32-bit or 64-bit?

The reasons for designing the 64 bit OS was never about the ability to access more RAM. It was all about providing a vastly larger virtual address space to the system and to native 64 bit applications. Compatible 32 bit applications receive a small benefit. Most of the advantages of a 64 bit OS stem from that.

If all that was wanted was more RAM access that could have been provided at much less effort in a 32 bit OS. Windows 2000 Data Center edition was able to access as much as 32 GB RAM some 14 years ago. This was made possible by using the PAE CPU feature and a special kernel. PAE is often thought of as some kind of ugly hack but that is not the case at all. It is just a small extension to the normal methods of RAM access and is in fact simpler than that used in a 64 bit OS for all RAM accesses, even on systems with less than 4 GB RAM.

The 32 in a 32 bit OS refers to the size of the virtual address space as seem by applications. This has nothing, and I mean NOTHING, to do with how RAM is accessed. This is very complex and I will not attempt to describe it. The Pentium Pro introduced in 1995 had a 36 bit address bus that could theoretically access as much as 64 GB RAM (if a compatible OS existed and that much RAM could be provided). Most later 32 bit CPUs also have a 36 bit address bus. That is what limits RAM access, not the 32 bits used by applications.

To be sure, a 32 bit application has severe limits on how much RAM it can efficiently use but that comes from the limited virtual address space. That is why 64 bit operating systems were designed. Many systems also used device drivers that behaved very badly with more than 4 GB RAM installed.

If anyone wants to use PAE on a 32 bit client OS such as Windows 7 or Windows 8 you can forget it. The ability to access more than 4 GB RAM is explicitly denied in such systems. This is for specific server operating systems only.

Lady Fitzgerald said:

I don't know why the OP even bothered with this thread since it appears his mind was already made up and didn't care what anyone had to say.

My mind isn't made up but yours is. I asked a simple question and after getting some replies here I figured out that continuing to the discussion is not useful and I try to find the answer from else where so I made this thread solved and I don't know while I thanked all of you and said that the thread is now solved but STILL you go on in posting with an inappropriate writing!