mov R6,#30H
mov R7,#0
mov DPTR,#2000H
mov R2,10
L1:
movx A,@DPTR
inc DPTR
anl A,#0FH
swap A
mov R0,A
movx A,@DPTR
inc DPTR
anl A,#0FH
orl A,R0
push DPH
push DPL
mov DPH,r6
mov DPL,r7
movx @DPTR,A
inc DPTR
mov R6,DPH
mov R7,DPL
pop DPL
pop DPH
djnz R2,L1