org 100h
start:
        mov ah, 9h
        mov     dx,Head   ; write txt
        int     21h

        cld
        mov     cx,5 ; length
        mov     si,FromString+6 ; otkuda
        mov     di,ToString ; kuda

rep     movsb

        mov ah,9h
        mov dx, ToString
        int 21h

        mov ah, 9h
        mov     dx,Exit
        int     21h

        mov ah,8h
        int 21h
        ret

Head     db      "String transfer example", 0dh, 0ah, '$'
Exit        db      0dh, 0ah,"Press any key to exit...", 0dh, 0ah, '$'
FromString    db      '01234567890','$'
ToString    db      10,0,10 dup('$')
-----------------------------------------------------------------
org 100h
start:
        mov ah, 9h
        mov     dx,Head
        int     21h

        cld
        mov     cx,10
        mov     si,FromString
        mov     di,ToString+9

metka:
          movsb
          sub di,2
          loop metka

        mov ah,9h
        mov dx, FromString
        int 21h
        mov ah,9h
        mov dx, ToString
        int 21h

        mov ah, 9h
        mov     dx,Exit
        int     21h

        mov ah,8h
        int 21h
        ret

Head        db      "Transfer string example", 0dh, 0ah, '$'
Exit   db      0dh, 0ah,"Press any key to exit...", 0dh, 0ah, '$'
FromString    db      '0123456789', 0dh, 0ah,'$'
ToString    db      11,0,11 dup('$')