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simulating external memory with out P2 addressing

I'm trying to simulate a simple design (written in assembler), in uVision4, that has a few memory mapped peripherals and uses P2 for GPIO. In "options for target" I set "Off-chip Ddata memory" to:
Start: 0x0000
Size: 0x0100
When I run the simulator, external memory access is being done using P2, which causes problems when the value of P2 changes for GPIO. While searching the forum posts I found some mention of P2 addressing being the default for PDATA access, but found nothing about how to disable this for the simulator. Perhaps a parameter passed to S8051? Any ideas or insight would be appreciated.

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  • There's nothing wrong with the design. It works quite well. All access to external memory is done with movx a,@R0 or movx @R0,a So the only values on P2 are the reset value or what was written on the last GPIO access. External memory on the Intel 8052AH is off chip. The designers of S8051 module made an assumption about how the external memory would be connected to the MCU. Their assumption doesn't match my configuration. I'm asking if there is anyway to change the configuration so that the value on P2 isn't used to address external memory in the simulator.

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  • There's nothing wrong with the design. It works quite well. All access to external memory is done with movx a,@R0 or movx @R0,a So the only values on P2 are the reset value or what was written on the last GPIO access. External memory on the Intel 8052AH is off chip. The designers of S8051 module made an assumption about how the external memory would be connected to the MCU. Their assumption doesn't match my configuration. I'm asking if there is anyway to change the configuration so that the value on P2 isn't used to address external memory in the simulator.

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