Thread: How to reduce the size of a gmapsupp.img file on a card???

@Monz
Yes the solution is there. The only reason you don't understand fully what's written is that you and many more people haven't yet understood the confusing difference between the original binary interpretation of a gigabyte (which is now more correctly known as "gibibyte") and the more recent decimal interpretation of gigabyte. 1 gibibyte has a value of 2 to the power of 30 bytes or 1,073,741,824 bytes (i.e. put more simply, a multiplication factor of 1024 to higher values, bytes>kibibytes>mebibytes>gibibytes etc.) and the abbreviation of gibibyte is "GiB".

The term gigabyte now is usually given a decimal interpretation where 1 gigabyte has a value of 1,000,000,000 bytes (10 to the power of 9, or a factor of 1000) and it's abbreviation is "GB". I say usually because Microsoft is sticking stubbornly with the original binary interpretation which adds to the confusion seeing Linux and Mac OSs now both use the decimal sense for gigabyte. That seems even more weird as MS's Windows OS runs in base 2 but actually displays storage capacities using the current prefix for base 10. In their defense they're simply sticking with the original binary interpretation of those prefixes.

So, you can maybe now clearly see that 2 GB is 2,000,000,000 bytes but 2 GiB is 2,147,483,648 bytes. Also your so-called 2GB CF card only has effective storage available of ~1.90 GiB or 2,047,541,248 bytes. Your garmin-based GW Navi can actually read an image up to the FAT 16 file size limit which is one byte less than 2GiB or 2,147,483,647 bytes so by using a card larger than your 2GB CF you can get a slightly bigger img file on it, almost 100,000,000 bytes or ~10 MB larger in fact. If you have a later model GW with an SD card navi then your 2GB SDs have even less space than a CF.

If you've got your head around the above info, you'll now understand what's written in Post #23. If you still don't get it, read this page:

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