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Industry conversion to 64bit and WOW64

Discussion in 'Hardware' started by HMS Beagle, Jun 20, 2005.

  1. HMS Beagle

    HMS Beagle Guest

    Niether Microsoft, AMD, nor Intel are coming clean out to the public
    about what the conversion to 64bit architecture really entails for
    backward compatibility and performance degredation of existing

    Backward compatibility has been the bane of CPU designers for the last
    20 years. In order to get clunky CISC chips to run at 1.0 GHz and
    higher speeds, they have had to re-design the core pipeline of the CPU
    as a RISC core, because RISC cores are much simpler than CISC cores,
    and therefore, can run cooler at higher clock speeds. The problem is
    that these new Pentium IIIs needed to run software that was compiled
    to run natively on 486s, 386s, or even 286s (be that as it may). In
    order to pull this off, extra hardware was added to convert old CISC
    instructions on the fly into small lists of RISC instructions so that
    the RISC core could execute them.

    The idea behind the upcoming conversion to 64bit is that we abandon
    backward compability, so that the complete computer, from OS to
    software to motherboard to CPU, is all seamlessly integrated in

    But Microsoft realized very quickly that not allowing compatibility
    with existing 32bit apps would be a business nightmare. (Although it
    would be a utopia in terms of computer speed). So what they did was
    bundle a WoW64 system with their 64bit versions of XP. Which is the
    XP Professional x64 Edition.

    Interestingly enough, neither Microsoft, AMD, nor Intel is coming
    straight out to the public about what this conversion to 64bit
    platform really entails.

    If you google about the details of the WoW64 system you will see that
    is indeed called an EMULATOR of 32bit apps. Meaning the computer is
    not sending 32bit code directly to the CPU, but instead traps every
    incoming 32bit instruction and converts it to 64bit before sending it
    to the native 64bit processor. Anyone who is familiar with the
    difference between emulation and "compiled native code" will realize
    that this entails a hefty performance degredation of 32bit code run on
    a 64bit platform.

    How severe is this performance degredation? Well essentially what
    is happening is that every single reference to memory in old 32bit
    code will have to be trapped so that all those memory pointer
    references can be converted into 64bit memory pointers.
    Applications write and read from memory nearly all the time. 90% of
    all instructions run, reference memory in some way. Very rarely do
    you have spans of code that juggle things in the registers of the CPU

    Ironically, if you google about WOW64, you get webpages claiming that
    a 64bit computer can run old 32bit apps "without performance
    degredation". This is clearly a bald-faced lie coming out of

    I am glad that the CPU industry has finally given up wholesale on
    backward compability. It needed to be done at some point even though
    its a "growing pain" of sorts. But what has essentially happened is
    that the issues of backward compatibility have been outsourced to the
    Operating System, with the hopes that the end-user will not "notice" a
    performance degredation.

    It is likely that professionals running 32bit business apps in an
    office probably will not "notice" a performance degredation at all.
    But those of you who work with intensive graphics applications or
    physics simulations beware.
    HMS Beagle, Jun 20, 2005
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  2. HMS Beagle

    Cool_X Guest

    HMS Beagle,
    With that kind of post you just made, you must be VERY good at what you do (which I don't even
    know what specifically that is).

    I just have a few questions:

    1. The difference between M$'s first 64-bit Windows XP (I don't remember the exact title) and
    this new Windows XP Professional x64 Edition is that the former would only run on Itanium
    (assuming version 1 and 2), and the latter will run on x86, right? (please correct me if I'm

    2. How many different types of 32-bit programs will have significant performance degradation,
    on WoW?

    3. Can you be any more specific and give me numbers, or the titles of the hardest-hit programs
    in each program category?

    4. You said:

    "But those of you who work with intensive graphics applications or physics simulations beware."

    But won't all those people who are running 32-bit programs in WoW with a significant (enough to
    notice) performance hit be entitled to an upgrade to a native 64-bit program doing the same thing?

    5. Continuing #4, for the sake of not losing their customers, won't those upgrades (described
    in #4) be very cheap, if not free?

    I hope that you read this NG again soon (it's a small NG), because I hope to have an answer to
    these questions (also soon, please).

    So please let me know about this as soon as you can, because I am very curious about these things.

    Cool_X, Jun 20, 2005
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