One more try - Can you ID this S-100 Serial board?

[drlegendre .]

"My guess would be cost. Those headers back then were somewhat expensive
due to the heavy (30) gold plating."

Wow. I never even considered that a header could be more costly than a
 74LSXXX chip - doesn't make sense. But then again, I wasn't in the field
back in that day.

On Thu, Oct 1, 2015 at 10:48 PM, Tothwolf <tothwolf at concentric.net> wrote:

> On Thu, 1 Oct 2015, drlegendre . wrote:
>
> Also, I'm curious about the 50-pin headers.. why were they never
>> installed? All of the other work was done, all the expensive parts (chips)
>> are in-place - so why not a couple of cheap headers? Yes, a few resistor
>> SIPs are gone, as is one chip missing, but still, you get the point.
>>
>
> My guess would be cost. Those headers back then were somewhat expensive
> due to the heavy (30) gold plating.
>
> I found out today that as of August 3M has discontinued their 3000 series
> gray box headers and the last time buy on them was October 1st. They are
> replacing them with the D3000 series made with black fiberglass reinforced
> nylon instead of the gray nylon they've always used. (3000 series datasheet
> attached)
>
> The part numbers for the 50-pin headers without eject levers for 1/16"
> thick pc board would be 3433-5002. Mouser shows some stock, however their
> system may or may not be correct and they might try to substitute the newer
> D3000 series.
> http://www.mouser.com/ProductDetail/3M/3433-5002/?qs=%2fha2pyFadugF4%2fyP%252bp8%252b57ygnI%2fCWx880e6iwa7L1bU7rpqbpN%252bwEQ%3d%3d
>
> I also spotted some 3433-5402 on eBay at a reasonable price that might
> work, however those use a roll pin to attach the eject levers, so they are
> much harder to remove than the ones that used snap-in eject levers.
> http://www.ebay.com/itm/3M-3433-Locking-Ejector-Header-50-pin-right-angle-gold-plated-0-1-tails-1-x-1-/201386884555
>
> Also, don't forget about C2. It and C1 were probably a matched set for the
> crystal.