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Using Multiple CPU Cores in DOS? (Miscellaneous)

posted by bretjohn(R) Homepage E-mail, Rio Rancho, NM, 19.09.2011, 20:25

> Yes but I though that when accessing all mem >1MB in PM it use some native
> mode where all CPU address pins go directly to memory and A20 hack logic is
> disabled. I belived this is used only in real mode to access HMA. But I may
> be wrong.

Since I hadn't messed directly with PM before (all I had ever done was set up some Descriptor Table entries), I thought that as well. But now that I've done some testing, I know it's not true. A20 has to be enabled to access memory above 1 MB, even if the CPU is in PM. I tried it with A20 disabled -- it didn't crash, but the data was garbage.

 

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