Depends on what exact “UNIX file system”. If it was Linux, the most chances are that it is ext2/ext3 file system. You can use it with http://www.fs-driver.org/ driver or similar (http://sourceforge.net/projects/ext2fsd , there are more). Try to detect what FS is there with some tool like recent PartitionMagic. With different FS you should use different drivers.