history:
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1.08a
  (1) disable driver when on-board IDE is disable and try to install IDE driver
1.08b
  (1) disable driver when boot with SCSI and try to install IDE driver
  (2) 32 bit file access with 3 hard disks simutaneous access problem
1.09a
  (1) fill prefetch buffer
  (2) fix channel1 slave channel lba hard bug
1.09b
  (1) let qt mode 4 to run master
  (2) don't install global time_out routine
  (3) fix slave disk error setting dma mode