From http://www.digitalmars.com/ctg/dos32.html :

"With XMS compatible devices like Microsoft's himem.sys: 64MB. This is due to limitations in the XMS interface."

From the dosx readme file:
"Release notes: May 15, 2001 [...]
1.  X-32 now knows how to allocate more than 64 megabytes from himem.sys."

OK, more than 64 MB. How much? Does anyone know?

From http://www.digitalmars.com/ctg/ctgMemoryModel.html

"4GB is a theoretical maximum. Under DOS or XMS, the maximum extended memory is limited by BIOS function calls to just under 64MB. The DOSX 32-bit DOS extender can handle up to 3GB, because it allocates 3/4 of the available extended memory. There is no system that supports 4GB of memory at this time."

Is this information still valid? Or are there systems that support 4GB ore more? If so, where can I find them?

Thanks, OP