gEDA-user: Re: Pointer to 3d CAD?

[Dave McGuire]

On Nov 1, 2006, at 10:58 PM, DJ Delorie wrote:
>>    It all depends on what you're into.  I've been discussing a
>> project with a friend that would involve building what amounts to a
>> copy of the PDP-8 ("Straight-8", no suffix) with individual
>> transistors.  It's fun, cool, and highly educational in a number of
>> areas.
>
> Are you going to be true to the time and use TO-92, or "cheat" and use
> SOT-535's?

   Well my tentative plan is to duplicate the functionality of the  
individual boards, but not to scale.  Many DEC machines of that era  
were built with "Flip Chip" boards, 2.5"x5" PCBs with card-edge  
connectors that typically implement relatively little logic...say, a  
pair of flip-flops.  The PDP-8/S, for example (a model I've studied  
much more closely than the Straight-8), uses maybe fifteen different  
types of Flip Chips, but hundreds of them.  I'm thinking of cloning  
the functionality of those Flip Chips board-for-board, but much  
smaller, perhaps the size of a large postage stamp, using 0805  
resistors & capacitors and SOT-23 transistors.

   Though I have no problem with TO-92 packages, I'm no longer a big  
fan of through-hole components in general...too much of a pain to  
work with when compared with surface-mount, and using smaller parts  
makes for a much smaller...perhaps even desktop...finished unit.

   I'm very hot to do this, but I won't be able to devote much time  
to it anytime soon, as my employment is going away in a few weeks and  
I'm busy scrambling to find work in the middle of a technological  
wasteland.

> The Museum of Science in Boston has a computer that plays tic tac toe.
> It's made of wooden Tinker Toys.

   That is just too damn cool.

               -Dave

-- 
Dave McGuire
Cape Coral, FL