  <b>Previous Research: </b> SPIN is not the first extensible system I have worked on.  In my <a href="http://www.cs.washington.edu/homes/ddion/jwz/prev_research/research.html">undergraduate  studies</a> at <a href="http://www.nd.edu">Notre Dame</a> I helped  implement user-level memory management for an extensible communications  subsystem.  <p>
