Designs (was Re: OT: how big would it be?) - test-drb@ccmp.vtda.org

20 Oct 1999

-----Original Message-----
From: Chuck McManis &lt;cmcmanis(a)mcmanis.com&gt;
To: Discussion re-collecting of classic computers
&lt;classiccmp(a)u.washington.edu&gt;
Date: Wednesday, October 20, 1999 3:13 PM
Subject: Re: Designs (was Re: OT: how big would it be?)

...
 At 02:28 PM 10/20/99 -0400, Allison wrote:
 Flip chips, M series and all were really dictated
not by what could be put
on a board but how many connections the bord could make.  For a flip chip
it was 18 or 36 (someone?).  A 16 bit parallel load register like say a
pair of LS573s would need 32 IO, plus power and controls.  See the
problem? 
Ok, so this suggests a possible solution/idea. We use simm sockets. You can
get them fairly cheaply, there is a wirewrap version, and the PC houses all
have a standard template for the bottom of the board. I suppose one could
even make a Q-bus that small (its 72 pins as well IIRC). 

You bring up a good point. If a board can be designed with TWO connections
to the simm socket (one on top, and one on the bottom) so that you would
flip the board for one operation and flip it the other way for another
operation then prob. two different types of boards could be used for the
whole CPU:

ie:
BOARD 1
    side 1: 4 FF, 2 Inverters, 2 nand/nor
    side 2: 2 xor, 2 and/nor, ???

BOARD 2
    side 1: one shot, pulse amp, etc..
    side 2: more gates and inverters.

limiting the CPU to two boards means I can ship it over to a manufacturer in
Taiwan I have used before. 2 boards in 500 quantities/ea with just
transistors and diodes(+ res + cap) is quite cheap. Maybe they would charge
$2/ea. I designed a Frequency synthesized data transmitter (FM) with synth,
risc chip, and many support transistors for a product. I could not keep up
the production with my guys at the time so we shipped it off to Tiawan and
they knocked them out in Qtys of 500 for $8 ea (PCB, parts, built and
tested). I could not even buy the parts in qtys of 5000 for $8 here.

Anyway, it seems this CAN be done quickly and cheaply if two boards can be
standardized with a series of gates and flip flops.

Should be serial, smaller and more fun!

john

...

Unlike Tim I think TO-3's would be way to much of a pain, but TO-92s are fine.
...

--Chuck