I know that humminbird now has 6.300 available for the 798ci Si.  I have not done a good job of saving my old files but now I might want to downgrade from 6.300 to the latest before that.  I see in the download section we have 5.840 and 6.300.  Is 5.840 really the last version before 6.300?   I tried piecing the information together from the humminbird faq but its not clear what code version is intended for what equipment, so thought I would ask.  Ideally looking for a list of the code that could be run on a 798ci si.  
Am looking for the same information for the 778c, if anyone knows where that can be found.
thanks
bp