Thanks for the reply.
You are right,FlashGet keeps task info in a .jcd file.
About the disk fragmentation,if FlashFXP stores the received data in order,then the fragmentation should not exist,but in fact it does. For example,I just formatted partition E in NTFS,and downloaded a 2GB file in this partition by FlashFXP without any interruption.Then I run the Windows XP defragment and it said I should defrag this partition...It seems FlashFXP store the data in a random order
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I'm not worried about the fragmentation now,just a little curious.