Hi Oleg,

The way this chip work is you can only configure HCR1 & HCR0 during program download time, you can't change these registers when your code is running. Only SFRs from 0x80 and above can be change in run time.

Remapping to 0x8400 won't help either because all of external RAM will be map from this address. From the cpu perspective any external RAM whether on the chip or off the chip is external RAM.

-John G-