Bootblock woes again

[Felix Schroeter <uk1o_(_at_)_rz_(_dot_)_uni-karlsruhe_(_dot_)_de>]

Hello!

You perhaps remember my last mail reporting problems with the new
OpenBSD/i386 bootblocks. Yesterday I wrote a floppy with
  disklabel -r -w fd0 floppy3
  newfs /dev/rfd0a
  mount /dev/fd0a /mnt
  cp /usr/mdec/boot /mnt
  /usr/mdec/installboot -v -h 2 -s 18 /mnt/boot /usr/mdec/biosboot fd0
  umount /mnt

It worked ok at home (rather modern Pentium box), but not here (older
486 box, Adaptec 1542 controller). The bootstrap prints this:
  Loading /boot....
  pc0 detected
  using pc0..
  mem0: 640K:19456K
  Probing disks: fd0 fd1 fd2 fd3
and here it hangs.

The old boot floppy that works doesn't know 'machine diskinfo' yet,
so I can't proceed in trying to finally get the bootstrap working on
that disk.

Regards, Felix.

PS: At home, on my disk are still the old (Dec 96) bootblocks.
How do I backup them the best way so I can try to install the
new ones on the harddisk and still being able to revert to the
old ones if the new ones should not work?