1. Don't worry about gimgxor.exe for this. It's only rarely needed to 'unscramble' a previously XORed image file. If you want a full explanation about when it's used and why, see [Only registered and activated users can see links. ].

2. Remove the .gma and .unl files. They are specific to the GPS you've pinched the map from and cannot help when you try to use the map image with your Astro [they can only hinder correct operation in a different unit] .

3. Your description makes it seem that the map is on a microSD card in the Astro, not in the internal memory. It's fine to be on the card as long as it correctly placed, see 6 below. Move the img file from your Astro or it's card and make a copy of it to keep somewhere safe in case something goes wrong.

4. Open a terminal window on your Mac and then do the steps in either Method 1 or Method 2 given in catymag's post immediately above your post. Those instructions have been copied and pasted from the link previously given for the mac version of gimgunlock.

5. After you've unlocked the map image, move it back to the Astro or it's card.

6. If the map is on the card, it is usually quite safe to unlock the image on the card itself if you want to skip the step of moving it to your mac then back after unlocking.

&. The correct path on the card is x:/Garmin/gmapsupp.img. Not directly in the root.