t;</samp>
</pre>
<p>
  An invalid parameter leads to an error like this:
</p>
<pre>
<samp>C:\&gt;<kbd>MODE 0</kbd>

Invalid parameter - 0

C:\&gt;</samp>
</pre>
<p>
  We will edit this error message to be slightly more helpful.  The
  following debugger session shows how.
</p>
<pre>
<samp>C:\&gt;<kbd>DEBUG C:\DOS\MODE.COM</kbd>
-<kbd>S 0 FFFF 'Invalid parameter'</kbd>
117C:19D1
-<kbd>D 19D0 19FF</kbd>
117C:19D0  13 49 6E 76 61 6C 69 64-20 70 61 72 61 6D 65 74   .Invalid paramet
117C:19E0  65 72 0D 0A 20 0D 