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  1. #91
    Master sergio2's Avatar
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    Hi
    Can't download ImgTool from post #85.
    Another link ?

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  3. #92
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    Quote Originally Posted by sergio2 View Post
    Hi
    Can't download ImgTool from post #85.
    Another link ?
    Code:
    Please Login or Register to see the links

  4. #93
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    Quote Originally Posted by GPSFranz View Post
    3. Why do some IMG files contain unlock codes (i.e., why are the unlock codes in the IMG file, not just in a separate .unl file)?

    4. Is a separate .unl file required, even if an IMG file contains an unlock code?

    5. If a separate .unl file is still required, do the unlock codes in the IMG file and in the separate .unl file have to be identical (or can they be different, yet both valid unlock codes for a given GPS unit or SD card)?

    6. What software product puts the unlock codes in the IMG files, and when (or under what conditions) does it do so?

    7. Why and when (or under what conditions) does an IMG file contain more than one unlock code?
    These questions and answers are off-topic, but here we go anyway.

    Historically, a Garmin MapSource product was shipped in CDs/DVD along with an unlock code on a yellow sheet or sticker. To use the map, you must install it on PC and enter the unlock code to unlock it so MapSource.exe can read and display it. To install the map into your GPS device, you select the map tiles you want and MapSource.exe will generate the file gmapsupp.img with the unlock code embedded then writes to your device.

    If you select map tiles from more than one MapSource products then the resulting img file will have more than one unlock codes embedded, one for each product. You can display, add or delete embedded unlock codes in an img file by GMapTool. This kind of unlock code is tied to the unit ID of your device such that the map cannot be used on other devices.

    Then, Garmin sells pre-generated maps in SD cards. Each card has one map file and one .unl file. The latter contains an unlock code tied to the ID of the SD card. This allows the map to be used when the original SD card is inseted on other devices. However, the map and unlock code will not work if copied to a different SD card due to different SD card ID.

    A .unl file can have multiple unlock codes. Just join them together without space and end-of-line in between. Each unlock code can be tied to the unit ID or SD card ID. Most SD card savvy firmware will read in all unlock codes, regardless of location (embedded or .unl files) and ID type (unit ID or SD card ID). A map will be unlocked if at least one of them is valid and matches the map product.

    Later, Maps pre-installed in a new GPS device or sold/upgraded by downloading also take the .unl approach.

    Lastly, new maps sold and downloaded are protected by the GMA scheme. On devices with old firmware, it is still possible to unlock them by either method above. On new devices with GMA savvy firmware, they can only be unlocked by a valid .gma file or an unlocker tool. Also, for completeness, the MMR subfile for cityXplorer cannot be unlocked by an unlocker tool. Change of MapID and .unl are required.

  5. #94
    Master sergio2's Avatar
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    Hi,
    I could’nt download ImgTool.
    So I followed Merlinboy’s advices in post 73 and used Hex Editor to add lacking number in the header of .img Topo Transalpine 2012. By now, new .img file allows new active routing in Basecamp !
    By the fact, here is a link to download a hex editor easy to use for people like me with no skills : follow exactly post 73 and all will be easy.
    [Only registered and activated users can see links. ]
    An off-topic question :
    Does anybody know easy litterature on how a code like 10 D4 40 56 14 91 0D 14 41 put on the right area into the hexaeditor table gives the number 010-D1160-00 well located in the .img header, or is it too difficult for a novice ?

  6. #95
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    Quote Originally Posted by sergio2 View Post
    Does anybody know easy litterature on how a code like 10 D4 40 56 14 91 0D 14 41 put on the right area into the hexaeditor table gives the number 010-D1160-00 well located in the .img header, or is it too difficult for a novice ?
    See message #2 [Only registered and activated users can see links. ] and in this link you will find a description of this algorithm in message #3.

  7. #96
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    The part number contains 12 characters (example 010-D1160-00).
    It is coded in binary with 9 Bytes.

    So when you have your 9 bytes ( example 10 D4 40 56 14 91 0D 14 41 or more precisely 41 14 0D 91 14 56 40 D4 10 because you have to reverse the bytes order) , this represents 8x9 bits i.e. 72 bits.
    Group your 72 bits by 6 : so you have now 12 groups of 6 bits.
    Each group of 6 bits give you an integer between 0 and 2^6 - 1 i.e 63 .
    Add 32 to these values : you have now 12 integer between 32 and 95 : each of these integers give you a character of the part number (using ASCI coding)

  8. #97
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    Quote Originally Posted by sherco40 View Post
    The part number contains 12 characters (example 010-D1160-00).
    It is coded in binary with 9 Bytes.

    So when you have your 9 bytes ( example 10 D4 40 56 14 91 0D 14 41 or more precisely 41 14 0D 91 14 56 40 D4 10 because you have to reverse the bytes order) , this represents 8x9 bits i.e. 72 bits.
    Group your 72 bits by 6 : so you have now 12 groups of 6 bits.
    Each group of 6 bits give you an integer between 0 and 2^6 - 1 i.e 63 .
    Add 32 to these values : you have now 12 integer between 32 and 95 : each of these integers give you a character of the part number (using ASCI coding)
    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...)
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  9. #98
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    @GPSFranz: just look at this topic: [Only registered and activated users can see links. ] , thread #6 , download the Excel-file and analyse what's happening.
    Good luck

  10. #99
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    Quote Originally Posted by GPSFranz View Post
    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.

  11. #100
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    Quote Originally Posted by syzygy View Post
    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.

 

 
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