Cheap board guy

[Holm Tiffe]

Ethan Dicks wrote:

> On Fri, Aug 21, 2015 at 2:13 PM, Mark G. Thomas <Mark at misty.com> wrote:
> > I picked up a bunch of the boards too. My results have been mixed, but
> > for the price and description, I expected some wouldn't work.
> 
> Sure.
> 
> > 1x M8028 - DLV11-F SLU works.
> > 1x Plessey 32kW memory, works.
> > 2x M8186-YA - KDF11-AA, works.
> 
> Cool.
> 
> > 4x M8192 - KDJ11 (AA or AB?) -- two work, two fail POST, with LEDs lit.
> 
> That was my concern.  $50 is a fine price for a KDJ11, but not for a busted one.
> 
> Did you scope out the POST code yet?
> 
> > 4x MMS1132-N3-128 Motorola 128kW memory - undetermined if works.
> > 1x MMS1102-34 Motorola 32kW memory - undetermined if works.
> >
> > I haven't figured out the jumpers on the Motorola memory boards yet.
> > As provided, if I plug one in with the KDF11-AA, I fail to even get
> > an ODT prompt.
> 
> They might not be strapped for 0000000.  Since they are not DEC, it
> might take unearthing manuals or tracing out the circuit around the
> jumpers and the upper Qbus memory bits.

I do have an M8192 and the Motorola 128KW Memory Board from that guy.
The M8192 sometimes worked, sometimes not. After cooling with some
spray in the xtal area I've checked the clock at the xtal and that was
missing most time.
The J11 worked on a KDJ11-DS, so I changed the Xtal. Bingo, it's running fine
now.

For the Motorola MMS1132...the board uses +5VB from the AV1 Pin which is my
H278-A Backplane is not providing. I've soldered a bridge on the card
between AA2 and AV1 (using the vias there)  ..still not working and no ODT
prompt. Found out that on the jumper pins near the QBUS connector (E28) two
pairs are slightly bent, but no jumper on them.  Looked closer to jims pictures
(imsoldtoys.blogspot.de/2015/08/dec-boards-kdj11-2-kdf11-and-motorola.html)
and found that 2 jumpers on my board are missing. Put the jumpers on them
and now the board ist working  at 0 (tested only with the memory address
program from http://www.psych.usyd.edu.au/pdp-11/hints.html, after run
160000 in R1).
At the linked picture above the last jumper on E19 seems to be open, that's
closed on my board originally, but this makes no difference at all, the
board is working with both settings.

Hope this helps,

Holm

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