Quote Originally Posted by singhrh View Post
device: NUVI 670 NA:
software verion 4.90
audio version 2.20
GPS SW Version 3.00
Bluetooth SW version 0.00

This might be a simple question but I thought I would get clarification before i proceed.

I have downloaded the unlocked City Navigator North America NT 2015.20 (Canada/USA) map image and unpacked it. The packed content included one file only (GMAPPROM.IMG approx 2GB file)

Now I have the latest GMAPPROM.img file on my PC. From what I have read it should be just an easy copy onto the device (location: Garmin_Nuvi\Garmin) and overwriting the existing old GMAPPROM.IMG file......and I am done????? What about the other files (GMAPPROM.unl, gmapsupp.unl and others). Do they not need updating?

I find it hard to believe that it is that easy. However, before I do this I would like to back up the files on my device. Is backing up as simple as copying the device files (including hidden files) or do I have to make a disk image of the device?

Any help would be appreciated or point me in the right direction for IMG file installation.

Thanks
Backups are just simple file copies from the GPS to the PC and restores simply go the other way. It's a fine idea to do it. No need to make a disk image.

The you said the latest gmapprom.img you have is "unlocked". Therefore you simply replace the original gmapprom.img with the new one. You must then delete the existing gmapprom.unl file from the gps. That .unl file is just a renamed .TXT file which contains the unlock key for your original map. Your new map is already unlocked so there's no need for a corresponding .unl (unliock) file. Any .sum files can be either removed or left alone. They are simply checksum files and are not necessary for anything.

If you have a gmapsupp.img and gmapsupp.unl leave it alone. That's some different map and its unlock file you have loaded on your gps.