[mkgmap-dev] problem seeing OSM maps on nuvi 255w

Tue Dec 22 16:49:28 GMT 2009

Hi Charlie,

On Tue, Dec 22, 2009 at 11:27 AM, Charlie Ferrero <charlie at cferrero.net> wrote:
> Can you have multiple gmapsupp files on a Nuvi?  I guess you must be
> able to, if you've got both North American maps and OSM maps at the same
> time.  I don't know if Nuvis are the same, but on a GPSMap you can't
> remove the basemap (though you can turn it off).

The Nuvi 255w appears as a 2Gb USB drive when you plug it into a
computer. This USB drive appears to have all the firmware and maps
files. The Garmin directory has the basemaps - gmapbmap.img (50Mb) and
the map files for the region you bought the GPS unit - gmapprom.img
(1.1Gb) - in my case Canada and USA.

To load external maps, you can either put the gmapsupp file in the
Garmin directory of the USB drive or you can put it in the Garmin
directory of an SD card. The nuvi will only load one gmapsupp file
giving preference to the file on the unit itself.

To remove the basemap or included maps, all you have to do is rename
or delete the appropriate file.

Ben