# difference between 32 bit and 64 bit applications



## chandhuonline (Sep 27, 2008)

Can anybody explain me the actual difference between 32 bit and 64 bit applications ?


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## Mr. Newton (Aug 26, 2006)

about 32 bits 

sorry, i couldn't resist.


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## Codiah (Sep 27, 2008)

Haha, good one.. 

anyway, here's my input on your question, as far as i know its just the difference in how memory will be handled.. i'll try and explain below, but keep in mind this is just my opinion and i suggest looking into it more on your own or waiting for someone who knows more on the subject to come along... 

ok, so 32bit is the old and current standard, for now anyway, but it was set as the standard assuming that 4G of memory would be sufficient enough to handle everything we needed, but its really only ment to handle the load of 4G of memory max, however It's pretty apparent how fast technology is advancing these days and we are quickly come up on that 4G memory limit, so 64bit was born, this is just a newer way of handeling memory of up to 16G's, so now or in the near future, whomever needs this tupe of memory load can put it to use..

This is a step forward is it handles more memory, or even the same ammount at a faster rate, but not all software is compatible with 64bit at the moment, so i presume that when the rest of the digital world catches up and begins to impliment 64bit capability into their products and software it will become the new standard. 

but its not to much to worry about, at the moment i'm on a notebook computer with an AMD Athlon x2 64bit processor, but still only running a 32bit OS.

A good way to think about it is, if you bought the current design of the Dell E520 desktop computer with 2G's of ram, that computer has two more slots to place ram in, and since we currently have ram setups with 2G's or even more on a single stick, you could easily load 8G's of ram into that machine, bit if your still running a 32bit processor, then its only going to utilize 4G's of the ram at most, so you just wasted your money on the other 4G's of ram the computer can't handle, but if you had a 64bit process it would be able to use all 8G's, or even up to 16G's of ram.

anyway, maybe someone who is a little more knowledgeable will swing through long enough to point out any of my mistakes and set everything straight and clear..


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## lotuseclat79 (Sep 12, 2003)

The difference is not memory, it is the processor's word bandwidth - i.e. in a 32-bit processor, the processor processes words 32 bits-at-a time, and in a 64-bit processor, the processor processes words 64 bits-at-a-time. Internally, in the processor, it means that the processor pipeline is either 32 bits or 64 bits wide and the architecture built likewise to accomodate the difference - i.e. a 32-bit architecture cannot process a 64 bit word, however, a 64-bit architecture can process two 32-bit words together and with the proper configuration, even separately.

This all means that, indeed, the difference in word size is 32 bits!

The effect is that libraries and executables alike must be of the same kind as the processor. Even the include files for compilation will be different because they will specify the size of a word at some level as either 32 or 64 bits.

-- Tom

P.S. What Codiah said is true, but misses the point. So, if properly configured, a 64-bit system can execute a 32-bit compiled application with the proper libraries in place, however, a 64-bit compiled application can never run on a 32-bit computer. Also, I would expect a 64-bit compiled application to take up more memory space than a 32-bit compiled application.


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## Codiah (Sep 27, 2008)

Thanks lotuseclat79, Well there you have it, i think that covers just about everything... even i got to learn something....


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## tomdkat (May 6, 2006)

Good explanation, Tom. I would also add that 64-bit CPU architectures have been around for a long time although they are relatively new to the desktop computing arena.

Peace...


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## mt2002 (Sep 14, 2005)

I would like to add that some cpu architectures (Most notably Intels x86) are backward compatible to support 16 bit and 32 bit operating modes. Because of this, you need a 64 bit compatible operating system in order to utilize the 64 bit functionality of the cpu architecture. Else, you can have a 64 bit cpu but still running in 32 bit mode.

I am uncertain if this applies to other cpu architectures as well.


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