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Solve : C8000-CBFFF Shadow to DC000-DFFFF Shadow? |
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Answer» What would the following option do? I see it a lot on mainboards but have never found a proper explanation. C8000-CBFFF Shadow to DC000-DFFFF Shadow (Copied from 41600011.PDF)Shadowing is when the ROM (bios) is copied to an area of memory and calls to the bios are executed from RAM rather the ROM chip. This was used extensively on older, slow machines to speed them up. With modern machines you probably won't notice any difference. It would just make that area of memory unaccessable to other apps. I can't REMEMBER using it since I retired my 386-16.Much obliged, Dummy 2K. I ALSO noted that some of the older Socket 7 mainboards have an option in their BIOS called Memory Hole at 15H-16H What would that do? And why is it recommended leaving it open?It is a PART of CMOS memory that holds information about base memory size. 15H - high byte, 16H - low byte. Old XT and AT machines did not always have the same base memory. Some were limited to 384K. Old IBM's were limited to 544K. 640K was a god send . The OS (DOS) and PROGRAMS had to have a way of knowing how much memory they had to work with, and that is where the CMOS stored that data.Once again much obliged, Dummy2k. |
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