thanks for the info on the map type, I have downloaded the 2015_40 Europa maps and un-archived them, I have read so much of the tutorials I am going round in circles, there is just too much to take in, especially for someone who has never touched a garmin before.

the unit has no expansion micro sd card inserted so all the current system is in the unit.

I have copied the content of the unit to the PC.

Can I update the system content on the PC and copy it to a new Micro SD card the same way as a TomTom?
If so, how do I prevent the old system from reading the internal system and memory? do I delete the existing system from the unit?
Will the unit then read from the Micro SD card?
or
do I delete the existing system from the unit and copy the new updated system to the unit from the PC.

do I copy the new maps, gmapsupp.img to a micro sd card and delete gmapprom.img from the .system? (Rename gmapsupp.img to gmapprom.img ????)

so many possibilities for disaster.