HP 64783A, Руководство пользователя

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Using the DeMMUer
The deMMUer circuitry reverses the translations made by the MMU (translates the
physical addresses it finds on the processor buses back to their corresponding
logical addresses) before sending the addresses to the analyzer.
What part of the emulator needs a deMMUer?
Actually, the emulator doesn’t need the deMMUer; the analyzer does. It can’t
provide its full symbolic features unless it has help from the deMMUer. The
analyzer normally receives its address information directly from the processor
address bus. It uses the symbols data base created for the program loaded in
memory to cross reference the addresses it receives to the symbols and
corresponding code in your source files. When the MMU is used, logical addresses
are translated to physical addresses before they are placed on the processor address
bus. Therefore, they no longer match the symbols data base.
What would happen if the analyzer didn’t get help from
the deMMUer?
The analyzer would get its address information directly from the address bus of the
emulation processor. It would have no way to know what translation had occurred
in the MMU. Therefore, it could not trigger or qualify its trace on any symbol
defined in the symbols data base. Further, its trace list could only show you the
physical address value it found on the address bus; it would not be able to show any
symbols associated with that physical address, or any corresponding source file
lines. You would have to figure out for yourself what portion of your program
address space was executing when that physical address appeared on the bus.
How does the deMMUer serve the analyzer?
The analyer does not get its information directly from the processor address bus
when the deMMUer is turned on. Instead, the deMMUer accepts the physical
address from the processor address bus, reverse-translates it to its logical address
value, and supplies it to the analyzer. By having the logical address corresponding
to the transactions on the processor address bus, the analyzer can accept trace
Chapter 10: Using Memory Management
Using the DeMMUer
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