The author takes no responsibility for any damage that may occur when accessing your printer port . Remember that most , if not all modern P.C's t he printer port is actually on the motherboard (on the super IO chip I think) , so if you damage this you could be in big trouble .

We will try and draw some scematics to show you can protect your PC , this is usually done with either diodes , a ttl buffer chip or optoisolators .