S-100 backplane board spacing

Andrew Lynch lynchaj at yahoo.com
Sat Feb 7 14:06:34 CST 2009


S-100 backplane board spacing

Al Kossow aek
<mailto:cctalk%40classiccmp.org?Subject=S-100%20backplane%20board%20spacing&
In-Reply-To=> at bitsavers.org 
Fri Feb 6 09:13:35 CST 2009 


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 > does anybody have a handle on where I

 > could obtain 5 S100 edge connector sockets?



You also need to specify the spacing of the circuit and component

side pins on the connector for your backplane. There are at least

two different spacings that were used. Most were the wider style,

early MITS backplanes had closer spacing.


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-----REPLY-----
 
 
Hi!   Thanks Al!  My question is really what are the commonly accepted
standards for appearance, casing, etc.  I agree there seem to be an early
"narrow" width and a later "wide" width between S-100 connectors.
 
Is there a standard or commonly accepted practice for center to center
"wide" board spacing or is it arbitrary?  My intent is for a small (4 slot)
motherboard used for hobbyist prototyping not a full blown system.  The
primary application would be the development of new peripherals using
prototype boards.  I expect that the use of wire-wrap sockets would be
common requiring some clearance on the copper side and that the ICs and
passives would be socketed.
 
My estimates are that wire-wrap sockets need just bit over 1/2" clearance on
the copper side and that most socketed ICs/passives require 1/2" clearance
on the component side.  Allison's estimate of 1" centers for the boards
seems like a reasonable compromise.  It won't get every possible combination
but enough to be useful.  The purpose is to allow low cost prototyping not
for a full blown long term system installation.  Cost is of primary
importance which translates to little PCB surface area as possible while
still being useful.
 
BTW, Digikey carries a couple of types of S-100 compatible connectors but
they are not cheap.  Sullins and EDAC 0.125" spaced, 50 position, 2 row, 100
pin, PCB through hole solder tails card edge connectors run from about $8 to
$12 a piece.  I can get them surplus occasionally.  eBay sells them too but
are the wire-wrap variety which would work but is a gross abuse of a
wire-wrap connector to solder it into a PCB.  It can be done but I wouldn't
tell anyone about it.  :-)
 
Thanks and have a nice day!

Andrew Lynch



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