title: int 21 h is not working with AH=0Eh
body: <p>I want to change the default drive to drive D: but it doesn't work, on screen shows up the same drive. Does anyone know why? What did I do wrong?</p>
  
  <pre><code>assume cs:code,ds:data
  data segment
  data ends
  code segment
  start:
  mov ax,data
  mov ds,ax
  
  mov cl,3
  
  mov ah,0eh
  mov dl,cl
  int 21h
  
  
  mov ah,19h
  int 21h
  
  mov bl,al
  
  
  mov ah,02h
  mov dl,bl
  int 21h
  
  mov ax,4C00h
  int 21h
  code ends
  end start
  </code></pre>