Subject: VAX 11/780 progress ... just a little
To:, port-vax <>
From: Gunther Schadow <>
List: port-vax
Date: 09/24/2003 22:36:10
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 
from PDP-11 people ... but that's adequate since I am still 
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 


PS: this is what the DUABOO.CMD does:


        G  0000000E  00000200

        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?