Early PDP-11/45 backplane SPC power

Fritz Mueller fritzm at fritzm.org
Tue Jun 28 14:36:42 CDT 2016

On 06/28/2016 11:55 AM, william degnan wrote:
> DD11A or B would have power to CA1 unless you remove the wirewrap, right?

The way the prints look to me, the DD11A and B take +5V on CA2, DA2, 
EA2, FA2, which is per normal for SPC slots that I've seen.  I can't 
find reference to CA1 in the DD11 prints, and indeed looking at the 
several DD11 cards that I have on hand the CA1 pad is not connected to 
any traces.

Also, all the SPC pinouts I've seen list CA1 and CB1 as the NPG chain.  
So it would be weird/wrong to have power there?  So I'm suspecting this 
is a typo in the 11/45 maint manual.

I'd be interested to know from anybody else out there who has a running 
11/45 or 55, do you have +15V on slots 26-28 CU1?  What about slots 
26-28 CA1?


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