Re: [hatari-devel] Hatari and OUTSIDE (virtual memory manager)

[Uwe Seimet <Uwe.Seimet@xxxxxxxxx>]

Hi,

> The reason for this, though, is that Uwe's OUTSIDE.IMG contains an
> invalid file system. The C: drive on it has 16 bit FAT entries, but only
> 1003 clusters. The FAT filesystem specification unequivocally states:
> "There is no such thing as a FAT16 volume that has less than 4085
> clusters". EmuTOS's file system code adheres to the specification,
> decides -- based on the number of clusters -- that this must be a FAT12
> filesystem and consequently fails to properly read files (such as
> OUTCONF.APP) from it.
> 
> This neither an issue with Hatari nor with EmuTOS but with the disk image.

Even though this may formally be correct it may not be the best approach for
GEM/BGM partitions, as we can see with this image and AHDI (or other drivers).

HDDRIVER, by the way, signals a 12 bit FAT for *DOS compatible* partitions
of type 0x01 with less than 4085 clusters, but a 16 bit FAT for GEM/BGM
partitions of the same size. For floppy disks in USB floppy disk or LS-120
drives the situation is more tricky because the medium inserted may or
may not have a partition table. If there is none, deriving the FAT format
from the number of sectors has worked fine for me, in order to support
regular floppy disks in these drives.

Best regards

Uwe