Add Free World Base Map for nüvi with a Mac

Another thread discusses how to obtain a 2003 base map of the world from Garmin for the nüvi at:
http://www.poi-factory.com/node/15809

Why would you want this? It adds major roads and towns from around the world. It may be useful when traveling internationally if you don't need detail routing and POI info. I find it is nice in southern Arizona where the regular base map just shows a blank space in Mexico. The worldwide map shows the major roads and towns.

The map is available at:
http://www8.garmin.com/support/download_details.jsp?id=461

You can use this as a supplement to your current maps by putting it on a SD card. The map is 31.1MB. It may fit on a 32MB card. I used an old 64MB card.

The Garmin map shows it is a .exe file but you can extract what you need with the free utility The Unarchiver:
http://wakaba.c3.cx/s/apps/unarchiver.html

Here's the steps:
1. Mount the SD card and create a folder named GARMIN. You will need a SD card reader to mount the card.

2. Download the map and extract the map by right-clicking on the file and select to open with The Unarchiver.

3. A folder named "iQue3600 World-WideBaseMap_301" will be created. Go to the folder "worldwide" and copy the file "GMAPBMAP.IMG" to the GARMIN folder on the SD card.

4. Rename the GMAPBMAP.IMG file GMAPSUPP.IMG.

5. Insert card into nüvi and restart.

That's it! You can check to see if the map is being read by looking at Settings>Map>Map Info. You can also check or uncheck the supplemental map if you want to test its effects on performance, or see the differences with or without the map.

You can see what the map adds by entering some coordinates for an international location and select View Map.

This procedure maintains your nüvi maps and adds the supplemental map with no harm to the maps on the GPS.