Reanimating a PDP-11/23

[Pete Turnbull]

On 01/12/2009 07:22, Pontus Pihlgren wrote:
> Pete Turnbull wrote:
>> On 30/11/2009 21:03, Ethan Dicks wrote:
>>
>>> Also, what is your board arrangement in the backplane?  You have a
>>> very simple system (CPU, MEM, SLU, termination+boot), but you still
>>> have to preserve the grant chain between the CPU and the BDV-11.
>>
>> Actually, you don't.  If anything else uses the grant chain, you must 
>> preserve the chain between the "anything" and the CPU.  However, it 
>> was common to put the BDV11 in the last slot, leaving others empty, 
>> and that's a standard configuration.
>>
> I'm somewhat confused by this, I know how and why you need grant cards 
> in a Unibus machine. But I thought the Qbus made away with that need,

Not entirely.  There are no jumpers to change, though.

> although I have read something about it being needed for certain cards 
> and that some controllers need to be the last card. 

The RQDX1 needs to be the last card, because it doesn't pass grants. 
I'm not aware of any other card with that problem.

Anyway, I have mine
> in the order: CPU, MEM, SLU, TERM, with some space between for easier 
> handling.

You don't want to have spaces, except perhaps between the terminator and 
the cards above it.  Put the memory right under the CPU, and the SLUs 
right under that.  If the BDV11 is further down, it'll be fine, and if 
you need to add another card, it still easy.

> The backplane is not the serpentine version, when I got it, it had a 
> RL01 controller in it (I got two RL01 drives too) which I believe need 
> the straight backplane.
> 
> I will check the console cable, it came with the machine but is home 
> made, it goes directly from the card (i.e. no cab kit). I'm fairly 
> certain of the baud speed, the manual was quite clear on the jumpering 
> on the DLVJ1 (I call it that because the pdp-11 field guide lists it as 
> such).

It got renamed late in the microVAX/microPDP-11 era.  Strictly speaking, 
only the late revisions of the card should be called that, because only 
those revisions work in certain late systems, which was the point of the 
renaming.  Most people still refer to them all as DLV11-J.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York