This is topic How saves work and checksums in forum Research Lab at The Azure Heights Forum.

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Posted by pika (Member # 1908) on 07-08-2004, 08:07 AM:
well I reversed sav files yesterday.
The game reads them in chunks of 0x1000bytes in each chunk at 0xFF4 there is an id - which tells the game where to put the chunk in gba ram and how many bytes to copy (usually 0xF80 bytes). It only does this if a checksum matches... well and I have writen a program which corrects these [Wink] .

If you want it get it and it's GPLed Source here:

Posted by MK (Member # 1445) on 07-11-2004, 02:16 PM:
hehe, sweet pika. Keep up the good work. [Smile]

Karpe Diem