On Thu, 14 Feb 2008, Gavin Melville wrote:
  Not completely on topic, but my boss wishes to
build a computer using
 modern knowledge, but only materials, IO etc that existed as at 1st Jan
 1900.    The basic premise is that had a need existed, and they knew how
 to make one, could have it been done.
 That initially seemed hard, and certainly isn't easy, in that I'm the
 one doing the "building" :-)  however we have fairly quickly identified
 that magnetic logic is the only likely candidate. 
 I'd be thinking fluidic logic, but I'm strange. 
No idea why, but whenever I come across a system, I end up asking myself "how
could this have been done* without electronics?" - I find mechanical analogues
of electronic/electrical systems fascinating...
* Not cheaper, faster, to the same scale etc. obviously - just whether it
could be done at all.
Anyway, my first thought on reading that previous message was how to do it
using pure mechanical devices (and fluidic logic's a definite possibility).
And now's probably a good time to mention the Heath Robinson Rube Goldberg
computer again ;)
cheers
J.