On Thu, 13 Aug 1998 16:52:12 +0200, Fabrizio Catalano wrote:
> Internal video hardware is used with an Apple 16" RGB monitor, i get the
> same problem on a Quadra 700 and on a Quadra 650.
> 
> The kernel is 1.3.2 GENERIC, RAM is 20MB with 40MB of swap.

Can you try another, newer kernel?  That might fix the grf mmapping
problem.  You can get current snapshot kernels from
ftp://ftp.netbsd.org/pub/NetBSD/arch/mac68k/snapshot

Ken