Hello, Could you pls help me answer this question: - Please take a look at my small Assembly program that reads a tring from keyboard, then displays all the characters that are not uper-case letters in reverse order: Code: .model small .stack 100 .data tb1 db 'Pls enter a string, enter to finish $' tb2 db 10,13,'The characters that are not uper-case : $' xau db 80 dup(?) .code Main proc mov ax,@data mov ds, ax mov es, ax mov ah,9 lea dx,tb1 int 21h xor cx,cx lea di,xau nhap: mov ah,1 int 21h cmp al,13 je thoi cmp al,'A' jb dung cmp al,'Z' ja dung jmp nhap dung: stosb inc cx jmp nhap thoi: mov ah,9 lea dx,tb2 int 21h dec di mov si,di std mov ah,2 quay: lodsb mov dl,al int 21h loop quay mov ah,4ch int 21h Main endp End main The code above runs very well, even though i did not use the Clear Direction Flag (cld) instruction after the instruction in red (lea di,xau) The string processing is still in forward direction. The question is that: Why? I appreciate your help. my email: firstname.lastname@example.org Regards, Duy.