I'm guessing that can be stored in the IC K5n5629ATA (NOR Flash) 256Mb.
In theory it should be the NV ram. It is not logical that the region 0xC (boot.bin).
I guess until you get to read the eMMC Ic not really know this.

Already Garmin's engineers are not going to go through here, but in this forum there are people with much knowledge. hehe