Figure 16.3 illustrates the Windows NT virtual memory spaces and their relationship to system physical memory.
Figure 16.3 Windows NT Virtual Memory Spaces and Physical Memory
As Figure 16.3 shows, virtual memory is backed by paged physical memory, and a virtual address range can be backed by discontiguous pages in the CPU. User-space virtual memory and system-space memory allocated from paged pool are always pageable. That is, any noncurrent process and its data can be paged out to secondary storage, usually on a disk.
The hyperspace area shown in Figure 16.3 is a dedicated range of system-space addresses, used by the NT Memory Manager to map the current process's virtual address space to a set of physical pages in the CPU. Note that any noncurrent process's virtual addresses are not visible, so its memory space is inaccessible.