EMS physical segment
EMS works by remapping addresses in the 1MB 8086 addressable space to expanded memory. An EMS physical segment is a 16KB block of addresses in the 1MB 8086 address space, that can be mapped to part of an expanded memory allocation. When a physical segment is mapped to an EMS logical page, accessing the physical segment accesses the logical page. Logical pages can only be accessed through physical segments.