Cheap board guy

Ethan Dicks ethan.dicks at
Fri Aug 21 13:36:59 CDT 2015

On Fri, Aug 21, 2015 at 2:13 PM, Mark G. Thomas <Mark at> 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.


> 1x M8028 - DLV11-F SLU works.
> 1x Plessey 32kW memory, works.
> 2x M8186-YA - KDF11-AA, works.


> 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.

> Since none of this has a bootstrap,
> I run the bootstrap from ROM provided by a Dilog SCSI card here, but typing
> "DU" or "DU0" at the * prompt spins the floppy ever-so-briefly, then kicks
> out an error about no boot media found. Suggestions? Maybe I should try
> other bootstrap?

Hmm... maybe you could enter the real DEC DU boot from ODT?  I
wouldn't trust a Dilog boot to work with a DEC card until I inspected
the code to see what it was doing.  If the Dilog card is fully
register-compatible with an RQDX3, it could work, but I'd not assume
it does.

I've always had a BDV11 with my KDF11s, so that's the bootstrap I've
used.  I don't think it covers MSCP (I have RL02s and RX02s) so I
haven't been in your exact position of trying to boot an RQDX3 on a

> 2) I could use PDP11GUI, or other tools to load XXDP via the SLU. If anyone
> has already done this and wants to talk to me about it, I welcome some help.

I have no experience with PDP11GUI.  Sorry.

> I'm a little confused about what should work and what should not work, with
> just the 18 bit qbus. Do I need to wire wrap the additional address lines
> to be able to do anything with these KDJ11 CPUs? Does anyone have good
> instructions for this modification -- I'll probably want to do it. Do I just
> add the additional address lines, or are there other considerations?

If you want to stick more than 128kW of memory on any of your
processors, you'll need the upper 4 address lines.  I've added them.
It's not particularly difficult.  If you don't need more than that
128kW, you don't need it.  Any 22-bit processor will work on an 18-bit


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