Do-It-Yourself PDP-11 help!

From: Gordon JC Pearce <>
Date: Wed Feb 16 05:30:07 2005

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:


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...

Received on Wed Feb 16 2005 - 05:30:07 GMT

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