title: Can I access the Parallel Port normally when using USB to Parallel Port adapter?
body: <p><strong>Preliminary story</strong></p>
  
  <p>There is this program which uses the Parallel Port to synchronize with other hardware. It will set the Parallel Port output to a specified (byte) value. This works without problems when using the built-in Parallel Port of a PC. The target platforms are Windows XP to 7, all worked fine so far. Source code is in Delphi, accessible and can be modified.</p>
  
  <p><strong>How it works</strong></p>
  
  <p>In Delphi I can use the <em><a href="http://www.geekhideout.com/iodll.shtml" rel="nofollow noreferrer">io.dll</a></em> to set the value of the Parallel Port, but there are also other solutions available, like <em>inpout32.dll</em> or <em>port.dll</em>. I call something like <code>PortOut</code>, specify a port number and the byte value and the port is set.</p>
  
  <p><strong>What I now want to do - and where I need help</strong></p>
  
  <p>Now the change: this needs to work on a machine which has no Parallel Port built-in (not even on the mainboard). There are several options available:</p>
  
  <ul>
  <li>use a USB to Parallel Port adapter to add a LPT port to the PC</li>
  <li>use a PCI card which adds a LPT port to the PC</li>
  <li>use a PCI Express card which adds a LPT port to the PC</li>
  </ul>
  
  <p>I am currently heading for and concentrating on the easiest and cheapest possibility: a USB to Parallel Port adapter.</p>
  
  <p><strong>Main question</strong></p>
  
  <p>There seem to be differences between Parallel Port adapters which are made to connect just a printer and other adapters which seem to be more powerful. Is there really a difference? Or can I just use one of these 5$ printer-adapters, plug in my own hardware and access the port from Delphi code? Or do I need a special adapter? Has anyone experience with this? There is a related question <a href="https://stackoverflow.com/questions/3182646/controlling-a-parallel-port-via-usb-adaptor-on-modern-hardware-and-os">here</a>, but the different adapter types (if existent) are not mentioned there. <a href="http://www-user.tu-chemnitz.de/~heha/bastelecke/Rund%20um%20den%20PC/USB2LPT/index.html.en" rel="nofollow noreferrer">This page</a> suggests that there are indeed differences:</p>
  
  <blockquote>
    <p>Contrary to all other USB parallel ports which can connect to printers only, this makes  connection to most hardware.</p>
  </blockquote>
  
  <p>I hope there exists a solution via USB because for this you don't have to open the PC, which means the adapter can be added on demand.</p>
  
  <p><strong>Sub-question</strong></p>
  
  <p>Do you have experience with PCI (Express) solution? I have to use one if the USB approach is not successful.</p>