On Nov 17, 2011, at 12:43 AM, Chuck Guzis wrote:
  Years ago, asynchronous computing was a hot
topic--essentially,
 instructions were unclocked and took however long it required to
 signals to propogate through the logic to complete.
 That was the gist of Achronix' idea--that you could get some
 freakingly fast computation out of a clockless design.
 I also recall that the Philco System 2000 was one of the few
 commercial versions utilizing that idea.  "Asynchronous" was part of
 their advertising campaign--and, for a very short time, they had one
 of the fastest transistorized machines. 
Chuck Moore's newest Forth chips (which is painting them with a broad brush,
they're stack machines, but they're really meant for Forth) at
http://www.greenarrays.com run asynchronously.  Those are actually some pretty neat chips.
I don't know if they're going anywhere, but his previous Forth chips have had some
success in the market, and I'd love to play around with one.
- Dave