Relay computers

[Jules Richardson]

On Fri, 2004-09-24 at 16:27 -0400, Paul Koning wrote:
> >>>>> "Vintage" == Vintage Computer Festival <vcf at siconic.com> writes:
>  Vintage> "Element 2: The movements of ball and racquet, as well as
>  Vintage> the collision detection take place in a metal chassis under
>  Vintage> the glass cover. Each moving game compoent has a mechanical
>  Vintage> counterpart, which is moved by electric motors. When these
>  Vintage> parts collide, contacts are closed and the relays in the
>  Vintage> computer switch the direction of rotation of the motors."
> 
> What I meant is that the relay control is not doing position
> calculation.  It doesn't know where the ball and paddles are (only
> whether certain motors are turning). 

I was going to say that it does need to know what quadrant of the field
the ball is in so that it can return the ball to the centre position
after a point has been scored - but looking at the wiring diagram it's
actually cleverer than that (I'm having to learn German as I go, here). 

All it does to return the ball is reverse polarity to the ball X/Y drive
motors when the ball goes out of play, and only stop each motor when it
reaches its respective centre line. Neat.

cheers,

Jules