Netbsd 1.6.1 kernel panic on RS6k 43p-140

Hi All,

I am trying to install NetBSD 1.6.1 prep port on my 
IBM RS/6000 43p-140:

CPU: 604e 332Mhz
Mem: 384M
Type: 7043-140

But the 1.6.1 prep kernel always panics. I searched
the port-prep list, but didn't find any posts showing
the same problem. 

Here is what I did:

1) I was using a serial null modem cable in the whole
process of installation.
2) I booted the machine with a floppy that had generic_com0.fs 
image on it.

dmesg is attached as follows:

>> NetBSD/prep BOOT, Revision 1.5
>> ([email protected], Tue Apr  8 22:30:01 UTC 2003)

Boot: Loading in()
2934572+255776 [159936+130869]=0x352080
start=0x100000

[ using 291380 bytes of netbsd ELF symbol table ]
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 1.6.1 (GENERIC) #0: Tue Apr  8 22:40:27 UTC 2003
    [email protected]:/autobuild/netbsd-1-6/prep/OBJ/autobuild/netbsd-1-6
/src/sys/arch/prep/compile/GENERIC
Model: IBM Model 7042/7043 (ED)
total memory = 384 MB
avail memory = 347 MB
using 2048 buffers containing 19760 KB of memory
trap: kernel write DSI @ 0x1160bfd8 by 0x216668 (DSISR 0x42000000, err=14)
panic: trap
Stopped in pid 0 () at  cpu_Debugger+0x10:      lwz     r0, r1, 0x14
db>

...

Could anybody kindly tell me what's going on and how 
to install NetBSD 1.6.1 prep port on my 43p-140?

Thanks very much,

Rongsheng