[Coco] [OT] Analog computer from Radio Shack

[Gene Heskett]

On Tuesday 19 December 2006 13:41, Leon Howell wrote:
>Beleive it or not, the first home computer was sold in 1957! It was
> analog, sold by heathkit. I saw a picture of it in one of their 1980's
> catalogs. It had a bunch of dials and gages if I remember right, and
> looked like it would probably fill an average sized table.
>
>I wonder what you would compare something like that to in terms of
> digital processing power? How would you compare analog to digital?
>
>I have no doubt the CoCo 1 could handle anything even the big analog
> computers could do. It would be very interesting to see a CoCo 3
> graphical simulation of an analog computer. (An emulator, even?) Not
> that useful of course, but still fun!

One of the real ones could be quite a bit more accurate than than you 
folks have estimated them to be.  When I first went to work for KOTA-TV 
in Rapid City, circa 1964, the Chief, Elmer Nelson, had made himself one 
of them, ISTR it had an output meter and 8 input dials plus 
a .1,.2,.5,1,2,5 style of range switches over about 5 decades for the 
input dials.  Using the then magic and expensive op-amps, and .1% 
precision resistors and 10 turn .1% Beckman pots for input, he estimated 
the overall accuracy at maybe .25%.  He used it to design all the tuned 
circuits in his microwave equipment he was building, and which worked 
quite well.

They had tried several makes of microwave gear for their dual channel, 
bi-directional back to Hays Springs/Alliance (KDUH-TV), 6 hops to Lookout 
Mountain (KLZ-TV then) in Colorado for their network microwave, but none 
of it could have the door slammed on the mountaintop shacks for more than 
30 days, a rather important consideration when you might have to hire a 
helicopter to get you there in the wintertime.  So he built one using all 
millspec tubes, mostly 6922's that could go a year between visits to the 
shacks.  And that was his computer at the time, but he eventually 
graduated to an HP-85 in about 1965 or 66.  That HP-85 used a spark 
discharge printer, and that's the first time I ever saw a smith chart 
actually plotted.  I hope Elmer still lives, the last time I was in Rapid 
City was in 1994, and I stopped at his shop, "Tepco Inc" and shot the 
breeze for an hour or so.  But, he was in his mid 70's then, not as spry 
but still as sharp as ever, so I've no idea if he is still working or has 
sold it to the help, one of which had been with him for at least 30 years 
then.  Tepco's main product is tv translators at the 10 watt power level, 
good for shadow fills & such. See at <http://www.rapidnet.com/~tepco/>


I had fun with Elmer, he was a 'papered' engineer, and was always amazed 
at just how much this 8th graduate knew about electronics.

-- 
Cheers, Gene
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Copyright 2006 by Maurice Eugene Heskett, all rights reserved.