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.TL
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Preface to the Third (2000) Edition
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.LP
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A great deal has happened to Plan 9 in the five years since its last release.
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Although much of the system will seem familiar, hardly any aspect
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of it is unchanged.
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The kernel has been heavily reworked;
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the graphical environment completely rewritten;
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many commands added, deleted, or replaced;
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and the libraries greatly expanded.
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Underneath, though, the same approach to computing remains:
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a distributed system that uses file-like naming to access and
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control resources both local and remote.
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.LP
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Some of the changes are sweeping:
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.IP
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Alef is gone, a casualty of the cost of maintaining multiple languages, compilers,
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and libraries in a diverse world,
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but its model for processes, tasks, and communication lives on
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in a new thread library for C.
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.IP
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Support for color displays is much more general, building on a new
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alpha-blending graphical operator called
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.CW draw
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that replaces the old
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.CW bitblt .
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Plan 9 screens are now, discreetly, colorful.
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.IP
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A new mechanism called plumbing connects applications together
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in a variety of ways, most obviously in the support of multimedia.
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.IP
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The interfaces to the panoply of rotating storage devices have been
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unified and extended,
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while providing better support for having Plan 9 coexist with other
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operating systems on a single disk.
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.IP
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Perhaps most important, this release of the system is being done under
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an open source agreement, providing cost-free source-level access to the
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software.
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.LP
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Plan 9 continues to be the work of many people.
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Besides those mentioned in the old preface,
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these people deserve particular note:
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Russ Cox did much of the work updating the graphics
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and creating the new disk and bootstrap model
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as well as providing a number of new commands;
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David Hogan ported Plan 9 to the Dec Alpha;
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and
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Sape Mullender wrote the new thread library.
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.LP
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Other new contributors include
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Bruce Ellis,
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Charles Forsyth,
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Eric Van Hensbergen,
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and
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Tad Hunt.
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.sp
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.in 3i
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Bell Labs
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.br
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Computing Science Research Center
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.br
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Murray Hill NJ
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.br
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June, 2000
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