extended memory specification (XMS)
The Extended Memory Specifications (XMS), also called Extended Memory Area(EMA), refer to the addressing range of main memories above 1 MB, i.e. above the Expanded Memory Specification( EMS).
This area could only be addressed by processors from the 80286 onwards. Older processors such as the 8086 and 8088 can only address 1 megabyte (MB), with 640 kilobytes( KB) of conventional and 384 KB of Reserved Memory.
Because the addressing ofRAM memory areas was limited to 1 MB for the DOS operating system, DOS programs do not automatically have access to the extended memory area (XMS). Windows from 3.x and OS/2 take XMS into account and therefore do not require special device drivers for the extended memory. XMS was developed by the companies AST Research, Intel Corporation, Lotus and Microsoft.