Dword or Qword?

[sethm1]

I have a Win 7 PC using 64 Bit.

When entering a new name in the Registry and the particular tweak that I am reading says to create a new Dword, instead should it not be a Qword - which is 64 Bit entry?

 

[clifford_cooley]

That would depend on the length of your entry. You would only need to use a Qword if your entry calls for it. Dword and Qword has nothing to do with the bit version of Windows.

To make things simple a Qword is four 16-bit words not one 64-bit word. This is why a Qword can exist on a x86 machine.

Some computer architectures define the term dword (double word) to be a unit of data that is twice the size of a word. The x86 platform originally had a word size of 16 bits (2 bytes) and that usage of the term is confusingly retained even though the actual processor word size is now 32 bits or even 64 bits. In that platform, a dword designates a 32-bit (4-byte) unit.

Similarly qword (quadruple word) is a unit of data that is four times the size of a word. On the x86 platform, this unit of data is 64 bits long because the definition of word on an x86

Read more here - http://en.wikipedia.org/wiki/Dword#Dword_and_Qword

 

[sethm1]

thanks for the explaination

 

[amecurty]

but for example, if I wanted to create a Dword entry on regedit with the corresponding hexadecimal value of 5GB, would it accept it and show 5GB on the add/remove programs? Cause I tried that but the maximum value it shows is 3.99GB so i was wondering if changing to Qword it'll show 5GB.
Thanks

 

[clifford_cooley]

That would probably depend on the program reading the registry entry. I wouldn't know what the results would be by manually changing the value from dword to qword. My guess would be if the program was designed to read a qword value, that would be the value found in the registry. You can try because it is possible, I simply can not say for sure it will work.

Please be careful, editing the registry can render an operating system useless.

 

[amecurty]

yeah.. I've tried it and didn't work and didn't show anything at all. But thanks for your reply.

 

[brock samson]

That would depend on the length of your entry. You would only need to use a Qword if your entry calls for it. Dword and Qword has nothing to do with the bit version of Windows.

To make things simple a Qword is four 16-bit words not one 64-bit word. This is why a Qword can exist on a x86 machine.


Read more here - http://en.wikipedia.org/wiki/Dword#Dword_and_Qword

I wanted to get more detail/clarification on Dword vs Qword when you say it depends on the length of the entry - is this like how many characters are in the subkey or like how many characters are in the decimal value of said subkey or is it something else entirely?

To give an example when you find windows specific tweaks that changes how windows 7 behaves or some speed items up - here is a example link to a quick google search I did that hopefully better explains my question http://www.wincert.net/forum/index.php?/topic/8781-how-to-speed-up-aero-peek-thumbnail-preview/ This link is just one example.

So to make sure I am asking the correct question....when performing OS tweaks like this - If you are running 32bit windows - do you select Dword? and if you are running 64bit windows can/should you select Qword? Or if it more the length of the entry - how does one know when looking at the tweak of which type of key to select?

 

[clifford_cooley]

REG_DWORD - 32-bit number

• The range of integer values that can be stored in 32 bits is 0 through 4,294,967,295. Hence, a processor with 32-bit memory addresses can directly access 4 GB of byte-addressable memory.

REG_QWORD - 64-bit number

• A 64-bit register can store 2^64 (2 to 64th power) = 18,446,744,073,709,551,616 different values.

I think there are other uses for DWORD and QWORD but you get the picture. A QWORD is simply twice the length of a DWORD, looking at it from a length stand point of how many bits the value was stored with.

I wish I could tell you all the ins and outs without any doubts. This is about the extent of what I understand myself.

 

[brock samson]

I understand the math behind 32/64 bit processors and the powers 2^32, when you do the math that is why 32bit windows can only use up to 4GB of Ram and why 64 bit can use so much more...but this info does not address my question....maybe I am not making myself clear or am asking the wrong question.

 

[clifford_cooley]

Maybe it would help if I knew why you were asking.

What is it exactly that brings this question to the table?
Are you working on something that requires the use of DWORD or QWORD?

 

[brock samson]

When performing registry tweaks of an OS the author of tweak does not always specify 32bit or 64bit....(does it even matter?) Or if they do specify to create a new Dword (32bit) value but maybe you are running a 64bit system - Do you still follow the 32bit instructions, or do you need to modify the instructions and create a new Qword (64bit) with the same data in the decimal value instead?

