DOS ain't dead

Hi,

Can you explain to me why a DMF floppy disk freeze at boot when the same disk but in 1.44Mb format (the DMF file converted using WinImage) works?

I have the problem with older DOS but not with more recent ones so I assume it's a problem of unsupported format in the kernel files?

Thanks

Upload of my test images:
megawrzuta.pl/mmctkfxc

as DMF has more sectors per track (normal: 18, DMF: 21), kernel may not know part of itself is in "extra" sectors of same track.

> as DMF has more sectors per track (normal: 18, DMF: 21), kernel may not
> know part of itself is in "extra" sectors of same track.

Thanks, so there nothing that can be done...(?)

> > as DMF has more sectors per track (normal: 18, DMF: 21), kernel may not
> > know part of itself is in "extra" sectors of same track.
>
> Thanks, so there nothing that can be done...(?)

For FreeDOS, maybe you can modify its boot sector source and FreeDOS boot related source to handle BPB and DMF disk?

https://archive.org/details/vgacp625

vgacopy says that it supports DMF (Win98), I already tested it with FreeDOS and 3,5 inch diskettes, worked fine, but I do not know if the older 5,25 diskettes are supported too.

Even if we slightly switch of subject, thanks.

1. The maybe only impossible solution will be to have 2 types of track size, 18 sectors for around 250-300Kb and 21 sectors for the rest of the disk, or someking of dual partitions?

2. Can someone test 2M please, I try on 86BOX and QEMU, I still got density error when I try to format using MS-DOS format or 2MF? (https://www.youtube.com/watch?v=venQZPVeCNs / http://www.win3x.org/win3board/viewtopic.php?t=25019&view=min). Even using VGACOPY and selecting the 2M size didn't works...

> Even if we slightly switch of subject, thanks.
>
> 1. The maybe only impossible solution will be to have 2 types of track
> size, 18 sectors for around 250-300Kb and 21 sectors for the rest of the
> disk, or someking of dual partitions?
>
> 2. Can someone test 2M please, I try on 86BOX and QEMU, I still got density
> error when I try to format using MS-DOS format or 2MF?
> (https://www.youtube.com/watch?v=venQZPVeCNs
> /
> http://www.win3x.org/win3board/viewtopic.php?t=25019&view=min).
> Even using VGACOPY and selecting the 2M size didn't works...

emulators don't support custom size of floppy well.

> Can you explain to me why a DMF floppy disk freeze at boot when the same
> disk but in 1.44Mb format (the DMF file converted using WinImage)
> works?

Hardcoded values in the bootsector/and or a bios call there that doesn't support DMF ?