Which DEC machine made use of th pre Flip-Chip board?

Jon Elson elson at pico-systems.com
Fri Dec 21 11:08:33 CST 2018

On 12/21/2018 07:19 AM, Noel Chiappa via cctalk wrote:
>      > From: Mattis Lind
>      > I cannot figure out which early machine it comes from.
> They're called 'System Modules':
>    http://gunkies.org/wiki/System_Module
> and they were used from the PDP-1 through (I think) the PDP-7; at least, this
> PDP-7 internals image:
>    https://www.soemtron.org/images/jpgs/decimages/sn113robertjohnson85680004.jpg
> seems to show System Modules at the top, and FLIP CHIPs at the bottom. (I'm
> pretty sure even the first PDP-8 - the 'straight 8' - uses only early FLIP
> CHIPs - transistorized ones.)
> The DEC brochure for it (P5141) is a little puzzling; it says (p. 2) that
> "INTEGRATED CIRCUITS are basic elements of the low cost, newly designed
> silicon FLIP CHIP modules used throughout PDP-7", but AFAIK, the first FLIP
> CHIPs (R-series, B-series, etc) were all transistors; the later M-series were
> the first ones to have ICs. Maybe this is some old meaning of "integrated
> circuits"?
Yes, PDP-5 and DEC LINC were made with "System Building 
Blocks", similar in technology to the board pictured, but 
single-width and wrapped in an aluminum frame, with a blue 
connector hand-wired to one end.  Single-sided, 
paper-phenolic PCBs.
Kind of similar to half of the board in the picture.  I 
think this same technology was used in a number of other 
machines.  Discrete transistors, diode-steered 
capacitor-coupled FFs, really ANCIENT technology.

The "classic" PDP-8 was built with basically the same 
circuit technology, but on smaller, unframed glass-epoxy 
PCBs with etched and gold-plated card-edge fingers, with 
color-coded handles indicating what technology was on it.  
So, basic logic was R with red handles, memory boards 
(select, read amp, etc.) were G with green handles, etc.


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