It's a Kenwood DNX5140 car stereo. It is not eqipped to use a SD card, just the onboard hard drive that is of fixed size. I have about 1.6gb free after I deleted the old map and the new maps are around 1.84gb.
Properties of a gmapsupp.img for CNNANT 2014.20 map of JUST US & Canada is listed on an XP system as
Bookmarks