CPU Description
Keep in mind that the use of independent stack pointers in emulation
mode allows independent stack areas to be secured for each mode,
which keeps the stack of one of the modes from being destroyed by an
erroneous stack operation in the other mode.
The SP, IX, IY, and AH registers and the four segment registers PS,
SS, DS0, and DS1 used in the native mode are not affected by
operations in 8080 emulation mode.
In the 8080 emulation mode, the segment register for instructions is
determined by the PS [CS] register and the segment register for data
is determined by the DS0 [DS] register. The DS0 should be set by the
programmer immediately before the 8080 emulation mode is entered.
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