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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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  • This is a simulator configuration question. I'm trying to find out if there is a way to configure the S8051 module so that P2 is not used for external memory addressing, since in my design (and many others I suspect) only the address lines supplied by P0 give a more than sufficient address space, and GPIO pins are at a premium.

    I know of no '51 processor that will toggle !R/!W without loading 'something' on P2. Thus it is not the simulator, but your 'design' that is faulty.

    Erik

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  • This is a simulator configuration question. I'm trying to find out if there is a way to configure the S8051 module so that P2 is not used for external memory addressing, since in my design (and many others I suspect) only the address lines supplied by P0 give a more than sufficient address space, and GPIO pins are at a premium.

    I know of no '51 processor that will toggle !R/!W without loading 'something' on P2. Thus it is not the simulator, but your 'design' that is faulty.

    Erik

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