help - 11/34 console problem -- first LA output

[Gooijen, Henk]

Tony wrote:

> > I have, it's a Biomation K100-D. When I first set it up
> > Sunday afternoon,
> 
> Amazingly that's what I have... I didn't get the pods with 
> mine, but a bit of work and some 10124 TTL-ECL translators 
> got the thing useable with TTL level signals
> 
> [...]
> 
> Be careful!. I have in the back of my mind the idea that the 
> 8008 has an internal (8-ish level) return stack and doesn't 
> use RAM for this. So you could still have RAM problems.
> 
> -tony

Making your own pod...! Again, points earned Tony!  Chapeau! :-)
Jim already told me that the 8008 uses an internal stack, but
I am now not so sure that the RAM is OK, so I will connect the
other 8 LA probes to the databus, to see what is taken out of
the RAM to put on the displays.

Yesterday evening was short. Much to do ... but I managed to
look at the matrix signals. It sort-of looks OK, but I admit
that I must make some better measurements to be 100% sure that
it is not there where my problem lies. The outputs of the 8881's
(on page 4, KY11-LB console board) look as described before, and
that is also what I see on the inputs of the 8093 (page KY-3).
But taking samples on the outputs is more work, as that is the
databus (input). So I see a lot of pulses are on those lines, and
it needs more setup work to find out if a stuck bit is messing
things up.
It is not likely a problem of a stuck bit on the address or data
bus, because that would corrupt the program execution of the
ROM code. I still have the feeling that there is no problem with
the RAM, ROM, CPU, 3-state transceiver, and the decoding logic.

This evening I hope to check out (thoroughly) the keypad circuits.

  thanks for the input!
- Henk.

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