I was just simulating my code in Keil. When I write to external memory, I don't see anything happen in the memory window. I am using cypress FX2 as the chip. Here's my code: Just writing FF to location E000h
MOV A, #0FFH MOV DPTR, #0E000H MOVX @DPTR, A
I don't see anything happen at 0E000h in the memory window.
E000 to E1FF is data RAM. E200 to FFFF are USB registers with some reserved space.