Thread: Convert 3790/3760/3750 to 3490

Whoa! It is not a signature, its a full book! LOL! I think I have seen this in the past, but I thought it was some garbage at the end of the file. I compared 34xx v350 with v360 and it is a very different garbage which does not even look like garbage. So it may well be a 256-byte signature.

If you have seen it in the dissasembly, that just means we need to bypass it in the boot.bin or X-loader.bin, right? Have you tried to do so and flash a gcd without the signature? Or, do you need to flash the modified boot.bin first with updater.exe before you can update with a regular gcd?

The signature is checked in fw_all.bin before running boot.bin from the GCD file.

After reading thread here seems I would need to reflash 37xx logo if I converted to 34xx and wanted to go back to 37xx.
So using 37xx boot.bin (extracted from GUPDATE.GCD version 4.6), I did following to create a rgn file to allow return to 3790 logo.
Opened Region Tool (84) and loaded boot.bin (from 37xx 460 version) then loaded logo.bin (37xx from turboccc post on how to change logo) then saved file as 37xx_460_logo_hid1101.rgn.

Surprised to see that the logo.bin file size for 37xx in RgnTool was 3145728 compared to only 10281 for 34xx logo bin. Does this sound right or did I screw up logo somehow?

Logo in 37xx is a 800x480 image in a 1024x512 frame. LOgo in a 34xx is a 800x480 image in a 800x480 frame. Yes, logo in 37xx sh9ould be bigger than the logo in a 34xx but the size on your 37xx is way to high. Replace logo with GIR_Editor then check the final size of the logo.bin. There should not be that much difference.

Logo with 3MB size is a direct dump form nuvi memory. You can remove trailing FF from it. Maybe GIR_editor could have an option for truncating bin file?

I think GIR_Editor already cleans the trailing FF, no? It rings a bell, but I am not sure. Maybe if you just extract the logo and replace it, it will.

@turboccc and Kanopus
I opened the 3MB logo and edited file by loading the tmp.png auto generated by gir editor as the new logo. Saved the result and the new file size is only 11KB. Sound like the 'truncating' has been carried out by Gir Editor.
At least now I am not concerned at the large discrepancy in logo file sizes. Clearly some logo files had been truncated and some not.

Don't worry too much.

1- The logos are in PNG format. This is a compressed format which will depend on the image content. The Garmin logo becomes very small, but my Angry Birds logo is pretty large. All of this is normal.

2- Flashing extra data will not hurt the GPS unless maybe you flash something that is bigger than the reserved space for the logo region at which point the gps will probably simply refuse to flash it.