I malloc()'ed a large chunk of memory, but when I check values returned by _go32_remaining_physical_memory(), I don't see any change...

When I free() allocated RAM, _go32_remaining_physical_memory() reports there was no change in available RAM.

In non-DPMI modes, go32 only pages in memory when it is actually accessed. If you only malloc() it, but don't access it, it won't grab those pages. Try calloc() and see the big difference. When you call free(), go32 doesn't return memory to the system, it just adds it to its internal pool of free pages. So, from the system point of view, these pages are not ``free''.