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Executing program from XRAM

Is is possible with the 8051 architecture
to copy a program or function into XRAM
and execute it? Or do the separate
code/data address spaces prevent this?

What I'm trying to do is to write a boot
loader that can put the loader routine
into flash, so that the flash chip
the boot loader resides in can be erased
and re-written. The plan is NOT to
update the boot loader portion of the flash,
but the application portion.

The flash chip we're using doesn't allow
you to execute out of the flash if
any portion of the flash is being
programmed.

We're using the Philips 87C51MB2 chip,
which is an MX part.

Thanks,

Ed

Parents
  • With the addressing capability of the MX it should be simple: OR RD and PSEN to both the ROM and RAM reads, make !WR go to both. Then decode the msb of the address and allocate different address spaces to ROM and RAM. Then which memory is active becomes a simple matter of the address. Been there done that.

    Erik

Reply
  • With the addressing capability of the MX it should be simple: OR RD and PSEN to both the ROM and RAM reads, make !WR go to both. Then decode the msb of the address and allocate different address spaces to ROM and RAM. Then which memory is active becomes a simple matter of the address. Been there done that.

    Erik

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