[x86 Assembly] How can I store user-input data to bx register?

[jch053]

I am unsure of how to actually store user-input data to a register. I would like to prompt the user for a signed base-10 integer, then store that integer to the bx register. What I have does not seem to be actually storing any data from what I can tell:

;get user input
 
   mov   ah, 0Ah
   int   21h
 
 
while:
    mov   bx, ax        ;save char to bx
    cmp   ax, 13        ;is char = carriage return?
    jmp   endwhile      ;if so, we're done
    int   21h           ;get another char
    loop  while
endwhile:
    ret                 ;end loop
 
;print data stored in bx to console
 
    mov   ah, 09
    mov   dx, [bx]
    int   21h
 

Anything in particular sticking out that I'm doing wrong?