title: Batch file to remove first 18 chars from txt file
body: <p>I have a .txt document with over 32,000 lines of commented machine code. It looks like this:</p>
  
  <pre><code>Display menu window
  C0/000E:    E220        SEP #$20
  C0/0010:    C210        REP #$10
  C0/0012:    20640B      JSR $0B64
  C0/0015:    20750B      JSR $0B75
  C0/0018:    C220        REP #$20
  C0/001A:    A90001      LDA #$0100
  </code></pre>
  
  <p>I need to convert the code as follows for compiling purposes:</p>
  
  <pre><code>; Display menu window
  SEP #$20
  REP #$10
  JSR $0B64
  JSR $0B75
  REP #$20
  LDA #$0100
  </code></pre>
  
  <p>Specifically, that means:</p>
  
  <ul>
  <li>Blank lines must remain unchanged.</li>
  <li>If a line starts with "C0/" then the first 18 characters are to be deleted, including tabs.</li>
  <li>Otherwise, it's a function title, so add a semi-colon followed by a space at the beginning (not mandatory).</li>
  </ul>
  
  <p>Any help would be greatly appreciated.</p>