machine, as explained in this article. (Java does specify that signed multiplication is equivalent to two's complement multiplication with truncation. Java is more "low level" than C in this regard.) -- BenRG (talk) 23:28, 7 July 2012 (UTC)

temporary lack of Internet access
While I was on the Internet, the browser (Firefox), as sometimes happens, informed me a site was unavailable. But then it turned out that no other sites were accessible either. I checked the lights on my modem and router and all was normal. A full 5 bars of wireless connection power was displayed. I quit and restated the browser and tried Chrome, but the problem remained. I rebooted the machine with no result and went to Control Panel, where I invoked the Windows 7 Internet troubleshooter, which found nothing. I scratched my head and looked at the browser again. This time I had access as usual. The total time out was 15 minutes or so.

Any idea what might have happened? Is it anything to worry about? --Halcatalyst (talk) 20:04, 7 July 2012 (UTC)


 * Most likely your ISP lost connectivity for some reason. Looie496 (talk) 20:11, 7 July 2012 (UTC)