Of course you should always back up your registry before making changes, but I am just trying to understand what is proper and still safe to achieve the desired results of the tweak - no matter what system you have.

 

[clifford_cooley]

DWORD and QWORD is tied to the application that is using the value not the OS.

I would only be guessing when I say:

DWORD should work for all values unless using a value larger than what a DWORD can store. If you need to store a value larger than a what DWORD can store, the use of QWORD would then be required.​

 

[Thrax]

I understand the math behind 32/64 bit processors and the powers 2^32, when you do the math that is why 32bit windows can only use up to 4GB of Ram and why 64 bit can use so much more...but this info does not address my question....maybe I am not making myself clear or am asking the wrong question.

The OS (Any 32bit OS) can only address 2^32 bits (4,294,967,295) of memory-mapped I/O (MMIO, henceforth). Damn near anything on your computer has an MMIO address; the BIOS, the buses, your VRAM (Which supersedes your DRAM addressing). The computer reserves blocks of MMIO addresses for VRAM, then buses/bridges/BIOS, then DRAM. Your RAM gets all the addressing space left, which is usually 2.5-3.12GB.

That's why.

 

[brock samson]

Let me see if I can break this down....What originally brought me to this line of thinking was a article in PC world about tweaking Windows Aero effects -This article said to create a new DWORD to achieve the effect, so i got to thinking (i know bad idea) - But I am running 64bit, so do i still follow the instructions exactly or can the same thing be achieved by choosing QWORD instead with the same data or would the 32bit tweak not work on a 64bit system.....Now I could not find the same article online as in print, so i referred to a similar article I found online in which it is mentioning to use 32bit or 64bit when tweaking windows check out this link i mentioned in my 1st post http://www.wincert.net/forum/index.php?/topic/8781-how-to-speed-up-aero-peek-thumbnail-preview/

Like i said this one is just an example, so when i find future Windows tweaks - you mention it is just the value data that matters, but is that literally like how many characters you put into the value to decide to use a DWORD or QWORD? Or is there more to it than that?

How does one tell DWORD or QWORD when making tweaks to windows which to choose?

To use the link i mentioned to be more clear - at the bottom of the linked page, it talks about if you wanted to delay the aero peek preview (dont know why someone would want to do that) but still you could enter many characters to achieve this delay and you would need many, many characters before you reach that 32bit limit - so that doesnt make sense...Do you see where I am going? where do you get your data from to know which type of key you need?

Or can you take the simple route, If I have a 32bit system then choose DWORD, but if I have a 64bit system and I am tweaking a 64bit application then choose QWORD?

Am I making sense - just hit me in the head if the answer is no!

 

[Thrax]

It's almost always dword. 99% of the time. Qword is rare as hell. It's that simple.

To put it another way, if you're tweaking a Windows setting, it's always going to be dword.

 

[brock samson]

It's almost always dword. 99% of the time. Qword is rare as hell. It's that simple.

To put it another way, if you're tweaking a Windows setting, it's always going to be dword.

Thanks i think that is what i am looking for....can you mention some examples where someone would need to use QWORD then?

 

[Thrax]

I cannot honestly think of any examples. To show you how rare qword is actually used, this thread is already on the first page of Google for using qword in Windows--which means nobody has ever found a use for it.

 

[clifford_cooley]

I've been trying to say it's the data being stored and the application calling the data that dictates which is used. But I have no idea how accurate that statement would be.

It would be kind of silly for a programmer to use only DWORD values but store them as a QWORD's.

Thrax, when exactly do you think a QWORD would be needed, that is a huge value.

 

[Thrax]

Maybe if a particularly large value needs to be stored in the registry. I don't know. It seems useless for the foreseeable future.

 

[TrainableMan]

So the answer is NO, never substitute QWORD instead of DWORD even if you have a 64-bit system. In fact, in the article you listed brock, it seems like some words are missing but I'm not sure why the poster even mentions it at all in that context.

Now I can tell you this. There is often a different or sometimes a second registry location that needs tweaked on 64-bit systems, but still the entry is typically DWORD. People who offer such tweaks generally specify any differences in 32 or 64 bit; just use what is posted.