>
> Does the Mac provide easy useful access to the memory management unit?
> Using the MMU to handle the write barrier could allow an efficient
> background collector of oldspace. I think this is described in a paper
> by Appel from the mid eighties.
>

Also used by QKS in their Smalltalk on the mac for many many years.

However the Squeak VM has very little/none notion of MMU.  This makes  
it very portable, but it means
the logic above it is not feasible.
--
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John M. McIntosh <johnmci at smalltalkconsulting.com> 1-800-477-2659
Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
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