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  1.    #1  
    Just figured out a neat trick that I'm sure will be very useful for some of you.

    Basically, there is a way to reduce the size of custom roms beyond what you can normally achieve using Shadowmite's ROM tool. Because the roms are standard ZIP files, all you have to do is create your custom ROM, then unzip it and remake the ZIP using an archiver with more advanced ZIP compression. Shadowmite is likely using standard ZIP libraries in his tool, which are great for all around use but not as good when it comes to super squeezing data using the ZIP algorithm.

    7-Zip in ultra mode appears to work the best. For reference, a ROM created by ShadowMite's tool is 7,119 KB. The same ROM compressed by 7-Zip in ZIP mode with Ultra compression is 6,888 KB. So that's 231 KB of extra compressed space, which approximates around 560 KB of extra uncompressed space if you assume 50% compression!

    I've flashed a ROM made like this and it works fine. ZIP's are ZIP's!

    P.S. I had to write a quick program to regenerate the MD5 hash that accompanies the ZIP after remaking the ZIP with 7-Zip.
    Last edited by rkuo; 08/01/2005 at 11:41 PM.
    Treo 650 with 1 GB SD card!
    http://www.rkuo.com
  2. #2  
    WHA?? The ROM isn't compressed when you flash it, right??? So, what difference does it make what compression method/format you use if it's uncompressed?

    Or is it really compressed?

    I'm confused.
  3. #3  
    Quote Originally Posted by grndslm
    WHA?? The ROM isn't compressed when you flash it, right??? So, what difference does it make what compression method/format you use if it's uncompressed?

    Or is it really compressed?

    I'm confused.
    You and me both.

    Your compressed size IN NOT the actual size of the ROM, that's why it's called a "compressed" file. Are you saying once extracted, your ROM is smaller??
    MaxiMunK.com The Forum That Asks, "Are You Not Entertained?"

    Remember: "Anyone that thinks the Treo should just work right out of the box, shouldn't own a Treo..."
  4. #4  
    Quote Originally Posted by grndslm
    WHA?? The ROM isn't compressed when you flash it, right??? So, what difference does it make what compression method/format you use if it's uncompressed?

    Or is it really compressed?

    I'm confused.
    I think hes talking about the ace-palmos.zip. The Palm OS will only allow it to be 7mb. Anything above that won't allow you to flash the ROM. But the total capacity for the actual ROM is 8mb. Not sure what the other 1mb is being allocated for but most likely the zip (onced decompressed) isn't using up the entire 1mb otherwise his procedure will not work. I'm sure there's a limit to his method as well.
    Last edited by aznmode; 08/02/2005 at 07:46 PM.
  5. #5  
    ruko:

    Good trick about the recompression. I've used that technique to also upload ROMs to some internet sites which only allow 10MB uploads, and that techinique has helped some squeek by. For the actual ROM updating/upgrading, the actual ROM size will be dependent on the number of files on the zip'd 0ace_palmos.zip) package.

    Your technique may be helpful for some who need a little extra space (15MB) on an update, when space is tight on their Treo. Good idea.

    Maria

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