title: What's the difference between using int 0x20 and int 0x21 / ah=0x4C to exit a 16-bit assembly program?
body: <p>At various times, I've used both</p>
  <pre><code>int 0x20
  </code></pre>
  <p>and</p>
  <pre><code>mov ah, 0x4c
  int 0x21
  </code></pre>
  <p>as ways of ending a 16-bit assembly program.</p>
  <p>But what is the difference between the two?</p>
  <hr>
  <p><strong>EDIT</strong>: Thanks for your comments everyone.  Following up on Alexey's reference to the PSP (program segment prefix), yielded <a href="https://jeffpar.github.io/kbarchive/kb/072/Q72848/" rel="nofollow noreferrer">this nugget from Microsoft MASM support</a>.</p>
  <p>The article seems to suggest there's more to the difference than just return codes.</p>
  <p>Happy to award the accepted answer to anyone who can tie the two together a bit more definitively.</p>