PDP-11 with real ADV11-C board still unhappy

From: Pete Turnbull <pete_at_dunnington.u-net.com>
Date: Fri Jan 18 18:27:20 2002

On Jan 17, 0:36, Tom Leffingwell wrote:
> I finally managed to obtain an ADV11-C without parting with a
> large sum of money, but unfortunately, it didn't solve my problem. The
> system still hangs at the same point it did when I used a DZ to "fake"
> ADV11 by setting its CSR to 770400. If I remove the ADV11, the program
> runs, but it is forced into its simulate mode because the missing
> hardware. I set the vector to the default on the DRV11, DRV11-B, and
> ADV11-C. I didn't check the serial module though. Could this be a
> setting problem, or do I have the wrong symptoms? Is there anything I
> learn by halting the system when its hung and looking at addresses in
> memory?

Probably, but I'm not sure what :-) You could try halting it and see if i
always halts in the same place(s). If so, it would be worth looking to see
if you can figure out what instructions it executing at that point. It
might be a WAIT or a polling loop. Also look at the vectors in low memory
(from locations 0 to about 20), and the vectors for the devices you have in
the system. They should point to somewhere in the program.

> I did try doing a "770400/" and it returned 000000, with the
> module out it gives a ?, so that seems good. 770402, the data buffer
> returns 007777.

Sounds like you have it set up correctly, at least as far as addressing is

> Does anyone know what to try next? I'm running out of ideas.
> The only difference between my system and the one I'm trying to replace
> that the backplane is 4 slot instead of 9, I don't have a BDV11-A like
> original had, and I have a DSD systems generic RX02, instead of the real
> DEC M8029. Also, do the limit of backplane space, my modules are in a
> slightly different order.

The order of the modules shouldn't matter, though it's best to have
CPU-memory-serial followed by whatever device needs highest priority
response. I expect the DSD RX02 controller works just like a DEC one as
far as addresses and interrupts are concerned, so that's unlikely to
matter. The BDV11 is another story, though. It includes a line-time
clock, and your system may need that. IIRC, it's controlled by a
combination of a switch on the BDV11, a bit in a register on the BDV11, and
the LTC switch on the front panel. All of those have to be enabled, and
the BDV11 must be present, for the clock to run. I have seen systems that
boot but then hang if the software needs a clock but it's not present or is

Pete						Peter Turnbull
						Network Manager
						University of York
Received on Fri Jan 18 2002 - 18:27:20 GMT

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