title: x86 partial register usage
body: <p>If I save a value, let's say 10, in 8 bit register <code>DH</code> and then another value, 15, in 8 bit register <code>DL</code>. Would that work or will they override each other since they are both in 32-bit <code>EDX</code> register? </p>
  
  <pre><code>mov $10, %DH
  mov $15, %DL
  cmp %DL, %DH
  
  jle done
  </code></pre>
  
  <p>Basically I'm just confused when I'm using the 8 bit register how will it affect the 32 bit register and vice versa. 
  Thanks. </p>
  
  <p>Also, can you save the value 7 in <code>EDX</code> and <code>DH</code> and <code>DL</code> would still have their own values or will they now have 7? </p>