Holy cow, I wrote a book!
Commenter Herb wondered
how a 32-bit program running on 64-bit Windows can allocate more than 4GB
Easy: The same way it allocates more than 4GB of memory on 32-bit Windows!
Over a year before Herb asked the question,
I had already answered it in the tediously boring
two-week series on the myths surrounding the /3GB switch.
Here's a page that shows
how you can allocate more than 2GB of memory
by using shared memory
(which Win32 confusingly calls file mappings).
That code fragment allocated 4GB of memory at one go,
and then accessed it in pieces (because a 32-bit program can't map
an entire 4GB memory block at one go).
To allocate more, either make the number bigger in the call to
CreateFileMapping or just call
CreateFileMapping multiple times.
The following week,
I talked about how you can
use AWE to allocate physical pages.
Again, you can allocate as much memory as you like,
but if you allocate enormous amounts of memory,
you will probably not be able to map them all in at once.
The claims of the program are true,
but 64-bit Windows wasn't necessary
for the program to accomplish what it claims.
and the magic feather.
"Dumbo can fly with the magic feather in his trunk."
Well, yeah, but he didn't actually need the feather.
(On the other hand,
64-bit Windows certainly makes it more convenient to use
more than 4GB of memory, since you can map the memory
into your address space all at once and use normal pointers to access it.)