Files are in the „garmin“ folder in the root of filesystem. Tested on my Garmin nuvi 255W.
- on device:
- gmapbmap.img – base map of Earth – e.g. World Map v4
- gmapoem.img – this map cannot be disabled in menu – e.g. Adresy CR (czech)
- gmapprom.img
- gmapprom1.img
- gmapsupp.img
- on SD:
- gmapsupp.img
Another info from here:
(Nuvi 2×0, 2×5, 3×0):
gmapprom.img – Primary/Preinstalled Maps
gmaprom1.img – Secondary Mapset
gmapbmap.img – The base map
gmapoem.img – OEM Maps (cannot be deselected from device if used)
gmaptz.img – Time Zone Map
gmap3d.img – 3D Buildings Map
gmap3d1.img – 3D Buildings Map – Secondary Mapset
gmapsupp.img – Mapsets installed via Mapsource/Mapinstall
The SD or Micro SD card for a garmin device can only contain gmapsupp.img
Nuvi 1xxx (eg. 1490):
The nuvi 1xxx series has the advantage/ability to load any number of maps from it’s internal memory. Simply create a folder in the root of the nuvi drive called „Map“ (no quotes) and copy your desired map into that folder. The map does NOT have to be called gmapsupp.img nor any of the older nuvi naming conventions…in this case you should give it a more descriptive name such as Topomaps.img (or anything else for that matter). The only stipulation is that it ends with the .img extension.
Note: Tested … it’s working.