I have a good CR800/850 program that I have been running for years, is it possible to run this program in the CR300 series or can it be easliy adapted to run...or am I starting from scratch to write a whole new program?
You will have to make some changes. The voltage range selections, channel number selections, and pulse count options will be different.
Copy code into a new CR300 program in CRBasic Editor and try to compile. That will flag with errors pretty much anything that needs to change.