Please look at the program below:

ST: MOV A,R7 ;Start w/ R7=0
MOVC A,@A+DPTR
MOV P0,A ;Display
CALL DELAY
INC R7
CJNE R7,#0EH,ST
MOV P0,#00H ;All finished.
JMP $

I've checked many many time carefully, but the program still not working. It supposed to be display some LED patterns but it didn't. I've wrote another this kind of program using DPTR, but it was work. So I make a change to the register using: replace R7 with R5, and the program works fine. Why is there a difference?

Stanley