String Logic

[Jules Richardson]

Marvin Johnston wrote:
> I was listing some books on VCM, and ran across a mechanical EXCLUSIVE OR
> demonstration photo using string. I had never seen or heard of such a thing
> before and thought it was very cool! The book is Computer Hardware Theory, and a
> jpg of the string XOR picture is at:

Excellent - thanks! My brain's having an off-day, but that design actually 
"feels" a little over-complex - or were requirements placed on what mechanical 
devices other than string could be used?