How do you access the upper 256 bytes of Expanded RAM (ERAM) in the Expanded RAM series?
When EXTRAM = 0, the 256 bytes of ERAM can be indirectly addressed using the MOVX instruction in combination with any of the R0, R1 registers of the selected bank or the DPTR, an access to ERAM will not affect ports P0, P2, P3.6(WR#) and P3.7(RD#). Address locations 00H – FFH are internal RAM (ERAM). Address locations 100H to FFFFH are external RAM. The 256 bytes ERAM is physically located on-chip and logically occupies the first 256-bytes of external data memory when the EXTRAM bit is cleared.
