Thread: Garmin TransAlpin 2012 Pro

Originally Posted by GPSFranz

So they saved 3 bytes (a 12-character part number coded in 9 bytes).
This looks like a lot of effort to save 3 bytes (in files that usually measure in hundreds of megabytes).
What was the reason for all this effort?
Are there any technical reasons?
Did they believe that their coding scheme would not be discovered?
Or what?
(Scratching my head...)

From what I can see, the main reason is indeed to save space, a 25% saving. By design, Garmin reserved some areas in their img header for future use and expansion. As time goes, these reserved areas gradually become defined and used. The 9-byte part number at offset 48 is just one example. It is obvious that you want to minimize the use of reserved areas as much as possible so there are more rooms left for the future.

Originally Posted by syzygy

From what I can see, the main reason is indeed to save space, a 25% saving. By design, Garmin reserved some areas in their img header for future use and expansion. As time goes, these reserved areas gradually become defined and used. The 9-byte part number at offset 48 is just one example. It is obvious that you want to minimize the use of reserved areas as much as possible so there are more rooms left for the future.

I totally agree with this analyse: Garmin wants to save space, not in the whole img but in the header.