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Concepts
automatically; the user can manually transfer the EMSIM to the SIM or the
SIM to the EMSIM or display their differences at any time.
Concepts of the EMRAM
Most members of the 6833x family of processors have one or more internal
RAM modules. For example, the 68335 has three internal RAM modules.
These internal RAM modules can be used like any other system RAM; that is,
their memory hardware can be assigned to support any desired address range
within the 6833x address space.
The address range that a particular internal RAM module will support, and
the qualifiers that might additionally be assigned to that address range are
defined by the values contained within registers in the 4K Module Control
Block of the processor. The values of these registers are supplied to the
emulator as part of the EMRAM copy. The emulator uses this information to
determine where memory accesses should be routed, based on the current
emulator memory map.
The emulator cannot emulate internal RAM modules when the internal RAM
is enabled. Internal RAM accesses will typically not be seen outside the
processor, and therefore emulation memory will be ignored. The only way to
get the processor to access emulation memory which has been mapped to the
same address range as internal RAM is to disable the internal RAM, by
resetting the processor. Note that internal RAM accesses may be seen
externally by the analyzer using the show cycles feature, discussed below.
By default, the internal RAM module(s) in 6833x processors are turned off.
The internal RAM(s) are enabled and positioned by loading the EMRAM
registers. The contents of the EMRAM registers are automatically copied to
the RAM registers each time the emulator enters the monitor from emulation
reset.
502
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