MOV P0,#HIGH(RAM_ADDR)  ; i.e.: MOV P0,DPH
SETB P1.4               ; load to latch enable
CLR  P1.4               ; lock A8...A15 into latch
MOV  R0,#LOW(RAM_ADDR)  ; i.e.: MOV R0,DPL
MOV  P0,#0xFF           ; prepare as input
MOVX A,@R0