How to invert a string in tasm?

Question

assembler

you need to enter a string and invert it.
what I have is not working. What could be the problem?

Text    segment
        assume  CS:text,DS:data
Begin:  mov AX, data
        mov DS, AX
        mov BX, offset txt
        mov SI,0
inpt:   mov Ah, 01h
        int 21h
        cmp AL,0
        je ex_ascii
        mov [BX][SI],AL
        inc SI
        jmp inpt
ex_ascii: mov AH, 08h
        int 21h
        cmp AL, 10h
        je output
        jmp inpt
output: mov DX, offset message
        mov AH, 09h
        int 21h
        dec SI
next:   cmp SI,0
        jl exit
        mov DL, [BX][SI]
        mov AH, 02h
        int 21h
        dec SI
        jmp next
exit:   mov AX, 4c00h
        int 21h
text    ends
data    segment
message db 10, 13,'$'
txt     db 80 dup (?)
data    ends
end Begin

PS please, if possible, the code in the usual tasm. I don't understand small or tiny. Thanks

Answer 1

The question "what doesn't work for me" is answered by debugging your code step by step. And the search for the place where reality diverges from what was intended.