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From: tonya@hpldsla.sid.hp.com (Tony Arnerich)
Newsgroups: sci.electronics
Subject: Re: How do mechanical car-radio preset pushbuttons work??
Message-ID: <1990023@hpldsla.sid.hp.com>
Date: 18 May 91 01:16:07 GMT
References: <9105151026.aa18960@PARIS.ICS.UCI.EDU>
Organization: HP Scientific Instruments Division - Palo Alto, CA
Lines: 56

>Arn't mechanical computers neat?  There's lots of these things:
>
>- Some things have a row of buttons, but only one is allowed to be in at
  >one time.  Some even have more exotic combinations, button 1 & 2 may be
  >in at the same time, but button 3 may be in only alone.  How was it done?
>
>- How did electromechanical juke-boxes queue-up your record selections?
>
>- How did automatic record changers work?
>
>- How did dishwasher and washing machine controllers work?
>
>- How did slot machines work?
>
>- How did telephone switchers work?
>
>- How did 8-track players with direct track accessing (a button for each
  >track) work?
>
>- How do automatic transmissions work?
>
>- How does spark timing advance work on car engines without computers?
  >(I junked my last car because the electronic version of this broke.  If it
  >was mechanical I could have fixed it for very little money (and it probably
  >wouldn't have broken))
>
>- How do differentials work?
>
>- How does power steering work?
>
>- And, of course, how do clocks work?  Especially ones with chimes?
>
>Anyone else can contribute to this list?  I'd like to here about other nifty
>mechanical computers.  I'm sure there's lots of them.
>-- 

First of all, I'd say that only a few of the above are computers. But clocks,
auto transmissions, and juke box mechanisms would be excelent candidates. Most
of these are just *machines*. (For example, a digital buffer is certainly not
a computer, whereas a flipflop or an AND gate might be, according to some
definitions of computer-ness).

Other possibilities:

All-mechanical vending machines;
Combination locks with settable combinations;
Planimeter (device that measures areas under graphs);
Orrery (model of solar system - a clock is a model of only one body in the
        solar system);
Pressure regulators;
Stonehenge (maybe - if we can believe what some people say it predicts);

At UC Berkeley I once saw an all-mechanical Fourier-transform calculator. That
would certainly rate as a computer in my book!

tonya@sid.hp.com