Originally Posted by johnpitts01
Finally I have all the maps and I am ready to install. City Navigator 2013 and Topo 100K.
I am on a Mac.
I don't see any option to install the maps to the uSD ONLY.
MapInstall will, by default, load everything on the uSD card first, before using GPSr internal memory. Nothing prevents you from transferring *.IMG files between them as you wish, once the install in complete.
Detailed info available here