[syslinux] Large Floppy Images

[Remko van der Vossen]

Hello,

On Thu, Apr 12, 2007 at 12:31:33PM +0200, Bernd Blaauw wrote:
> improper bootdisk then. Adding a DOS bootsector under Linux on an empty 
> disk image doesn't seem to be easy,
> I remember some PERL script being used to implement a FreeDOS bootsector 
> for example.

This is indeed not particularly easy. I've made a 10MB ms-dos image a
few years back by mkdosfs under linux, dd-ing in a boot sector from an
ms-dos 1.44mb image and hex editing the boot sector to include the
correct geometry and copying the files (including hidden and system
files of course) to the 10MB image which you can mount through loopback.
I succeeded in booting from such an image with isolinux+memtest and also
in bochs.

Something along the lines of:

# dd if=/dev/zero of=floppy.img bs=512 count=23040
# mkdosfs -F12 floppy.img
# dd if=floppy.img of=boot.sct bs=512 count=1
# dd if=bootablefloppy.img floppy.img bs=512 count=1
- hexedit floppy.img correcting the msdos fat header attributes
  ie set correct geometry (cyls=80, heads=8, spt=18) set correct fat
  sizes, sectors per clustor, root directory sector, etc. copy from
  boot.sct where necessary
# losetup /dev/loop0 floppy.img
# mount -t msdos /dev/loop0 /mnt/floppy
# losetup /dev/loop1 bootablefloppy.img
# mount -t msdos /dev/loop1 /mnt/bootablefloppy
- copy all files including hidden and system files) from
  /mnt/bootablefloppy to /mnt/floppy
# umount /mnt/bootablefloppy
# losetup -d /dev/loop1
- copy necessary files from other install floppies
# umount /mnt/floppy
# losetup -d /dev/loop0

I do not have such an image at hand however, plus that ms-dos is
licensed software and thus not mine to hand out. I could make such a
FreeDOS image, but that probably would only complicate things if you
want to make an ms-dos installer floppy image.

Regards,

Remko van der Vossen.
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