This repository contains the source code of a fork of Plan9
meant for education.

Plan9 is an operating system considered by many to be the successor
to Unix (see https://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs).
The code of the original Plan9 is available at https://9p.io/plan9/
There are a few other forks of Plan9:
 - 9front: http://9front.org/
 - 9legacy: http://9legacy.org/
 - 9atom: http://www.9atom.org/
 - Harvey: https://harvey-os.org/
 - Nix: https://code.google.com/archive/p/nix-os/
 - Jehanne: http://jehanne.io/

or close descendants  of Plan9:
 - Inferno: http://www.vitanuova.com/inferno/

The specificity of my fork of Plan9 is to see Plan9 as a great
educational platform to learn about programming and computer science.
The code of Plan9 is so elegant and small that you
can realistically understand the whole operating system.
In fact, I explained the whole code in my Principia Softwarica
book series (see https://principia-softwarica.org).

This fork, because it is used to support my Principia Softwarica
book series, contains only the essential programs used by a programmer
(e.g., compiler, linker, assembler, kernel, windowing system).
This fork does not contain all the programs of the original Plan9;
I've selected only what I consider to be the essence of an operating system.
Moreover, this fork supports only the ARM and x86 architectures. Even though
the original Plan9 supported more architectures, I think ARM and x86 are
enough for the educational purpose of Principia Softwarica.
Finally, as opposed to the original Plan9, this fork can also be
cross-compiled from Linux, MacOS, or Windows, which makes it easy
to experiment with.