i want to play with some circuits , serial and parallel ports. What precautions do i need to take. can i have a some kind of protection circuit?

 

buffer circuits or optocouplers are a good way to keep your devices from destroying your ports...... http://www.google.com/search?q=Para...s=org.mozilla:en-US:official&client=firefox-a

B. Morse

 

If you want to use a parallel port buy an extra parallel port card, that way if you do blow something it is not the motherboard.