Doesn't happen all the time, but I sometimes get:

. . .
fpu0 at mainbus0 (mc68040)
vm_fault(18c00, 34410000, 1, 0) -> 1
  type 8, code [mmu,,ssw]: 505
trap: type 0x8, code 0x505, v 0x3441073b
kernel: MMU fault trap
..some more hex stuff..
db> t
_Debugger(...) ...
_panic
_trap
faultstkadj
_domaininit
_main
_main

This was copied by hand so I left out a lot of hex that I wasn't sure mattered.

When the above doesn't happen the system hangs after the setting ttyflags
message.

This is a Quadra 840-av with 32MB RAM, a MacCon Ethernet card in slot d
(unconnected now) and the motherboard Ethernet connected.  Apple HiRes RGB
monitor at 640X480 B&W.  Booting from MacOS 7.1update3.

The last few days (since I got back from vacation) I've been seeing a *lot*
of errors on the screen from the MACE-5 kernel which I reported before and
think indicate collisions.  MACE-5 now frequently dies after the starting
network boot message and the traceback suggests to me that it is running
out of memory allocating socket buffers.  If this is still relevant let me
know what info you want.

Signature failed Preliminary Design Review.
Feasibility of a new signature is currently being evaluated.
h.b.hotz@jpl.nasa.gov, or hbhotz@oxy.edu