data segment
info1 db 0dh,0ah,'input a decimal number:$'
info2 db 0dh,0ah,'output a decimal number:$'
data ends

code segment 
  assume cs:code,ds:data
main proc far
  call decibin
  call binidec
  call crlf
  call stop
main endp

decibin proc near
  lea dx,info1
  mov ah,09h
  int 21h
  mov bx,0
newchar: 
  mov ah,01
 
h
  int 21h
  sub al,30h
  jl exit
  cmp al,9
  jg exit
  cbw
  xchg ax,bx
  mov cx,10
  mul cx
  xchg ax,bx
  add bx,ax
  jmp newchar
exit:
  ret
decibin endp

binidec proc near
  lea dx,info2
  mov ah,09h
  int 21h
  mov cx,3
  mov ax,bx
  push bx
  mov bx,10
LP1:
  xor dx,dx
  div bx
  add dl,30h;餘數在dx裡
  push dx
  loop
 
 LP1
  mov cx,3
LP2:
  pop dx
  mov ah,02h
  int 21h
  loop LP2
  pop bx
  ret
binidec endp

crlf proc near
  mov dl,0dh
  mov ah,2
  int 21h
  mov dl,0ah
  int 21h
  ret
crlf endp

stop proc near
  mov ax,4c00h
  int 21h
  ret
stop endp

code ends
  end main