title: /dev/port vs /dev/mem
body: <p>I need some clarification.  I can directly write to <code>/dev/port</code> to get direct access to a parallel port and it works fine (I can turn on LEDs plugged into the port connector).  However, I thought I could do the same with <code>/dev/mem</code>? (http://tldp.org/LDP/khg/HyperNews/get/devices/fake.html).  When I try to read and write to <code>/dev/mem</code> I get no errors, but the writes never seem to be reflected on the external connector.  I ask just because this isn't what I expected based on what I've read about writing to <code>/dev/mem</code>.</p>
  
  <p>Can you not access ioports via <code>/dev/mem</code>?</p>