TITLE: Index-Card Computing
AUTHOR: Eugene Wallingford
DATE: July 31, 2004  4:12 PM
DESC: a teaching example for associate memory
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BODY:
This story is a wonderful illustration of the idea of associative memory:

<BLOCKQUOTE>
I remember my grandad, who worked in the police, telling me how they
used to keep details of criminals on filing cards.  On the edge of each
card there were a number of punched holes, some punched right the way
to the edge.  Each punched hole corresponded to some fact about the
person -- whether they were a burglar or a mugger or things like that.
So, if you wanted to pick out all the burglars, you'd take a metal
skewer and slide it in through the appropriate hole and lift it up.
All the cards whose hole had been punched right to the edge
(non-burglars) would stay behind, whilst all the relevant ones would
get lifted up.
</BLOCKQUOTE>

I found this story in an article on DNA-based computing at
<A HREF="http://www.nobugs.org/blog/archives/2004/07/06/dna-computing/">Andrew
Birkett's blog</A>.  If you've ever wondered about how biocomputing
can work, read this article!  It's really neat -- yet another example
of how Mother Nature can do intractable search using massive replication
and parallelism.
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