Enabling Unreal Mode
To enable unreal mode without using any undocumented features of the CPU, the program has to enter protected mode, find or create a flat descriptor in the GDT or LDT, load some of the data segment registers with the respective protected mode "selector", and then switch back to real mode. After returning to real mode, the processor will continue using the cached descriptors as established in protected mode, thus allowing access to 4 GiB of "extended" memory from real mode.
Undocumented features of the CPU, such as LOADALL, can be used to enter unreal mode more quickly.
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Famous quotes containing the words enabling, unreal and/or mode:
“Labor came to humanity with the fall from grace and was at best a penitential sacrifice enabling purity through humiliation. Labor was toil, distress, trouble, fatigue—an exertion both painful and compulsory. Labor was our animal condition, struggling to survive in dirt and darkness.”
—Shoshana Zuboff (b. 1951)
“Error is a supposition that pleasure and pain, that intelligence, substance, life, are existent in matter. Error is neither Mind nor one of Mind’s faculties. Error is the contradiction of Truth. Error is a belief without understanding. Error is unreal because untrue. It is that which seemeth to be and is not. If error were true, its truth would be error, and we should have a self-evident absurdity—namely, erroneous truth. Thus we should continue to lose the standard of Truth.”
—Mary Baker Eddy (1821–1910)
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—Henry David Thoreau (1817–1862)