VAX 11/780 progress ... just a little

Hi, I'm still wondering if I'm left the only one actively messing around with a VAX 11/780, because all the help I get comes debugging the UNIBUS. I now made sure the NPG line is interrupted under the M7486 part of the UDA50 adapter set. Now I no longer get a 3 on the M7485's LEDs but it properly goes up to the 4/5 blink. Even the port light on my RA90 lights up so that it feels like it's going to come up any minute. But it doesn't. The VAX console never shows any sign of life, the RUN light goes off and the M7485's LEDs show a constant 5 (no more blinking 4/5). Then the drive's port light goes off too. When I interrupt the console and UNJAM it says "HALTED AT 000007B7" The interesting thing is that I can set the R3 register (that indicates the device unit on the UDA50) to a different value (my drive is set as unit 0) and indeed the drive's port light never lights up, as it should. However, the machine hangs in the exact same way and when I interrupt it, it comes up at the exact same address 000007B7. Would that mean that we get stuck even before the boot sector is loaded from the disk? I have two straws of hope to hold on. One is that the basic diagnostics tells me that KA780 module M8230 fails. So I can replace that once I have a spare. The other hope is that my UNIBUS isn't properly terminated. I have what looks like a UNIBUS terminator card but whenever I plug that in, the UDA50 acts strangely and effectively never reacts to the host at all, just constant cycling pattern as if nothing ever happened. Also, my level 2 diagnostics fails when this terminator card in is. When I remove that terminator I see at least the UDA50 and host communicating a little as described above. And without terminator the diagnostics level 2 finishes flawlessly. How essential is the UNIBUS terminator? Does the missing terminator explain why the host hangs and silently stops during boot? I never get a machine check or anything. Or, am I just impatient??????? I do know from my other VAXen (6400) that they turn on all fail lights and make the drive's port LED go off during the first phase of the booting activity. Could it be that the VAX 11/780 just needs several minutes for this job? I don't think so... Who knows what the address 7B7 in Thanks, -Gunther PS: this is what the DUABOO.CMD does: EXAMINE SP ! SHOW ADDRESS OF WORKING MEMORY+^X200 G 0000000E 00000200 LOAD VMB.EXE/START:@ ! LOAD PRIMARY BOOTSTRAP LOAD DONE, 00004800 BYTES LOADED START @ ! AND START IT does that mean the VMB.EXE is loaded at 00000200, so that 00000747 is relative address 547 in VMB.EXE? Is there a commented disassembly listing for VMB.EXE somewhere?