help - 11/34 console problem

[Gooijen, Henk]

> This suggests it is correctly counting the digits you enter 
> (or shifting them into a register), but is not displaying 
> them correctly. And it is only updating the bottom 8 bits.

Yes, I got that feeling too. That is why I am puzzled, because
the 8008 'seems' to execute its program ... sort of.

> Alas DEC didn't publish a source listing (or even a binary 
> dump) of the console firmware in the printset. This is going 
> to make troubleshooting a little harder, since you probably 
> don't know what it should be doing. It is clearly running a 
> program, and that program is reading the keyboard and 
> scanning the display. So it is somewhat correct.

Well, in the Maintenance Manual of the KY11-LB that I have
*is* the 8008 software, there is even a chapter that describes
the 8008 instruction set (IIRC, I skipped that chapter).

> What does it do if you press 4 repeatedly? Does it flash the 
> bottom 3 or bottom 2 digits? If it's only updating the bottom 
> 8 bits, you see, then only 2 digits will flash from 0.

I will check that tonight! I remember that pressing the '7' key
does not have any effect at all. No display flash, nothing.

> > AFAIK, the entry of the digits, for example the numeric 
> > entry '165020' does *not* need the UNIBUS, but only sets up
> > an internal register. The 'LAD' button, and 'DIS AD' will
> > start a UNIBUS cycle (to access a memory location). Correct?
> 
> I think so.

Ok. I am working on a theory.
My first step (already done) is to minimalize the system. It is
now just the PSU (...) and the DD11-PK backplane. I removed the
cache and FP11 option. The backplane now only holds the 2 CPU
boards, and the M9312, M9302, the SLU and the KY11-LB.
All other slots have in position C-D a G7273 grant-cont card.
The symptoms are still the same, btw.
The theory is as follows. If the KY11-LB does not do UNIBUS
accesses when just the keypad is used, you could have the
KY11-LB the *only* board in the backplane via an extender to
make measurements to pins easy ... Going to the attick to get
the printset from the big pile!
Since I removed all boards, thus unplugged several flat cables,
to clean the BA11K thoroughly, it might have developed a problem
in the wiring. Perhaps the printset will give insight in this
strange behaviour.

> > BTW, the voltage on the CPU backplane (DD11-PK) is 5.08 V. and
> > the +15 and -15 read +/-15.x V. (Can't remember the exact value).

Come to think of it ... I did not check ACLO and DCLO. I will ahve
to see if the KY11-LB uses them or not!

> > I have an other 11/34 with an M7958, but never powered up that box.
> > I took that M7859 and installed it in the 11/34C. The display stays 
> > dark. According to the M7859 doc, that basically means that 
> > the board is dead.  So much for board swapping.  Sorry, could not 
> resist to try an easy success.  I don't have other spare M7859 ...

> You may find the totally dead board easier to debug. At least 
> you can check for a clock at the 8008, and for activity on 
> the internal bus to the firmware ROM, etc.

The KY11-LB manual says that this is the hardest to solve case :-)
But then, that was for a field engineer ... I assume that the board
was simply swapped and continue from there.
I have put the 'dead' KY11-lB back in the box where it came from,
but added a label to it saying "DEAD ??".  For later ... :-)

> -tony

Thanks Tony. I will test the keypad response.
Ah, I remember one more thing. Pressing the 'LSR' button does turn on
the 'SR DISP' LED. One more thing that makes it like it is working,
almost ...

thanks, I will post updates!

- Henk, PA8PDP

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