Kearney & Trecker Core memory, may be PDP8

Johnny Billquist bqt at
Sat Nov 15 14:12:21 CST 2014

On 2014-11-12 12:30, jwsmobile wrote:
> 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.

Uh? They are definitely flip chip connectors. No need to even squint. 
Just magnify the pictures.

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

Well, it all depends on if there were anything to connect to on those 
places, and if any needed signals were located there.


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