By popular demand, many people ask me about “how to put more than 1 map on GarminXT” ,so there you go:
MAP # 1 copy “GMAPBMAP.IMG” (basemap) to your Storage Card in \Storage Card\Garmin”
– This is your BASEMAP, YOU WILL NEED THIS LATER FOR WORLDWIDE ZOOM-OUT! DO NOT REMOVE.
MAP #2 rename to GMAPPROM.IMG copy to your Storage Card in \Storage Card\Garmin”
– This is your primary map, GarminXT will read it as map from internal FLASHROM
– And this is will be your 1st Map, look at the Name! rename it that way.
– Create “GMAPPROM.UNL” <— attention!
– Copy it along with the MAP file GMAPPROM.IMG
MAP #3 “GMAPSUPP.IMG” and copy to your Storage Card in \Storage Card\Garmin”
– Make sure the name of the file is “gmapsupp.img”
– Then Create “gmapsupp.unl”
MAP #4 “GMAPSUP2.IMG” copy to your Storage Card in \Storage Card\Garmin”
– Make sure the name of the file is “gmapsup2.img”
– Then Create “gmapsup2.unl”
MAP #5 “GMAPSUPP.IMG” copy to your ROOT Flash ROM in \PPC\Garmin”
– Make sure you read this carefully, put the map into your Internal memory/ROOT, the Other “Garmin Folder”! its not the one at
– if you got an error, just remove it and try different map.
– Make sure its small file/map (ie: singapore & malaysia map) and make sure you check your Internal memory capacity on your PDA. if
its too low, don’t install this.
– In most older PDA the internal memory are Small, some newer PDA with big Flash ROM able to put this map easily.
– make sure you still got 5~6 MB FREE Space on your Internal Memory or your PDA will CRASH/Freeze/Hang.
– Don’t forget to create “gmapsupp.unl”
– Attention: The fifth map (#5) NOT always Works! Some Map will, Some Don’t.
– Using this method the total of the map are 5 maps including basemap.
– Make sure you install the map one by one, if one map succeeded go to the next one, don’t put all the maps in one go.
– Why most garmin maps comes with “gmapsupp.img” instead of “gmapprom.img”? because Garmin set the default of the internal map on
most FlashROM are “gmapprom.img”.
– Basemap will help you in worldwide zoom-out for browsing other countries.
– Basemap able to solve your problem for detecting your “details map”.
– Some of you want to delete the basemap, its your choice. but i wouldn’t do that if i were you.
– Some people with limited Storage Card, prefer to delete the basemap right after you get a fix signal from birds/satellites and
after zoom in to your current location.