>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.

You can use the NetBSD fdisk to do this (of course, you need NetBSD installed
already, but I made a boot disk a while back with fdisk on it).

>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).

The i386 install scripts just say:

disklabel -w -B sd0

And they seem to work, so presumably you don't have to spell out each of those
partitions.

--Ken