片内ram，(30h)=38h,(38h)=40h,(40h

MOV A,40H
MOV R1,A
MOV P1,#0F0H
MOV @R1,30H
MOV DPTR,#1234H
MOV 40H,38H
MOV R1,30H
MOV 90H,R1
MOV 48H,#30H
MOV A,@R1
MOV P2,P1