2 Nov
2005
2 Nov
'05
midnight
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. > 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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