By Collin Allen

Backing Up GPS Maps

June 21, 2005

Recently I got a Garmin iQue 3600 GPS/PDA. I like it a lot because it runs Palm OS, has GPS capabilities, and also doesn’t lock out off-the-shelf SD cards for map storage. To store more maps than I’ll probably ever need, I purchased a 1 GB SD card to go with it, which it happily formatted and took advantage of. I also used the SD card for a short period in my Minolta Dimage G500. I like having plenty of storage in both devices, and wished there was an easy way to swap the card back and forth. I could just let my camera erase the card, and then re-download the maps onto it when I need them, but that requires Windows and about an hour and a half of my time – probably much longer running Virtual PC, as opposed to a real PC.

I discovered that I could read the SD card in it’s map-storing state via a PCMCIA card reader, and I imagine any SD capable adapter would allow the same. The iQue formats the SD card as FAT16, and Mac OS X is able to read it. Using Disk Utility, it’s easy to create a new image of the card onto my hard drive by selecting the device and choosing New, Image From disk2 (where disk2 is the Unix device for the card). With a 1:1 duplicate of the SD card’s maps on my hard drive as a read-only disk image, the card can be reformatted for use in my digital camera. When I want to quickly load the maps back onto the card, I plug it in and restore the .dmg file back to the card. Now I can swap the card back and forth while on the road without having to wait an hour, or use Windows.