In September you guys posted a thread about subnetting and using the TI-81 calculator to do decimal to binary conversions and back again. I am doing the same thing now in class and I can't figure out how to get my TI 81 calculator to convert back and forth. Is there a program I have to dl, and a cable I have to buy to transfer the data from my pc to my calculator. Since you did this David, I was hoping you could enlighten me a bit. Thanks....