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System Debug automatically tracks the translation bits in the processor status
word (IPSW). There are two IPSW bits of interest, the C and D bits. These bits
indicate if the machine performs "code" and "data" translation, respectively.
If the C bit is off, the machine interprets all code addresses as
REAL addresses rather than virtual addresses. Likewise, if the D bit
is off, any data address is interpreted as a REAL address rather than
a virtual address.
The windows honor this convention by examining the current
settings of the bits in the processor status word. This means that
any virtual window displays data based on the IPSW D bit. Likewise,
the NM program window is affected by the C bit.
The NM program window is flagged as REAL when code translation is
turned off (for example, the C bit equals 0). Likewise, virtual windows and
user windows aimed at virtual address space are flagged as REAL when
data translation is turned off (for example, the D bit equals 0).
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