11/34 up! (sort of)

Jon Elson elson at pico-systems.com
Wed Jan 28 22:49:11 CST 2015

On 01/26/2015 09:42 PM, Jacob Ritorto wrote:
> Woohoo, I finally, after over a decade of being somewhat out of the pdp11
> hobby, have managed to bring back to life one of my pdp11/34s!
> It's a plain 11/34 with dl11-w, ky11-lb, ms11-L, rl11 and a M9312
> terminator/boot rom board.  I have an emulex controller and some fuji 160s
> I'll tack on later so I can run 2.9BSD once I get the basic build confirmed
> safe.
> It's not in great shape at the moment, apparently, as these xxdp 2.5 diags
> are crashing left and right.  But it at least boots the os and tries.
> I initially had, but mysteriously lost the console emulator/ODT
> functionality, seems it's starting at 165000 instead of 165200 at poweron.
> Maybe a 9312 switch mis-set...  So I'm booting from the panel by calling
> the address of the ODT or the rl02 boot rom, which does the trick.
Thinking about this problem, I'm wondering if one of the 
address bits is stuck?
I'm guessing since 165200 seems to work better than 165000, 
that maybe the
200 (octal) bit is stuck on?  You could try depositing 1234 
to location 0, and
4321 to location 200, and then read back both locations.  If 
they both read
4321, then probably that address bit does not change as the 
CPU is
commanding it to.  It is also possible that the diag/ODT ROM 
is not properly
sensing the address bits on the Unibus.


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