On any 32-bit OS, processes have at most 4GB of address space, because that's how much you can address with 32 bits. In practice some of that is reserved for t

On any 32-bit OS, processes have at most 4GB of address space, because that's how much you can address with 32 bits. In practice some of that is reserved for the kernel, so you get less for use by the process itself. Historically 2GB on Windows, though there were some non-default compilation/linking options you could set to get 3GB. A 32-bit process running on a 64-bit kernel can get 4GB of address space. And yes, lots of computers have >4GB physical RAM, even if you don't count swap/page files.