OK, I've done some more testing and I think I've found a genuine hardware
problem with my 433s (since it happens with both HPUKES and NetBSD).

When I remove the framebuffer from the system, it has terrible performance
on input ethernet packets (about 1 error per 10 packets, giving sustained
transfer rate of ~20 KB/s).

When I change the jumper from 25 to 33 (adding a wait state for RAM), there
are less errors, and the transfer rate is higher (~120 KB/s instead of ~20
KB/s).  Obviously this helps a little, but there are still a lot of
ethernet errors.

I've tried changing the interrupts around.  This doesn't help.  I've tried
removing all framebuffer drivers from the kernel.  This doesn't help either.

Oddly enough, I've got a 425s, which doesn't have this problem.  I don't
have physical access to it to look for differences on the motherboard.

I don't have access to a PROM burner to try a different version of the
bootrom.  So, I guess this message is more for informational purposes than
anything else, since there's not much else (hardware-wise) to change on
this system.

If anyone has any suggestions on what to do (other than "leave the
framebuffer in"), I'd appreciate it.

The 433s has:
BOOTROM  Rev. 2.0  29 NOV 90
MD11 REV 1.95 1990/12/12.14:35:26

The ROM is labeled:
1818-4990
REV2.0/1.95
4-9-91
WY-6

The motherboard is labeled
REV C
A1421-69514
C-3115

The chipset is 1LY5-0302, except the one by the CPU which is -0304

The serial number is EA040X100LS

The RAM is labeled A-3026-56, EA1400886342 and EA1430085561

And just for the record, removing a framebuffer from a 433s does *not* set
the bootrom to use the serial console.  The NetBSD bootloader is smart
enough to switch over.  Further, as has been suggested before, sending
anything over the serial port does not reset the machine and use the serial
port as console.

For a 433s, you must actually have an HIL or Domain keyboard present to
change the console from screen/keyboard to serial port, or interact with
the bootrom at all when it's set in "local" mode.

HTH,
  -- MW