I am attempting to share two disks between DOS and NetBSD.  I have been
merrily wiping out disk partitioning schemes right and left.  I *think* that
the way this works (at least my system is now bootable) is:  first I use
fdisk to prepare a DOS partition record in sector 0 of the disk, splitting
the disk between DOS and UNIX.  Then, I write a BSD partition record and
boot blocks to /dev/rsd0a rather than the traditional /dev/rsd0d (i.e. to
the base of the root partition, not the whole disk).  (I don't offset the
'd' partition because the only partition number that works if its type is
"unused" is 'd'; labelling a partition "4.2BSD" just to access a raw disk
image doesn't feel right...)

Is this all correct?  Is this all as clumsy as it feels, or have I just been
spoiled by nicer disk configuration tools?