Kearney & Trecker Core memory, may be PDP8

jwsmobile jws at
Wed Nov 12 14:30:23 CST 2014

On 11/12/2014 7:43 AM, Johnny Billquist wrote:
> On 2014-11-12 06:12, Jon Elson wrote:
>> On 11/11/2014 09:18 PM, Johnny Billquist wrote:
>>> On 2014-11-12 04:00, Jon Elson wrote:
>>>> On 11/11/2014 07:33 PM, jwsmobile wrote:
>>>>> I can't tell for sure, but this auction may be for  PDP8 core board.
>>> The fact that the board have four edge connectors and not six totally
>>> excludes PDP-11.
>> The first and last picture of the ebay listing above clearly has SIX
>> edge connectors.
> Doh. I was mixing up different images from different listings. Sorry.
>> And, in fact, a number of PDP-11 peripheral boards had only 4 
>> connectors.
>> CPU boards and memory did usually have 6.
> There were definitely quad height boards, but I don't think I ever saw 
> a PDP-11 board that was hex height with only four edge connectors. But 
> I'm sure you will point me to one now. :-)
>     Johnny
I never said the boards with 4 connectors which appear to be hex high 
were anything to do with Dec, other than they were replacement boards of 
some sort.  I was sort of hoping they might be Harris 6100 boards and 12 
bit, but as Al K pointed out the processor chip is probably Motorola 
which rules that out.

If you zoom in you will notice that none of these boards seem to have 
flipchip connector.  I have not squinted to see if they might fit 
without the keying feature on the board as well.  Dec was very 
protective of that and sued or hassled anyone who used that form factor 
or edge card arrangement, and these guys may have kept the form factor 
for card cage physical handling and used other connectors.  I've not 
seen much other than this one vendors boards.

I guess they didn't need the count of connections and dropped two 
connectors for cost.


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