Originally Posted by
cecial
.....but not sure about 4G limited, because no map now beyonds 4G.........
And map .img files won't for as long as Garmin use FAT32 as a file system in their continuing products. The 4GiB limit for file size is a limitation factor of Window's File Allocation Table, not of Garmin's you see.
It was never intended for a FAT32 file system to see files of 4GiB and larger, they must be at least 1 byte less than that. That file size limitation is the very reason why MicroSoft came up with NTFS (New Technology File System) developed back before Windows NT was introduced. It's been ubiquitous since Win XP and nobody i know formats their big hard drives in FAT32 even though there are 3rd party tools to do it. Flash drives of more than 32GB which are formatted by default at manufacture to exFAT are a different story and often get reformatted by users to FAT32. Garmin has stuck with FAT32 though no doubt for some other very good reasons but in doing so locks themselves to map images below 4GiB on their handheld devices. I think the limitation with Garmin's software such as GMPC is much more to do with when it's code was written however because it's invariably running under NTFS now.
Originally Posted by
cecial
one more thing i remeber about the size displayed in the map is that:
i also tried a map which size is 1.87GB, but it is displayed as 2*** MB, FYI.
And by that statement it's clear that you didn't read or at least didn't understand what i was saying in my previous post about the decimal Gigabytes and the binary Gibibytes. In simple terms, decimal is factor of 1000 therefore 1KB is 1000 bytes, and 1MB is 1,000 times more at 1,000KB etc, whereas binary is a factor of 1024, therefore 1KiB is 1,024 bytes and 1MiB is 1,024KiB and so on. You can easily see that 1,000 x 1,000 x 1,000 is 1,000,000,000 [1 billion] bytes which is a decimal Gigabyte. Then if we do the same with a binary factor of 1024 we can see that we'll have a much higher number resulting: 1024 x 1024 x 1024 = 1,073,741,824 bytes. So if we double that to get 2GiB we'll have 2,147,483,648 which is of course approximately 2.1475GB. So you can see that if your example of 1.87GB is actually 1.87GiB it cannot be higher than ~1915MiB or ~2,007,897,210 bytes. But 2 billion bytes is 2GB [Gigabytes] or 2,000 MB [Megabytes] which is Decimal and it may well have been displayed that way in a different environment to Windows.
So the simple answer is that the map size of 1.87GB was displayed by windows in the binary sense, now more correctly referred to as GiB. M$ is technically correct as binary numbers were used in IT since its inception and it was only the fact that the HDD and flash drive manufacturers tried to hijack the binary names and make them decimal back as far as the '90s. Why? Because it makes their drives seem bigger is why. Plug your 64GB USB stick or media card into your PC and see what size is shown, it won't be 64GB, sure it might show 64,000,000,000 bytes or close to it, but that's actually ~59.4GiB [Gibibytes] which Windows will display as 59.4GB [when it's actually GiB, Gigabytes] because they refuse to yield to the games of the drive manufacturers.
If you think my simplification of binary as a factor of 1,024 and decimal as 1,000 is confusing, here's some light reading for you any other interested or confused readers:
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Have a look at how they explain the binary factor .....
If only M$ would roll over and accept the new naming the confusion might end ..... but i'm not holding my breath for that.
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