
Xinu Is Not Unix - colinprince
https://xinu.cs.purdue.edu/
======
austinl
I took the course at Purdue that built on Xinu (CS 354, Operating Systems) —
Xinu is really just used for teaching purposes. Doug Comer (the creator of
Xinu) was my favorite professor — it was inspiring to hear from someone who
was pretty close to the development of the Internet and TCP/IP in the 70s
([https://en.wikipedia.org/wiki/Douglas_Comer](https://en.wikipedia.org/wiki/Douglas_Comer)).

------
airocker
Took this epic course. Getting virtual memory to work on x86 is still one of
the most satisfying projects ever done! Thanks Dr Comer and everyone.

~~~
bionsystem
How does it compare to os161 as a teaching OS ? What I really like about it is
how fast it builds and runs and how comprehensive the course is with a decent
amount of assignments.

~~~
airocker
I never did CS161. They look similar from the course page.

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tuckerpo
Huh - my old RTOS professor from undergrad contributed a lot to Xinu and used
to shill it to us in class. Didn't think I'd ever see it again.

~~~
baylessj
Agreed, I was an EE at Purdue but still familiar with Xinu from CS clubs.
Didn't expect to see it on HN, but a fun throwback!

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DonHopkins
Not to be confused with the Berkeley software company "Mt Xinu". (The
operating system's name is a recursive acronym, while the company's name is a
backwards spelling.)

"We know UNIX TM backwards and forwards." -Mt Xinu

[https://en.wikipedia.org/wiki/MtXinu](https://en.wikipedia.org/wiki/MtXinu)

Famous for the great posters they handed out at Usenix:

"4.2 > V" BSD -vs- System V, X-Wing / Death Star Poster

[https://raw.githubusercontent.com/ashaferian/Drive/master/Mt...](https://raw.githubusercontent.com/ashaferian/Drive/master/Mt.Xinu%20BSD%20Poster.png)

[https://www.ericconrad.com/2008/12/](https://www.ericconrad.com/2008/12/)

I love all the old telephone equipment in the explosion!

------
Koshkin
Very little info on the website and Wikipedia about this OS.

~~~
airocker
You could find more in the book. The OS was done mostly for teaching purposes.
You could write the building blocks of the OS: virtual memory, context switch
etc in an easier environment than Linux/UNIX.

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dwheeler
I'm sorry, but I don't see why anyone should waste a moment with a proprietary
operating system with such limited use.

If you need a simple educational operating system with a book, Minux is
available and open source software.

If you need a fully capable operating system kernel, Linux is available and is
open source.

There are also many other open source software systems, including the *BSDs,
Zephyr, and so on.

It takes time to learn the details of an operating system. I read parts of
those books years ago, but I wouldn't waste any of my time with them today.
Better to learn details of something you can use, or at least something you
are legally allowed to change and share.

If it is open source software, and my comments don't apply, but then they
should make that much clearer on their front page.

~~~
felipelemos
$ tar xzvf Xinu-code-Galileo.tar.gz

$ cd Xinu-code-Galileo/

$ cat COPYRIGHT

<<<begin COPYRIGHT>>> Portions of this software are covered by the following
copyright:

    
    
            Copyright (c) 2012, 2015 Douglas E. Comer and CRC Press, Inc.
                            All rights reserved.
    

Redistribution and use in source and binary forms are permitted provided that
this notice is preserved and that due credit is given to the copyright
holders. The names of the copyright holders may not be used to endorse or
promote products derived from this software without specific prior written
permission. This software is provided `as is'' without express or implied
warranty. The author assumes no liability for damages incidental or
consequential, nor is the software warranted for correctness or suitability
for any purpose. Portions of this software are documented in the book:

    
    
            Operating System Design -- The Xinu Approach, CRC Press,
            Boca Raton, FL, Linksys version 2012, Second Edition 2015.
    

This software may not be sold or published in printed form without written
permission from the copyright holders. <<<<end COPYRIGHT>>>

~~~
dwheeler
The first part is a standard BSD license, however it has a weird extra
restriction. It cannot be sold or published in printed form. That is a
restriction on use that almost certainly makes it _not_ open source software.
It certainly isn't a common license. Game over.

But even if it was open source software, it's unreasonable for people to have
to untar that file on a phone. As I posted earlier, if it's OSS, that info
needs to be a lot clearer. It certainly needs to be on the front pagd.
Requiring a untar is absurd for such basic information.

As a piece of history, it's cool, though I think the Lyons book is more
important.

~~~
JdeBP
In years gone by, it was common practice to look inside archive files to
inspect README files and suchlike. Certainly, one is quite reasonably expected
to look inside an archive of a teaching operating system where reading and
understanding the source tree is part of the process. I think that you are
unwittingly making a strong case for your 'phone being the wrong tool for the
job. (-:

~~~
dwheeler
> In years gone by, it was common practice to look inside archive files to
> inspect README files and suchlike.

That's true, I did it many times. But those years are long ago. Good riddance.

Most of the time today, for most people, a smartphone is the _only_ tool you
have available at the moment. When I made that comment I was nowhere near my
laptops or desktops or tablet, and I think that's true for many people today.
According to Statcounter the _majority_ of pages viewed today are viewed using
a smartphone: [https://gs.statcounter.com/platform-market-share/desktop-
mob...](https://gs.statcounter.com/platform-market-share/desktop-mobile-
tablet)

> Certainly, one is quite reasonably expected to look inside an archive of a
> teaching operating system where reading and understanding the source tree is
> part of the process.

Not to find out the license. A license is important information that you need
to know _before_ you look at the archive.

I'm don't think it's even reasonable today to ask that people unarchive just
to look at some code. GitHub, GitLab, SourceForge, and many other forges/repo
sites make it quite easy to look at code without having to download and look
inside an archive. By all means provide a simple link to download its archive
(GitHub does this automatically), but it's also important to give people an
easy way to look at its individual source files using a URL. I'll note that
the Linux kernel does this just fine.

Things are hard enough on potential developers and potential users. Developers
should work to make it _easy_ for potential users and potential users. If
nothing else, their projects are more likely to do well that well.

