Very old discussion, but I had to solve this today and her is what I did.
Case: old firmware and no reading of the smalest CF card I could fint on the net.
Using my old Navionics
256 Mb CF card.
Checking available space on it. about 256-187= about 60+ Mb
Copying datas (backup) my Navionics
CF card to Dropbox.
Saving my waypoints to the Navionics card (about 1 Mb)
Saving waypoints to Dropbox
Downloding the 5.04 update for C80
Copying the 2 files from the *.zip file to the /root directory og the Navionics CF card
Booting the C80 with the Navionics CF card(with the firmware upgrade files)
Accepting the firmware upgrade. Wait for updating
When finished system hang on problem with exiting from upgrade card.
Turn system off (cutting the power to the unit)
Put the card in to cardreader and remove the 2 upgrade files.
Boot C80 up again with the Navionics CF card including waypoint file
waypoints via Data button.
There you go. Almost simple
Just one question remains. How du I get a backup of my old Navionics CF card map. If anything should happend to it... Anyone??
Best regards LA2WHA Jon Helge