[syslinux] Possible memdisk issue

Ady ady-sf at hotmail.com
Tue Jul 8 18:03:55 PDT 2014


> On 07/08/2014 05:55 PM, H. Peter Anvin wrote:
> > On 07/08/2014 03:05 PM, Alexander Perlis wrote:
> >>
> >> Question: what's special about the transition from 8203KiB to 8204KiB?
> >> Both have CHS=8/64/32 and both involve a fractional end cylinder.
> >
> > Fractional cylinders with floppy disks is almost certainly a very bad thing.
> >
> 
> Agreed, but that doesn't appear to be the issue here. Fractional 8203K 
> FreeDOS does work, yet larger values, including non-fractional ones, do not.
> 
> Alex
> 
 
My guess is that the problem is not the total size (I have used 
MEMDISK with bigger superfloppy sizes), but the cluster size or the 
FAT size.

For instance, FAT12 should not use more than 4078 data clusters for 
maximum compatibility.

Unless we have at least the exact CHS (not the assumption of MEMDISK 
nor according to the total size of the image but rather from the FAT 
values), the amount of FAT sectors (9 for standard 1440KiB floppies, 
max. 12 for FAT12), and the amount of data clusters, there is no way 
to know whether the problem is in the superfloppy image or in 
MEMDISK.

Regards,
Ady.


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