Random source code change

Hi, people!

I would like to make a robot with a higher degree of unpredictability, so I was thinking about making a robot that can randomly change the details of some of it's own source code (like the speed of the wheels and so forth...) every time you turn it on - and then save the changes for next time, it is turned on. It's especiall this last part, I'm wondereing about - the saving of the changes. Can it be done? And what command/commands can be used. Or du I need to change the program in the computer every time something new should happen?

Thanks in advance!

/Dan.