Strange Problem on DECstation 2100

Robert Jarratt robert.jarratt at
Sun Dec 21 03:13:18 CST 2014

I have been trying to get my 2100 working. I have been using MOP to boot the
machine and try to install Ultrix, although this is not working for some
other reason at the moment. Until this morning, it was booting from MOP just
fine, but now it, after leaving the machine overnight and not doing anything
to it, I get this when I try to MOP boot:


Ultrixload - V4.5  Thu Sep 14 07:07:53 EDT 1995


Excptn:    (vtr=NRML)
Excptn pc: 0x807001f8
Creg:      0x30000010(CE=3,EXC=RADE)
Sreg:      0x30000000(CU1,CU0,IPL=8)
Vaddr:     0xaaaaaafe
Sp:        0xa13fbba8
  0xa13fbba8 : 0xaaaaaaaa 0x80701310 0xa0003b60 0x80700000
  0xa13fbbb8 : 0xaaaaaaaa 0xaaaaaaaa 0xaaaaaaaa 0xaaaaaaaa
  0xa13fbbc8 : 0xaaaaaaaa 0xaaaaaaaa 0xaaaaaaaa 0xaaaaaaaa
  0xa13fbbd8 : 0xaaaaaaaa 0x80700048 0xa00039c8 0xaaaaaaaa
  0xa13fbbe8 : 0xaaaaaaaa 0xaaaaaaaa 0xaaaaaaaa 0x00000000
  0xa13fbbf8 : 0xaaaaaaaa 0xaaaaaaaa 0x00000001 0xa00039c8


The really strange thing is that if I attach a CD-ROM drive and boot off
that first, then try the MOP boot after that, the MOP boot works! Before
anyone asks, I have other problems which mean it won't successfully install
Ultrix from the CD-ROM, and I am trying the MOP route because of this. The
CD-ROM problem is something to do with the block size, I know about the
block size jumper and have tried with the jumper installed and removed.


I have a workaround which is to connect the CD-ROM, boot off the CD-ROM, let
the CD-ROM installation fail, then unplug power from the CD-ROM and boot
from MOP. But that is horrible, and wasn't necessary until this morning.


Any ideas?





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