IFD540/440 Touch Screen GPS/NAV/COM : DataBase Updates

I did my first nav data/chart/obstacle service updates yesterday. Using the 8GB USB FOB that comes with the 540 unit, I was able to download (using JSUM) the revisions for both radios including US IFR and Jepp Charts on one FOB.

Then I simply programmed each 540 separately using the same FOB. 

After I programmed the FOB with JSUM, I found only four files on the FOB:

authorize.dat

Charts.dsf

navdata.dsf

obstacles.dsf

I can only assume that next time I do an update, JSUM will overwrite these files with the exact same named files preventing someone from having two different revisions on their USB drive.

As a side note to OSX users like myself, the OSX JSUM will not program the Charts. It works for everything else, but after three separate laptops failed to load the charts with a 500 error, I called Jeppesen and they suggested trying windows. 

I booted into Windows XP on my parallels and it programmed just fine!