I think that w/ the TI82 GraphLink software, there is a little box that you can check to edit lock the program. There is also a program called Doslock which will do the same thing. There is also a way to do this if you edit the program in hexadecimal, but I won't get into that now. -The Great and Powerful Llama http://members.aol.com/greatllama/index.html "No longer under federal investigation"