The SFR area is between 0x80 and 0xFF, also the Upper RAM area is between 0x80 and 0xFF. I can access the SFR using direct addressing and the Upper RAM using indirect addressing. My question: are the SFR and Upper RAM physically 2 different memorys? If I use all of the SFR registers can I also use the Upper RAM memory (both have the same address area)? (overwrite data) data crash? Thanks
Memory areas are different. You can use all SFR's as well as the complete area in the address range from 0x80 to 0xff. However, access to the data memory is possible only if it is declared as IDATA. In ASM you have to use indirect addressing modes using r0 or r1 as a pointer to the data memory (i.e. mov a,@r0; ...). HHK