FDS2: MOV A,R7 MOV R6,A MOV R2,#0 FD21: CLR A MOVC A,@A+DPTR XRL A,R4 JNZ FD22 MOV A,#1 MOVC A,@A+DPTR XRL A,R5 JNZ FD22 CLR OV MOV A,R2 RET FD22: INC DPTR INC DPTR INC R2 DJNZ R6,FD21 SETB OV RET