There is another solution that was posted on the comp.os.minix topic.
Using any disk or file editor (I used Norton Utility), search for the
following hex sequence in the DRDOS system files::



24 7f		and al,7fh		;clear top (secure) bit

3c 01		cmp al, DOS20_ID	;is this a DOS2.x partition?




	(The assembly code is courtesy of Rob Huehn of Geac Computer
Corporation, who fixed the bug for DRDOS 5.0) (huehn@geac.com on
internet).



Simply replace the 7f with ff, and DRDOS will no longer try to strip
the high bit off the MINIX partition type (which turns an 81h for
MINIX into a 01h for DOS).

I appears that the default for Linux is also 81h or 129 decimal.

I had MINIX and DRDOS 5.0 on my system together for one year and DRDOS
6.0 by itself for almost another year with the above modifications
with no problems, so I believe it works fine.

I informed Digital Research of the problem, but heard nothing of it.


Hope this helps someone, 
Jason