what is x64?

sfleurietsfleuriet Texas New
edited October 2005 in Science & Tech
I understand that Windows x64 is 64-bit as opposed to the normal Windows XP's 32-bit, but what does that mean? I saw some screenshots of it in PC Magazine and it looks the exact same. How is it different? :scratch:

Comments

  • EMTEMT Seattle, WA Icrontian
    edited May 2005
    64-bit is not a facelift, it's nothing on the surface. As I understand it, the processor just works on 64 bits of data at a time instead of 32. For data that is less than 32 bits (4 bytes), this won't help much; larger data operations could see a performance improvement greater than 100% though.

    Since the machine code is different on an x64 processor, every application needs to be compiled in 64-bit to utilize x64. That's what Windows x64 is; before it the processor was just running Windows in its 32-bit backwards-compalibility mode. But each individual application will also need to be recompiled to use 64 bits.
  • sfleurietsfleuriet Texas New
    edited May 2005
    so what would have to be done to recompile it to 64-bit?
  • primesuspectprimesuspect Beepin n' Boopin Detroit, MI Icrontian
    edited May 2005
    The developers have to recompile it using an AMD64 compiler....
  • adderekadderek
    edited October 2005
    Something more.
    It is not just an recompilation.
    Code had to be adjusted to new processor functions, some code is added, some removed, some WinAPI functions are now present, some 16-bit-mode functionality is lost (however I think that they could do it better), entire 32-bit mode is now "emulated" (AMD64 processor in "64-mode" works only in flat mode of memory mapping) and a lot more.
    This is the same code but many things are now doubled: you will find them in x64 and x32 version.
    Just to show that it wasn't just an recompilation without any changes I will say that first betas were only for AMD64 and EMT64 was not supported (EMT64 = Intel's version of 64-bit).

    And there are some good things about x64, and some bad, too.
    For example: memory is now consumed more (due to a little different aligment and because there are more things now in the mem). But I'm not sure about it. I know only that the same application usuallu consumes less memory in x32 windows than in x64.
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