Thread: (Nuvi 660) Is it possible to convert OEM FW to regular one?

Thanks for the very quick replies. But I am too much a newbie to even comprehend the instructions... :-(

I got the tools mentioned here, as well as updater.exe and FW 4.90 from Garmin (extracted gupdate.gcd).

* Loading gupdate.gcd into rgn_tool, It shows HWID 596, SW version 490, for both bin files (boot.bin and fw_all.bin). I could save either file, but gir_editor refused to load either because they are not logo or gir files. Actually gir_editor also refused to load the logo files from ddabcd277's links (error 6: overflow).

* I was able to add the logo.bin into the gcd file as the third bin file, and save it, but I am not sure what this will do. In particular, I could add another one (the 670 one), and when I load the modified gcd, I saw both of them listed despite they all have the same parameters. So I am wondering how the gcd works -- does it just load the sections in order, and overwrite earlier writes if later ones use the same address? In other words, if I just add it as the third bin file and load the modified firmware, would it be loaded over original and if it happens to be the region where the logo is accessed, then It gets replaced? From the addresses they don't actually seem to overlap ... but then since the firmware update does not change the splash, maybe the logo was at a different place. The addresses are:

boot.bin: section 0800, size 270048, RGN region 0C
fw_all.bin: Section BD02, size 10355456, RGB region 0E
logo.bin (from nuvi660OrigSplashScreen): Section 1005, size 270274, RGN region 10

* I actually don't know if my splash screen is firmware preloaded -- all I know is that it does not get replaced by firmware update, and it shows up first thing (before the copyright info etc shows up). In the garmin/ directory of the gps, there is a file named gmapoem.img (51K). I am not sur eif this has anything to do with the splash screen? I suppose the img files are some kind of archive (because there is also the gmapprom.img, which is over 1GB, and I suppose it is the actual map); How do I unpack them (7zip or winimage won't recognize them)?

* was able to get into maintenance mode by holding upper left corner while power up, but could not get into diagnosis mode (I think I once accidentally entered it, but now I could not recall how ...). I'll keep trying.

I'll appreciate further advice. In particular, if I should just add the logo.bin to the gcd and load it (And in the case it does not work and/or messes up the gps, is it possible to reload the original? I would assume that the gps has "pre-boot" code built in that is not altered by update, and it would allow the load of new firmware. Is this true? )

Thanks again!

Sean