This is a re-release of the 3rd Edition of Plan 9 from Bell Labs.

3rd Edition was originally released by Lucent Technologies in 2000. It
was the first release available freely to the general public, under a
custom open source license, the Plan 9 Open Source License Agreement.
Although the ideas behind the system are the same, the 3rd Edition
represents an extensive reworking of many of the interfaces. A new
graphics model replaces bitblit, and with it rio(1) and draw(3)
replace 8½. Alef is gone, but thread(2) has arrived to bring a
CSP-style threading to C. And the plumber(4) makes its first
appearance. The original release notes for this edition can be found
at /sys/doc/release3.ms.

Given its age, this release is mostly for educational and research
purposes, although given the inclination and appropriate hardware we
believe you should be able to run it. Note, however, that the 9p
protocol and authentication mechanism have changed between this
release and modern Plan 9, so interoperability might be tricky.

The only changes between this release and the original 3rd Edition
release are the new NOTICE, LICENSE, and README files, and moving the
old ones. In particular, any copyright notices attributing things to
Lucent Technologies or Bell Labs, or notices on restrictions of their
use, should be read as historical; all such rights have been
transferred to the Plan 9 Foundation and released as open source.
Parts (notably, the fonts) maintain trademark and copyright to their
respective parties (such as Bigelow & Holmes Inc.) and were included
in Plan 9 by permission; those copyrights are unaffected by the
transfer to Plan 9 Foundation and remain in effect per the terms found
in this distribution.