Kernel traps while initializing kernel on a PowerMac 7600

[Kris Hepler <khepler%gmail.com@localhost>]

So I dug my old PowerMac 7600 out of storage, and am trying to get
NetBSD running. I did this once before on a 9600, but it's been a while.
Anyway, I got so far as loading the kernel from the install CD and then
it hits a trap every time. Initially it was always an MCHK trap, but
after powering off overnight it's now always a PGM trap at the same spot
as before.  It hits a trap every time, and the numbers (IP and SRR1 reg
values?) don't change across reboots for each trap type.

Can anyone tell me what this means or possible causes?  I'm at a loss as
to where to go from here.

MCHK trap boot transcript:
----------------
0 > boot scsi-int/sd@3:0
OF_open bootpath=scsi-int/sd@3
read stage 2 blocks: 0. done!
starting stage 2...

>> NetBSD/macppc OpenFirmware Boot, Revision 1.12
open /netbsd: Device not configured
open /netbsd.gz: Device not configured
5058040+125888=0x4f1e70
 start=0x100000
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007, 2008, 2009, 2010, 2011, 2012
    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 6.1.5 (INSTALL)
total memory = 49152 KB
avail memory = 41356 KB
found Grand Central PIC at f3000000
bootpath: scsi-int/sd@3/netbsd.macppc
mainbus0 (root)
cpu0 at mainbus0: 604 (Revision 3.5), ID 0 (primary)
cpu0: HID0 0x8000c084<EMCP,ICE,DCE,SGE,BHT>, powersave: 1
cpu0: 120.00 MHz
bandit0 at mainbus0
pci0 at bandit0 bus 0
pchb0 at pci0 dev 11 function 0
pchb0: vendor 0x106b product 0x0001 (rev. 0x03)
obio0 at pci0 dev 16 function 0: addr 0xf3000000
esp0 at obio0 offset 0x10000 irq 12: NCR53C94, 25MHz, SCSI ID 7
scsibus0 at esp0: 8 targets, 8 luns per target
mc0 at obio0 offset 0x11000: irq 14,2,3: address 00:a0:40:10:38:24
zsc0 at obio0 irq 15,16
zstty0 at zsc0 channel 0 (console i/o)
zstty1 at zsc0 channel 1
awacs at obio0 offset 0x14000 not configured
swim3 at obio0 offset 0x15000 not configured
cuda0 at obio0 offset 0x16000 irq 18
nadb0 at cuda0: Apple Desktop Bus
iic at cuda0 not configured
mesh0 at obio0 offset 0x18000 irq 13: 50MHz, SCSI ID 7
scsibus1 at mesh0: 8 targets, 8 luns per target
mesh0: couldn't establish power handler
nvram0 at obio0 offset 0x1d000
bandit1 at mainbus0
pci1 at bandit1 bus 1
trap: pid 0.1 (system): kernel MCHK trap @ 0x133100 (SRR1=0xc1030)
panic: trap
rebooting
----------------

PGM trap boot transcript:
----------------
0 > boot scsi-int/sd@3:0
OF_open bootpath=scsi-int/sd@3
read stage 2 blocks: 0. done!
starting stage 2...

>> NetBSD/macppc OpenFirmware Boot, Revision 1.12
open /netbsd: Device not configured
open /netbsd.gz: Device not configured
5058040+125888=0x4f1e70
 start=0x100000
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007, 2008, 2009, 2010, 2011, 2012
    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 6.1.5 (INSTALL)
total memory = 49152 KB
avail memory = 41356 KB
found Grand Central PIC at f3000000
bootpath: scsi-int/sd@3/netbsd.macppc
mainbus0 (root)
cpu0 at mainbus0: 604 (Revision 3.5), ID 0 (primary)
cpu0: HID0 0x8000c084<EMCP,ICE,DCE,SGE,BHT>, powersave: 1
cpu0: 120.00 MHz
bandit0 at mainbus0
pci0 at bandit0 bus 0
pchb0 at pci0 dev 11 function 0
pchb0: vendor 0x106b product 0x0001 (rev. 0x03)
obio0 at pci0 dev 16 function 0: addr 0xf3000000
esp0 at obio0 offset 0x10000 irq 12: NCR53C94, 25MHz, SCSI ID 7
scsibus0 at esp0: 8 targets, 8 luns per target
mc0 at obio0 offset 0x11000: irq 14,2,3: address 00:a0:40:10:38:24
zsc0 at obio0 irq 15,16
zstty0 at zsc0 channel 0 (console i/o)
zstty1 at zsc0 channel 1
awacs at obio0 offset 0x14000 not configured
swim3 at obio0 offset 0x15000 not configured
cuda0 at obio0 offset 0x16000 irq 18
nadb0 at cuda0: Apple Desktop Bus
iic at cuda0 not configured
mesh0 at obio0 offset 0x18000 irq 13: 50MHz, SCSI ID 7
scsibus1 at mesh0: 8 targets, 8 luns per target
mesh0: couldn't establish power handler
nvram0 at obio0 offset 0x1d000
bandit1 at mainbus0
pci1 at bandit1 bus 1
trap: pid 0.1 (system): kernel PGM trap @ 0x200 (SRR1=0x80000)
panic: trap
rebooting
----------------