XMS (Extended Memory Specification)

XMS is ram above the 1Mb address boundary. Only 80286 (or greater) CPU's have the ability to address ram above the 1Mb boundary. The 80286 chip can access 16Mb of total address space, and the i386 chip can access 4 gigabytes of total address space. The 8088 and 8086 microprocessors can only access 1Mb of address space, (640Kb conventional and 384Kb reserved memory). The DOS operating system was not designed to access ram above the 1Mb address boundary, which means that DOS programs do not automatically have access to XMS. However, many DOS based computers do have more than 1Mb of ram on the motherboard. Certain DOS applications, (such as Windows 3.x), and the OS/2 operating system do use XMS because they were specifically written to use XMS. No special drivers are needed to access XMS. Only programs that are written to use XMS can utilize extended memory.      XMS, developed jointly by AST Research, Intel Corporation, Lotus Development, and Microsoft Corporation for using XMS and DOS's high memory area

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Last Update: 2:20 PM 11/8/01