From: John Stone (
Date: Wed Jun 11 2008 - 01:37:58 CDT

  As Axel already mentioned, the standard process memory size limit
for 32-bit windows apps is 2GB. There is a way to compile 32-bit code
for the windows large memory address space extension that raises this
slightly to about 3GB, but the resulting binaries only run on a subset
of the versions of Windows out in the field. Now that I'm getting ready
to update our builds to Tcl/Tk 8.5.x, I'll be re-trying to build a
Win64 version of Tcl/Tk, if that succeeds, then I should be able to
ship a 64-bit Windows version of VMD, which would be the ultimate
resolution of that problem. Another feature on the drawing board
that will help with all of this will be support for out-of-core
trajectory playback in a subsequent version of VMD, so that the
you will be able to work with datasets FAR larger than your
actual physical memory, while still getting good visualization/analysis

  John Stone

On Wed, Jun 11, 2008 at 09:41:24AM +1000, wrote:
> Hi Folks,
> I have a PC (AMD Phenom X4, 4GB memory) running
> Windows XP at home. For some reason, VMD 1.8.6 crashes when memory use
> exceedes
> 2GB. I don't think it is memory its self to blame because I can have
> two instances of VMD running simultaneously with <= 2GB of memory usage.
> Is this because the windows version is 32 bit but the architecture is 64
> bit?
> Any ideas about the cause/remedy?
> Thanks,
> Aaron++
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