50g

There are no real differences between the 49G and the 50G except I think the driver installation is started and completed using the CD that also installs the application program.  Nothing notable. The back up file is somewhat of a mystery.  I don't know what it's for or how it serves to back up your data.  Thanks for the information on the back up file though.  That's kind of what I figured.  Thanks for the information on editing files in the calculator on the computer.  That I can do now.  The only thing I have left to do, is figure out how to write the program on the computer then send it to the calculator.  Doing it on the computer is much easier than doing it on the calculator when doing large programs.  Got a quick way to do that?