> In the book Adams/Tondo "Writing DOS device drivers in C" they describe a > WORM 3363 device driver that tells DOS that it accesses a 32 MB FAT disk. > The driver then maps these 32 MB to the 200 MB WORM drive. If DOS tries to > write to the emulated 32 MB FAT disk, once the 32 MB are used up, DOS writes > to yet unused sectors on the WORM drive well beyond the 32 MB which DOS > thinks would be available.
> So again, the block device driver interface is not limited to FAT disks. right. *disks* ! the above mentioned driver emulates a 32 MB read/write drive using a 200 MB WORM drive, and presents a 'normal' 32 MB disk to DOS. the *file system* is still FAT. in a similar (and even reasonable) way, a driver could locate a 32 GB disk image DOS.IMG inside a EXT/NTFS/exFAT/Reiser/whatever disk, and present this to DOS as a virtual drive, and DOS handles this disk as a 32 GB FAT disk. parsing a filesystem *once* to translate a single file into a linear range of sectors is no big deal, and could easily be done. but the generation and interpretation of file names inside this DOS.IMG would be handled by the DOS kernel, not the device driver and follow FAT rules. Tom ------------------------------------------------------------------------------ _______________________________________________ Freedos-devel mailing list Freedos-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-devel
