Reserved Memory

Reserved Memory is the address space between 640Kb and 1 Mb and was designed to be reserved for system operations. The system BIOS ROM, video ROM, and ROMs of some add-in cards reside in the reserved memory addr. space. Keep in mind that this is "address space", meaning that there doesn't have to be any physical memory located at all the addresses from 640K to 1 megabyte. The system BIOS ROM can be found at hex addr. F0000 or 960K. If you have a VGA or EGA video card you can almost always find video ROM at hex addr. C0000 or 768K. Between the video ROM and the system BIOS ROM at hex address D0000 for example, there might not be anything at all. This "address space" is unused and available, and drivers such as Intel's EMM.SYS (Expanded Memory Manager) can "map" blocks of memory within the C000-DFFF address range (between 768K and 896K), which means that the memory EMM.SYS controls on an Intel memory board will appear within that address range.

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