amp>
</pre>
<p>
  We first open <code>MODE.COM</code> with the debugger.  When we do
  so, the entire program is loaded into offset 0x100 of the code
  segment (CS).  Then we use the <code>S</code> debugger command to
  search for the string "Invalid parameter".  This prints the offset
  at which this string occurs in memory.
</p>
<p>
  We use the <code>D</code> command to dump the bytes around that
  offset.  In the first row of the output, the byte value 13 (decimal
  19) represents the length of the stri