Do-It-Yourself PDP-11 help!

[Gordon JC Pearce]

Vintage Computer Festival wrote:

> 
>>When I power the machine up, three of the diagnostic LEDs on the KDJ11-A
>>come on, then go off after about 1/2 a second, leaving just D3 on -
>>which appears to mean that it can't communicate with the SLU.  Now, I'm
>>guessing that means it can't see the serial console, which I believe is
>>on the Baydel card.

> 
> The CPU should go first.  And depending on interrupt requirements, some
> boards may need to be closer to the CPU than others.  But I think your
> current configuration is fine.

OK, the Baydel card has termination resistors on it - does that mean it 
needs to go last in the chain?

Looking at my backplane it appears that it is serpentine, rather than 
Q22/CD if I understand the documentation correctly - ie. AN2 on row 1 
goes to CM2, then CN2 goes to CM2 on row two, and so on.

> I'd remove the DHV-11 to simplify things.  In fact, I'd remove all but the
> CPU, Baydel, and memory cards, and troubleshoot with that.

OK, I have (looking at the handles)

   M8192   M8044
(nothing) Baydel

I have confirmed that the M8044 passes the bus grant stuff through, and 
that the backplane is sending the signals where I think it is.

The SLU led *still* stays on.  Yes, the power supplies are good.

I did *once* get the following:

173026
@

from it.

> If you've got another card with a console port to try out then that might
> be something to try.

Haven't got one.  Are they difficult/expensive to get hold of?

> Keep us posted!

Heh, I suspect I'm going to keep bugging the list until I get somewhere...

Gordon.