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From: jallen@csserv1.ic.sunysb.edu (Joseph Allen)
Newsgroups: sci.electronics
Subject: Re: How do mechanical car-radio preset pushbuttons work??
Message-ID: <1991May18.011316.8747@sbcs.sunysb.edu>
Date: 18 May 91 01:13:16 GMT
References: <9105151026.aa18960@PARIS.ICS.UCI.EDU> <1991May17.034530.21765@sbcs.sunysb.edu> <9534@sail.LABS.TEK.COM>
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In article <9534@sail.LABS.TEK.COM> johno@sail.LABS.TEK.COM (John Ollis) writes:
>>Arn't mechanical computers neat?  There's lots of these things:

>One of the things that fascinated me is the Selectric typewriter.  The keyboard
>mechanically produced a 6-bit binary code which is then interpreted by the
>type ball positioning mechanism (4 bits to control the roll of the ball and
>2 for the tilt).  The only place electricity was used in those things was to
>make the motor go around.

Teletype were also like that- only they used a distributer (just like in a
car) to decode the aynchronous serial signal. 

>And how about mechanical calculators.

How do these things divide :-)

>I have a lot of respect for the engineers who designed this sort of thing using
>that technology.  Electronics makes a lot of things a whole lot easier.

Me too.  It saddens me when I see mechanical engineers who don't even know how
a car works.

I got some responses about juke boxes- these have seen many phases of
technology:

From: Thomas Tonino <ttonino@bio.vu.nl>

I've seen an electromechanical jukebox (tubes...) with a little mat
of core memory...

From: MULLIGAN@coral.bucknell.edu
I have worked on a few of these things, and here's how:

There is a big round storage device that holds the records.  Each is accessed
by turning this device until the desired record is at the correct spot for the
arm to grab it.  Around the outside edge of the device are metal fingers, one
for each selection.  The fingers on the desired selections are either pressed
down or picked up (I don't remember which) and the unit revolves until the next
set finger is reached.  That's why the songs play in numerical order, even if
that's not how they were entered.  If you set the fingers by hand, the unit
will play without putting any quarters in.  Working at an amusement company
helping to service jukes and video games can be fun!
-- 
/*  jallen@ic.sunysb.edu  */     /* Amazing */     /* Joe Allen 129.49.12.74 */
int a[1817];main(z,p,q,r){for(p=80;q+p-80;p-=2*a[p])for(z=9;z--;)q=3&(r=time(0)
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]?a[p+=a[p+=q]=q]=q:0:0;for(;q++-1817;)printf(q%79?"%c":"%c\n"," #"[!a[q-1]]);}