SD Card Boot mode

[themeowthteam]

i recently got a magellan gps for 12 dollars at a thrift store and i cannot get the usb mode to work on my computer as it has driver problems and after messing around i found 3 menus. a shell menu (hidden menu),a diagnostic menu? and an sd card boot "menu" i i tried many sd cards of many sizes and i can't get the menu to read the sd cards but one a lexar 4gb sd card behaves differently. Instead of saying "SD card boot please wait... waiting!!" it says "SD card boot please wait..." if someone can tell me what im doing wrong or what sd card i should be using that would be great
GPS Model is Magellan RoadMate 2200T

 

[Nuvi-Nebie]

I don't own any Magellan units or know anything about their operation so what follows is guess work, I think that for SD card boot to work the SD must contain bootable files eg. runnable 'boot' files, they will have specific file names that the GPS unit looks for when it first powers up (or 'sees' an SD card insertion ?), if the unit doesn't find these files it will be 'Waiting' for ever