Question : Mixing x32 and x64 apps and OS's

Hello All

I'm a little confused by the whole 32 and 64 bit compatibility issue.

I have an HP Server that is a 64 bit machine. I also have some applications that were designed for 32 bit OS's.

Questions:

i) Can I install x32 Windows 2003 Server on an x64 hardware machine. Is this recommended? Or better to install x32 Server on 32 bit machines and x64 Server on 64 bit machines?

ii) Can x32 applications be installed on x64 Server OS's?

iii) Can x32 apps be installed on 32 bit Server 2003 but running on 64 bit hardware?

iv) And does the same apply for client OS's (Windows 7, XP etc)

Thanks in advance!

Answer : Mixing x32 and x64 apps and OS's

First and foremost let's get this out of the way.  Your hardware is based on x86 architecture.  Here is some quick knowledge on that: http://en.wikipedia.org/wiki/X86.  The key takeaway there is that starting with the AMD Opteron the x86 registers were extended from 32-bit to 64-bit.

Now to go down your list:

1) Yes you can install 32-bit versions of an operating system.  This is because you are really installing an x86 version of the OS.  The OS is compiled for either the 32-bit or 64-bit register.  Now if your hardware predates the extension to 64-bit, then you will only be able to install 32-bit.  To answer your question more directly: It depends on what you need to do with your server.  64-bit allows for addressing > 3GB of RAM and is the future of the MS Server Operating Systems (2008 R2 is only 64-bit).  Can whatever role or application you are installing support a 64-bit architecture?

2) Yes, through what Microsoft calls WOW64 (Windows 32-bit On Windows 64-bit).  Now that does not mean that every piece of 32-bit software will run on a 64-bit Operating System, and it is best to check your software documentation to reference its support.  For more on WOW64: http://en.wikipedia.org/wiki/WOW64

3) Yes.

4) Yes

In closing, remember that 32 vs. 64 bit can raise a lot of questions, and if you are planning to make the jump consult all your installed software, drivers, peripherals, etc... before making a switch.