Okay.
After a lot of fiddling and rebooting, I got it working now and have now a grub boot/back-up floppy I can mount.
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*** Important ***
Make sure that all "savedefaults" are removed from your menu.lst, otherwise those OS's won't boot. All the others will though.
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* Also take notice of that these commands are optimized for Ubuntu as I installed it (all mount points in directory /media), you'll probably need to adjust the floppy mount point in the code.
Perform as root:
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$ fdformat /dev/fd0
$ mkfs -t ext2 -c /dev/fd0 *or* $ mkfs.vfat /dev/fd0
$ mount /dev/fd0 /media/floppy
$ mkdir -p /media/floppy/boot/grub
$ cp /boot/grub/stage1 /media/floppy/boot/grub
$ cp /boot/grub/stage2 /media/floppy/boot/grub
$ cp /boot/grub/menu.lst /media/floppy/boot/grub/menu.lst
$ umount /dev/fd0
$ grub
$ root (fd0)
$ setup (fd0)
$ quit
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And you're done.
Now you have a grub back-up floppy/boot disk, which one can also mount.
I hope you'll find the disk useful.
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If you do not want all the command-line fuss, I uploaded an image file of my disk, together with 2 programs of which (according your choice) you'll need 1 to write the image to disk. (rawrite and/or rawwrite)
Once written to floppy, you'll only need to copy your own menu.lst file over mine and your done.
$ cp /boot/grub/menu.lst /media/floppy/boot/grub/menu.lst
You can find the zip-file here:
http://www.beebab.be/que/linux_boot_+_rw.zip
(About 297 KB.)
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My thanks go to:
j1alu (on this forum), who pointed me to this URL
http://sidux.com/index.php?module=Wikula&tag=GrubFloppy
There where some mistakes in that file that I adjusted (well, perhaps they were not really mistakes, but the correct commands for that distribution(?))
Take care, you all!