How do I use Mapsource to load additional maps onto my Garmin Oregon?
The best place to start is the Mapsource manual in the section called Loading Maps to Your Garmin GPS Unit. The basic operations required to send maps to the Oregon are: • Connect the Oregon to your computer • Select a number of map regions in Mapsource called a map set that you want on your Oregon • Use Mapsource to build the map set and transfer it to your Oregon or the Oregon’s SD card Mapsource transfers the map set to the Oregon as single file called gmapsupp.img which is stored in [OR drive]:\Garmin or [OR SD drive]:\Garmin . Every time you repeat the process above you delete the previous map set and replace it with a new map set. Maps cannot be added or removed incrementally using Mapsource. This implies that if you are trying to load maps from multiple Mapsource products (i.e. Topo2008 and City Navigator) that you will need to include map regions from both products in the same map set. Mapsource supports this by allowing you to select the first Mapsource product via a drop down
