On 07/08/2017 17:05, Philipp Hachtmann via cctalk wrote:
On 04.08.2017 09:24, Rod Smallwood via cctalk wrote:
Hi List
Hi Rod!
I looks like I have at last got a KK8-E CPU set to continue
getting my 8/e back running again.
It looks that you have one more set stored in my facility in Hannover!!!
I became feeling more and more bad about that. Then I forgot it again.
Then I felt even more bad by not remembering WHOSE boards those are
(because there is no "Rod Smallwood" written nowhere on the packet).
Now I have connected that again....!
The system has a working rebuilt PSU with all of the caps reformed or
replaced. Voltages are good.
Wow, I never did that. I always made a smoke test.
There's 16k of core at the back with a terminator at the end.
Not bad.
Power up and all the lamps come on either bright or dim (off) except
the RUN light.
Sounds not so wrong.
2. Are there any tests like resistance I can do on the CPU board set
before inserting them in the correct front slots?
There are no "correct" slots. Not for *any* of the boards. You can mix
it up completely. Even the front panel could be omitted, doubled, or
put into an expansion box.
BUT.. There actually IS a DEC recommended order, yes... And having the
terminator board somehow at the end of the Omnibus seems to be a good
idea.
3. In the event the CPU set does not even do a simple write to and
read from memory. Where do I start to look?
At the schematics? Front panel (!), timing generator, major state
registers.
The DEC stuff was designed quite wrong-insertion resistant. But:
There is just one MAJOR fault you HAVE TO AVOID: NEVER NEVER NEVER
plug in the middle board of an RK8E controller upside down!!
I did it. Once. It leads to impressive fireworks on many boards.
Regards
Philipp
Its now running just fine.
Count test runs.
The second set of 4k core is in and checks out.
Async. board has just gone in and is running.
I'm getting output RS232 on my BOB when the print test is toggled in
and run.
So to-morrow connect up a terminal that will do 110 baud and try an echo
test.
Next part is interesting. There should be a way to fake a reader / punch
and feed in tape images.
Rod
--
Wanted one pdp-8/i rocker switch leaver to copy.
