Technical data

FIRE Emulator for H8S and H8/300H 1 5 B a s i c s
©1989-2014 Lauterbach GmbH
The emulator uses a two stage strategy to realize “the best possible” dualport access method:
If MemAccess is set to Request, the emulation controller “tries” a bus arbitration access as dualport cycle.
This is possible if memory is mapped to internal and on read cycles to shadow memory. Shadow memory
means, that memory is mapped in the emulator (map.ram), but the area is mapped external (map.extern).
On access to external mapped memory and write access to shadow memory the dualport is executed as a
spot point if CpuAccess is enabled. Dualport on access to external mapped memory and write access to
shadow memory is disabled if CpuAccess is disabled.
If MemAccess is set to Denied and CpuAccess is enabled, the emulation controller uses a spot point to
realize the dualport cycle. If MemAccess is set to Denied and CpuAccess is disabled, dualport access is not
possible.
The following table shows how the dualport is realized depending on the used system setting:
request: The bus arbitration interface of the CPU is used for dualport access. Application performance is
only slightly influenced.
spot: The emulation is breaked, memory access is done via CPU, emulation is continued. Application
performance decreases with this method.
Format: SYStem.CpuAccess <option>
<option>: Enable
Denied
Enable If a dualport read/write access is requested to a non-mapped memory, a spot
point (emulation break and go) is used to access the memory.
Denied Dualport access via spot point is not possible.
Mem
Access
Cpu
Access
Read
Map
Int.
Write
Map
Int.
Read
Shado
w
Write
Shado
w
Read
Map
Ext.
Write
Map
Ext.
Request Enable request request request spot spot spot
Request Denied request request request - - -
Denied Enable spot spot spot spot spot spot
DeniedDenied------