Hardware Reference
In-Depth Information
As you can see, RISC OS is a fully functional lightweight desktop. You may also now appreciate where some of our
modern graphical user interfaces came from. Take some time to use RISC OS; I am sure you will find some things you
like about it.
Plan 9
Plan 9 was developed at Bell Labs. Bell Labs is a division of Alcatel-Lucent, and it has developed and pioneered a large
range of technologies over the years. One such project is Plan 9.
A History of Plan 9
Plan 9 was an operating system designed to evolve Unix's concepts. It was extensively worked on inside Bell during
the 1980s and even managed to replace Unix on some of Bell's internal research systems. It was only in 1992 that the
first edition of Plan 9 was released to universities. Soon after that a commercial version of Plan 9 became available.
Around the same time Bell Labs opened up Plan 9 for distribution under a noncommercial license, which allowed any
one with supported hardware to install Plan 9. The license was not the GNU General Public License (GPL) but was an
in-house Bell Labs license model, which added a lot of confusion for the end users of Plan 9 because the license was
less than clear about what you can and cannot do with Plan 9. With the fourth release of Plan 9 in 2002 Lucent moved
Plan 9 to a much clearer license model.
Sadly by 2002 a lot of people had lost interest in Plan 9, but lucky for you there is now a port of Plan 9 to the
Raspberry Pi. Let me talk about why you may want to take a look into Plan 9 and what makes it so very different from
any of the operating systems listed in this topic. You need to understand that Plan 9 was originally designed to meet
Unix's shortcomings. Unix during the 1980s was a fantastic multiuser operating system that gave end users a lot more
freedom than the batch job-oriented alternatives at the time. Unix was not perfect and it fell short in distributed
computing. This is where the people originally behind Plan 9 saw the chance to improve, and Plan 9 was born.
Plan 9 Considerations
Plan 9 is a distributed grid computing platform; it's designed for the network and is part of the network at a very low
level. What exactly is a distributed grid computing platform? A grid style of computing is where each node is part of
a larger grid of systems that is spread across any location. Applications running on one node may pull resources and
even CPU time for any members of the grid. The grid can be made up of one node or many nodes across any form of
commutation and across any administrative boundaries. There would be no technical reason why your Plan 9 system
could not be a member of the same grid that my Plan 9 system is in. This gives Plan 9 a huge benefit from the ground
up as Plan 9 is fully distributed, including in CPU time.
In a Plan 9 grid there are normally three types of systems:
•
A system called a terminal is what the end user would sit in front of and operate with a
keyboard and mouse.
•
A system called a CPU has one job: to process commands from terminals on the grid. A system
called file stores files, although the file server is a little more advanced than that.
Terminals don't necessarily need a local disk and it's not the best way to get Plan 9 up and running as well. Plan 9
terminals can be run right off the network with all their storage hosted on a file server. This is seamless to the end user
as Plan 9 makes all requests for any resources over the network to start with. Even if you're sitting at a local terminal
with a local disk, Plan 9 will not treat this any differently than if you were connected to a remote file and CPU server.
Plan 9 achieves this via a protocol called 9P, or more recently 9P2000. This protocol is what ties all of Plan 9
together. The 9P2000 protocol has one strange aspect that can take some time to get used to. There is no API. There is
no API for anyone; it's not hidden or reserved for special people at Bell Labs, there just is no API (you'll see why this
is the case later in this section).
