Async logic

Julian Skidmore julianskidmore at
Tue Mar 23 06:09:22 CDT 2010

Alexey Toptygin wrote:

> What's wrong with pulse or async logic designs? I personally find them
> fascinating, but I've never gotten to play with an implementation of
> one... Are there problems with designing like this that made people switch
> to sync designs? Anyone know of any good books on non-synchronous logic
> design?

Probably the best resources are the Amulet resources from Manchester

In the late 90s they experimented with Asynchronous ARM processors.

The difficulty with asynchronous design is that it's far more prone to
race hazards than synchronous design. Also, they found that even the
simple handshaking protocol they used limits performance. Nevertheless,
they do have some advantages, for example their EMF emmissions tend to be
evenly spread across a broad spectrum.

Incidently, modern synchronous design is far less synchronous than it
used to be; high clock rates mean that CPUs are subdivided into 
differently clocked domains to avoid clock skew.

-cheers from julz @p


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