32-bit OS are physically limited to just over 4Gb. Windows has reasons for reporting less
than that figure---though 32-bit Vista SP1 onwards lies about it and lists 4Gb.When Windows was created
it was decided (coded) to split the 4Gb limit in half between the OS and 32-bit apps, so in a 4Gb system, Windows takes 2Gb even though it needs less than one, leaving the other 2Gb of space for the app(s).
The 64bit versions of Windows are again coded to some limit (8Tb) but 32-bit apps running on them are still limited to 2Gb (again code rather than a real limit) of space (I do not know if a simulation of the /3G switch could work). Few such apps use anywhere near this much space anyway so not a big deal. I assumed modern Windows could run multiple 32-bit sessions at the same time but maybe it switches instead.
Since so little can take advantage of 64bit space yet you see little need for more than 8Gb of RAM and a RAMdrive coming back into vogue (since the 640k limit DOS days) to make use of more than 8Gb of space (hey, RAM is cheap).
The solution is 64-bit apps. Eventually, the 32-bit code will get dumped but I suspect that would not happen until windows 11 or 12, when experimental 128-bit OS is released. Of course that is assuming it is needed on a iPhone or tablet . . . the only two devices the industry apparently expects us to own.http://msdn.microsoft.com/en-us/library ... 85%29.aspx